How Tall is Too Tall: Wheel Profile

[pjmsj21]

I am looking at purchasing a set of carbon wheels for my wife with a 38mm profile. We ride in mountainous conditions with some side drafts. In addition we are older riders at 65 and with age comes a bit more cautiousness when descending.

Her current wheel set is probably in the 25 mm area/

Would you be concerned about 38mm profile?

[Matthew]

I went from low profile DT Swiss rims to Shimano C 35's recently. I honestly can't tell a big difference with wind. Here in west Michigan we get a ton of wind due to the fact Lake Michigan is 60 miles wide and there is nothing to block the breeze! I was expecting a big difference but I have really not noticed much. Others may feel differently. Matthew

[Dead Man]

Why do you want a taller rim? Sounds like a shorter rim is more appropriate for what you're doing

[Matthew]

I would add that braking issues may be your biggest concern. Are they going to be full carbon wheels or have an aluminum braking track? Make sure you use the right brake pads and test them in various conditions.

[Dead Man]

Why do you want a taller rim? Sounds like a shorter rim is more appropriate for what you're doing

I think I understand - a deal has popped up, and it just so happens they're taller.... not that you're looking to GO taller.

In that case, you probably won't have any real issues. I think lower is probably "better" for all around riding, but my new "all around" wheel is a 32, and it's not bad in the wind. I do think I get tugged around more than with my 24s when it's gusty, sure... but it's not like I'm getting throw off the bike

except for that one time last week when I did literally get thrown off the bike...

[pjmsj21]

Why do you want a taller rim? Sounds like a shorter rim is more appropriate for what you're doing

Actually I am trying to balance a small bit of speed increase with a very rideable wheelset.

Plus the wheelset is 38mm.

[fuzzalow]

I am looking at purchasing a set of carbon wheels for my wife with a 38mm profile. We ride in mountainous conditions with some side drafts. In addition we are older riders at 65 and with age comes a bit more cautiousness when descending.

Her current wheel set is probably in the 25 mm area/

Would you be concerned about 38mm profile?

Ride aluminum alloy rims with tubulars under these conditions. A rider can largely employ the brakes however they wish to whatever level of caution desired. The resultant heat is less likely to destroy the rim and in so doing lessen the chance of crashing the rider.

Aero means nothing in the climbs. I know you asked about carbon but with the conditions you've specified, there is a pretty big mismatch of equipment to task. IMO.

[shovelhd]

Aluminum wheels are a better fit for cautious descenders.

[ergott]

I don't think the 38mm wheels will do much for her. Enve 3.4s or Zipp 202s are nice and all, but that's a real big cost for fractional gains in speed.

What wheels does she have now? I agree that if descending is a concern alloy is more user friendly in unfamiliar areas.

[makoti]

I'll echo some thoughts here, already. Carbon for mountains & cautious descending don't seem to be ideal to me. Wanting faster wheels I understand, but to use all-around, I'd go alloy.
I would consider getting a set of alloys built up for her. Matched to her weight & riding style, she'd probably be happier.

[Ken Robb]

Being an old guy myself I wonder how much extra speed she can gain from aero wheels. At what speed does their aero advantage begin to matter? Can you maintain that speed on the flats? Are you presently bombing downhills without braking and wishing you could go 2 MPH faster while doing it?

[pjmsj21]

I don't think the 38mm wheels will do much for her. Enve 3.4s or Zipp 202s are nice and all, but that's a real big cost for fractional gains in speed.

What wheels does she have now? I agree that if descending is a concern alloy is more user friendly in unfamiliar areas.

She is riding a set of clinchers on Kinlin XR-270's on King Hubs with CX-Ray 20/24.

She would be moving to a very low mileage set of 1300 gram set of 38mm carbon tubular wheels.

[shovelhd]

I have no problems with bombing 50+mph descents on 38mm carbon wheels (1200g tubulars). With the right pads and proper technique it is safe. I'm not a cautious descender.

