so far as i could tell from countless threads on this, most of the pro road-disk arguments collapsed to 'oh well you can't fight big bike whaddya gonna do, become a communist?'

i found the whole thing bizarre, and i theorize that really the deal is:

a) people want carbon wheels
b) they don't want tubulars
c) the don't want alloy brake tracks

given those constraints, i can see how we end up with road disc.

but the constraints are ridiculous. a hed jet style wheel with good pads seems to actually have the best demonstrable trade off in terms of all performance factors.

the only thing that gives me pause is intimations by trusted industry types like damon rinard that maybe you can make an overall more aero bike with disc. but ... i have not seen any actual evidence of this.

But, that all depends on what you're comparing to...e.g. in the Tour test, they claimed that the disc bike was actually slightly less drag than the rim brake bike...BUT, that's comparing to a rim brake setup that's completely "exposed", cables and all. That's a low bar to get over.

Even with the latest Madone disc/rim models, they made an odd design choice on the rim version (swap the front brakes to the back of the fork ) that prevented them from fully utilizing the UCI rule changes that allowed for an effectively deeper section downtube, something they DID implement on the disc version. If they'd left the brakes in their previous incarnation, the down tube on the rim version could've gotten deeper as well.

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You don't like disc brakes, we get it!
They won't stop making rim brakes anytime soon, so don't worry about it.

No, you don't get it.

Disc brakes are just fine...in their proper application. Road racing and TT/Tri bikes just aren't that application, and as this test demonstrates, the supposed "game changing" performance attributed to them for road racing purposes isn't "all that"...

Hell...and I ride a bike with disc brakes more than any other bike I own...




No...but the choices are already getting limited, especially if you're looking at high performance road bikes. As of now, any aerodynamic advances are basically only being used to make disc-braked bikes more "palatable", not to make lower drag bikes overall :-/

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i think that's a bit off, i'd say that designers are always trying to make the "best" bike they can, within the various constraints they are given. this includes UCI regs, handling, comfort, weight and now yes, for various reasons disc brakes seem to be on of the pre-decided aspects.

the madone has more or less remained the same, front of pack aero. the venge has gotten faster, as well as a vastly better all-round bike - specialized say its as fast as most TT bikes. the new cannondale is also seemingly as fast if not faster than anything we've seen before... in the age of "peak aero" we're still seeing improvements. with different design parameters we might see more aero improvements but thats not where we are.

the real issue, as you say, is whether or not disc brakes are actually an good design choice for road bikes. i'm somewhat dubious as to whether they actually improve braking significantly, i'm concerned by all this talk of issues. any braking surface can overheat if overused and i'm inclined to think discs will be better in that regard - at the very least your melted braking surface not being a structural part of the wheel has to be good if that happens. as a long-time user of hydro discs in mtb i struggle to see that disc or fluid issues could be significant, though long brake dragging descents are more common on the road.

it does seem like discs are coming, ready, wanted/needed or not... i'm just trying to decide when to make the leap

Stay tuned for the upsell option of NOT having disc brakes

I actually find most tour test underwhelming.. I still read them, but I dont know why some place uber value in some of their testing.

Yeah...I hear you. Then again, I think that might say something about the "quality" of other tests typically put out there in the cycling media...

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.. hopefully the test was not too late for the next S5 ..

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I’m glad someone has finally tested disc vs rim. I agree it was very much apples to oranges. They should have either used cable actuated disc brakes or used a hydraulic rim brake like the Magura RT8.

I also find the Madone design choice as odd. I can’t wait until the last generation is available at a reasonable price.

I don't have a problem with cable vs hydro on the rim setup. Heck, the cable setup on my 30 year old Bianchi using Shimano "aero" brake levers on first gen DA dual pivots is the "lightest" lever feel of ANY of my brake setups, including hydro. In other words, done correctly, cable shouldn't be an issue.

At least they used aluminum braking surfaces. It would be interesting though to see results with just KoolStop Salmon pads or SwissStop BXPs pads in place. If you're going to test wet braking, then it makes sense to use wet condition pads, no?


Yeah...why couldn't they do the right-angle actuation they implemented with the brakes still on the front?

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I worked in the industry for 7 years. I ride a disc brake bike a good 10 hours a week, and when I was looking at road bikes this last year I wanted a rim brake bike. For mixed terrain, I would 100% of the time recommend disc brakes.

While the industry is trending towards discs, I just see bigger headaches. My CX and MTB have been in the shop a combined 4 times for disc related problems in the last 18 months. All of them different issues. The road bike? Nothing.

I also worry about traveling. With a cable rim brake bike, if there are any issues I can fix them with very basic tools. With a disc road bike? It gets complicated if I need to bleed the brakes or do anything to the system. I do not travel with a bleed kit and it may require leaving it at a shop for a few days.

The market has spoken, discs are here to stay. As a shop manager, we are having our best year yet with the primary driver being high end road bike sales with discs. Since Jan 2017, we’ve only sold 1 road bike over 3k with rim brakes. We’re in central Delaware so discs aren’t really needed around here.

Overall, discs are less maintenance, and maintain optimum performance over time vs rim brake for the average rider. Let’s see the tour test redone with bikes that have 500,1000, and 2000 miles on the braking system without service.

I guess that's sort of interesting. I struggle with this fact though: bikes are not like cars, whose braking distance on dry ground is often limited by brake power. The braking limit on a bicycle is determined by how much front brake you can grab before endo'ing. (At the limit of braking the rear tire is unweighted so the rear brake plays no role.) Since it's super easy to grab enough front brake to endo on rim brakes, especially on a 10% slope, in theory the two should be the same. The 2-3%, then, can only be the result of better modulation/control. So, I guess the argument is that the disc brakes had slightly better modulation? That seems plausible I guess.

For me it always seemed like the advantage of disc brakes was in the wet. In the dry there really is no advantage.

There's literally no reason. Heck, it would have been a touch easier to service too. IMO, it was done to purposely make the rim brake version slower. No tin foil hat here either. Trek has amazing development resources at their disposal. I remember Carl saying that, towards the end of his tenure, their in-house CFD had gotten to the point where it was basically 1:1 with what they saw in the tunnel and that they were virtually never surprised. There's no excuse to design a bike that's actually slower then the prior generation (which is basically what they did with the rim brake version).

I'm shocked how anyone can be surprised by these results? A simple Shimano 105 rim brake (even operated by females with small hands) is able to actually lock your wheel in place without the use of excessive force on the lever (not that this would be the fastest way to come to a stop but we're talking power of the brake here). So if thats a given then how could any different braking system actually pose a huge improvement in terms of pure braking power.

The advantage of disc braking is that you don't need carbon wheel mfg to come up with a good carbon braking surface and pad combo. So we get a bit more fool proof in that area. Also hydraulic brakes (rim or discs) have other advantages like improved braking modulation and how they help when braking gets mushy with very tight cable housing radii on cable brakes with certain framesets. Neither of these advantages can be measured by a simple braking power test, nor are they relevant for the majority of people.

If I get it, you are saying discs are better because shops like yours make more money? I have always thought that is the only reason, but you are here to prove it.

Regarding maintenance in the dry weather of Madrid, my 2012 Scott foil has had zero maintenance. In the same space my 930 spark, with orders of magnitude less usage, has required a couple of bleeds an 3 pad changes.

To what service are you referring?

I have ridden 10s of thousands of miles with rim brakes without having to ever touch them. During that time, I have never perceived any changes in braking performance. When the brake pads finally wear to the point of requiring replacement, it's a 10 min job, tops.

You do need to keep an eye on rim brake pads as they wear to keep them on the brake track and not dropping into the tyre or spokes. Carbon setups wear quickly and pads are expensive compared to disc setups.
No reason why a Scott 930 would need 3 bleeds, somebody is having you.
Your 930 is operating in far harsher conditions than a road setup so not really indicative.
I can easily get my MTB discs turn multicoloured if I ride it down a big steep bitumen road near me, those advocating 140mm discs for a road bike need to consider the higher speeds involved on road. I also see 160mm rotors coloured on road bikes.
Teams bleeding tour bikes between stages have not bled them properly the first time, a common problem of roady mechanics not having a clue with well established MTB tech.

