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sidewall buldge...


By bigfoot bandit - Posted on 11 December 2006

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

hey fellas just hoping for your opinions on this...
I just replaced a new tube in my front tire... every thing looking fine untill i inflate it... in one certain spot just near the valve a large sort of and egg appears on the sidewall... almost like the air is all just stopping at this point and building up... i have taken the tube out several times and made sure it was in evenly, not twisted ect but i keep gettin the same thing...

any ideas?
Cheers...

Tags

Check your tyre sidewall, it may be damaged, which is the simplest solution. If its fine with no cut, wear or scrapes, check that the bead on the tyre is also fine. The tube wouldn't be able to make the tyre bulge if its in ok order below about 200 psi

I have checked the side wall like you suggested and even rotated the tire on the rim so that it is in a different spot but the sidewall is still buldging in the same spot as before (about 3-4 inches from the valve... Are you certain the tube could not be doing this? Would it even be worth buying another tube to see if that makes any difference?

Thanks for you help...
Kyle...

Are you sure it's the sidewall that's bulging? I've seen (read: done it myself and only noticed when the bike felt like a pogo stick...) something similar where the tyre wasn't seated right and the inner tube started to bulge out between the rim and tyre (which had slipped out.

Are your tyre and sidewall the same colour? if not it would be easy to tell what's sticking out, maybe chuck some chalk on the tube to assist (ie. if it's chalky its tube).

If you've rotated the tyre then I'm 99% sure it's not the sidewall too. Also the fact that it's near the valve rings bells as it can be troublesome to get the tyre seated round the valve.

Tip 1 - Make sure you're not pulling the valve all the way through the rim and tightening the little circular thing that holds the valve in place, leave that loose when you're putting the tube in first so that it can sit in the middle of the tyre (it might be a tad tricky to get the pump on but presta valves are pretty long, assuming it's presta... and if it's schraeder you shouldn't have that problem).

Tip 2 - inflate the tube a little before you put it in the tyre, so that it's perfectly round but not too inflated that it gets too big, that way it should sit properly in the tyre naturally, then put the tyre on the rim with no further inflation first.

Tip 3 - Once it's in the tyre and you've got the tyre fully on the rim inflate the tube just a bit more so that it's just starting to push out the tyre then go round the tyre making sure it's still properly seated in the rim, if not let some pressure out, jiggle the tyre at that spot a bit till it's seated and repeat (still with the valve loose through the rim at this point, only put that little circular nut on once it's all inflated).

One other thought - what pressure are you running, if it's too roadie it might force the tyre off the rim, you should only go for 30-60 psi for an mtb, any more than that and you start to develop lycra.

If all that doesn't work then your rim may be busted, which you'll be able to tell by sight pretty obviously, take the wheel to your LBS and they will most likely be able to bend it back into shape if it's out of shape.

If 9-Lives "lesson on tube replacement 101" doesn't solve the problem take the tube out of the tyre completely and inflate it, the tube that is, not the tyre. Don't go overboard on pressure here. You should be able to tell pretty easily if there is a problem with the tube not inflating properly or having a weak spot. If thats the case take it back were you got it and ask them to swap it. It could also be possible that you have pinched the tube putting the tyre back on the rim, this particularly happens when you use levers to put the tyre back on, avoid this if you can.

...yes my attempts at self-effacing can translate to patronising sometimes! Must be the mother country in me, trying to beat it out by stacking regularly...

On the contrary 9-lives. Not at all patronising but a really good guide for someone who thinks they are doing something easy or straight forward for the first time without realising the little things that will catch them out.

Thanks for all the help guys, much appreciated... Problem solved thismorning. It seems that the pump i was using at the servo was just inflating it too fast and causing this somehow... I realized this when i decided to use my hand pump. Pays not to be so lazy i spose lol...

Thanks again...

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