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Tire rubbing chainstay
#1
I have an old 2001 Giant NRS 2 (with a few upgrades) that I'm having an issue with. The rear tire rubs the left chainstay whenever I pedal hard and put a lot of tension on the chain. When I'm just cruising, the tire is still within a few millimeters of that left chainstay. I flipped the bike over and looked down the tread of the tire towards the frame and discovered that the wheel is not in line with the down tube. The wheel is at a very slight but visible angle. So with the bike upside-down, if I kneel directly behind the rear wheel looking down the length of the bike and picture an imaginary line following the center treads of the tire, the line is not parallel to the down tube. If I spin the wheel while doing this, there isn't any wobble and the imaginary line does not change its angle. Is this likely a problem with the dropout/hanger? I don't think there is much play in the chainstays at the pivots but I guess they could be slightly bent. I'm running a 2.1" Small Block Eight UST tire on the back and I'm tempted to just buy a smaller tire but I like what I already have. Also I'm broke. Does anybody have any advice?

Thanks
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#2
That's not uncommon. The most likely culprit is your rear skewer. Either not closed with enough force or the serrations against the dropouts are worn allowing the axle to move under high torque. As your dropouts are vertical, this would be a miniscule amount unless the dropout was also worn and enlarged.
Next, is the wheel 'trued'? Not just radially and laterally, but also centered? If you have OSB (offset spoke bed) rims, this gets to be a problem when people put larger size tires on certain frames. That is compounded by Mfr variances in tire width claims. Just this week I saw a Specialized Ground Control marked 2.00 and, on a Bontrager Ranger rim, it was easily 2.3 at the outer knobs!
Personally, I seldom run larger than a 1.95 on a FS rig. The main idea behind a larger volume tire is more cushion, which a FS is already giving me. Since weight is also a factor (to me), the narrower tire weighs less than ... uhhh... u know what I mean. 2.1 on the HT, baby!

I don't see how even worn bushings on a NRS could cause that. The NRS's were "built".
Inspect your skewers first, 87. If that doesn't solve the problem, give me more specs (hub, rim, tire brand/model, v-brakes(?), etc) and snap a pic of the wear on the chainstay. Also check if it is rubbing on the seatstay. That is usually minor and easily missed.
As luck would have it, we have a used NRS (from 2000 to 2002 I guessed by the Judy) on the floor that I can compare notes to. I'll be back at the shop on Tuesday.

Rob
Wheelies don't pop themselves. (from a QBP fortune cookie)
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