paulie2424

Hello everybody-
Last summer and already this season I've had a number of flats on my road bike. After examining the tire and tube after each incident I would find the tube to be split open right around the valve stem while the tire itself always appeared to be perfectly fine. I've tried loosening the little tightening ring that goes on the valvestem, but the flats kept occuring. When I would change the tube, I would always inflate the tube and tire, deflate them, and then re-inflate them again before riding because I thought this would help seat the tube within the tire. Could the problem be cheap tubes or am I doing something wrong here?
Thanks for the help!

San Rensho 

Very common. Be sure the valve hole had no sharp edges, use a round file to clean it up. Be sure the rim strip is good and I would also put a piece of duct tape over the hole from the inside and pierce the duct tape with the valve stem as you put it through the hole.

Steev

What sort of pump are you using? If the connection to the tire is integral to the body then you need to hold the spokes as well as the head so you're not wrenching the valve stem back and forth as you pump. This will cause the failures you're seeing as well.

phoebeisis

Good points above-careful when inflating tire-gently on the valve stem-and make sure you take any edges off the rim-duct tape or a second layer of rim tape in that area sounds good also.If the rim is double walled-take the edges off both walls.Use a rat tail file,and then 600 grit wet-dry sandpaper(wrapped around file or something thin.Make sure you get rid of any metal shavings(blast with hose.)
You might try one extra technique during the 1st inflation.
1)After you have installed the rim make sure the stem comes straight out at 90 degrees.If it doesn't, then gently pull the tube and tire around to make it 90 degrees.Grab the tire tube with one hand-grab the spokes with the other give a gently pull-work your way around the rim-maybe 10 pulls-until it is 90 degrees.
2)Then slowly pump the tire up to 25 lbs.Have the stem just barely held in place with the set ring nut-it should be really loose.Once it is up to 25 lbs-screw the lock ring down to just barely tight.Now bounce the tire around -all the way around for 30 seconds or so.
3)Now let almost all the pressure out.Slowly pump it up to normal pressure.Bounce it a bit.Now lock the nut down to reasonablyfinger tight.
Luck,Charlie

Al1943

Good advice from the others. I would add that I have seen defective tubes with cracks and/or weak spots in the area where the stem is molded into the tube.

Al

rmfnla

It's always a good idea to chamfer the valve-stem hole on new rims; this is why.

Wil Davis

Last year I had a three flats of the type you describe, all in succession. I'd changed many tyres and tubes on those wheels and had never experienced this type of problem before, and came to the conclusion that it must have been a bad batch of tubes - they were "Giant", from what I remember. You might want to take care not to overtighten the retaining nut on the valve stem. I've done many tyre and tube swaps on those wheels since then, all without any problems. FWIW -

- Wil

paulie2424

Thanks for the great advice - I just looked at my wheels and the valve holes are pretty sharp. I have a small file that I'll use to soften the edges. The duct tape idea is one I'll use from now on as well. Thanks again everybody.

rmfnla