So...Tour mag tests disc brakes vs. rim...

Aug 6, 18 12:56

Post #1 of 153 (12531 views)

...and even with a less than ideal pad on the Ultegra rim brakes (stock Shimano) and regular aluminum rims, the disc bike stops only ~2-3% shorter in a full stop (95kg bike+rider+backpack, 10% slope, 46 km/hr start speed) as compared to arguably the best road disc braking system on the market, and using 160mm diameter rotors to boot.

https://www.tour-magazin.de/.../aktuelles_heft.html

Imagine if the pads were swapped for KoolStop Salmons or Dual Compounds...or, they used some Hed Turbine track wheels? How about hydraulic rim brakes? Any one of those changes would easily overcome that 3% difference, and also vastly improve the wet stopping "lag" they measured.

So much for the performance difference being like "night and day"...

There's a good discussion of the results here on Weight Weenies: https://weightweenies.starbike.com/...php?f=3&t=152911 .

There's a link in that thread to an interesting French blog post that highlights some of the issues the mechanics were having with discs during the TdF. Sounds like they were replacing braking discs quite often...and bleeding the systems quite frequently :-/ https://www.matosvelo.fr/.../les-echos-du-velo-3

I bought the magazine issue and between my limited German understanding and Google Translate, I attempted to decipher how they exactly tested this out. I have to say, for a Tour test, I'm actually a bit underwhelmed. I would think they'd have a bit more objective data at hand...their "cornering speed" test seems odd to me. However, at least they're putting this to the test of some sort and doing it in a more "apples to apples" manner than some other "tests" out there (like GCN's, for example, where they were comparing wet braking on carbon rims to a disc). Oh, and they happened to cause the aluminum portion of the Ice-tech rotors to reach the thixotropic state ("jelly") again...something they've done before.

Anyway...the gist is ~same braking performance (not even considering easy upgrades to the rim setup), for ~500g more mass, and more expense (recurring). Woop-de-doo...

http://bikeblather.blogspot.com/

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 13:20

Post #2 of 153 (12436 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [buzz] [ In reply to ]

Aug 6, 18 13:28

Post #3 of 153 (12402 views)

buzz wrote:

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.

http://bikeblather.blogspot.com/

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 13:37

Post #4 of 153 (12378 views)

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

Re: So...Tour mag tests disc brakes vs. rim... [NUFCrichard] [ In reply to ]

Aug 6, 18 13:47

Post #5 of 153 (12340 views)

NUFCrichard wrote:

You don't like disc brakes, we get 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...

NUFCrichard wrote:

They won't stop making rim brakes anytime soon, so don't worry about it.

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 :-/

http://bikeblather.blogspot.com/

Last edited by: Tom A.: Aug 6, 18 13:48

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 14:18

Post #6 of 153 (12283 views)

Tom A. wrote:

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"...

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 :-/

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

Re: So...Tour mag tests disc brakes vs. rim... [pk1] [ In reply to ]

Aug 6, 18 14:23

Post #7 of 153 (12253 views)

Stay tuned for the upsell option of NOT having disc brakes

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 16:12

Post #8 of 153 (12094 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [spntrxi] [ In reply to ]

Aug 6, 18 16:18

Post #9 of 153 (12079 views)

spntrxi wrote:

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...

http://bikeblather.blogspot.com/

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 18:23

Post #10 of 153 (11930 views)

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

*
___/\___/\___/\___ the s u r f b o a r d of the K u r p f a l z is the r o a d b i k e .. oSo >>

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 18:29

Post #11 of 153 (11911 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [GreenPlease] [ In reply to ]

Aug 6, 18 19:10

Post #12 of 153 (11832 views)

GreenPlease wrote:

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 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?

Quote:

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

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

http://bikeblather.blogspot.com/

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 19:27

Post #13 of 153 (11785 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 19:27

Post #14 of 153 (11784 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 19:30

Post #15 of 153 (11775 views)

Tom A. wrote:

...and even with a less than ideal pad on the Ultegra rim brakes (stock Shimano) and regular aluminum rims, the disc bike stops only ~2-3% shorter in a full stop (95kg bike+rider+backpack, 10% slope, 46 km/hr start speed) as compared to arguably the best road disc braking system on the market, and using 160mm diameter rotors to boot.

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.

Re: So...Tour mag tests disc brakes vs. rim... [Tom A.] [ In reply to ]

Aug 6, 18 19:35

Post #16 of 153 (11767 views)

Tom A. wrote:

Quote:

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

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

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).

Re: So...Tour mag tests disc brakes vs. rim... [GreenPlease] [ In reply to ]

Aug 7, 18 0:09

Post #17 of 153 (11529 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [BBB1975] [ In reply to ]

Aug 7, 18 1:34

Post #18 of 153 (11450 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [BBB1975] [ In reply to ]

Aug 7, 18 3:58

Post #19 of 153 (11310 views)

BBB1975 wrote:

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.

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.

Last edited by: Andrew Coggan: Aug 7, 18 4:13

Re: So...Tour mag tests disc brakes vs. rim... [Andrew Coggan] [ In reply to ]

Aug 7, 18 4:21

Post #20 of 153 (11247 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [lyrrad] [ In reply to ]

Aug 7, 18 4:29

Post #21 of 153 (11236 views)

lyrrad wrote:

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.

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.

Last edited by: Andrew Coggan: Aug 7, 18 4:52

Re: So...Tour mag tests disc brakes vs. rim... [lyrrad] [ In reply to ]

Aug 7, 18 4:56

Post #22 of 153 (11179 views)

lyrrad wrote:

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.

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.

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

Re: So...Tour mag tests disc brakes vs. rim... [AutomaticJack] [ In reply to ]

Aug 7, 18 5:23

Post #23 of 153 (11123 views)

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.

Re: So...Tour mag tests disc brakes vs. rim... [Andrew Coggan] [ In reply to ]

Aug 7, 18 5:50

Post #24 of 153 (11067 views)

Andrew Coggan wrote:

lyrrad wrote:

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.

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.

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.

Re: So...Tour mag tests disc brakes vs. rim... [Andrew Coggan] [ In reply to ]

Aug 7, 18 6:19

Post #25 of 153 (10992 views)

Andrew Coggan wrote:

BBB1975 wrote:

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.

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.

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?

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