The big bonus for hydro disc is great feel, ease of tortuous cable runs, cheap carbon deep dish wheels, low cost brake pads, auto adjustment, wet weather etc.
For tri, the only real advantage is cheap wheels and easier aero cabling.

Although that can happen on MTBs, 'cross bikes, or tandems with, e.g., V-brakes, with properly set-up road bike calipers you will be scraping the brake pad holders on the brake track first.

Add a little water to the test and rerun it and the results will be much different, even with high end brake pads and aluminum rims.

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"...the street finds its own uses for things"

Rim brake pads can also get stuff embedded in them that chews up carbon brake tracks. Ask me how I know lol. Plus brake tracks just wear down over time.
I’m getting a System Six (hopefully) soon. I ride mixed terrain and fast descents a lot. I think disc brakes modulate much better, and you can brake later before entering a corner. I’m the rain it’s no contest.
That said I don’t think they’re needed on a TT bike or if you live somewhere pancake flat.

Pretty common to find brake pads rubbing tyre when servicing.
Dual pivot brakes have one side swinging in a tight upward arc and this is what causes the problems.

Here we go with the N=1 arguement where to prove a point, you leave out important details on how to get optimum performance from rim brakes for 10’s of thousands of miles. You know, things like:

- replacing cables
-lubing cables
- replacing cable housing
- increasing cable tension as the pads wear
- replacing pads
- handlebars get turned too sharp and now the brake block

Disc brakes? Periodic re-bleeds, and pad swaps that are quicker and easier than rim brake swaps.

Discs take more time to set up initially but for the most part they are set it and forget it. Rim brakes? Not so much.

How many threads do we have on Slowtwitch about crappy brakes on Tri bikes?

I was a fairly early adopter of discs. I am 100kg and ride lots of big climbs. I do my own maintenance.
Every one of my friends who rode carbon wheels with rim brakes melted their rims at least once. Envy's, Reynolds, and Eastons. The riders range in size from 100 pounds to me.

Disc won't brake much better (if at all) than rim brakes on dry conditions with an alloy brake track.
They ARE more maintenance than a rim brake. It's not even close.
They aren't cheaper. I go through pads a lot more than a rim brake ever did. Factor in melting a set of carbon wheels and it may be different.
My tt bike has carbon wheels with rim brakes. The braking can best be described as mediocre.
My road bike was no heavier than the previous year's rim brake version.

That being said, I've never cooked a set of carbon rims with them. I would take them over any carbon wheels with rim brakes.

We can drop the hyperbole in these types of discussions and quit with the confirmation bias, or we can keep things entertaining.

As has already been alluded to, I like to ride carbon rims in the wet and not fear for my life on fast technical descents - of which there are plenty in the UK.

After racing in Cornwall last year in the pouring rain, I lost a load of time riding carbon rims with Yellow pads every time we hit a fast technical descent. Ergo, I'm holding out for affordable TT bikes with disc brakes.

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29 years and counting

When the debate rages about whether discs or rim brakes are more aero on a road bike, I recall this Win Tunnel episode where, once you put a slab of meat on top, a 2015 vintage Venge tested only 1.25 seconds a kilometer faster than a 90's vintage stick steel framed road bike with downtube shifters and enough exposed cables to wire a small starter home. I'm guessing that once you put a rider on, the differences between a new Madone Disc, a new Modone rim-brake, and old Madone rim-brake would be hard to distinguish from the background noise.

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"They're made of latex, not nitroglycerin"

a) people want carbon wheels
b) they don't want tubulars
c) the don't want alloy brake tracks

given those constraints, i can see how we end up with road disc.

THIS!

Not that I agree with this at all - In 30+ years of road riding in my area (this point key), I've never seen the need for anything braking beyond well adjusted Dura Ace brakes with good pads - even carbon rims!

BUT, the only time I see a need is long winding, fast alpine descents where heavy braking and rim heat build-up would be an issue with carbon clincher rims. Again, that's not my everyday riding terrain. So I don't see the need. If I was to take a trip to the Alps, or a similar area, with that type of mountainous terrain, I would look into renting a road bike with disc brakes.

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Steve Fleck @stevefleck | Blog

I thought there were legit issues of carbon rim brake wheels overheating on descents. Hence, disc brakes.

Rec riders not doing a big mountainous fondo wouldn't matter as much.

Maybe for messy riding like gravel in the rain or CX it is still a "thing".

I can't see a joe club rider who does 50mi a week on paved roads with less than 5000ft climbing ever needing discs.

Well sure...over the last 4-5 years the drumbeat has been strong. Marketing works.

That said, how many of those over $3k bikes were bikes intended for pure road racing and/or TT/Triathlon? I'll be surprised if the vast majority of those you mention weren't intended for more "all-around" usage, such as fondo, light gravel, etc. Is that true?


Based on my experiences, I beg to differ. Of all of the braking systems in my garage, the ones I have to fiddle with the least are the 1st gen dual pivot Dura Ace brakes on my old Bianchi, and the SRAM Hydro R rim brakes on my Stinner. I installed the Hydro Rs on that Stinner over 2 years ago and bled them once during the install. In the ~12-13K miles I've put on the Stinner since then, the only "service" has been periodic pad replacements and minor adjustments of pad spacing (simple knob turn) while riding every every month or so.

My disc brake systems on the other hand...constant cleaning and fiddling to keep them from making noise, and pad replacements at much quicker intervals (mileage-wise).

But, I have a feeling that the "average rider" isn't going to be self-servicing their disc brake systems...and I also have a feeling that a shop manager likes that idea :-)

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They did, and noted an ~1s difference in "actuation time". Of course, as noted above, that was with pads known to not be the best available for wet conditions, nor with a more advanced rim surface treatment (i.e. just bare aluminum).

Don't fall for the fallacy of comparing to braking on wet carbon. That's just silly.

BTW, all of these advantages of hydraulic actuation aren't exclusive to disc implementations. You can get the same properties with a hydro rim application.

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Maybe I'm misunderstanding you. Why aren't we allowed to compare to braking on wet carbon? Seems like a reasonable comparison to me.

Hmmm...are you sure that's a rim vs. disc thing? I'm only asking because of all those things you list above, my hydro rim brakes don't require or suffer from any of those besides the pad replacing part.


Pad swaps that are "quicker and easier"?...yeah, right. Just make sure you don't accidentally touch the pads or rotor :-/ Oh yeah, hydro rim brakes don't even require bleeding as often (since fluid temps are significantly lower in operation).



Depends on the rim brake. See hydro rim example above.



Those are typically implementation issues, not technology issues.

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Because using an organic material as a braking surface isn't the best idea, especially in the wet. People discovered that early in the last century when aluminum rim extrusions quickly replaced wooden rims, mostly due to the vastly improved wet performance.

And if we're talking about deep-section clincher rims, considering that it's possible to get equivalent aerodynamics with wheels with metal braking surfaces as with all-carbon rims, and within 10s of grams of their mass, then it's pretty easy to see that an all-carbon rim construction is really a mis-optimization for a bicycle wheel.

If there's one thing I agree with road disc proponents on, it's that braking surfaces should be metallic. "Friends don't let friends brake on carbon" ;-)

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I find this debate fascinating. MANY decades after the motorcycling community has accepted that bigger brakes are better, the bicycling community is still wringing its hands over it. Even the smallest, simplest, cheapest single-rotor brake setup on any motorcycle can lock up the front wheel or endo the bike (depending on weight distribution). So why, then, would you want large Brembo dual-rotor brakes on a motorcycle? They just add weight and cost. Well, they also add vastly better modulation, better wet weather performance, and vastly reduced fading on long and/or multiple stops. Of course, a cheap single-rotor front brake on a motorcycle will come very close to a high-end Brembo setup on the first stop in a maximum stopping test. That's perhaps the least relevant test I can possibly think of. Throw in 10 consecutive stops back-to-back and it's a different story.

I can grab a handful of brakes on my Cervelo P4 and lock up the wheels. No problem. I dare ANYONE here to say that the P4 has good, or even decent brakes. I live in a pretty hilly area, and almost all the good riding routes have a good amount of climbing/descending. Coming down a 6 mile descent on a P4, even with good pads and aluminum brake tracks, is nothing short of pucker-inducing. The same ride on my Cervelo C5 is glorious. On my old Trek 5200 I would go through rims every few years, as the rims would heat up, start flaking off bits of metal into the brake pads which would then start to squeal something awful as they ate the (aluminum) rims. I've yet to heat up the discs on my C5 to the point that they've faded or made any noise at all, no matter how long the descent or how many repeated braking efforts I've thrown at it.

