Just realized the irony of disc brakes on an aero bike.

[Mark McM]

Originally Posted by ergott

Bottom line, like the brake arguments here you can't say one is a clear winner and you should just buy what works for you. To say that tubeless tires are at a distinct disadvantage to clinchers hasn't been the case for quite some time now and there have been great improvements in tubeless tires especially in the last 2-3 years.

Which is of course why I never claimed that tubeless tires are a distinct disadvantageous (for rolling resistance). As I think we've both shown, they are roughly on par, with no clear advantage one way or the other. But that's not what has been claimed in the past - many people promised that tubeless tires would be better.

There have been many claims about disc brake bikes/wheels having an aerodynamic advantage. We may have to wait a bit more for definitive data, but from what we know so far, they have not yet proven to have the distinct advantages claimed.

[ergott]

Both disc and tubeless for performance road are in their relative infancy. Seeing how fast there have been legitimate development tells me we haven't reached any sort of peak. You can't integrate rim brakes into the frameset like you can disc. The ones that have tried (Trek, Specialized, Ridley) have had relatively poor performing caliper brakes. Tubeless tires have gotten significantly more supple and better performing in the last couple of years. The difference between my current Schwalbe Pro Ones and the first Hutchinson Fusions I had is big.

[Mark McM]

Originally Posted by ergott

Both disc and tubeless for performance road are in their relative infancy. Seeing how fast there have been legitimate development tells me we haven't reached any sort of peak. You can't integrate rim brakes into the frameset like you can disc. The ones that have tried (Trek, Specialized, Ridley) have had relatively poor performing caliper brakes. Tubeless tires have gotten significantly more supple and better performing in the last couple of years. The difference between my current Schwalbe Pro Ones and the first Hutchinson Fusions I had is big.

"Fusion power is the energy source of the future - and always will be".

"Where's the my flying car?"

I don't make equipment decisions based on promises for the future, I make them on current performance and characteristics.

[Bonesbrigade]

Originally Posted by Mark McM

I don't make equipment decisions based on promises for the future, I make them on current performance and characteristics.

A current performance went down today at the tour of Columbia. The top 2 teams in the TTT were on disc brakes. EF actually won a TTT!

I am by no means saying they won because of disc brakes, my main point is they are putting all the R&D money into disc brake system design, and the best current ones are already very good.

[54ny77]

Can we get back to doping while testing for aerodynamics?

[Burnette]

Originally Posted by 54ny77

Can we get back to doping while testing for aerodynamics?

Exactly, we're just rehashing disc thread stuff that we've all done to death. To summarize this thread: ride what you like and let the riders around you do the same.


The search for "proof" of anything requires testing.
For real world testing in real time we have to dope and ride vigorously and for long periods. Which I'm sure we'll forget to collect data on the first go around, cause short term memory loss, so then the retesting phase begins after that.

[54ny77]

Who said anything about riding vigorously, or riding at all?

Originally Posted by Burnette

Exactly, we're just rehashing disc thread stuff that we've all done to death. To summarize this thread: ride what you like and let the riders around you do the same.


The search for "proof" of anything requires testing.
For real world testing in real time we have to dope and ride vigorously and for long periods. Which I'm sure we'll forget to collect data on the first go around, cause short term memory loss, so then the retesting phase begins after that.

[zmalwo]

I assume a lot of the pros choose rim brakes to save weight. Contador used mechanical groupo until very recently IIRC to save that 200g of weight on mountain stages. When you have to climb 3 everest mountains every grand tour, the lightest bike is the way to go. I assume the same for aero bikes, i have not seen 1 aero bike in any size that's even close to 6.8kg. Until disk brakes become lighter than rim brakes, pros are going to stay with rim brakes.

[benb]

Originally Posted by Mark McM

I'll believe that when I see it. Many times potential advantages have been promised, and yet they never come to pass. We were told that tubeless tires would be lighter, have better traction, and lower rolling resistance, yet this hasn't happened. We've been told that disc brakes will allow wheels to be more aerodynamic, but this hasn't happened either. Exactly how do you imagine that rims can be reshaped for aerodynamics that rim brakes don't allow? Some have clamed that disc brake wheels don't need to have parallel sidewalls, which is true - but neither do rim brakes. I've got several sets of rim brake wheels with sidewalls (brake tracks) angled for aerodynamics.

This may be yet another case of counting your chickens before they hatch.

Hilariously there are lots of Walmart super cheap bikes with rim brakes that have angled rim sidewalls... it is not a cost thing.

