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Truing problem -- sudden "blip" to the right

601 Views 6 Replies 5 Participants Last post by  Monte
I just finished rebuilding an almost 20-year-old bike for a friend. I am very new to truing wheels, and I'm running into some trouble with the rear wheel on the bike.

When I spin the wheel in the frame and watch the distance between the wheel and the brake pads, the wheel deviates back and forth by about a millimeter. You can notice the side-to-side movement if you look closely, but it is tons better then the original 1/8-1/4 inches of movement that I began with.

However, with the tire on the bike, if I spin the back wheel and look down watching the tread on the tire, there is one point in the rotation where the tire tread whips to the right by perhaps 1/4-inch, and then it comes back again. It's a really obvious and sharp deviation.

So the tire deviates by a lot, in that one spot, but the rim hardly deviates at all.

It is a cheap tire. Could that be the entire problem? I'm thinking there must still be some problem w/the rim that I am just not seeing.

I'm hoping to get time off from work this week to seek help from my bike shop, but I could use some suggestions in the mean time.
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Tires are rarely perfect. Don't worry about it.
sounds to me like the tire bead may no be seated correctly. i would trying adding some more air to see if it pops into place, if not, pull the tire off and try putting it on again
There is usually a line molded into the tire sidewall that is just above the bead and should be visible just above the edge of the rim with tire inflated. This line should be concentric with the rim. If it isn't then the tire isn't seated properly. Deflate and check why. If it is ok then the cheap tire is just that. That's assuming that the tire casing isn't damaged. Look inside the tire at the wobble point.
Guys, thanks. I should have thought to check that the tire is seated properly. The bike is back at my friend's now. I'll try and make a run over there this evening and check things out.

If the problem is all in how I mounted the tire, I'm going to feel rather foolish.
JonathanGennick said:
If the problem is all in how I mounted the tire, I'm going to feel rather foolish.
You shouldn't do that at all. It's an easy mistake and not something that most people would ever check for or notice. If it isn't seated, to give a concentric ring, try this - inflate slightly (maybe 10psi) then find where the sidewall line dips below rim level. At that spot, try to roll the tire off the rim away from you. Push with the thumbs. The line should pop up above the rim. I always check for this on both sides when mounting a tire.
Besides Mike's trick, you can also use some soapy water to lube the bead just like the auto tire guys do. Works every time.
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