If the only time you ride your tri bike is on race day or flat ground, then I'd agree that you don't need discs. If you want to actually train year-round outdoors on your tri bike, then I just can't understand why we're having this debate.

Well, there are different type of "people" for sure. Like those fat ass mamils who think of themselves as real bike and race "experts". Who top at 20 mph on their bikes ... for any distance :) These people are the main target of bike industry with all this road disc brake bollocks, wide (28 or whatever) tyre hype, road tubless and road single chainring stupidity etc. These people desperatly want all this stuff, they all want to have 3T Strada bike :)

Then there are people who actually race the road bikes, pro, amateur, masters, whatever level, usually they've done it starting from the childhood (and yes, a lot of them can also be fat ass mamils too, but in a positive way :). These people use road tubulars and simply want fast, light, aero bikes and don't like to spend money for things that dosen't have a real effect on racing results or even are counterproductive (those unlucky Aqua Blue team lads with their horrendous 3T Strada bikes. Really sorry for them).

Hed Toroidal 2.0 designs like the Cannondale Knot 64 wheels are made viable by disc brakes.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Other than Pro tour teams, I don't see a lot of road racers using tubulars. Where are you seeing this out of curiosity?

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Of course you don't see them a lot because there aren't a lot of road racers in the world. But if you are lucky enough to spot a road racer of any age or body composition, he has tubulars. Always.

Ha, this is funny. I was wondering if you were trolling, now it's confirmed.

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Oh don't you know, you're a MAMIL Fred if you don't ride tubulars, despite the generally inferior rolling resistance and aerodynamics.

Tubulars for (1) CX, (2) track, (3) hill climb bikes, and (4) pro road racing where you need to ride a flat before you can reach a support vehicle. No pink.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

What makes the P4 so pucker inducing? How much of it is due to being a tri bike and having more weight on the front wheel, resulting in making it easier to endo no matter the braking system. Apples to apples, a P4 will not be able to brake as hard as the C5, even if it had disk brakes. I mean the P4 front brake is fine, so it is going to behave just like any other rim brake bike on the descent.

Is there a reason why a rim brake couldn't be designed that would work with that rim width?

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It's not the width, it's the shape. Not needing a brake track means rim designers no longer need to include a flat surface in their rim design.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

Not really you normally don’t only brake with the front brake. That’s the only useful brake on the bike. So braking feels completely different than with two working brakes.

Note that I specified "properly set up."

In my hands, this mean:

1) brake pads perfectly aligned with the brake track, and

2) only a few millimeters clearance.

Since the brake arms move minimally during braking, pad wear has little impact on things.

(And for anyone who brings up cable stretch: that also doesn't happen if you set things up correctly to begin with, i.e., if you pre-stretch the cables the way I have always done, including on the Schwinn Varsities that I used to assemble for piece-rate back in high school.)

You're right about the forward weight distribution of a tri bike, so a comparison to the C5 is not fair. However, even compared to my old aluminum P3 (very similar geometry and nearly identical position on the bike) with Ultegra dual-pivot brakes front and rear, the P4 performs far worse on long downhill braking. The main culprit is the horrible rear brake. It takes so much lever force to get any sort of braking out of it that you can forget about any sort of modulation of the rear brake. Normally, the rear brake might contribute 20-30% of the total stopping power downhill but not being able to effectively modulate the rear brake means that locking up the rear wheel becomes a real concern so I'm lucky if I'm getting 10% of my braking from the rear brake. That puts a tremendous load on the front brake. For this reason, I run a Tririg Omega X during race season but switch out to a Dura-Ace dual-pivot on the front for most of the year.

That "shape" at the brake track isn't any different than the "shape" of most aero rims currently. Heck, even my old Zipp 101 aluminum rims had a curved/angled brake track.

Rim designers long ago realized brake tracks didn't need to be flat and parallel on aero rims, even with rim braking.

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To be fair, the rear braking of a stock P4 is so bad that I usually quip that the rear brake is there just for regulatory conformance. The front brake (my P4 came stock with a 2011 SRAM Red caliper) is perfectly adequate. I'm not familiar with el gato's descending skills, but I'm man enough to admit that mine suck (usually first up the hill and down last), and descents on my P4 are not my favourite passtime.

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Citizen of the world, former drunkard. Resident Traumatic Brain Injury advocate.

Comparing the braking needs of a 400-800lb motorcycle that has a 50,000-150,000 watt motor to a 20lb bicycle with a +/- 300 watt "motor" is kinda ridiculous. Kinetic energy increases with the square of speed. Motorcycles can go much faster than bicycles, and can power themselves to high speeds even on flats or up hills. Even a moderately powered motorcycle can tango with 130 mph, while 1-Liter Super Sports are capable of 180+.

A sport bike's brakes a built to withstand the repeated heavy braking one might encounter on a race track. A mid-level cafe racer (something like a Ninja 650) would need to convert something in the range of 2000 kilojoules of kinetic energy to heat every two minutes lapping Laguna Seca. Even with a clydesdale rider up top, a 20 lb bicycle braking from 50 to 10 mph for a hairpin is a ~25kj event. Without 50-150 kilowatts of power to re-accelerate, a bicycle isn't going to get to the next extreme braking event nearly as soon as a motorcycle, giving the brake rotors more time to cool. How many times in two minutes are you likely to go from 50-10 mph, even in the most technical descent? Three times, maybe?

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"They're made of latex, not nitroglycerin"

Here's just one example of the type of descent I have around me. This is nearly 7 miles of hairpins, mostly 6-10% grade. There's actually a LOT of accelerating/decelerating on that descent, and it's by no means the longest one around here. The climb from San Jose to the the Lick Observatory on Mt. Hamilton is 19 miles of hairpins. Being able to modulate the brakes effectively going into corners and not have your brakes fade on you is just as critical on a bike as on a motorcycle.

Since most of my outdoor riding involves this sort of climbing/descending to some degree, I do most of my offseason riding on the C5, but as i get into the final 12 weeks before my A race and I'm on the tri bike exclusively, I end up severely limited on the routes I can ride if I have to stick to flatter ground.

Right and your unique circumstances represent probably less than 1% of the riding population.

Once I realized I do 90% of my rides indoors, almost never (intentionally) bike in rain, and don’t live in an area like you described I found myself wondering why I would need disc brakes even assuming for the sake of argument they offer better performance. My circumstances are probably far more common than yours.

Good braking isn't just for technical descending.

let me give you another real-world example. You're cruising along a dead-flat suburban area and a car pulls out of a driveway in front of you or a driver makes a left turn in front of you. With good brakes that I can modulate well, I can make a solid panic stop competently. On the P4 it's probably 50/50 that I'll lock up the brakes and eat shit and end up under the car. That's a real situation that 100% of riders face. The few times that I almost died on my motorcycle were all from people making left turns in front of me.

Agreed. That is more like what I may face. Brakes don’t matter until they do. I weighed all of that and I’m confident in the braking performance I will get from Omega X with kool stop salmon pads and HED Blacks.

I found the best wheel for either Diablo or Hamilton is c24. Light, stiff, smooth and rim brake.

The Salmons might be slightly soft for the Blacks (and turn the brake track orange)...I mostly run just plain Kool Stop black pads with my Blacks. Work VERY well.

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Thanks for the tip!

You mean this segment? https://www.strava.com/...analysis/12688/13398

Doesn't really look that taxing on brakes, honestly. One ~45-30 decel, and another 40-25, with a handful of 10mph scrub-offs over ~7 miles/12 minutes. I can't imagine a bicycle with a pair of 160mm rotors (or even 160F/140R) and the right pads couldn't do that kind of work all day, every day, without overheating.

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"They're made of latex, not nitroglycerin"

Whoever that is has way bigger cajones than me through some of those turns.

Quite. Two weeks into my new job back to cycle commuting, I had my first collision in many years - guy turned right across the oncoming traffic (UK) didn't see me in the cycle lane. Fortunately I managed to scrub off a bit of speed with my discs and steered into his direction of travel to avoid a 90 deg impact. Hopefully his passenger door needed an expensive repair. Apart from a my finger I got away quite lightly.