This stuff tends to be a bit hilarious.. < 10w at 27mph. I can't TT at 27mph. I don't even race anymore. Not going to worry about it.

It seems the Pros aren't worrying a lot about a lot of it either when they keep choosing the rim brakes even when the discs are supposedly so much better, etc...

Even when you've got the guys at the razors edge at the top of the sport it so often seems like the races are determined not by these aero engineering items but whether a given rider has something going on with their back that prevents them from hitting the optimal riding position for aero, or whether another rider seems to have an attention issue and crashes.

Ignoring the dope they were both consuming no amount of aero advantage would ever have allowed Ulrich to beat Lance in the TdF. Lance had that back shape thing that hurt his aero probably more than anything Trek could have done to his bikes, but it didn't matter when Ulrich failed to keep the rubber side down so many times.

As for tubeless I think all those claims have borne out on the MTB side.. I think if we all changed our mind and were clamoring for tubeless road it would spur enough R&D the tubeless tires would start improving more rapidly. Chicken and Egg?

[ergott]

The biggest reason for a pro to skip disc brakes right now is the thought of trying to get a spare wheel in a race. The other stuff is minuscule in comparison.

[EDS]

Originally Posted by Mark McM

I'll believe that when I see it. Many times potential advantages have been promised, and yet they never come to pass. We were told that tubeless tires would be lighter, have better traction, and lower rolling resistance, yet this hasn't happened. We've been told that disc brakes will allow wheels to be more aerodynamic, but this hasn't happened either. Exactly how do you imagine that rims can be reshaped for aerodynamics that rim brakes don't allow? Some have clamed that disc brake wheels don't need to have parallel sidewalls, which is true - but neither do rim brakes. I've got several sets of rim brake wheels with sidewalls (brake tracks) angled for aerodynamics.

This may be yet another case of counting your chickens before they hatch.

As far as aerodynamics for disc only wheels, since you no longer need a flattish brake track could wheel designers more fully optimize the shape of sidewalls to improve wheel/tire intersections from an aero perspective?

I do not know if the above is possible, just asking the question.

[Mark McM]

Originally Posted by EDS

As far as aerodynamics for disc only wheels, since you no longer need a flattish brake track could wheel designers more fully optimize the shape of sidewalls to improve wheel/tire intersections from an aero perspective?

Maybe, but it hasn't really been demonstrated yet. Also, it should be noted that flat, parallel brake tracks on rims is a relatively recent innovation (just the last couple of decades). Before that, rims commonly had curved and/or angled sidewalls. There were even some rims with concave sidewalls.

Here's a popular rim from the 1980's, the Campagnolo Lambda Aero:



And even though sidewalls are typically flat today, not all of them. Here some more modern Zipp rim brake wheels - which are clearly angled and curved for aerodynamics:






Would these rims be shaped differently for disc brakes?

[Burnette]

You know can check all wheel sellers sites that offer disc for said info, trying to argue it out backwards here is a bit of a waste.

[Ed-B]

Originally Posted by zmalwo

....The whole purpose of an aero bike is to use them....where constant speed is high enough that the aero advantage of aero tubes offsets the weight penalty....caliper brakes would offer better aero gain than disc brake, as well as reducing overall weight.... But since everything in the bike industry is about marketing and forced gear retirement, the manufactures probably don't want you to know this.....

See, with a little editing, the theory in the original post is true, and the poster vindicated! (I just needed to clip out the parts about flat roads and relative braking performance.)

Originally Posted by Mark McM

This seems to be borne out by a recent Tour Magazine test of the latest aero bikes. A link to the test and a discussion of it can be found here:

https://weightweenies.starbike.com/f...p?f=3&t=154692

Here's a summary of the results:



The aero road bikes from every manufacturer in the test got slower when they redesigned it for disc brakes, except for Cannondale. But even for the Cannondale, they redesigned and re-optimized the entire bike, so who knows whether redesigning and re-optimizing around rim brakes wouldn't be faster still?

I've read the Cervelo white paper on the S5 Disc, which claims that the S5 Disc is faster than the previous S5 (no surprise there - every manufacturer claims their new bike is better than their old bike). But if you look closer, you'll see that they changed many aspects of the design (such as routing all the cables internally through the special stem, headset and fork). They mention how much power each change saved, and it adds up to more than the power saved by the whole bike - which implies that switching from rim to disc resulted in a power loss, for which they had to redesign other parts to make up for.

[Mzilliox]

Originally Posted by zmalwo

I think a medium size road bike with a 120mm+ stem and 75cm+ saddle height look the best personally.

me too, hey, i resemble that