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Thursday
Jul132017

Does aero trump weight?

Who's ready for some heresy?!?!?!?

There are a lot of word pairs and stock phrases in cycling - crit monster, breakaway artist, TT specialist, and don't get me started on Phil and Paul and light the touch paper and that crap - but one of the more popular ones in the last several years has been "aero trumps weight." It's always phrased like that.

Of course there are formulas for this, and you can go to a site like Analytic Cycling (piece of trivia - that site was created by Katie Compton's dad) and plug in various numbers and parameters and see what's going to go faster when. Since nothing ever unconditionally trumps anything else, except ice cream and Charlie Watts which are both categorically superior to anything else, the buried premise here is that "it is easier to choose a piece of gear which has an aerodynamic benefit that's greater than what a similarly easy to execute weight swap would provide." In other words, it's easier to find a small yet impactful aerodynamic advantage than it is to find a similarly impactful weight advantage. And I'm not even going to really argue with that. My question is does any of it even bear fruit, and more directly does it matter to the average cyclist in our audience really even at all?

If you are racing time trials or triathlons competitively, you're nuts not to chase after aerodynamic gains. In those venues, only an idiot would argue that aerodynamics isn't important. I consider myself to not be an idiot and I would argue that aerodynamic differences between different pieces of gear are wildy oversold, but that's a different tangent.

If you are like our more typical customer, you ride your bike a lot, relatively quickly, and for enjoyment. Enjoyment might include the occasional race or race-like event, but far more often than not it's just riding, group rides, days getting lost in the hills or on the trails, making the motorcycle noise when you feel good, wishing it would all be over soon when you don't. 

Mike will suggest that I artfully put a bunch of links in here, which is hard to do in this, so I will put them in (what's the opposite of artfully? - clumsily?) clumsily. Some of the best wheels we make are FSW3, RFSW3, Select, Select Disc, Select MTB, and Custom

Without going into the fine points of all that this entails (against character, I'm going to make this real short), the wheels that we build are designed around being the best for those purposes. The applicability of a 70mm deep set of wheels (because in actual fact that's sorta kinda about where you need to be to really reap the gains) to that use case is limited. You're toting around extra weight, which may not have much quantitative penalty but which does make the bike feel differently in a way I have seldom to never heard anyone profess to prefer. You're toting around handling difficulties, and you're toting around either a big expense premium or a reliability question or both, probably toting around substandard-to-scary braking, and we just plain don't know what good that does for the people we address. 

It's well proven (and if you don't believe us, download issue #8 of Tour Magazine from 2016 and believe them) that the aerodynamic differences in the wheels that we use in the real world are pretty darn small (Tour says 13 watts between a Ksyrium - long the butt of many aerodynamics jokes - and a 404).

What we think you want, and certainly what we think makes the most sense given the whole context, is good quality components that are well chosen for your bike/tires/riding/weight/etc, assembled with great skill and care. You want to be reassured knowing that you're making or being guided to the right choices, and you really like when someone's got a meaningful, considered, relevant, and informed "because" on the back end of any recommendations. And that's all that we aim to do. If we could make it sexier, we would, but given the recent kit order propaganda (you can order it here), you've all seen enough pictures of my butt and that's about all the sexy the world can take from us. 

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Reader Comments (9)

Whoa, wait a minute, Dave. Are you telling us to be pragmatic, acknowledge our limitations, and buy reasonable wheels instead of daydreaming of 50 watt gains simply by spending $3,500 on whale-skin pattern rimmed wheels? What heresy!

July 13, 2017 | Unregistered CommenterWaldo

Not even asking people to accept their limitations - with the exception of top level TTs, you can do anything you want on any wheels we make, at zero disadvantage to any other clincher. Tubulars can offer a weight savings that no clincher can provide, so there's that, and that's a whole other tangent to this. Holding up whatever tubular that the pros use (as they are contractually bound and compensated to do) as proof of concept of the clincher with the same model name is absolutely preposterous but it happens every moment of every day.

And from what we hear from customers, most people get more enjoyment riding pragmatic (good word) wheels. The number of "my other wheels now gather dust" comments we get is fun.