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29 years and counting

I guess the point is, if you have the best brakes in the world, you can still ride on a trainer and not use them. But if you do find yourself riding in the hills in the rain, you'd be covered there too.

How often will that situation arise? I don't know, but it's nice to have your bases covered. I take a spare tube, money, my phone, a mini pump and a co2 canister even for short road rides. How often do I need them? almost never, it doesn't mean they aren't nice to have if I puncture or get stuck a fair distance from home though.

Agreed. I said above that Brakes don’t matter until they do. For me, I just realized that necessary hard braking occurs in far less than .01% of my rides (hasn’t happened once this entire year). With good brakes and good braking wheels (ie not carbon) I will get very close if not equal stopping power in the event it does ever matter and save hundreds on costs. I can certainly understand others who swing the other way as I was very close to a disc purchase recently but ultimately decided the cons outweighed the pros.

Threads like these always remind me of Brexit & Trump discussions on social media. I want to just post...

Look you lost, discs are coming, accept it and stop whining.

;-)

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29 years and counting

Ummm...yeah...with those 2 examples, sounds like an apt analogy :-/

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but like brexit, discs breaks cost people money lol ( i wanted to just post ...),
but i feel like iam wining as i will get a cheap non disc break disc soon lol

It wasn't an analogy though was it Tom; I just wanted to post that paraphrased response. Lighten up.

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29 years and counting

I think Julian Alaphilippe would disagree with “ you can’t get down a mountain pass with any speed on a rim brake bike with that have carbon brake track wheels “

whereas i believe sagan was on discs when he crashed so case closed ;)


oh, but then yates was on rim brakes... oh no, what to do!

i do believe discs brake better, whatever this test says... i'm just not sure that in the (dry) road context it makes enough of a real difference to justify the downsides (including new bike and wheels cost). everyone i've spoken to who has them loves them but how many people don't gush about their latest bike upgrade, whatever it might be?

This might not be the best place to ask, but what is the current thinking on buying cheap chinese carbon clinchers with disc brakes?
In the past people were worried about rim blow outs and poor braking, that 'shouldn't' be an issue with discs, are they now a better proposition?

Needing discs for riding in the rain is my justification for getting an additional road bike. Unfortunately my cross bike has cantis, and in the wet it is easily the worst braking bike i have so that isn't an option. My rim brake tarmac is unpredictable braking in the wet on descents, and on the days i get stuck in the rain i will change my route to avoid steep descents where i either have to turn or stop. I'm hoping discs and 28s will be much better on those wet, hilly rides.

Sounds like your brakes aren't set up correctly. (Cantilever brakes are common on tandems for very good reason.)

Canti brakes on cross bikes were (are?) traditionally set up to maximize pad travel for mud clearance as opposed to stopping power. Definitely isn't common knowledge that you can go the other way with 'em. But you do pretty much have to pick one or the other.

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If only there was a type of brake that allowed for both large pad clearance AND high leverage (AKA "stopping power") once the pads came close to the braking surface <cough...cam actuated center-pull...cough> ;-)

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The constraints that they are given is that they need to feed their family (even if that is just themselves). These constraints may (and sometimes do) diverge from what a performance data driven focus would be.

Stephen J

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I believe my local reality has been violated.
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Happiness = Results / (Expectations)^2

The Shimano brakes use servo wave.
This does bring the pads in quick and then increase leverage once contact is made.
It is also incorporated into all of their traditional brakes.
SRAM brakes use taperbore to achieve a similar effect on their hydraulic systems.

There is simply no problem with a properly setup disc system with disc rub.

The only problems here are people being scared of a technology they don't understand and haven't yet figured out how to fix themselves.

When you have to always compare an entry level abused non serviced system to the best in class well maintained system, you have obviously lost the debate.

I like discs and it is because there are several places where a disc system is simply better for the riding I do as well as ease of build when putting together new bikes.
If there are 2 bikes to build and one is electronic/hydro disc, I will pick the electronic/hydro disc everytime, they are just easier.

For me the ride comfort of a full carbon rim over any alloy combination is a major decider.
It is just better.
Same reason I use latex tubes, they are just better.
And wanting latex tubes is very similar to wanting discs, there are particular things you need to know to successfully run latex but if you understand them they outperform conventional tubes in almost every way.
3/4 of the world cannot seem to manage latex tubes and no doubt there will be a shitload of people who will never manage discs, but that is not a problem with the technology, just the user who thinks that their bicycle is a car that they can jump in and abuse for 50000km and then get a service and all will be peachy.

Having said that, if I were to build a tri bike tomorrow to race on, I would pick any old frame that fit me, get some cheap second hand tubs that nobody wants anymore and race on a shoestring.
Realistically any tri bike is a race bike only, they are just not good training bikes, so all of the cheap yesteryear tech is just fine and cheap as chips with very little loss of speed over the latest and greatest.
But for a roadbike to train and race on putting in a lot of KM's, give me a disc bike any day over a conventionally braked bike..

Clarification: there's no problem once you adjust the calipers to fit a particular wheel/rotor combo. But, swap out the wheels/rotors and there's a good chance you'll have to adjust the calipers or you'll get disc rub. Not a problem with rim brakes.

Not really, until a few years ago I rode exclusively on a far forward tri bike. So over 25 years without even owning a road bike.
But traffic nowadays and living in more hills makes riding a tri bike simply dangerous.
Several training rides around here have simply banned people from turning up on tri bikes because of descending on some popular rides.
A road bike is just a better choice for regular riding.

Haven't found a single road bike that cannot swap wheels with the latest groups.
Through axles are very consistent and it is easy to set up wheels to a set distance if you are worried.
But the latest groups have plenty of pad clearance for wheel swaps.
Not only that, but todays wildly varying wheel widths leave many conventional brakes set up for narrow rims not even able to take a wheel with the quick release fully open and a lot that have no brakes even when you screw the adjuster out to the end of it's travel when you put a skinny rim in.
Even if there is disc rub, it will not slow you down, it is just an annoyance.

Just one data point - I did a little test (that I've never done before)...

-One bike, stock fork, stock 12mm front thru axle
-Two sets of wheels from the same manufacturer with the same model/year of hub
-One pair of Shimano Centerlock rotors used on both sets of wheels

I built the bike up with one set of wheels. Everything was fastidiously adjusted, including spending a LOT of time getting the rotors as straight as possible. I set up the pad clearance as generously as possible (i.e. requiring a lot of lever travel, to maximize pad clearance in the caliper). All was well. It rode like a bike.

I move the rotors over to the other set of wheels. Put the wheels in the bike. Rear is fine. Front... 'ting, ting, ting' (making noise). I triple checked with both setups that the front wheel was 100% square before snugging down the thru axle. Even with trying to control every variable, the rotor location within the caliper was off just a tiny bit, exaggerating any remaining imperfection in the rotor. I had to laugh.

End of the day, I was able to adjust / fix it. Not a massive deal. But it definitely took more time than swapping wheels on a rim brake bike... and for those that aren't mechanically inclined, they'll just have to live with the noise. No more last-minute wheel changes before the race.

I had a thought yesterday... It sounds like disc brake bikes are helping to boost new bike sales for retailers. But I'm wondering if they'll hurt aftermarket wheel sales because of the increased difficulty of swapping wheels. 5, 10, 15 years ago, it seemed like the industry and consumers had really taken to the idea of a "quiver" of wheels. With one bike, you can tailor the performance characteristics by swapping out different rim depths. I don't see nearly as much of that with disc brakes. People either seem to ride one set of "race" wheels all the time (i.e. for training too), or they have one set of training and one set of racing wheels. But I don't think I know anyone with a "quiver" of disc brake race wheels outside of a small handful of pros.

Yep...just one of the things you have to consider with disc brakes and multiple wheel sets. If you want to be able to swap them, then your going to have to "tune" the disc mount of at least one of the wheels.

