Strange thing happened to me today.
Yesterday i changed my tube because the former one was no longer patchable (damn glueless patches).
My tire is a 700x25c, so i put a bontrager 700/18-25 tube and start to pump. The tube doesn't seem to fill the tire very well but i haven't reach the recommanded pressure yet, so i keep pumping to 90psi... Looks good.
This morning i take my bike, and i feel a bump every wheel turn. Now i have spend half an hour trying to put the tube and tire back to place but the only thing i can do is move the tire bump. It seem that the tube isn't pushing the tire radially enough to place the tire beads in the bead sits, causing an unround tire.
Tonight i will swap tube, but have i done something wrong with this one ?
The rubber at the valve stem may be caught under the bead.
Are you using the valve stem nut?
Undo it, deflate the tire, push the stem into the rim then reinflate.
Most users of that type of valve don't use that nut anyways.
i'm not sure i've been clear enough, so here are a few more details :
1) The bump is caused by the beads being too much inward, resulting in a lower tire
2) By replacing the tire i can move the bump around but can't seem to remove it
3) The tire is a pretty new Continental ultra sport, which has never done that before
I ended up swapping tyres over between 3 bikes (don't ask) and found that two sets of wheels accepted all 3 sets of tyres with the bead even all round. However, the F.W.Evans bike (with, I presume, Evans own wheels) had the problem you describe. the bead was even for 90% of the circumference, but the bead disapeared into the rim for the remainder. My mate, who has more patience than me spent about 20 minutes on each wheel until he had an even bead all round. I had never had this problem before. One final thought, I'm pretty sure the wheels were original equipment on the bike (Evans have a good reputation for their wheels) but they were specced in the catalogue as having 28 section tyres and we were fitting 23 and 25 section. Another thought, could the Evans wheels have been 27"? We were fitting 700C......
One final thought, I'm pretty sure the wheels were original equipment on the bike (Evans have a good reputation for their wheels) but they were specced in the catalogue as having 28 section tyres and we were fitting 23 and 25 section.
That may be part of my problem as well. My rims (ZAC 19) are rated 28-38, but since the bike came with 25 tires, i've always put 25.
It is the first time i've had this problem although many tube change, and that's why i blame the tube