Strange problem with tube in R460 rim

[jessand]

Had a puncture the other day and when I took the tube out I found that it had ripped near the valve. On closer inspection I realised that the tube had been pushed into the valve hole causing a shoulder to appear - this is where the tube had split. The hole in the top of the rim is big enough to put a schraeder valve in although the hole on the underside isn't. The rim is DT R460 which is tubeless ready, is this why the top valve hole is so big? Pic shows the shoulder that has formed on the tube. I'm obviously concerned that this will happen again. The tube is a decent quality Schwalbe SV by the way. Any suggestions on preventing this?

[colin54]

Schraeder/Presta adaptor...
https://www.sjscycles.co.uk/rims-tape/m ... to-presta/

[pwa]

Yes, wot he said.

[Brucey]

as a kludge fix (which works surprisingly well) you can fit a locknut to the base of the valve stem before fitting the tube to the rim. Schwalbe locknuts have a ridge machined on them which means that they locate in the larger hole quite nicely.

cheers

[jessand]

Thanks all.
Am I right in thinking the hole is larger to accommodate a tubeless valve?

[Brucey]

Thanks all.
Am I right in thinking the hole is larger to accommodate a tubeless valve?

Maybe; however many rims were (badly) made like that before tubeless was a thing for road bikes. Oftentimes a stronger than average rim tape protects the base of the valve to some extent, but there is no doubt that the valve itself is best supported by a close-fitting metal collar. If you look closely the valve stem will have a small ridge at the base; this will allow full support of the valve provided the collar is a close fit.

cheers

[jessand]

Thanks Brucey,

I'm using 'plastic' rim tape - Schwalbe I think. I'll fit the locknut as suggested. I bought the R460s as folk said the were easy to fit tyres to but I struggle with them and Michelin Pro 4 SC, not helped by geriatric hands!

[NATURAL ANKLING]

Hi,
Always check for burrs on any valve hole.
Even with the correct hole size on Presta valves I Like others here make a washer from an old innertube in place that over the valve before fitting.

[MikeDee]

Thanks all.
Am I right in thinking the hole is larger to accommodate a tubeless valve?

Do tubeless valves need a larger hole? I don't think they do.