And, it's not necessarily the result of component manufactures not being able to hit reasonable dimensional tolerances on these components. It's really just a result of the tight pad to rotor clearances that are required with these systems and the tolerance stackups of the pieces in the system. The high pad forces necessitated by using a small diameter steel surface for braking means that the systems are going to have a high force multiplication from the lever to pad, and thus a naturally large travel ratio. Small travel at the pad for a given lever travel (high force multiplication) means the pads can't be very far from the braking surface to start with.

Also, the fact that the vehicles they are being mounted on have fractional horsepower "engines"means that the common practice in motor vehicles of allowing the pads to touch the rotors at all times isn't an option.

Of course, if you make the braking "disc" dramatically larger in diameter...let's say, oh, somewhere around 622mm?...that allows for lower pad forces and thus larger allowable pad clearance. One could probably get away with an aluminum surface and elastomer pads as well ;-)

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...zing! ;)

I have two identical wheelsets for my cross bike, same brand/model, identical build, bought at the same time, and mounted with identical rotors. I keep different tires mounted on each. I have to adjust the disc calipers every time I swap them. It doesn't take long, but it still sucks.

Determine which of the front wheels and rear wheels have the disc furthest inboard (towards bike centerline). Shim it to match the other front and rear wheel. Pre-cut shims are available.

A one-time adjustment is better than having to do one each time ;-)

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The ting ting will not slow you down, the same argument for high pad forces also means that minor tapping of a rotor means zilch.
So in a race situation, it just doesn't matter.

For a wheel swap at home, you may very well have to move the cable clamp as well as line up pads or even change pads when changing good ol standard braked wheels.
A disc brake may require you to loosen two bolts and tighten them up again to align the rotor.
Same difference, but different.

A standard rim brake setup pretty much requires pad alignment every time you swap wheel models unless you have chosen compatible wheels with the intention of swapping them.
2 bolts and probably a turn on the barrel adjuster.

Disc brake, align the caliper if required but may also need to take notice of disc diameter, something that is often overlooked.

Ting ting ting, is a bent rotor, that is maintenance, not a system problem.
Rub rub rub is a buckled wheel, that is maintenance, not a system problem.
Same but different.

Standard brake problems are looked over simply because people are used to them.
Disc brake problems are highlighted, simply because people are not used to them.

That's a bunch of BS. Yes, rim brakes sometimes need adjustment, but it is just not the same. If you swap identical wheels into a rim brake setup it never needs adjustment. If a rim brake does get misaligned, they are so easy to adjust that you can literally adjust them on the fly mid-race if need be. Any idiot can do it. Many people would have to take their bike to the shop to get the discs adjusted. It's just a feature of the disc brake design, which has much higher pad forces and much tighter tolerances.

The only adjustment you have on the fly is to open the calipers.
Slightly buckled wheel, out of dish, all of a sudden you have no lever left.

Any disc wheel that is majorly out of spec for disc position has a bent rotor or worn out bearings.
Again, maintenance.
Most TT brakes are next to useless. Luckily they are not required to do much generally in race.
In a workshop situation, more bikes come in for a regular brake fix than a disc brake fix.
A large majority of athletes cannot manage swapping in race wheels on an under BB rear brake.
Many times you have to remove the crank just to adjust the brakes.
Brake rub is still major problem with stiff wheels on conventional braked frames and a small amount of bearing play makes them many unable to prevent rub and keep any lever.
Disc brakes will never tear open the side of a tyre.

The single biggest downside of disc brakes is that numpties will have nothing to blame but themselves when their latex tubed tyre blows off the rim through poor installation :)

Haha. Great post.
Bikes aren’t rocket science. Maintenance is easy on most everything with the exception of suspension forks (especially Lefty’s).
I’m looking forward to the arrival of my system six.

I've done this before with 6-bolt rotors. The bike I'm dealing with has Centerlock (which are a lot easier to install/remove... but you can't adjust them laterally).

There's more than that. In the case of standard calipers in the standard location (i.e. not down by the bb), you can fully open the cam, or do small adjustments with the barrel adjuster. Or pull the brake slightly to one side in the case of an off-center brake. Of course, with a hidden TT rim brake, you typically get none of these.


I think this discussion is going down the path that I see happen in many of these threads - oversimplification of a complicated topic. TT brakes are being lumped in with standard caliper brakes (and yes, you do need to use your brakes in a triathlon or TT - there are many courses with significant descents and turns). It's pretty rare that I see brake rub on a rim brake wheel. When I do, it's often coupled with a funky combination of level/caliper, or poor brake adjustment, or a strong/heavy rider on a wheel without enough spokes. More road bikes come in for rim brake service because, at least as of now, most road bikes, hybrids, and low-end bikes still have rim brakes. I suspect this will change as discs take more marketshare and hit lower price points and OEM spec. If you go to a mountain-bike-heavy shop, you'll see a lot of disc brake work going on.

I guess I get confused when I see pushback on what I consider to be a simple fact that disc brakes require more work than rim brakes. That doesn't mean they're garbage. That doesn't mean that they don't have advantages for certain situations. But I've worked on a ton of bikes (and worked for a large manufacturer of rim and disc brakes), and it is absolutely clear that discs are more complicated for the average cycling consumer (the exception to this being some of the REALLY difficult hidden TT rim brakes... which should all die a quick death in favor of direct-mount Shimano brakes). It doesn't get any easier than a nice set of standard road caliper brakes or V-brakes. They don't require ZERO maintenance, but the maintenance that they do need is incredibly easy.

Group hug!

So here's a question I'm curious about. Triathlon is pretty open to new tech and less restricted by tradition, rules or compatibility like road racing.

How about we (and by we I mean someone who isn't me) properly develop single sided forks and chainstays? Then make the hub part of a stub axle. Then include the brake in the stub axle. Basically, set it up like a car. (For the rear, the cassette and freewheel etc are all on the hub.)

That way, for a wheel change, you're not disturbing the brake at all.
Further, for a tyre change, you don't even need to remove the wheel in the first place.

Before someone says "spokes" - let's then restrict ourselves to fully formed (eg 3-spoked or disc) wheels. Then the brake rotor assembly can be hidden inside the wheel. No additional drag. win win.

I thought there are centerlock shims?

Like this: https://novemberbicycles.com/...rotor-shim-pack-of-4

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One sided...like on a Cannondale Lefty fork?

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Exactly. Though I was more thinking Lotus bike.

Are you aware that removing the wheel on a Lefty fork requires the loosening of both caliper mounting bolts and the removal of one so it can swing out of the way?

I didn't realize that fact until I was riding a bike with a Lefty at Interbike one year and it had a front tire that was going flat. I went back to the bike's vendor tent figuring they'd just give me another bike. Unfortunately they didnt have the same size avaliable right then, so i said "no big deal, just swap the wheel of of one of the others and I'll head back out. The looked at me like i was crazy and I was trying to figure out why the mechanic was trying everything besides simply swapping wheels to fix the leak...until he finally broke down and started on the wheel swap. It took awhIle before I was on my way again :-/

Oh yeah, being a track bike, I don't think that Lotus was designed with an eye towards brakes ;-)

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Like this? https://vonrafael.com/rafael-r-023-2/


Keep in mind this bike uses drum brakes which have the potential to really suck. A single sided frame does open up some interesting possibilities though. I could see a lefty (er... righty) helping airflow at the front of a bike. A lefty fork and frame also open up some interesting manufacturing possibilities such as filament winding.

Have you seen Cannondale's new "Lefty Ocho"? It seems to have addressed the major issues with caliper and wheel removal. Personally I think a "lefty" aero bike is a concept worth pursuing. I could see how you could manufacture the fork via filament winding and one could even manufacture the frame in a similar fashion. For the frame, you would make a "mandrel" out of stamped steel which would be one piece consisting of the head tube, down tube, and chainstay. A machine would then wrap this mandrel in carbon fiber. The top tube and seat tube could be manufactured similarly and then you could join the two pieces.

Looks like they "sorta" addressed it. Wheel removal STILL requires the caliper being loosened/removed...they just made it a single-bolt process.

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I mean, that's just incompetence on the mechanic's part. I rode an old Lefty-equipped bike for a few years, and being the proud owner of a Fiat Punto it necessitated frequent wheel removal... Let's just say I started stocking 5mm hex keys in every corner of the car, but it's really not that difficult. Thanks to old-school IS tabs, you really just need to loosen the two slightly and rotate the caliper out of the way - keeps the alignment safe, even.

