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Tech Interesting aero article from Road.cc


Far beyond the black horizon
Oct 9, 2015
The main part about the rims and aero vs. weight is fairly interesting, but the actual figures about disc brakes, and how they are approximately 16% less aero than rim brakes is definitely useful, especially given that it comes from actual testing by a named entity, and not just hearsay. 16% of drag is a fair increase.

Makes you wonder if discs might not be the best thing to pursue and develop for racing... something like an internal hub drum brake would be better.


Maximum Pace
Sep 20, 2012
Thanks for the link. Very interested to hear about the disc brake drag. Will be noting that for later


Bokeh master
Sep 28, 2011
by the time you add up all the tiny incidentals that "cost" us power its a wonder we can ride at all.

7% for shaving legs
5% for aero wheels
6% for the chain lube you use.
up to 20 W for your tyre choice...

Now how about bearings....

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Far beyond the black horizon
Oct 9, 2015
Marginal gains and all that. It is all a bit 'icing on the cake' kind of thing, with the difference between 20mm and 50mm wheels being very small in terms of overall time / power saved. The sort of thing you would worry about after you have wrung the very last drop out of your own fitness and want to find something to give yourself the edge.

Good to investigate though from a nerdy technical engineering perspective, but speaking from experience, the things that have given me the edge the most are not aero wheels, but rather having stuff that doesn't break or creak, eating and sleeping right, and training hard. I did my best time up Shiraishi with a 38mm carbon clincher on the front, and a Dura Ace c24 aluminium clincher on the back, for example. @GrantT done me by about 20 seconds on a bike that weighs about 1.8kg more than mine.


Maximum Pace
Sep 6, 2014
I will never go back to rim brakes, that is for sure (if I am not forced to use them in competition due to regulations of course). The confidence they give me in downhill sections is way more important for me than the aero gain.
The lost power is pretty low as well, since it seems to be 16% of the front wheel aerodynamics. If I understand this correct, it should be in the range of 3-7 watts.
This article also states 1-3 Watts in normal conditions and at most 8 W in strange wind angles:

The tire is very important as they state. Also, it should not be wider than the rim if you want air to stick on the rim and not cause turbulence in the tire-rim transition. However, it is important to check with rim manufacturer about what tire widths you can use.
This seems to be more important regarding aerodynamics than the disc brake.

As about 70% of the wind resistance comes from the body and about 30% from the bike, it also amaze me that so many people have their handlebar in a very high position and never use the lower part of the handlebar...
It might be good to spend a bit more time in the hoods ;-)


Maximum Pace
Aug 27, 2012
Yep I read the 16% refers to wheel dynamics alone with wheels accounting for around 10% of overall wind resistance.

Given I don't do any UCI racing, thinking about pulling a washing machine apart to get some real gains......;)
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