Are the new KH drilled rims more susceptible to pinch flats?

Has anybody else found that the new KH rim gets pinch flats a lot more often than the older KH or Alex DX32?

I’ve had 4 pinch flats since i’ve had mine, which is 4x as many as I had on my old tyre/rim set up running the same PSI (25).

Anyone else having this problem?

My vote would be yes, they are more susceptible. On my old 05 KH20 (the older KH rim), I didn’t pinch flat once in about 8 months riding.

On my new ISIS KH with the drilled rim I’ve already pinch flatted once jumping down a 7-set. Having said that though, I still like the new drilled rim for looks :stuck_out_tongue:

Maybe we need a poll on here?
Anyone care to ask Harper if its ok? :stuck_out_tongue:

Grr, I hope not.

I never pinch flat on my rim, but I rarely bottom out.

Im gonna hate if I have to constantly patch or buy new tubes, maybe just getting the 2006 rim put on there would be better. Or put my Alex rim on the 2007 once I get it.

Ill just have tow ait and see if it does end up giving me pinch flats.

What size wheel (trials or muni)? What type of tube? What tyre?

I’m going to assume a trials wheel. Standard 20" tubes are already stretched thin to fit a trials tyre. If the wider rims are more prone to pinch flats with trials tyres then the overstretched tube is going to compound the problem.

There is a moped tube that will fit a trials wheel. I’m not sure of the exact size designation for the moped tube, but municycle.com sells it. It’s a thicker tube, which also means it’s heavier.

There is also the theory of putting talc powder inside the tyre to keep the tube from sticking to the inside of the tyre. That allows the tube to move inside the tyre which may help prevent some types of pinch flats. But there is debate about that.

On my Norco Twenty with a Maxxis Max Daddy, I run a Puncture Resistant tube from Canadian Tire. I know after a while I have to let some air out, and pull the tire on the rim a bit to slide the tube back into place, or I risk shearing the valve stem right off. I have this problem on my BMX too after I do a lot of hopping.

I could just see any powder making this problem worse for me. But I’m not running a 19x2.5 tire, it’s a 20x2, and 20x2.1 on my BMX.

But these Puncture Resistant tubes, NEVER pinch flat, they’re absolutely awesome. I could run around on 20psi and I weigh 140 pounds, jump off any ledge I can find and it won’t pinch flat.

That can happen when the tire slides on the rim. If the tube is stuck to the inside of the tire the tube will rotate with the tire, possibly shearing the valve stem off.

When you run low pressure in the tire there is less force holding the tire in place against the rim. So a low pressure tire is more likely to rotate or slip on the rim like that. In extreme cases people will glue the tire to the rim to keep it from slipping or rotating on the rim.

If the tube is free to slide inside the tire it is possible for the tube to stay where it should and not have the valve stem go all wonky. No guarantee of that though. Still, it’s easier to straighten out the tube again if it’s talced and not stuck to the inside of the tire.

I agree with JC.

IRC makes fat 19" tubes that fit trials tires perfectly. try one of those.

edit:

the valve stem on the irc is threaded all the way down to the tube, and has a metal “base” before going into the rubber, and they supply two nuts for you to lock down on the rim, problem solved.

Joe’s been using the stock trials tube in his tire - a cheng shin 20x2.125 trials tube.
I am running a two tube setup, instead of using a rim tape I use a trials tube which has been split down the center. But im not using a drilled rim either

This may be true, but they are not available in 20 x 2.5" size AFAIK. I bought one of these puncture resistant tubes at a bike shop, thinking it would halt my string of pinch flats, and installed it immediately on my trials wheel. It did not stretch at all, so the tube was pumped up hard and the tyre was still loose. I returned the tube straight away and got a standard one instead.