Inner tube

Just brought new inner tube to fit to my partners bike. But when I pump it up it bulges over a certain part? Why?

is the bead sunk right into the hook of the rim or is it trapped between the rim and the tire

I actually took out the inner tube completely suspecting this and it still bulges?

It still bulges when pumped up alone? Sounds like a bad inner tube. I've never had that happen..

i used to have this problem a lot, found a little bit of grease on the inside of the try sorted it by letting the inner tube move around a little and even itself out. Never thought about it before but dunno if the grease has some kind of bad effect on the rubber, havent had any probs yet.

Hold on - does it bulge when its under a tyre? Because if it only bulges when you pump just the inner tube up on its own, thats totally normal. It's designed to be constrained by the tyre's dimensions and has almost no strength on its own, so it won't be an even size when pumped up unconstrained.

Inner tubes often bulge oddly when inflated on their own. No probs.
If the TYRE bulges at a certain place on the rim then your tyre isn't seated properly or the tube is stuck under the tyre's bead or similar. You need to deflate it and then check the area, reinflate and try again. Some tyres are more likely to suffer this problem and you might be able to help by using talc or inflating a little, wiggling the problem area so the tyre is even, then inflating fully.

Hippy = Tyre Guru.

just don't ask for contis!

i had the same problem with my Stelvio Plus tyres.
I then realised that the wheel was vertically buckled slightly by 3mm or so.
After putting the tyre on, the tire seemed to wobble up and down much more than 3mm more like 9-10mm.
After wiggling and shifting the tyre here and there whilst half inflated i eventually managed to minimise it. Just gotta fiddle with it until its right.
i guess :)

Inner tubes often bulge oddly when inflated on their own. No probs.
If the TYRE bulges at a certain place on the rim then your tyre isn't seated properly or the tube is stuck under the tyre's bead or similar. You need to deflate it and then check the area, reinflate and try again. Some tyres are more likely to suffer this problem and you might be able to help by using talc or inflating a little, wiggling the problem area so the tyre is even, then inflating fully.

Thanks. That sorted everything. Why do inner-tubes bulge when not inserted? Surely the pressure must be equal throughout?

The rubber isn't going to be exactly the same thickness all the way through, so some parts will be weaker than others and hence stretch more.

i used to have this problem a lot, found a little bit of grease on the inside of the try sorted it by letting the inner tube move around a little and even itself out..

Talc does the same job, a dry lubricant.

I fucking love this forum. I Google'd "Inner tube bulge" and this thread was the first in the list. Cheers for the words of wisdom Hippy. I was about to throw this wheel out the fucking window!