July 14, 2017 | Unregistered Commenterdave

I'll offer my two cents:

Whether you're looking at weight or aero benefit, any individual piece of equipment matters very little unless, as a racer, you're at the pointy end of the curve...and not just relative to yourself, I mean in absolute terms. If you're debating how to make your equipment setup lighter to improve your performance, you should already be really light yourself and be doing the types of events where that benefit is the crucial difference. If you're a 62kg rider with a legit threshold and pop people up climbs, it's reasonable to be a bit of a weight weenie. But for people into the working person's weight ranges and FTP, you are unlikely to see a big difference in performance by looking for really light options. And if you're riding at that level, you're probably paying for your own equipment, so unless you have truly disposable income, reliability is much more important.

Aero benefit is similar. You have to be hitting speeds where you are actually going to notice the benefit, and be in the wind yourself for a lot of it...the mythical breakaway artist (they do exist). For most people, this is more likely than benefitting from light equipment, but still most riders are not pulling in a difference in performance that is make or break based on their setup. Aero is certainly faster, but if the group ride is 2 hours at 35kph, there's almost nothing in it. So, again, you're incurring expense and potentially sacrificing safety for not a lot of bang for your buck. Reliability would seem more important. But if you're in the wind at crit nats, ride the 808's!

I think the most important aspect in a set of wheels is that the hubs are reliable and serviceable, they brake well, and aren't super heavy. If you're paying for your own equipment, you're more than likely in the group where safety and reliability will contribute more to your enjoying the equipment than any minuscule performance benefit might. Buy things that last and you can beat up, and ride as much as life permits.

I almost forgot: It helps massively if the wheels look bling, too.

July 14, 2017 | Unregistered CommenterJay M

Jay - Tough to disagree, especially with the bling part. Bling is in the eye of the beholder!

July 14, 2017 | Unregistered Commenterdave

Interesting perspective. However, they are a few examples of wheels being able to add in excess of 1 mph during tests outdoors, even at a recreational rider 200 W, I perceive that as significant.

July 14, 2017 | Unregistered CommenterAlfred

Alfred,

Sure, if you go from some low on the aerodynamic totem pole wheel to one at the top of the tree, there are significant gains to be made. But there are of course a bunch of caveats, the biggest of which is that most people are choosing between a ~58mm 404-depth wheel at the maximum and the entire range that's not as fast as that.

Please download and read 2016 Issue #8 from Tour. It's instructive as hell. As I said above, they call it a 13w difference between a 404 and a Ksyrium. No one ever chose a Ksyrium because it's aero. A 13w difference at 30mph works out to about a .25mph difference. You can call that significant if you like, and it might be.

More relevantly, Tour also tested a Kinlin 279/Bitex build and found a 7w difference between that and a 404, so now you are down to about .13mph difference. Is that significant? People love Dura Ace C50s and buy them for speed all the time. 5w between that and a Kinlin 279. 4w between a Campagnolo Bora 50 and the Kinlin. 2w between a DT38 (which is certainly a popular carbon rim depth, bought for "some aero benefit") and the Kinlin. And we know how the Kinlin 31 tested against the 303, which is in a dead heat. And that puts the humble Kinlin XR31T in a dead heat with a Campagnolo Bora 50.

You'll often hear (and we often say) that it's dumb to talk about aerodynamics and use a 32h box section or Ksyrium as your benchmark, because they are wheels that no one who's seeking aerodynamic benefit uses. But it's just as dumb to use an 808 or whatever other very very deep rim as what's readily available for aerodynamic benefit, because no one among the audience I describe above is or wants to be using them within those parameters.

As I very clearly state above, "If you are racing time trials or triathlons competitively, you're nuts not to chase after aerodynamic gains. In those venues, only an idiot would argue that aerodynamics isn't important." So go ahead and chase them. But if you think you are getting that 1mph by going from even a HED Belgium+ to a 404, you're absolutely deluding yourself. There isn't anything like that much "there" there. And the other relative strengths and weaknesses apply.

July 14, 2017 | Unregistered Commenterdave

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July 15, 2017 | Unregistered CommenterModerator

It would be kind of hilarious to wind tunnel test the wheels on a Walmart road bike shaped object.

July 15, 2017 | Unregistered CommenterJoe Bond

How do you think they get the data that says you can gain 1mph from a set of wheels? (just kidding). (for the most part).

July 17, 2017 | Unregistered Commenterdave

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