Bicycle Mechanics - How to prevent tire buldge at valve?
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06-17-09, 12:11 PM
Hey folks, several times when repairing flats I've had problems with the tire bead seating properly in the rim in the area of the valve stem. It tends to buldge out. In a couple cases the bead has popped out of the rim entirely as I inflate. In other cases the bead stays in, but the buldge is noticable when riding, I can feel the bump-bump-bump as I ride and the buldge ticks against the fender.
I just mounted up a new Armadillo on the back ... same thing, tire buldge at valve stem! I finally got it rideable, but nowhere near perfect.
What's going on? Is this common? Anything I can do to stop this from happening?
Oh, by the way, standard aluminum rims on a Specialized Sequoia with 700-25c tires.
06-17-09, 12:16 PM
Try a different brand of tube?
Also try mounting the tire bead right after the value so it's not near the end. Then squeeze the beads on both sides near the value before you start inflating.
06-17-09, 12:18 PM
Very simple solution, and i've had it happen a few times, and to a few friends. When you put the tire on the rim, push the valve stem into the tire once it's mounted. Them, push the sidewall in near the vavle to make sure the tube isn't protruding underneath the bead. I always "massage" the whole tire after doing that to make sure its seated and the tube won't be pinch in the bead of the tire. Do that and you shouldn't have a problem!
06-17-09, 12:51 PM
The firm rubber base of the valve is interfering with the tire bead essentially sitting below it - common on these narrower clincher rims with some tubes. Make sure valve is pushed up into the tire before starting to inflate.
Very simple solution, When you put the tire on the rim, push the valve stem into the tire once it's mounted. Then, push the sidewall in near the valve to make sure the tube isn't protruding underneath the bead. I always "massage" the whole tire after doing that to make sure its seated and the tube won't be pinch in the bead of the tire. Do that and you should have a problem!
+1 This is the way to do it. With the tire and tube mounted and with very little air in the tube, push the valve stem into the tire while seating the bead.
06-17-09, 02:17 PM
Thanks as usual for all the quick and excellent advice folks. Pushing the valve stem in during seating sounds like the solution, I'll try it tonight.
I used to have the same problem until I learned to inflate the tube with just enough air to give it shape after inserting the stem into the valve hole, eliminating the overlap that gets caught by the bead. Then I install the tire bead. Works every time. Of course this means that you use a frame pump or mini pump,as you can't partially inflate a tire with a cartridge.
Of course this means that you use a frame pump or mini pump,as you can't partially inflate a tire with a cartridge.
You can put enough air in a tube before mounting by blowing into it. I haven't carried a pump in 11 years.
06-17-09, 09:25 PM
Don't start and stop the tyre-mounting at the valve-stem. Start 90-degrees away and go towards the valve-stem along the way. Will take care of 90% of pinched-tube problems right away. The other 10% you can fix by pushing the stem back into the tyre at the end to un-pinch it at the end.
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