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

[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.