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Flat tires

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Posted by: medwaste---------------------

What causes a tire to go flat if there's no puncture? This is a reoccuring problem for our guy whether at the track or harescrambles. Is there a better rim? Anyone have tips?


Posted by: RM_guy---------------------

If you don't have enough air pressure the tire will compress and pinch the tube on the rim. Thicker tubes helps if you think you need low pressure.

Of course there are other things like a bad valve stem or a hole that you haven't found.


Posted by: rmc_olderthandirt---------------------

I am not sure I understood the question. If the tire mysteriously went flat, you removed the tube, inflate it and check for holes and it has none, then I would suspect someone is playing pranks on you.

On the other hand, if you remove the tube and it has a slice in it, perhaps two on opposite sides of the tube, then like RM_guy said you probably pinched the tube. Very common problem when running low air pressure but if you hit a sharp rock, or a curb, or railroad tracks, etc. hard enough you can pinch the tube even with proper air pressure.

Another possibility is that the valve stem gets ripped out. This happens when the tire slips on the rim. The rim lock is supposed to prevent this, so if you are ripping the stems out then you should tighten the rim lock more.

If the tube is just self destructing then it is possible that you have the wrong tube in the tire. Tubes stretch easily so you can stretch a too small of a tube or stuff too large of a tube into the tire but normal flexing of the tire may eventually cause it to rip apart.

Another common tube failure is from the spoke nipples poking it and wearing holes. You should have an extra strip of rubber between the tube and the spoke nipples. Many people use duct tape when their rubber strip breaks and they need to get their bike running now.

Rod


Posted by: 2-Strokes 4-ever---------------------

Have you taken the old tubes, put air in, and dunked in water to look for bubbles? I can't imagine valve cores/valve stems being bad on more than one tube. Something's up......... look closely. Moose, Michelin, Fly... they all offer some Ultra HD tubes. I run the heavy tubes, duct tape the rim (pitch the rubberband once the spokes have seated), 15 lbs of air in the rocks (I only weigh about 160#). I SHOULD get off my wallet and get some prescription goggles, I hit stuff I sometimes could have avoided, but... no flats in years.


Posted by: Tom68---------------------

I use soapy water in a spray bottle on the bare tube to find the smallest leaks. If you run tyre sealant slow leaks are impossible to find because they seal themselves when your looking for them but go flat randomly when the bike is parked.


Posted by: medwaste---------------------

His tube was pinched. He does run HD tubes and 15 psi but he's a big guy who rides hard and this is at least the 3rd time it's happened ( in 2 yrs). He couldn't finish the last lap at his first Ironman and was pretty 'disappointed'. Is there a foam product made to help prevent this?


Posted by: Tom68---------------------

Mousse tube best option, apparently you can still use rimlocks with them but they would be tough to fit.


Posted by: mideastrider---------------------

You can use mousse bibs or tireballs both work well. They are expensive but you want have any more flats.


Posted by: RM_guy---------------------

Quote:
Originally Posted by medwaste
...Is there a foam product made to help prevent this?
Not for a pinched tube.


Posted by: medwaste---------------------

Do you think mousse bibs will last a season? They are expensive.


Posted by: mideastrider---------------------

I'm not sure what kind of run time you get with the bibs. I never used the bibs but I think I will try a set next season. I us tireballs they work well but you will have to replace some throughout the year. But they are warranted for a year from date of purchase and will replace any that goes flat. You get about 6 extra front and rear and you use them switch out when you change tires.


Posted by: whenfoxforks-ruled---------------------

Inner tubes, they wear out. They get pinched when its below 15 pounds of air, run low profile tires, or get in real abusive situations(rocks). The standard tubes that most shops carry say HD, but look at the price. They make real heavy tubes, and the price matches! If I was having issues with pinching, my tire side wall is still good, I would sure look into the balls or solid tube.



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