Hi guys. Hope to get some advice for my mate. He recently bought a new set of wheels from Merlin. Wheels were built with Mavic EN321 rims. The problem is that when he puts a wider tire 2.3 he constantly gets not punctures but it looks like the tube is cut just on the bottom of the valve (and that even when riding on road). He tried several tubes and presta or schrader valves and managed to trash 8 tubes in a month, as its impossible to patch that cut as its so close to the valve. Tubes were always for tires up to 2.3 so its not the problem, has got good rim tape and has those plastic bits on the valve hole on the rim. Its really annoying as it keeps him from riding his bike.

Strangely the tubes are ok and not getting cut when he puts a 1.95-2.0 tyre. But he wants to run bigger rubber as his bike is a long travel HT.

Anyone had a similar problem with EN321? Any ideas how to solve that?

Some tyres and rim combinations don’t work so well and the tyre slips around the rim causing the valve to rip. The easy solution is to try Shraeder valves or if that doesn’t work you could try a different big tyre which is tighter on the rim.

I have the same rims on two bikes and had this happen once. But then it’s also happened with other rims. What I do in order to reduce the chances (and I run 2.35 Maxxis down to 25psi) ;-

1. Not use ultra thin or thin inner tubes – the hassle just isn’t worth it.
2. When using presta valves make sure the little grommet is in the rim to support the valve.
3. Remove any burrs from around the valve inner hole of the rim.
4. Use cloth rim tape and overlap the vavle hole then cross cut it to push the valve through so the tape surrounds the hole. (or stick a couple of pieces of gather tape over the hole and do the same thing)

Hope these help.