Same as when people moan about rearwards facing dropouts on triathlon bikes. Sure, it's a little bit less convenient - but if you have the technique right you can remove them quickly, without damaging anything nor touching the chain. It just requires.. mechanical-mindedness?

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ZONE3 - We Last Longer

this thread is going to be super funny in 5 years.

Oh...I agree it's not overly difficult. It's just additional steps that are the result of making the design decision to make the fork one-sided. Most aren't aware of that. I wasn't.

Don't forget, the mechanic wasn't putting the same wheel back on...it was swapping out to a different wheel, which again, would most likely require a caliper position adjustment after it was rotated back into place and the removed bolt tightened down. I can see how he was trying to avoid that if he could.

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What I think is super funny right now is that there's 5 pages of discussion, and barely anyone has addressed the substance of the first post. It's devolved into the same old "I don't get it" vs. "discs are coming whether you like it or not, so get over it" BS.

Actually, it's more sad than funny...

Edit: Well...upon further review...I take that back. There's actually been some good discussion in the first few pages.

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I officially learned something today!

And it's still early!! :-)

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Tom, you've brought up a lot of great points rebutting many of the reported advantages of disc brakes, however I haven't seen your reply to the possibility of overheating.

About a month ago a friend and I both had tires explode and rims de-laminate on a long, technical, and steep descent in Vermont. I should also mention that we're both rather lean and were not dragging our brakes. I can see only two solutions to this: stop occasionally to let our rims cool, or use disc brakes. I'd love to be wrong and hear option three.

I'll take a lot of the responsibility for that, for interjecting with my two-wheels-same-bike post!

But back to the matter at hand, I don't really think it comes as a big surprise. The main reasons I got started experimenting with road/CX disc about 10-12 years ago wasn't really for improved stopping distances (or at a higher level, to get "better" braking). It was to get to what I considered to be acceptable braking without noise. In other words... try to find a way to get braking on wide-tire bikes that would be as good as standard road rim calipers.

I think a lot of what pushed me to try it was cheap V-brakes, bad cantilever cable stop location (too high) and frames/forks with insufficient stiffness. I had CX bikes with terrible fork shudder... and thought that discs would fix it (but then had the same problem on a disc bike with a really light/crappy fork). I actually ended up with a really nice braking system on a Yeti CX bike with super stiff Alpha Q fork and V-brakes. Nice V-brakes work super well i.e. Shimano XT. I think a lot of people just have had bad experience with cheap stuff and assume that all V-brakes are that way (similar to arguments I've heard against triple cranks... when a person's only experience is on a Shimano Sora triple...).

What happened over time was that discs became almost unavoidable for me. That's how the industry goes. We talk shit about how stupid a technology is, but then later everyone gets scared of missing the bandwagon and then they ALL jump on the bandwagon (27.5" wheels, "Plus" tires, and all manner of axle, bb, and headset "standards"). It's just annoying because we're usually not solving many problems, and often create new ones. Rim brakes aren't the problem. It's poorly executed rim brakes, and frames/forks that don't support them well. And perhaps a lack of education on different pad compounds. There are some good disc brake systems that perform nicely, but I think we need a lot more data to show any sort of general conclusions (for example, take the Tour magazine test and use a bunch of different pad compounds for both brakes, or try some hydraulic rim brakes). For my personal bikes, I'm always going to go with the combination of performance and ease of ownership that best suits me. And I like riding (and sleeping) more than I like wrenching, so I typically err on the simple side, even if it's at the expense of a very marginal gain.

Option 3: Don't use all-carbon rims. You'll get better braking with little to no mass or aero drag increase using wheels with aluminum brake tracks.

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I had a blow out of a latex tube on a really steep descent with aluminum rims. I got stuck behind a car and was forced to use my brakes hard and long, and I had to bail into the grass on the right. That was the last time I used latex on the bike I ride hills with.
Honestly I think aluminum rims heat up more than carbon. I've felt both at the bottom of a descent just to see and I couldn't touch the aluminum rim. They don't delaminate though and I'm sure they cool down fasted too, but they do transfer the heat to the tube. I'm still not ready to try road tubeless yet even though I have been that way on the mtb and cx bikes forever

Tubeless doesn't help with delimitation, but might solve the tube blow out. I'm wondering if anyone has had a tubeless tire blow out on them from a braking-heat related incidence.

FWIW, I'm one of the few guys that actually doesn't have any issues with how my latest set of tubeless full-carbon wheels brake in the dry or wet. But wow did previous generations create some pucker factor waiting for bite in the wet and the incredibly long stopping distances.

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My YouTubes

As an aside about the lefty: it's actually pretty easy to change tires and/or throw in a tube with the wheel still on the bike :)

I've owned a few Leftys over the years and have a Scalpel now. It takes me about an extra 30 seconds to loosen the two bolts and slide the caliper off. It's really not that difficult lol

I know...but when I told the mechanic to just throw a tube in there (it was a tubeless tire that was leaking along the beads) he said "We don't have any".

I was all "WTF?" :-/

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I would check the inside of the rim bed for sharp edges...and also maybe consider using a double-layer of tubeless tape as your rim tape (more durable and better insulation).

Carbon rims DO get hotter and retain that heat more (less thermally conductive). That's been shown with measurements. The lower conductivity of the carbon is why they didn't feel as hot. Your hands don't have "temperature sensors" in them, so much as "heat flux sensors". Items that can dump heat into your hands faster (i.e. higher conductivity) will feel much hotter in your hand than lower conductivity items at the same temperature. I actually have to design around this effect often on hand held devices.

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I totally agree with this. The bike that's easiest to work on gets ridden more - especially true for tri bikes.

On the marginal gain part, the extra weight of disc's is more than a marginal loss. Other things equal, on the hill behind my house they cost around 15 seconds (more for most people). On other hills in the area it might even be a minute or more. Who in their right mind would race them? You've got people out there replacing all the little bolts on their bike with titanium to save a fraction of that, and now you want to bolt a dumbbell to your bike for no good reason? Count me out.

It was definitely the heat. I double layer stans tape and never had an issue before that. Same rim tape since many miles later with butyl tube.

Even Cadel Evans had a blowout with a carbon clincher at the end of the race I did last Saturday ;-)

On a straight dry line disc brake and rim brake are equal because braking distance is dictated by the distance from the rider center of gravity to the front wheel and the rider center of gravity height. The only exception would be old single pivot with bad pads that would limit braking. So the "Tour" comparison is moot because they don't understand what they're testing. Beware of Germans, they look serious but they make mistakes too. Also triathlete and time trialists should use bike with longer wheelbase because they don't have to suck a front wheel and it would improve their braking. Always buy the longer bike that fit you for Time Trial.

Disc brake have one big advantage : the braking is quite consistent in wet conditions. Rim braking on a wet rim is scary, and twice scarier on carbon rim. Sometime it'll brake, sometime it won't. Most of the time one need about 20meter to "reactivate" your pad so the braking became efficient. That is the main bad point of rim brake.
That said i'm not that much racing under the rain and on technical course at the same time. Rainy races are below 10% and for triathlete technical races are below 5% i would say. So that make a bonus for some very rare occasions. Sure for training purposes better braking is better but you can also be more cautious on those rainy days, not a big deal. So i'll keep my rim because i have nto unlimited money. If i had i would probably go for it but just don't expect any real gains.

Disc brake on the road have a few other plusses :
My girlfriend like the better braking with less force.
Better feel and modulation (but it won't help you win any races, it's not mtb).
Capable of more convoluted routing.
cleaner.

And obviously one downside :
It's heavier by a good 500gr or more for same spec and about 800gr to 1000gr to same price. Not negligible.

Also for people not used to disc brake a few care thing have to be learned. Never use lube in spray close to your bike, never touch the disc with your hand or a rag or anything. Just let those discs alone.

I always find GT85 brings the rotors up nicely.

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29 years and counting

Again, you know that 'get over it' paraphrasing was a joke right. Discs are horses-for-courses, dependent on road & riding conditions.

Seriously though, was there a similar discussion on phasing-out threaded BBs? I really miss the convenience & robustness of BSA68 bottom brackets.

