Aero Wheels not worth it?
rwoofer
Posts: 210
in Road general
GCN Tech did a great video on cheapest aero gains and one of the worst value for money upgrades were aero wheels
https://youtube.com/watch?v=hd0fXhDkH84
At 35kph (a reasonable speed) the saving from standard to aero wheels was only 5W. This rather suggests that light weight is a much more advantageous attribute that aero, which seems to go against all other advice you read. Did they get it wrong, or indeed are we all falling for the marketing BS.
Personally I've found the sweetspot for wheels to be semi aero (eg. 32mm) lightweight wheels.
https://youtube.com/watch?v=hd0fXhDkH84
At 35kph (a reasonable speed) the saving from standard to aero wheels was only 5W. This rather suggests that light weight is a much more advantageous attribute that aero, which seems to go against all other advice you read. Did they get it wrong, or indeed are we all falling for the marketing BS.
Personally I've found the sweetspot for wheels to be semi aero (eg. 32mm) lightweight wheels.
0
Posts
The sort of gain 50mm aero wheels give you at 30 mph is 1 kph. Not a lot but something.
The deeper the rim the more aero it is. 32mmm deep well that not that aero and you may be adding 0.3 mph maybe 0.5 mph to you speed vs a set of mavic kyrseriums.
It's obviously hard to perform controlled testing but I always ride with a dual sided power meter and the consistent improvement in times on strava segments (and the power required to record the times) could not be ignored - I pretty much straight away ordered myself another set of rims and hubs so that I could build up some for my disc braked bikes.
Obviously if you find you struggle to handle a bike with deep rims or are always riding in a group then I can see why you would avoid them but I'm an absolute convert.
Clean air at 0 yaw is almost never experienced in the real world, and the benefit of deeper wheels is that they keep the airflow attached to the surface over wider yaw angles.
If the wind is completely straight on (as in this video) then the wheel is basically sheltered by the tyre so has very little scope to offer an improvement even if you're using a full disc.
Hambini has a number of videos etc about all this if you want to go deep.
The thing is, obviously there is lots of speed to be gained from getting low and using tri bars and a big aero helmet, but that doesn't necessarily make it practical for your riding (if you have to ride in traffic, or are doing the saturday chain gang...) whereas deep sections can be used under most circumstances with minimal adaptation.
Hambini (who has been on GCN Tech videos) has done tests with lots of different aero wheels and has used the Mavic Kysrium as the shallow wheel to compare with:
https://www.hambini.com/testing-to-find-the-fastest-bicycle-wheels/
He found at 30km/h a 10 watt difference between the Kysrium and 50mm made by Malcolm who posted above and a 37 watt difference at 50km/h which is certainly a speed you're at quite often if you ride things like chaingangs.
Obviously, other brands vary and if you go deeper then the watts saved gets even greater.
Given aero wheels tend to cost £1000+ 10 watt difference is still fairly poor cost per watt saved compared helmets, bodysuits etc. which I think was the point of the video. I would be interested how quickly the aero benefit tails off. For example what is the difference between 32mm and 50mm, which is the rim depth of typical carbon climbing and allround wheels vs deep section 60mm+ wheels.
T.
Nonetheless, in the majority of the grand tours (Tour, Giro, Vuelta), you clearly see the pros changing to lower rims when things go steep.
Buying a set of wheels have to have those things into account: the terrain you ride the most or, if your budget allows, at lest 2 pairs of wheels for the same bike.
On a ride with 100 kms and, let’s say, 1500 elevation gain, you won’t gain nothing riding a 50 or 60 deep section wheel. The seconds you gain in the flats or descends will be much less important than the ones you loose on ascents because of the higher rotational and overall weight.
On top of that, saying that a wheel with a 50 mm depth will be more aero than a 33 or a 38 is just plain wrong. If you want a proof of that just look at the wind tunnel comparison of the A-Force AL33 and the Zipp 303. Basically 33 VS 45 mm and see the results, now at various yaw angles (so no excuses there).
Strava segments say nothing! You can put the exact same effort on a segment (which I really doubt), and have significant time differences related to a zillion of factors (your own weight, a bottle filled vs an empty bottle), humidity, asphalt conditions, your position on the bike, drag, wind and so on).
Summing up, I’m always saying to the friends I ride with that wheels are the most paradoxal item in cycling. Someone once told that they were the “best secret” in the business, and the guy who said that probably told it so many times that everyone started to believe it.
