I have a set of ritchey WCS Carbon wheels (made by zipp, non-dimpled 404’s).
My wife’s race set-up includes the front wheel from the 404-like set and she is running a tri spoke rear wheel. Because of the combo, I plan to send her out with two tubes with 42mm stems with valve extenders on them so they will work with the 404 if needed and she can just pull off the extender for the use on the tri spoke.
My problem is that the valve stem hole on the 404 rim is to small for the extra width of the valve extender.
I was thinking of just getting out my dremmel tool and epening up the hole a little but at the high speed setting with a drill bit in the chuck. So I don’t spliter the carbon I was going to first try to go in from the hub side. If that doesn’t work I was going to go in from the rim side and just put some duct tape over the hole on the hub side to prevent splintering on the exit hole.
I had this problem with a set of Planet X 50mm wheels. HOWEVER, rather than chance my “dremel expertise” on the carbon rim, I took the dremel to the valve extender and ground that down enough to fit through onto the wheel. Cheaper to replace the valve extender than the wheel.
One of my 404 rims had this issue. I never did like the valve extenders that simply go over top of the existing valve (Zipp extenders). I would suggest you try and find a Vittoria or Tufo (or similar) valve extender that is designed to hold the valve core on top. You will need a tube that has a removable valve core, but worth the effort. They are narrow and fit through the rim, you always have access to the valve core, etc.
well, here’s the thing. carbon isn’t like a metal. if you cause a tear like that, you’ll open up a micro fissure in the material, a micro fissure that will grow until it’s a full blown crack and failure.
Another thing to try: the latest version of the Vittoria Corsa EVO CX tires (the one’s with the 320tpi count) have fully removable valve stems, allowing you to extend the valve using their extender connected directly to the tire, with the original stem sitting on top of that (protruding out of the rim hole). This differs from other tires which have the valve stem permanently attached to the tire, requiring you to put the valve extender on top of the valve stem. They are also working on longer original valve stems (not available at the time I bought a set of these tires earlier this season) that allow you to avoid valve extenders all together- you just but the stem that will poke out of your rim.
If those don’t fit, I’d question the quality control of the valve hole on the rim, because those tires are top sellers and the valve stem is not overly porky. Shouldn’t require any further modification!
I also echo what others have said about cutting / drilling into carbon-- carbon can look great, right up until the second before it EXPLODES catastrophically! Speaking as a guy whose had 2 Zipps crumple underneath him (one front, one rear) I promise it’s not fun!
well, here’s the thing. carbon isn’t like a metal. if you cause a tear like that, you’ll open up a micro fissure in the material, a micro fissure that will grow until it’s a full blown crack and failure.
Well, you should not take a rough file and handle it like a brute…
A fine needle file or sand paper should do the trick.
Take your time, file away slowly!
Take the valve extender andstick it in your drill. Take a piece of sand paper and while the drill is on, sand the outside of the extender until it fits!!!
**do not drill the carbon rim. Extenders cost $5-$10. rims cost $200+; if you crash due to fracture propigation due to a stress riser that you introduce into the structure by some accident, the cost is much higher. **
No problem Dave. Remember to put on a little teflon/plumbers tape around the tire stem so that you dont need as much torque to get a seal…this way if you have taken a bunch of material off, it will still work. Remember, you only need it strong enough to withstand about 120psi, which can be done with very little aluminium.