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29 years and counting

This ^

Using a single, straight-line, dry weather test as "proof" that rim brakes are equal to disc brakes is nonsense. To use another motorcycle analogy, it reminds of of the ABS vs. non-ABS arugments, and the straight-line, dry weather tests using professional riders that "prove" that you can stop more quickly with a non-ABS motorcycle than an ABS-equipped motorcycle. What people don't like to discuss is that an average rider on an ABS-equipped bike will manage a stop that's at least 90% of max *on the first attempt*, and every single stop will be close to max performance with ABS. Conversely, on a non-ABS bike, it took even the pro's several attempts to get close to the max, and a normal rider's first attempt was horrendously bad vs. ABS, not to mention the likelihood of locking the brakes up in wet weather.

How does this all relate? Disc brakes on bicycles have better modulation, better wet-weather performance, and better fade resistance. All of this adds up to the 'normal' rider being able to execute a near-maximal braking effort *the first time*. You don't get 10 attempts to avoid that SUV that just turned in front of you.

Regardless of what brakes one chooses, the first time you do a near-maximal braking effort should *not* be in an emergency situation. This is an important safety skill all cyclists should practice and master.

So...it doesn't really rain much throughout the year where I live (SoCal), but we do get a fair amount at times during the winter months. Lately, on the rare occasions I've ridden on the road in the rain, if I know the roads are wet or it may be raining while I'm out, I'll grab my disc-equipped gravel bike...but, mostly because it has fenders mounted during that time of year (since it does double-duty as my daily commuter). It's infinitely more comfortable to ride in the rain IMHO if you aren't dealing with road spray coming up off the tires.

Anyway, to set the stage further...I've ridden MTBs for over 30 years, so I fully understand the differences between rim braking and disc brakes in conditions where the rims can get wet (stream crossings, for example) or muddy/dusty. Discs make a fair good of difference in those conditions, mostly by moving the braking surface to an area that's less likely to get wet or dirty while riding.

Now, I've also ridden in the wet an the road quite a bit in my lifetime with rim brakes and am quite aware of how the variables of rim brakes (i.e. pads, braking surface material, etc.) affect things. Just like with riding through a stream on a MTB with rim brakes, there's a bit of a delay while the water on the rim surface is displaced before braking can begin.

So, the first time I rode a disc-equipped road bike in the rain, the strangest thing happened. I was riding along in a moderate rain and the road was completely saturated. The first time I needed to brake from a reasonable speed, I grabbed some lever...and immediately started laughing out loud. Why? Because even with discs, in those conditions there's still a one wheel revolution delay before braking starts...you STILL have that "Oh shit, nothing's happening" moment. So much for the vast difference in wet braking behavior :-/

Now then, why might this be? Well, when riding on the road in a moderate rain, there's still quite a bit of water that ends up on the braking disc, both from the rain (depending on how hard it's coming down) and from road spray, and it still takes a revolution of brake application (at least) before the water is displaced. Oh, and they sure do make a racket after that (probably contamination from road grime and/or oils). Squeal city.

And guess what? IME, even when the water is displaced, once the braking occurs, it's really no better than a well set-up rim brake using KoolStop Salmons on an aluminum braking surface...which is probably a good thing (to prevent accidental wheel lock-up).

BTW, all those things you mention about "better braking with less force, better feel and modulation, and capable on more convoluted routing" are not disc specific. They can all be had with a hydraulic rim setup as well.

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I guess you've missed all of the complaints about press-fit BBs and the like? For example, https://www.bikeradar.com/...ttom-brackets-38220/

Or I guess you missed the push for the threaded T47 variant?
https://www.bicycling.com/...om-bracket-standard/

Or, the myriad of thread-together BB variants to go into press-fit BB areas?

There's a reason my custom bike was built with a BSA68 BB, and I was quite happy to learn my gravel frame was as well before I bought it ;-)

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That's the "common wisdom" and marketing push...but, as the original subject of this thread tends to point to, that's not necessarily a correct generalization.

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The article about your bike, along with not really giving a crap about how fast my road bike is, is a huge part of why I want my next roadie to be steel. With a threaded BB being a strong part of that.

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The point is, ladies and gentleman, that speed, for lack of a better word, is good. Speed is right, Speed works. Speed clarifies, cuts through, and captures the essence of the evolutionary spirit.

Unfortunately I don't speak (read) German, so I'm just going by the synopsis of the article in the first post. I don't see anything there that disproves the 'common wisdom'. I just see a straight-line, dry weather test, albeit with some weight added and downhill.

I've tested a lot of road discs that made Campy Deltas look overpowered in comparison...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

Can't say I disagree more.......Just last week on vacation I was riding in some down pours in Wilmington NC (ie, flat), cantis and aluminum wheels and the breaking was really poor. I would have like 5-10 wheel revolutions before I had some decent grab. Came home (hills) and out on my disc brake road bike out in the rain and would have to say I had zero delay in stopping power like you have mentioned......I was more worried about locking up my wheels than anything else. Now, everyone will have different experiences.....but just like I will not own a bike that doesn't have Di2, my personal experience is that disc on a road bike....is just that much better (for me). When it's dry out....I could go with either bike I own...cantis (only with aluminum wheels) or disc, but when it looks like rain, I'll choose my disc bike 100% of the time,

What pads?

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Both bike have Shimano brakes.......so both are using Shimano pads.

There's a big part of why your experience is different. Regular black Shimano pads can't hold a candle to wet condition pads like KoolStop Salmons.

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I ride generic tubulars in training and have found Swiss stop yellows to be best.

I really have no issues with these at the front and generic in the back.

...having said that, generally speaking you brake with your eyes, not your hands or pad/rim interface.

Maurice

Yup, I understand that.....actually have used KoolStop Salmons and although they were better....they definitely are not disc better. Pros and cons to both systems, I get that.....but stopping power in the wet - disc is the no brainer winner hands down!

Except you aren't listening to those telling you that's not necessarily the case.

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Why do you believe that your opinion is more valid than his opinion?

I bring data ;-)

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Not trying to be a jerk to you Tom, but if there's compelling data I have yet to see it. The 'test' in the OP is bullshit. The rest (as far as I've seen) consists largely of you expressing your opinion forcefuly and frequently, which doesn't make it 'data' IMO.

you bring the same opinion & wishful thinking arguments from every other pointless disc thread, plus one dopey Tour article. Every other segment of cycling has gone disc and exactly none of them have gone back. Mtn, cross, gravel, adventure, endurance road and now just regular racing bikes. TT bikes are the last one, more due to the segment size and cost to retool molds (and how long it took for Shimano/SRAM to make hydro levers for TT bikes).

If the goal "remove credibility making the same refuted arguments the die hards did in these other segments and now look really dumb" mission accomplished. Hang the banner on your aircraft carrier.

Yes, true "apples to apples" comparative data is scarce...something I've pointed out often. That said, I HAVE posted various items such as SRAM's own lever force vs braking torque data showing that their Hydro Rim brakes on aluminum have a curve that's within 10% of their disc brakes with 160mm diameter rotors. A simple pad change and/or brake track treatment change (e.g. Hed Turbine, PEO ceramic, etc.) and that difference is easily overcome, if not flipped. This current Tour test, even if somewhat imperfect, points in a similar direction.

Now, I also bring to this quite a wide experience with tinkering with various bicycle braking systems. I can't help it...I like tinkering with bike stuff, and my Mechanical Engineering training I think affords me some additional insight as compared to the average rider. Of course, I also try to back up that experience with data.

So, to say it's just me expressing my opinion "forcefully and frequently" is incorrect.

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Translated as “I know best, you’re all wrong”

SMH

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I ride:
Cervelo - P-Series/R3
GT - Sensor Carbon Expert

Supporters - Flo Cycling, Mount Bikes

Spoken like a true politician.......
I'll believe my personal use "data" vs a politicians data any day of the week. Like I said, everyone may have different experiences, but for me, it the wet, disc are a no brainer absolutely better, hands down.....and that's with aluminum wheels. Switch the conversation over to full carbon wheels....and you spit on them and the braking sucks. Yea, there may be a few of the COSTLY and higher end wheels with special needed pads that might brake ok......