Wheels are just that. Deep section really looks cool on your bike and you spend a lot of money for that. They really give you a - small - advantage over flat terrain and descends, but learn to tuck the right way behind your cockpit and you’ll blow away any advantage that a 2000€ wheel set will give you.
You can reply that tucking and adding a deep section wheel set will contribute even further to added gains, but a simple helmet will do a much better job and it will cost you 1/10 of the money!
I can ride my 50mm deep wheels on flatish terrain and hilly terrain in yorkshire and they feel great in both landscapes. Im not a pro so saving a three hundred grams over a "climbing wheelset" wont get me up any quicker.
No one has to buy a set of deep section wheels but to say they dont make a difference that is noticable is simply bollox. They make a difference but you can still enoy riding on high spoke wheels. threads like this always get the anti aero crowd out to spout there rational. These threads achieve nothing. Aerodynamics is not a field you can discern from a couple of graphs posted by Zipp and others. The best treatment of it is done by Hambini. Air flow in the real world is not static so static flow testing of wheels in a wind tunnel does not tell you much about they will perform in the real world it will tel you how they perform in that wind tunnel though. I am not sure how many windtunnels you ride in...
Thing is, I have an aero helmet, it's great for early spring and autumn but in summer I cook. But yeah, it was practically free from planet X so definitely worth getting one.
Similarly, getting low in the drops and slamming the stem, of course that helps, but it also can make it harder to get the power out, and fatigue you faster - it's a balance in short.
What works for riders in a huge peloton with a lead car is very different from what works for us in the real world.
If I can save a few seconds on the commute, or just plain have an easier time of it, then that's worth it to me.
Seriously, wtf? Can you not stick to one unit?
Winter
Racey
Special Favourite
If in doubt, blame Wiggle.
I cant say I have done back to back testing but on two consecutive calm days I rode both wheels. The carbons were faster, quite noticeable at times just how much faster as well.
Of course they are much more aero, but also better tyres latex tubes all add a bit, but they are genuinely quicker, your never going to suddenly become a pro slapping some deep wheels on but it will give you some extra speed, I wont say for free as you have to buy the wheels.
Also I think we should all be measuring speed in knots currently. general road conditions it would seem more appropriate.
Easty commuter
Tripster AT
No need to apologize. Forums are just that, a great way to share and discuss different points of view, hopefully with the right amount of common sense.
What do you mean by 'faster'? For whom? Doing what? Over what terrain? At what speeds?
'Aero' is incontrovertibly faster than 'not aero'. Would you make more gain from wearing a skinsuit? Yes, usually - but doing that on the commute would make you look a bit of a prat, whilst doing it on a TT would be appropriate
Am I 'faster' on my race wheels (60mm Rovals) than I am on my training wheels (regular Ksyriums)? Yes - appreciably. If I do a flat 40km training loop (no drafting, solo) on my regular wheels I average about 34k/k, whereas on the race wheels, I'm 2k/h faster. Is that a massive difference? Again - it depends what you're doing on them. If I was commuting to work, it might get me there three minutes quicker... but if I'm in a race and working in the break, it might mean I win as I'm doing less work than other people in the break (although they're likely to be riding deeps as well, of course)
Your post doesn't make a lot of sense, and there's no pointy getting hissy about it. People are pulling you up on it because you're making an assertion based on one small part of one GCN video and extrapolating it to fit some view that's counter to decades of aerodynamic science
There's a few excellent articles about 'bang for your buck' around the internet that suggest you should invest in things in the following order (for a time trial - obviously some of the stuff on this list doesn't apply to regular racing, and less still to 'normal' riding:
1 - Position (tri-bars, followed by a good tuck, followed by expensive analysis)
2 - Skinsuit
3 - Shoe covers
4 - Aero helmet
5 - Trispoke front (a deep section rim if you can't afford one)
6 - Aero frame
7 - Rear Disc
Even those are flawed, since they're largely based around 'value' eg: a set of shoe covers might save you 30 secs on a 25 mile TT, whilst an aero lid might save you a minute, but cost 200 quid. Also, the Skinsuit will save a huge amount of time, but only really over loose fitting 'regular' jersey and bibs - if you already ride in tight 'race fit' clothing, you won't get the same amount of benefit.
Specialising in Git Daaahns and Cafs. Norvern Munkey/Transplanted Laaandoner.