The theme for this year seems to be 3w. That's the amount of savings that wind tunnel tests say you save by using a Zipp 404 instead of an RFSW3 (or Al33 custom build) or an FSW3. Those are also at par with a Zipp 303 - 3w down to a 404. Then there are the other wheels right behind that group - HED Belgium+ and FLO30. I'll bend one of our rules and backstop the Easton R90SL with the HED/FLO group. Since that test in February, we've had a lot of conversations that focus on this 3w concept. But what exactly does it mean?
Ostensibly, 3w in a wind tunnel means around 9 seconds over the course of a 40k TT, assuming no other variables and a 30mph bike speed. More subjectively, it could mean the difference between basking in victory and choking on the salty tears of defeat (though I'd note that no Olympic or World TT margin of victory in recent memory would have been affected by the winner using box section wheels versus whole-hog aero wheels). It could be the increase in your FTP after a few hard weeks of training. Or it could be noise in the system as the simple test in this CyclingTips review of Roval wheels would indicate. Personally, I'm sold that it's more the latter, with a side of "though I try to stay in shape and would much rather be thought of as that sort of fast debonair older gentleman than that slow old fart I just don't see 3w being that difference in any case."
We've studied tires quite a bit before (like what became this blog, for which I was nearly burned at the stake as a heretic for concepts which we all take for granted 3 short years later), but this year it's been a big focus for us. With sites like Bicycle Rolling Resistance doing all the interesting work that they do, plus articles like this one in VeloNews getting more attention, it's really evident what a big roll (I'll be here all week, ladies and gentlemen!) tires play in your speed. WAY more than 3w on offer there. Heck you can reverse that 3w delta by using latex tubes versus regular weight butyl tubes, which is worth 3w per tire (and you're not supposed to use latex tubes with carbon because you might die!).
In addition to the speed gains from good tires, there's a comfort and enjoyment enhancement with really supple tires. I've gone from being a general "life is too short to ride crappy tires" guy to being an incurable tire snob, and I'm happier for it.
As so often happens, we're going to counter the bike industry and general market's proclivity to see things as "black and white, one way or the other" with our own completely muddled "well, it depends..." Are there aerodynamic differences between wheels? Sure. Can small amounts matter? The Sahara desert is made up of darn near microscopic particles, so yeah. But are there a whole bunch of other things that convolute the discussion? Yes, that's the big point.
8 comments
When talking about time required to cover a given distance, the time savings for a reduction in CdA actually goes up as speed goes down (however, the difference in speed does get smaller). A bit counterintuitive maybe, but that is how it works.
More than none, but aero benefits do scale with speed, so as your speed comes down the benefits come down quickly. But 15mph into a 15mph headwind is no different than 30mph. It’s also hard as hell to do, but the wind flowing over you and your bike doesn’t know if it’s your speed or the wind’s speed – all the same to it. But yes, it sure does seem like the “aero is everything” movement has little or nothing to do with the average active fit rider who isn’t doing TTs or trying to race at a super high level. And even the latter group has a lot else to consider.
30 mph for 40k? Who does that? I would guess that your average customer on an average ride averages between 15-20 mph in swirling winds and over an undulating profile. How much does difference does aero make at those speeds? Like, none, basically?