Snapped Off the Valve Stem

[michael whiteman]

Yesterday I had a flat on my rat bike and snapped off the valve stem (for the 2nd time). Last time this happened I inlarged the hole in the rim and chamfered both edges. The tube must be moving. Do I need to run more than 32psi ? I'm going to paint a mark on the rim and the tire. I don't think the tire is moving. If so, I'll run a few sheet metal screws into the bead like we did on our slicks back when we were drag racing. Your thoughts apreciated.

 

[Gordy]

Presta valve style tubes won't rip the valve stem as the stem is steel, but you can't run slime in them and they require an adapter to your air pump. I don't think the tube would rotate without the tire rotating. More tire pressure might help. I run 45 on my Cranbrook, but that ride isn't very cushy. I wouldn't run a sheet metal screw on a bicycle rim, there's not a lot of material there to begin with, and it could cause the rim to crack on a larger bump.

 

[Chainlube]

Tires will move when they get low on air. High outside temps will force out the air, requiring more maintenance.

 

[michael whiteman]

I took a closer look at Presta valves Gordy, and saw they attach to the actual tube in the same manner a Shrader type. My stem wasn't cut, more like it was pulled out of the rubber mound used to weld it to the tube. I'm going to try it one more time and run more air pressure like you hoping the tube and tire won't slide around on the rim any longer.
I don't know what else to do. Taking the rear wheel off is a real PITA.

 

[Wrench]

Last time this happened I inlarged the hole in the rim and chamfered both edges.

My stem wasn't cut, more like it was pulled out of the rubber mound used to weld it to the tube.

You shouldn't of enlarged the hole in the rim, The valve stem needs a tight fitting hole so the stem don't pop out , rip off

If you use a presta valve on a rim for a schrader valve you'll need to use a schrader to presta hole adapter

The tube must be moving. I don't think the tire is moving.

Yes the tire will move on the rim, especially if you have low tire pressure
The tube sticks to the tire and moves when the tire moves

Put baby powder inside your tire so the tube won't stick to it

. Do I need to run more than 32psi ?

Yes put at least 45 psi

BTW what tires are you using ?

 

[darwin]

What is it you're doing to snap the valve stems off? You need to figure it out and stop that behavior. 57 years of owning bikes I've never had issues with valve stems snapping off. I've had leaks in the valve, cuts in the stem from movement, never snapped though.

 

[robe]

I have some Slime tubes with Presta valves. They were on sale so I bought a couple. Also got a bag of adapters to fill them.
On some dirt bikes we had rim locks. Basically a metal U shape with a bolt sticking out of it. The U went inside the tire and the bolt went through a hole in the rim. Once set up a nut was tightened against the rim effectively clamping the bead to the rim.

 

[michael whiteman]

Bead locks on bikes ??? who would have thought. I run a double wall rim on the back and the original hole was way too tight. I only inlarged it for the stem to fit like all my other rims. I did not go oversize. Presta valves attach to the tube in the same manner, so I couldn't see any advantage there. I truely believe now that my issue is from low air pressure. The tire, and tube, must be moving under hard accelleration. I'm going to increase the pressure to 45-50 psi. Hopefully that will resolve this. Thanks guys for all your input.

 

[Wrench]

Bead locks on bikes ??? who would have thought. I run a double wall rim on the back and the original hole was way too tight. I only inlarged it for the stem to fit like all my other rims. I did not go oversize. Presta valves attach to the tube in the same manner, so I couldn't see any advantage there. I truely believe now that my issue is from low air pressure. The tire, and tube, must be moving under hard accelleration. I'm going to increase the pressure to 45-50 psi. Hopefully that will resolve this. Thanks guys for all your input.

Yeah, higher air pressure should do the trick But...
Put some talcum (baby) powder in the tire so the tube don't stick to the tire
That's why the tube moves it's sticks to the tire,

 

[robe]

I've been running about 30 to 35 psi and haven't had any problems yet. I tried 40 but just too bone jarring.
Granted I'm not running the hi output motors.
Talc is a good idea, I'll have to try that next time.