[Dead Man]

I have no problems with bombing 50+mph descents on 38mm carbon wheels (1200g tubulars). With the right pads and proper technique it is safe. I'm not a cautious descender.

Same same.... but I think the difference the guys above are referencing is the fact that she's probably going to be grinding the brakes the entire way down.... whereas you and I only hit the brakes momentarily right before curves, and the rims get a chance to cool between curves.

[shovelhd]

Same same.... but I think the difference the guys above are referencing is the fact that she's probably going to be grinding the brakes the entire way down.... whereas you and I only hit the brakes momentarily right before curves, and the rims get a chance to cool between curves.

Which is why I recommended aluminum wheels. Faired if need be, but aluminum brake tracks.

[pjmsj21]

Same same.... but I think the difference the guys above are referencing is the fact that she's probably going to be grinding the brakes the entire way down.... whereas you and I only hit the brakes momentarily right before curves, and the rims get a chance to cool between curves.

She's not that cautious. She get into the high 30's pretty regularly.

There is probably a 300 gram weight savings over her present wheelset.

[shovelhd]

Clinchers or tubulars? Carbon clinchers require more care when descending.

[pjmsj21]

Clinchers or tubulars? Carbon clinchers require more care when descending.

Tubulars

[happycampyer]

Wheels in that profile range are generally less prone to being blown around in crosswinds, and particularly the newer, blunted shapes from Enve and Zipp. I wouldn't say that they can't be felt, and generally the lighter the rider the more one will feel it. Does your wife ride in the drops when she descends? Having the proper amount of weight over the front wheel makes a big difference.

As others have noted, the braking is likely going to require more of an adjustment that handling crosswinds. The braking quality of carbon rims has gotten progressively better over the years (brake pads, too), to the point where at least in the dry there isn't a huge difference between the best carbon rims and aluminum rims. In the wet is another matter. I've been caught in the rain on a variety of latest generation carbon wheels (Zipp, Enve, Lightweight, Campagnolo) and would have been much happier on wheels with aluminum rims. If I'm expecting rain on a ride, I will take a bike with aluminum rimmed wheels on it. If these wheels will be your wife's only wheels, I would think twice about it. From the weight you mentioned, it sounds as if the rims are all carbon (i.e., no aluminum brake track).

It is possible to get a low profile, aluminum rimmed wheel that is much lighter than your wife's current set of wheels, and that will still ride solidly and confidently. If you get the carbon wheels, try them out on hilly terrain before heading for the mountains. It's important to get to know how differently the wheels feel under varying conditions before pushing ones limits.

[ergott]

She is riding a set of clinchers on Kinlin XR-270's on King Hubs with CX-Ray 20/24.

She would be moving to a very low mileage set of 1300 gram set of 38mm carbon tubular wheels.

More like a 150g drop in weight. That set is about 1450g.

If the deal is really that good and she likes them that's great. I wouldn't expect to see really large differences in speed. That's already a really nice set of wheels.

[pjmsj21]

More like a 150g drop in weight. That set is about 1450g.

If the deal is really that good and she likes them that's great. I wouldn't expect to see really large differences in speed. That's already a really nice set of wheels.

Well it is sounding like the trade offs don't really warrant a change.

[carpediemracing]

She is riding a set of clinchers on Kinlin XR-270's on King Hubs with CX-Ray 20/24.

She would be moving to a very low mileage set of 1300 gram set of 38mm carbon tubular wheels.

Why not buy the 38s and keep the Kinlins? The whole n+1 thing with wheels blah blah blah.

[El Chaba]

The "need" for aero wheels for anybody riding at speeds less than 40 kph (25 mph) is one of the most oversold aspects of cycling marketing at the current time....and the loss of braking performance in the most critical conditions makes the compromise even more incredible...

[oldpotatoe]

Actually I am trying to balance a small bit of speed increase with a very rideable wheelset.

Plus the wheelset is 38mm.

Due to...aerodynamics? Unless pretty quick, high average speed, I'd say the drawbacks(windy and being pushed around) outweigh and 'small bit of speed increase', even if there was some. IMHO.