What am I doing wrong?

term1te

I glued my first tubular tyres last night, I've always used tape up until now. I watched several video tutorials, and carefully read the instructions that came with the glue, but they are clearly not on properly. They are Vittoria Evo tubs on PX carbon rims, and I've used Continental glue for carbon rims. I cleaned the rims of all the old tape residues, gave them a going over with fine emery paper and finished it off with some alcohol, a nice Italian Sangiovese for me and fondue burner alcohol for the rims. Then applied a thin layer of glue to the rim and the tube tape and left them overnight. This morning I applied a second coat to the rim and set the tub in place, lined it all up straight and inflated it to around 80 psi. All looked OK

Went and had a look after about five hours, and on one side of the wheel the tub has separated from the rim by about 1mm all the way around, on both wheels. Looking between the rim and the tub tape you can see it has separated almost halfway across the rim.

This doesn't happen on the video tutorials, or in the instructions, so what am I doing wrong? All advice gratefully received.

sungod

remove the tub, then you can see what has happened

in decreasing order of general likelihood...

i) if the glue has separated from the rim, rim contaminated, maybe the fondue alcohol wasn't so pure

ii) if the glue has separated from the basetape, but the rim is still glued, maybe basetape contaminated or the glue has not seeped into the basetape enough or simply not enough glue

iii) if the basetape is still glued, and the rim still glued, do the tub and rim have radically different profiles? i.e. rim bed radius much greater than that of the tub, tbh i would not expect this to be the issue, but it's possible

fwiw i use vittoria mastik one on cf rims, it's very good, not tried conti glue but it's reputation seems to not be as good

i give the basetape a coat, the rim gets three thin coats 12-24 hours apart, mounting the tub on the last coat, once lined up, inflate a bit, straddle the wheel and push down on it to squish out any airpockets, gradually rotate the wheel until the whole circumference is done, inflate to max, ride it the next day; only real issue i've had is the bond being so strong it's hard to get the tub off

Semantik

Term1te wrote:

I glued my first tubular tyres last night, I've always used tape up until now. I watched several video tutorials, and carefully read the instructions that came with the glue, but they are clearly not on properly. They are Vittoria Evo tubs on PX carbon rims, and I've used Continental glue for carbon rims. I cleaned the rims of all the old tape residues, gave them a going over with fine emery paper and finished it off with some alcohol, a nice Italian Sangiovese for me and fondue burner alcohol for the rims. Then applied a thin layer of glue to the rim and the tube tape and left them overnight. This morning I applied a second coat to the rim and set the tub in place, lined it all up straight and inflated it to around 80 psi. All looked OK

Went and had a look after about five hours, and on one side of the wheel the tub has separated from the rim by about 1mm all the way around, on both wheels. Looking between the rim and the tub tape you can see it has separated almost halfway across the rim.

This doesn't happen on the video tutorials, or in the instructions, so what am I doing wrong? All advice gratefully received.

Don't think you've done anything wrong tbh.
I also run Vittoria Evo CX tubs(21mm) on PX carbon rims. The tubs don't fit very well- the rim profile is somehow not matched to the tyre. I also glued mine meticulously over a couple of days- same result as you. By comparison I fitted the same model of tub to a Fast Forward wheel and the tyre fitted much better- interface between rim and tyre seemed to be much improved.
Tbh unless you are cornering like a lunatic the tubs will doubtless be ok as they are- mine have been ok over 2 seasons. If you are still worried, you could deflate the tyre, brush some more glue into the 'gap' and re-inflate. But I challenge anyone to get things looking perfect with this tyre/rim combination.

ugo.santalucia

+1 to what Semantik said.
If the tube doesn't match the rim profile you get that, especially around the valve... nothing to worry about

mitchgixer6

I had an issue with conti glue/planet x/vittoria combo. Once I switched to Vittoria mastik I had much better results.

ugo.santalucia

I have fitted several Vittoria CX to Gigantex tubs (older 20 mm wide ones) and the fit is never perfect, as the OP described. Conti GP 4000 (22 mm) did fit a lot better

pippi_langsamer-2

I think you wasted too much time trying to remove old glue, but yes- I used to get "bumps", when I installed CX's on Shimano DA carbon 50's also. They never budged although it did bug the life out of me... #OCD

term1te

Thanks for the advice and comments. I think there is a fundamental mismatch in shape between the tub and the rim. I've removed the rear, which had the largest "gaps" and have started re-glueing the rim. If that doesn't work I'll try to get hold of some Vittoria mastik. That said, removing the rear tub took some effort, so it was obviously attached fairly well. The glue, where it came off, came off the rim rather than the tub tape.

term1te

So I reglued the rims and tubs and tried again. They looked a bit better, and after the obligatory 24 hour wait, I went out on them yesterday. Seem to roll very nicely, but there is a constant crackling sound coming from the wheels. I suspect strongly it is the glue snapping or crunching as the tub moves at the edge of the rims, where it isn't fully adhered. The tubs seem very firm on the rims, much less movement than there was when I used tape, but the crackling sounds not good is it?

Do I give this up as a bad lot, or get hold of some Vittoria mastik and try again? I've been using Conti carbon glue.

ugo.santalucia

Term1te wrote:

So I reglued the rims and tubs and tried again. They looked a bit better, and after the obligatory 24 hour wait, I went out on them yesterday. Seem to roll very nicely, but there is a constant crackling sound coming from the wheels. I suspect strongly it is the glue snapping or crunching as the tub moves at the edge of the rims, where it isn't fully adhered. The tubs seem very firm on the rims, much less movement than there was when I used tape, but the crackling sounds not good is it?

Do I give this up as a bad lot, or get hold of some Vittoria mastik and try again? I've been using Conti carbon glue.

No, it's the tyre... well known combination of Vittoria CX + Gigantex tubs... the tyre screeches on the tarmac and the vibrations are enhanced by the hollow structure of the rim.
Then there is the valve clicking, but that's another story...
Carbon huh? What a PITA...