Wide carbon tubular rims?

Everything about building wheels, glueing tubs, etc.
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by UpFromOne

TurboKoo wrote:
UpFromOne wrote:
TurboKoo wrote:I have R9100 tubulars wheels and 25mm Vittoria Corsa’s. Rims are 28mm wide.
28mm at the very edge of the tire bed? Or do they bulge out at the sides for toroidal aerodynamics, and that's where the 28mm is measured?
I measured 28mm from the brake tracks.
My rim is the one on the left
The profile of the tire bed on tubular rims varies wildly. In your spec, it appears there is a rather flat surface on each side for the tire, such that smaller tire might well fit, but you still risk gaps at the sides of a narrower tire.

by Weenie

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Location: Canada

by Geoff

Listen to Calnago. You are talking about a tubular rim. The width of the brake track is not the dimension you need to look at. What you need to be aware of is the width of the rim bed and its profile in relation to the tubular you are installing. That is why we always recommend test-fitting before gluing. You will be able to see that you have a good fit easily before you lay-down your first layer.

On those rims, you should have no problem with anything between a 23 and a 27.

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by RyanH

Further elaborating on Calnago's point about rim bed radius, you need to pay particular attention to your gluing procedure when the rim bed radius is not a perfect match for the tire. From my experience with my last few wheelsets and gluing larger volume tires on, if the tire is sitting high on the rim and not really seated into the channel (think something like this: O>) then from my experience the wheel won't feel very stable descending. I first experienced this back when I had Reynolds 32s and put 28mm Paves on them, bike would wander when descending above 30-35 mph. When I had the CCU, with a rim bed radius that was definitely designed for a 23, I had similar experiences descending with the 25mm tires on it. I remounted the CCU with 27mm Vlaanderen but paid closer attention to the adhesion and the end result was a stable wheelset again.

Even on my Enve, with the Vlaanderen, I had some slight lack of stability when descending. It wasn't bad with the Enve but getting on another wheelset it was apparent that the others felt better going downhill. When I pulled the Vlaanderen off last week, I noticed that the rim channel was pretty much untouched, so the tire was sitting "high."
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