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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http://bikeblather.blogspot.com/

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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