Some interesting aerodynamics info

We have a few more Celebrity Death Match reviews coming up, as well as some other topics, but I didn't want today's short bit to get buried in another post. 

Some of you may have heard of Hambini, a British guy who posts on forums and YouTube. Though we disagree with some of what he posits (he has a regrettable attachment to "all that matters is depth when talking about rim aerodynamics" which - spoiler alert - he may have let go given what we're about to point to), he's dead spot on with most of what he sniffs out. Ceramic bearings? Not a fan. Basically he's into practical stuff that works and tries to separate the usually frighteningly expensive snake oil from what's going to work and be efficient and effective for you.

He did a bunch of aerodynamics testing on a range of wheels. Two notable things stick out to me: the first is that an 88mm deep Yoeleo wheel hits with the deep wheels from the big brands. At slower speeds, it's the fastest wheel. The other thing is that there is a grand total of 17w difference at 30km/h, and 53w at 50km/h, from worst to first. At 30km/h (~18mph), the Yoeleo wheel is the fastest, and a 28mm Ksyrium (they have a talent...) is the worst. At 50km/h (~30mph), the Zipp 808 is fastest and - shockingly - the Ksyrium is the worst. The correlation between depth and speed is shown not to exist (which we've discussed a bunch of times before at this link and in a ton of other places), and some of the brands whose claims are going to drive me across the brink of sanity (rhyme with "Punt" and "Slow") are shown not to be all that and a bag of chips. Again, shocker.

Anyway, an impartial set of data for you to look at and process. No one's going to say that 53w isn't significant, but not too many people should be looking at 30mph as their most relevant speed, no one is choosing the Ksyrium as an aerodynamic option, and I don't know too many people who think that 80+mm deep wheels constitute anything like an "every day" option.

 


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  • Dave on

    Terry – Definitely not much. Narrower flanges have to be better, but they make a worse wheel. Funny thing is I noticed your comment just after I’d been reading something about the newest latest greatest $2400 wheels (that ship with $50 hubs, there’s more than one born every minute) and thought “just get the depth you like the look of, the actual differences mean squat once you’re past the Ksyrium/box section range.”

  • Terry Sappenfield on

    Just wondering how front hub shape might affect overall aerodynamics of an aero wheel. I suspect not much, but are there any studies out there?

  • Dave on

    Hi Alex – Glad you found us! Yes, it really is. And that’s sort of the thesis we’ve been working on for kind of the last 18 months or so since we did the test that included Zipp 303s and then some of the better alloy rims. There’s bad – Ksyrium and R-SYS, 32h box rim wheels with straight gauge spokes, etc – then there’s a huge middle ground, and then there’s the really deep wheels which get you an extra punch but at the expense of weight and, more important, practicality.

  • Alex on

    Thanks to a friend’s recommend, just discovered your site in a bid to find affordable but decent carbon hoops for my new aluminum disc brake road bike… and really appreciate you posting this info. That middle range really is tightly packed isn’t it?!


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