jvansant

So I'm riding a '77 schwinn sierra and I've been feeling a bump in my front tire. We took it out and looked at it and the tire was like really into the rim at some points and further out at others, resulting in the tread being kind of off center in spots (part of the tire size shown on the side of the tire was starting to be covered by metal of the rim). So we changed the tire and the same thing was happening. I don't know what the problem is. Also, my bars are immediately straying to the right whenever I let go, making me unable to ride no handed as well. Any ideas?

Thanks for your time

adclark

Can't tell you for sure, but it sounds as if the rim could be bent. I would suggest taking it to a local bike shop to have it looked at if it is something you can't figure out on your own.

Also, you didn't somehow manage to force a 700c tire on a 27" rim did you?

jvansant

sorry, i should have included this. the rim isn't bent, and it's not out of true.. we took a look at it and it's maybe slightly (extremely slight) out of round, but we couldn't really tell, so i don't think that's what's causing the problems like veering to the right and a noticeable bump/off centering of tread. Also it's a 27 x 1 1/4 tire

oilman_15106

Most likely a hop in the rim. If you do not have a wheel truing stand take it to a LBS and have them check it. This defect is often not apparent to just the eye.

dperreno

It could also be the case that the bead is not properly seated in the rim. Let most of the air out of the tube, then go around the wheel and use the heel of your hand to roll the bead up in those areas where it is too far below the edge of the rim. Go around both sides. Add some air and check, then pump it up. If you still have a bump/hop, then your rim is likely bent.

A bent rim could also be a key to your steering problem, provided it is a new issue. You may have hit a curb and bent your fork slightly, along with your rim.

alcjphil

If your bike still has the original rims, they are old enough that they may not have a modern hook bead. If this is the case, it is possible that your tires just won't seat properly at he high pressures used today. Bikes from that era usually came with wider, lower pressure tires than is the norm today. The problem would be worse if you are using folding tires, wire bead tires might seat better.

Velo Dog

You can check this on the bike. Remove the tire and tube and put the wheel back on the bike. Turn the bike over so it rests on the seat and bars, then give the wheel a spin. Find a place to brace a screwdriver or something so you can move it in so it just skims the rim (maybe across the fork). If the highest spot is more than 1/8 inch or so above the lowest spot, it could cause problems.
From the description, though, I'm inclined to suspect your old rim either didn't come with a hooked bead or is jus tworn out (rims do wear out, usually from the brakes rubbing through the sides. If you've worn a weak spot, it could be screwing up the way your tire mounts).