[stymie2000 offline]

I just got a new rear tire. A Kenda which I must say I'm not very happy with for more than just this reason. I rarely ever had flats until I put this on. My valve stems keep tearing. I noticed that after riding for a few 100 yards after putting a new tube in that the stem would be at an angle. I would fix it and it would slip again. Eventually it would tear right at the base of the stem. After a couple of times I roughed up the inside of the ture thinking this would help. However, it didn't change a thing. I've tried different tubes as well. I made sure I had the correct size written down when I bought it and the sales clerk confirmed it was the correct size. Any thoughts?

[trailrider247 offline]

are you using schrader or presta valves if your using presta valves you need to make sure that the nut on the valve stem is on the outside of the rim and tightened down finger tight, if your using a schrader valve you can try throwing some baby powder in the tire and rub some on the tube, that might help with your tube moving, the baby powder trick usually works as it reduces friction and allows the tire and tube to move free of each other, it also helps with reducing rolling resistance, also using a hand pump could cause you to tear a valve stem, hope this info helps

[stymie2000 offline]

Thanks for the info. I use a schrader valve. I thought it might be the pump but I used both a floor pump and, on the trail, a hand pump. Plus, I have rarely gotten a flat before and never had a valve stem tear. I'll try the powder and see what happens.

[Jfinnigan offline]

Have you resolved this issue? I have tried different pumps, a new wheel lining, new tire, different tubes, and now a new wheel and have the same problem. If I can't figure this out I guess I have to give up mtb altogether!

[jeremiahbwhite offline]

This is the one time on the face of the earth and the amazing sport of mountain biking I'm going to tell you this: Glue your tube to your tire.

Get some cafe latex and smear it all on the inside of your tire before installation, and check and make sure your rims aren't undersize. Should fix your problem.

[fat_billy offline]

How much air pressure are you running? Is the hole for the valve have sharp edges? Just wondering. Later,

[element22]

plus 1 on what fat_billy said...The talcum powder is another great idea....Also check out what type of tube your using....is it 26x1.50/1.75, 26x1.190/2.125, or 26x2.20/2.50....Check the weight....The lighter you go the thinner and more fragile the tube.. You should match the tube to the style of riding, your weight and the tire itself...

[Jfinnigan offline]

Thanks for the responses guys. I've pumped the tube to various pressure levels, it doesn't seem to make a difference. It can't be a sharp area of the hole on the wheel because I've used 2 different wheels with the same result. I'm using thorn resistant, thick and heavy tubes, although I have had the same result with a thin regular tube. By gluing the tube to the tire as the first responder suggested, won't the tire be ruined? I get the logic behind the suggestion, I'm just sick of spending money on this problem. I am taking the whole bike to a reputable bike shop today, hoping they will notice something I am missing. I will let you all know what they say. Thanks again.

[fat_billy offline]

I have seen tires with too much mold release slip on a rim that is worn smooth where the bead contacts the rim. Clean the tire (tyre) bead lightly but don't get it on the tread area with lacquer thinner as well as the rim to be sure it's clean. Blow it up to 50 psi and let it sit a few and put it on the bike and try it with the high pressure. The laquer thinner make the bead softer a it will stick better. Keep us posted as to the LBS cure.

[Adonai-Yeshua offline]

You may want to switch over to presta valve tubes and use a presta rim inserts in the rim if you are presently using schrader valve tubes. Also, what type of rim liner are you using? Cloth or rubber? Cloth tape works best in the long run and really helps with the tube moving and shearing the valve stem off.

Also, I totally agree with what element quoted, as this is very important......

Also check out what type of tube your using....is it 26x1.50/1.75, 26x1.190/2.125, or 26x2.20/2.50....Check the weight....The lighter you go the thinner and more fragile the tube.. You should match the tube to the style of riding, your weight and the tire itself.

A great all around tube is the Panaracer DH Super Tube 26 x 2.10/2.50. It a bit thicker and very strong, but not as thick as all the other heavy DH tubes (etc...Maxxis & Kenda). It comes in both presta and schrader.

http://www.jensonusa.com/store/product/ ... Thick.aspx

[fleetwood offline]

Have you resolved this issue? I have tried different pumps, a new wheel lining, new tire, different tubes, and now a new wheel and have the same problem. If I can't figure this out I guess I have to give up mtb altogether!

seems a little drastic

[fat_billy offline]

Since taking it to the LBS have you gotton an answer? Nosey people want to know. Just saying. Later,

[dallan1 offline]

I have the EXACT same problem, really love to hear if you get this solved...I blow my front tire EVERY time I ride now...presta valve tears at the base. I replaced the plastic rim strips that were in the rim when I bought the bike with cloth, i've used every size imaginable of tube, I'm running panracer fire xc's front and back - no issues with back tire but the front is giving me fits! --Gonna give the baby powder thing a try & i'll let ya know if it works...

-On a side note: I've flatted twice and wasn't even riding... I thought something was loose and lifted front wheel up and shook handlebars and was greeted with *pop* *whoosh* ... really?

[wbernest offline]

You guys just need to switch to tubeless. It is worth every penny. I have had 1 flat in 7 or 8 months (which is well over 1000 miles of riding).

[Jared13 offline]

I have the EXACT same problem, really love to hear if you get this solved...I blow my front tire EVERY time I ride now...presta valve tears at the base. I replaced the plastic rim strips that were in the rim when I bought the bike with cloth, i've used every size imaginable of tube, I'm running panracer fire xc's front and back - no issues with back tire but the front is giving me fits! --Gonna give the baby powder thing a try & i'll let ya know if it works...

-On a side note: I've flatted twice and wasn't even riding... I thought something was loose and lifted front wheel up and shook handlebars and was greeted with *pop* *whoosh* ... really?

Have you swapped the tires? I'm assuming you have the same rims front and back. If you swap the tires and it follows, then you know it's the tire itself that is causing the problem and not the rims.

That might help narrow it down to a cause.

Good luck!