In my shop, the market has spoken. We’re a Trek shop so on the high end, you have choices between disc and rim and as a company through 2018, Trek pretty much played both sides of the fence in the disc vs rim debate by offering both on their high end Domane and Emonda models. Not one Domane SLR or Emonda SLR has left our shop in the last year that didn’t have discs. At the SLR level, most have been Project 1 with the customer requesting discs. Customer feedback is no one would go back to rim if given a choice.

Slowtwitch isn’t the bike market as a whole. Most folks don’t want to be bothered with which color Swiss Stop pads work best with their new carbon wheels - they just want to ride and have a bike that works well and looks cool. From a customer perception standpoint, disc give them that.

From our shop data, our mechanics spend less time on road bikes with hydro disc brakes than road bikes with rim brakes. Granted, road discs ares still new and the one thing I’m worried about down the road is what will a 10 year old, semi neglected road disc system look like? Will a bleed, new pads, and new rotors bring it back to life like new pads, cable, and housing will do with with rim brakes, or are you getting a whole new system? We’re to early in the process to know.

I'm running a disc equipped Roubaix. Today the bike club left on a 50 miler knowing it would probably rain. Tuns out it rained for about 45 miles of the ride. It was pretty miserable. While others were discussing brake pads last night and this morning, all I did was rewax my chain and put my emergency cash I carry in my lower frame box in a ziplock bag. On the ride I just stayed off lines and manhole covers. Otherwise I just rods my bike like normal, and it responded to my requests like normal. Others were having issues. Whether real or imagined, they were slowing early and braking sooner. It started to get annoying. In the garage I wiped off the wheels. I didn't have to look at what was caught in the pads or scrub the brake track.

As for the original post, I finally had a little time to look at the test data. In units most of us are familiar with, they claim a 210 lbs rider going 28.5 mph down a 10% grade stopped in about 58ft. My gut tells me that is right on the edge of possible, and would require a very good road surface, a lot of skill, and high end tires. All things the average rider probably won't have. Since the stopping distance would then increase considerably for both braking systems, the "2 to 3%" increase gets considerably larger, to the point where it is no longer insignificant, and could be the difference between "almost" and "oh shit."

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"...the street finds its own uses for things"

Well...at least you finally answered my question from 4 or 5 pages ago in this thread in that those bikes you speak of aren't necessarily being purchased for road racing and/or TT/Triathlon use. They're being bought for more "all-road" and fondo type uses. Apples and oranges. Anyway, "markets speaking" doesn't necessarily equate to technological superiority...we all remember Sony Betamax vs. VHS, right? ;-)


It's too bad SRAM screwed the pooch with their initial Hydro brake launch and all of those hydro rim brakes spec'd OEM all got pulled off bikes (due to the master cyclinders in the levers being faulty - same lever used for rim and disc models) and never replaced with new hydros. You might have some experience with those then (I do)...after initial setup, the only ongoing maintenance is pad replacements. Don't even need bleeding due to much lower system temps. Significantly less bother than my disc systems.

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The racer / TT / Tri market is tiny for most shops so basing stocking strategies off that market would be result in a lot of expensive rim brake bikes sitting for a long time at my shop. Honestly we are amazed at how quickly road disc has taken over.

The folks that have bought bikes for racing from us have purchased Allez Sprint bikes since we’re also a Specialized dealer. Which, is an amazing frame for crit racing.

For the Tri market, we’re eagerly waiting for a disc Shiv and disc Speed Concept to drop (no information to give, just what we want the manufacturers to drop) . However, to sell in any volume, a non Di2 hydraulic TT lever is needed.

The brakes on most Tri bikes suck and hydraulic disc on “affordable” (less than 5k) Tri bikes from Cervelo, Trek, Specialized, and Felt will go a long way to reviving the Tri bike market. We did tech service at a Tri today - there are a ton of 3+ year old bikes from the above manufacturers looking to be replaced once road disc hits the Tri market in volume.

As for SRAM, they just aren’t good with hydraulic brake levers. Between their road fiasco and Guide MTB levers with bad pistons that expand when the temperature goes up, I’m weary of any TT hydraulic brake lever that comes down the pike from them. Plus, they kinda shat the bed with their afterthought TT solution for E Tap.

We did tech service at a Tri today - there are a ton of 3+ year old bikes from the above manufacturers looking to be replaced once road disc hits the Tri market in volume.

Well, that is good news. Soon all those perfectly serviceable bikes will be available to the rest of us at a discounted price. I will be able to buy my son a new bike on the cheap. Some of us rely on the lemmings to pay the premium prices for us. :)

Here is what it is all about...
1. rim brakes work crappy on carbon wheels... if you like the all carbon wheel idea, think disco for the brakes.
2. rim brakes work great on alum. rims in pretty much all conditions. If you are happy with alum rims get rim brakes.
3. if you travel and put your bike in a box for the airline to beat up. You are so screwed if you bend the disc or the fluid leaks out.
4. if you have a problem with a disc brake I am guessing 75% of bike riders can't bleed a brake, change pads or work on a disco set up.
5. bike shops love complicated bikes. They make lots of money off full suspension tune ups, disco brake tuneups, and putting together racers bikes.
6. My travel bikes are steel, S & S couples, alum rims, rim brakes. In the last 55 years of cycling for me i can fix 99.9% of problems with my steel bikes. My full suspension go fast mtb goes into the shop at least twice a year. I have 0% confidence that in flight that bike makes it without help from a shop.

Bottom line...they are all good but some are harder to work on than others. Love my S&S coupled steel track bike for travel. Not much to mess up there. If ya don't need brakes for carbon wheels, they all work well.

Had a chat with my mechanic the other day about the increasing numbers of disc brakes showing up now. Caveat:I live in a sunny, flat region.

He's a former pro road racer and now wrenches for a living. I asked him what he thought about disc brakes showing up.

His thoughts? Most people in our region will never need them. The costs of maintenance will go up, but so will the time he needs to spend on each bike. He's had multiple brand new bikes come in with problems with their braking systems (bent rotors, not bled properly, etc.). And that 'ting ting' absolutely drives people crazy. it may not slow you down- but people go nuts about breaky BBs- what more brakes? They're much harder to get right and customers alawyas complain.

Who'd have thought that an "old-tech", such as an aluminum frame, would be the go-to purchase for road racers? Isn't carbon better at EVERYTHING?? ;-)

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Yes, this is true for the most part (you can still find some rim brake bikes here and there, more at the low end of the market... but some of the high-end i.e. Richard Sachs). But I think the important thing to note is that this isn't purely due to superior function of disc brakes. High quality, well-engineered, properly installed and maintained rim brakes can work really, really well - and are usually really easy to live/travel with. But there are definitely some really bad rim brakes that have given some people a bad taste in their mouth.

It's a marketing problem. Manufacturers aren't going to waste time and resources developing technology for a segment (rim brakes) that they're fairly certain that the industry at large has given up on (regardless of whether the reasons for doing so are good or bad). They don't want to be seen as low-tech luddites. The bigger the company, the more this drives their decision-making. They're doing the math and want to make money. I think that some people miss this, and assume that the manufacturers are moving to discs (or whatever the new technology is) ONLY because it functions better or is easier to maintain for all cyclists in all situations.

The point I've been trying to make is that there are some people (me included) for whom the extra work and travel problems of discs on road bikes aren't worth the hassle, because they choose to ride with a very good rim brake setup, and don't have a riding style or other factors that make discs "necessary". I'm a long-time mechanic. I can make discs work well (short of the frequent product recalls we seem to encounter). I just get tired of spending a lot of time on it - and I don't want to lose the choice of buying rim brake equipment in the future. If someone else wants to buy a road disc bike, I'm not holding them back. It's just a bit frustrating to see a lack of education on what some of the costs can be (i.e. time, more cost with pad changes and bleeds, etc) for the uneducated beginner. I hope the technology can improve to become super reliable, quiet, and low maintenance... I'm definitely leaving the door open for that to happen.

I'm with Mr. Kopecky ^^^^

Well said.

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I saw this quote today about disc pad choices for road use and it reminded me of your comment above:



So yeah...now they just have to try to figure out which pad types work best for their purposes (i.e. resin, semi-metallic, metallic) where their trade-offs are good wear and wet performance but noisy vs. quiet(er) with worse wet performance and fast wear...and then, once they're contaminated, they all suck noise-wise and performance-wise. The questions/bother about pads aren't going to stop...

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