Was wondering why HED, ENVE and in fact most current wheel manufacturers seem to not favor 80+mm wheels (they are not even carried by quite a few wheel manufacturers anymore), and found this on the ENVE website:
“Once a rim goes beyond the 70mm depth, aero efficiency rapidly tapers off and the additional weight quickly begins to neutralize the marginal aero gains that the deeper rim provides. These are the learnings from more than a decade pursuing the ultimate Real-World Fast aero wheelset.”
Maybe I’m slow to this knowledge, but I don’t recall hearing this discussed as ‘general’ aero knowledge - is this the case now that everyone accepts this?
Based on the above wheel, I doubt that there much limiting the depth of rear wheels. Front wheels also theoretically benefit from more depth (if properly executed), but the main issue with wheels deeper than 80mm on the front is bike controllability in real world conditions.
That’s their super-custom wheel, that almost nobody is buying.
But for their general-road wheels, 88s are almost hard to find now. HED Vanquish goes only to V62, you have to ‘go pro’ for 88s. A lot of the Chinese brands, Superteam, Elite, etc. don’t make any 88s in their newest models, you have to get their oldest version if they even offer it to get it.
I do remember about 5+ years ago, 88s were readily available alongside their 50s, etc., but now they’re almost rare in the general-offerings. You have to buy super-niche stuff like that wheel above or dig through their website to find the 88s even they even offer it.
For a long time, it seemed like the common sizes were 45mm, 60mm, and 90mm. TBH, there has never been that much difference between 60mm and 90mm. We saw that when FLO was very active and publishing their data. And other manufacturers had similar comparisons.
When I moved from 60mm front to 90mm front, I had no fantasy that it was materially faster. I got it almost solely for the cosmetics. I think that a 900mm just looks a whole lot cooler on the front of a bike.
I would not be surprised if manufacturers did not see a lot of 90mm sales, and if the performance deltas are not huge, they just simplified their product lines to just 45mm and 60mm/70mm offerings.
I think that might be true for front wheels nowadays.
However - I recall a conversation I had last year directly with HED prior to a time trial I was preparing for at that time.
I had a few wheel combos to choose from and asked the experts if it would be faster to run a 60/disc or a 90/disc combo for that race.
“Rock the 90” was the answer I got, and that was after my contact at HED got back with their engineering and testing team.
So who knows …
A deeper rim might be marginally faster, but that’s primarily at higher yaw angles. If you’re fast enough that a handful of seconds might matter, you’re probably not seeing high enough yaw for it to matter, so the companies are better off consolidating their product offerings
Still surprised though as typical advice for triathletes or time trialists wanting to buy all the gains they can reasonably get used to be choose the 88/88 or 88/disc every time.
I’ve never heard choose the 50s over 88s unless you felt really unconfident in you crosswind handling.
For sure when I was buying my current gen tri bike I was disappointed at first that the wheel set only went to hed v62 after coming from 88/disc rim brake.
Looking at the flo data, i wouldn’t consider the 60 and 90 to be meaningfully different until we’re between 5 and 7.5 degrees of yaw, and even then we’re talking about a single watt @30 mph.
Looking at the chart, someone might think there’s a significant difference, but personally i mostly care about performance at 0-5 degrees, and making sure something doesn’t stall or do something super silly between 5 and 10 degrees.
When you narrow it down to this range, you can see the difference is quite small for aero, but the 60 is lighter and will likely handle a little better, so the 90 just doesn’t make sense outside of some niche applications where you’re spending considerable time in massive crosswinds
That’s good data I didn’t know it was now widely accepted amongst the wheel makers.
For sure though handling a 60 is easier than an 88 for a front wheel in crosswinds. Although I still miss that lean into the wind effect of the 88s that psychologically makes me feel faster.
My dream future wheelset, whenever I get my next disc brake TT bike, are either Zipp 858 NSW/Disc or Princeton Carbonworks Mach 7582/Blur. I just need my lottery ticket to hit.
So, I am a triathlete. I want a deep, fancy 80mm or 90mm up front.
I don’t know if I’m smart enough to read that test correctly, but if a 90 front wheel saves me 14s over the 60 in a 40k TT, I’m all in.
14 seconds is a LOT in TT’s!
It all depends on how you weight your yaw, and that would imply they’re weighting the higher yaw angles more heavily. If they’re using the numbers in the chart, thats a bit disengenuous since you’re not going to see >10 degrees of yaw at 30 mph.
I’d guess 4 seconds tops over 40k, assuming 10 grams of drag is worth 0.1 seconds/km, which is a rule of thumb i seem to remember reading elsewhere, although it may not be a great assumption. At speed probably more like 2 seconds, since that ~10 gram savings is between 5 and 7.5 degrees of yaw, but at 30 mph you’re likely to see less than 5 degrees. For a tt with any elevation or any amount of technical cornering, the lighter wheel might be worth that much
Again, niche everything for the pros. But I’m talking about the main wheel offerings to the mainstream amateurs. 88s have disappeared from a lot of wheelbuilders that had them in the past.
Which wheel builders are that? Enve is the only one I know but they have a 100mm front wheel coming. Though it’s unknown if it’s coming to the general public. But they were also the same company that said a disc wheel wasn’t faster.
Zipp, HED, PCW, Dt swiss, Swiss side all still have 80mm depth wheels.
I’m just doing quick searches, but it’s hard to find or not available in current-gen disc brake models for at least: ENVE, FLO (but they’re close 76mm), ICAN, Superteam, Light Bicycle, Hunt, Elitewheels and more. Most of these same brands made 80+ depth wheels in the rim brake era, but stopped making them with the current-gen disc models.
Because - yes - the advantages of the deeper wheels are marginal, triathletes/TT riders aren’t keeping the lights on for any of these manufacturers, and mass start riders aren’t buying anything deeper.
