Carbon Wheels Tradeoff

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CAAD8FRED
Posts: 161
Joined: Mon Jun 18, 2018 10:52 pm

by CAAD8FRED

At what depth rim does the trade off of aero and weight occur for carbon wheels? I know this is subjective based on brand and grade, but at some point the benefits of aero are outweighed by weight.

by Weenie


zefs
Posts: 351
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

Anything over 6% gradient I think, weight starts to matter more than aero. If you do a lot of elevation in one ride it adds up for energy savings, same for aero if you do a flat ride. You can optimize your position and see more aero benefit than getting deep wheels but it depends on your goals.

CAAD8FRED
Posts: 161
Joined: Mon Jun 18, 2018 10:52 pm

by CAAD8FRED

zefs wrote:
Thu Aug 02, 2018 7:50 am
Anything over 6% gradient I think, weight starts to matter more than aero. If you do a lot of elevation in one ride it adds up for energy savings, same for aero if you do a flat ride. You can optimize your position and see more aero benefit than getting deep wheels but it depends on your goals.
Would you say that 6% mark is based off of mid range depth like 50-64 mm

zefs
Posts: 351
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

Depends on the wheel weight and the speed you are going uphill. If you do a lot of hills but also flats a medium profile would be more suitable.
If you only do flats with a few hills now and then 50's would be better. There are a lot of variables as well, if you are light rider a too deep wheel can be unstable on crosswinds etc.
If you give us more information about your riding conditions and what you want to achieve there will be better suggestions.

alcatraz
Posts: 1889
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

For an uphill only race or strava climbing kom's go shallow.

For any other place/race with mixes of flats and descents I am 99% sure an 80-90mm deep wheelset still sees time benefits. Be it the difference is small to 50-60mm but if it were a time trial sure. For a race where you need mobility for attacks, and can hang around in a peloton the magic number is probably around 50-60.

So if riding alone and wind allowing, go as deep as you can. Front wheel is more exposed so the aero benefit is greater there of going deep.

/a

Imaking20
Posts: 1832
Joined: Fri Nov 18, 2011 5:19 am

by Imaking20

I'd love the 6% mark to be a hard rule - but I think there's definitely some bleed-over in either direction depending on how aero is aero, how light is light, and how strong the rider is. I remember the 6% figure coming most recently from Cannondale - and I believe that was figuring a rider climbing at 250w. Higher power output and the grade also increases before seeing a diminishing return on aero. Also, these comparisons are coming from ~7.5kg aero bikes and "light" bikes being the 6.8kg UCI limit.

So what if your aero bike is also ~6kg? :D
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CAAD8FRED
Posts: 161
Joined: Mon Jun 18, 2018 10:52 pm

by CAAD8FRED

zefs wrote:
Thu Aug 02, 2018 8:01 am
Depends on the wheel weight and the speed you are going uphill. If you do a lot of hills but also flats a medium profile would be more suitable.
If you only do flats with a few hills now and then 50's would be better. There are a lot of variables as well, if you are light rider a too deep wheel can be unstable on crosswinds etc.
If you give us more information about your riding conditions and what you want to achieve there will be better suggestions.
Have you ever had a problem with being light weight and being pushed around by crosswind.

CAAD8FRED
Posts: 161
Joined: Mon Jun 18, 2018 10:52 pm

by CAAD8FRED

zefs wrote:
Thu Aug 02, 2018 8:01 am
Depends on the wheel weight and the speed you are going uphill. If you do a lot of hills but also flats a medium profile would be more suitable.
If you only do flats with a few hills now and then 50's would be better. There are a lot of variables as well, if you are light rider a too deep wheel can be unstable on crosswinds etc.
If you give us more information about your riding conditions and what you want to achieve there will be better suggestions.
I live in Florida for 3/4 of the year near the coast (fair winds) and Connecticut for the other fourth. Connecticut is somewhat windy but it’s mostly punchy hills.

joejack951
Posts: 512
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

CAAD8FRED wrote:
Thu Aug 02, 2018 5:07 pm
Have you ever had a problem with being light weight and being pushed around by crosswind.
66kg cyclist and have been noticeably pushed around riding 40mm deep rims on a windy day. Building some 25mm deep rims not only for the weight reduction but to take out on those windy days as well.

zefs
Posts: 351
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

Yes same here, on that kind of weight (around 65kg) a 50 profile can be an issue with gusts of 30kmh+
There are wheels out there that reduce that effect (mostly high end) but still being a light rider you will be pushed around.

CAAD8FRED
Posts: 161
Joined: Mon Jun 18, 2018 10:52 pm

by CAAD8FRED

zefs wrote:
Thu Aug 02, 2018 7:59 pm
Yes same here, on that kind of weight (around 65kg) a 50 profile can be an issue with gusts of 30kmh+
There are wheels out there that reduce that effect (mostly high end) but still being a light rider you will be pushed around.
I’m even lighter. I wonder if high speed banking turns could induce a cross wind that could also be painful?

zefs
Posts: 351
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

If it's not windy I wouldn't think so. But one time I was turning right (downhill) and because of the wind the bike turned left which can be scary. Only happened once and even on low profile rims. I would say try before buying them somehow.

alcatraz
Posts: 1889
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I had scarier crosswind experiences with my 20mm shallow boxy alloy rims than I have had on my 88mm carbon toroidal rims.

The rim shape has a lot to do with crosswind stability. I was very cautious going deeper because of what people write. Looking back I think that was exaggerated. However it successfully brought my attention to side winds.

TobinHatesYou
Posts: 3292
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

My best times up 8% climbs are with ENVE SES 5.6 Discs and not my shallower wheelsets. The weight difference is about about 100g to my Zipp 202 NSWs. Perhaps with a lot of accelerations, the weight will make a difference, but if you are climbing at a steady speed and aren’t weak (somewhere around 10mph,) the deeper wheels should be faster.

zefs
Posts: 351
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

That's why I am asking what he is trying to achieve. A one time effort to get a PR would be different than many hours of climbing were wheel weight would matter more (100g not that much though).

by Weenie


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