Tire lull
 

I recently got a new pair of Continental Ultra Sport tires and MEC tubes-- cheap, I know, and maybe this is the problem, but I thought I'd ask anyway.

I put them on my bike, and immediately noticed a low point on my front tire-- I could feel the whole bike thump every revolution. I took it off and reinstalled it, and it went away.

Meanwhile, I have since changed the rear tube (I think I might have pinched it), and now the replacement has the same lull. In terms of speed and performance, there isn't too much difference. It's not rubbing on anything, there are no leaks; I just think that I'm putting the tire on wrong, somehow. These are my first 700c tires-- I have several bikes, but they are all late-70's or early 80's models, and so have 27-inch tires, and I've never had a problem like this with them.

Are there any secrets or tricks that I ought to know? I feel like all my problems with them stem from some ignorance on my part. The rims are brand new 700cs and hand-tuned by my LBS, so I know they aren't the problem.

Thanks!

It sounds like your tire isn't mounted correctly on the rim. Make sure tire is equal all the way around rim. If you find a spot where side of tire is further in rim than normal just let enough air out to pinch sidewall together, maybe spray soapy water between rim and sidewall to let is seat correctly.
I have had this problem as well and it has always been tire not mounted right.

+1. You can check this after mounting and minimum inflation by looking at the raised line(s) molded into the sidewall of the tire. Look at the distance between this line and the edge of the rim all the way around for any inconsistencies. If you see such, go around the tire again and wiggle it back and forth to seat it. When it looks good, slowly inflate while checking the distance again periodically.

Thanks!

Totally worked.