Bicycle Wheel Power Data 50km/h

Posted on 15 Comments

Over several years, bike wheels have been tested for aerodynamic performance. To date, this is the largest independent dataset available. Popular brands such as DT Swiss, SwissSide, Shimano, Mavic and Bontrager have all been tested. This dataset was originally derived from wind tunnel test data but has latterly moved over to Dinitriev number with a back calculation to give “wattage”. It is not a perfect test.

It should be noted that bicycle wheels are particularly sensitive to tire size and having a wheel and tire combination that bulges will cause a significant increase in drag. Ideally, the tire and the rim should be of the same width. These graphs are now updated on a regular basis and are plotted for interactivity. You can see some of the background for this data here.

Small differences in watts should generally be ignored as these will be affected by arbitrary things such as shoe overlap and the size of bike frame. A bigger differential will produce a bigger drop in drag but it diminishes as the wheel tends towards a disc. In general, a deeper rim will always have less drag. The spoke area which is of high turbulence is much smaller on a deeper wheel – hence the primary drag reduction.

15 thoughts on “Bicycle Wheel Power Data 50km/h

  1. I’m a fourth year MEng aerospace engineering student and haven’t heard of Dnitriev number before – can you explain what it is? You have referred to it a few times but I can’t find any information on it. How is it calculated, what factors affect it, what are its advantages? I want to include it in my thesis in aerodynamics as a comparison to other methods and metrics. Thanks!

    1. It is a ratio of local vector to global vector. Dinitriev is a “trade name”. It might be called something else depending on where in the world you are. Additionally, unsteady aerodynamics is rarely taught at undergrad level.

      1. Hi Hambini,

        Thanks for the explanation, and that makes sense why I haven’t seen it at uni. Do you have any good references / textbooks that explore it a bit more?

        1. Aerodynamics by Anderson has a section in it – I think

    2. It’s “Dimitriev” with “m” not “n”.

  2. What is that aliexpress 3 spoke wheel at the top? Can you feature that wheel?

    1. it’s a deerocatcher or something like that. it’s sold under various names

  3. Any chance you could review the ICAN Aero wheels? seem to hate them, but forums seem to think they’re a hidden gem. Not sure who to trust!

  4. I would like to see some data on old school wheels, how much power savings for 28, 32 vs 36 spoked wheels? Thanks!

  5. so the tri spoke is more aerodynamic than 88mm rim?. or both tri spoke and disc vs pair of 88mm rim?

    1. Tri spoke and disc is the fastest.

  6. Reynolds wheels seems to perform quite well with more of a V profile rim. Is this because it is closer to an aerofoil shape?

    1. yep it is and they tend to be slightly narrower as well.

  7. Have you ever tested any Boyd wheels?

    1. afraid not.

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