cervelo s3 wheelset problem

[thebadgerboy1982]

I've got problems with my wheelset!
currently riding a new style cervelo s3 with clearance for a 25mm tyre. I've got pacenti sl23, 20 front and 24 rear bitex lite hubs and sapim cx ray spokes. at 100 psi, my schwalbe one 23mm clinchers come up just over 25mm.

the problem is that I've got quite a bit of tyre rub against the chainstay near the bottom bracket area. so much that i can't ride the tyres at any pressure above 60psi.

is this due to the tyre being slightly above the 25mm clearance or due to a flexy wheel due to the low spoke count? I'm about 75kg.

my other question is about wide rim carbon clinchers. many have low spoke counts and wide internal rim widths meaning tyres sit wide on the rim. would i have the same issue with these wheels or would the stiff rim prevent tyre rubbing at the chainstay?

thanks
ross

[josephtroppo]

I'm riding my S3 with 25mm full carbon clinchers mounted with veloflex corsa 25mm. Still have more than enough clearance left..

With your weight spoke count shouldn't be the problem, just get the tension set right to eliminate the flex and you should be set to go...

[wingguy]

I'm riding my S3 with 25mm full carbon clinchers mounted with veloflex corsa 25mm. Still have more than enough clearance left..

Carbon clinchers usually have thicker sidewalls, so an external 25 usually means internal 17ish. The Pacenti is internal 20.5.

Still, surprising that there's rub with the 23s on a new S3. Probably a combination of inflated tyre size and flex.

[exctasy]

Rode the new S2 with enve 4.5 with 25mm corsas..no rubbing whatsoever

[Marin]

Guys, it's no help quoting sizes printed on the side of the tire. The OP should measure his tire with calipers and if it's over 25mm (likely) then it is too wide.

Light, ultra-wide, low profile aluminum rims with few, ultrathin spokes and a heavy-ish rider will also exacerbate the problem due to tire growth and sideways flex.