Bicycle Mechanics - newbie wobbly back wheel ?

hello all.
newbie bike question.

when i spin my back tire, i noticed that at times the wheel would rub against the brake. is something wrong with the way the rear brake is set? is the wheel crooked? it's a 300 dollar diamondback hybrid that i bought at the local bike shop about 2 weeks ago. i've used it mostly on bike paths in nyc, but it has gone over a few curbs.

i apologize if this is a question that's been discussed to death already. i did check some of the threads, and it seems like this could be a bent axle question, but i do not know.

btw, great forum. just registered and have it bookmarked.

If, when you spin the wheel, the rim only makes contact with the brake pads "sometimes," then I would suggest that the rim is "out of true," or bent. It's a fairly common and easy to fix problem. Check the info the LBS gave you when you bought your bike to see if they give free wheel truings. A common practice for many shops for the first few months after purchase.

If you didn't purchase from a shop. I.e., goodness forbid it, a large superstore, then I would find someone who actually knows how to build a wheel to help.

Good luck:)

hey thanks for responding. as far as 'sometimes' goes. it's the exact same spot on the wheel that makes contact with the brake pad every time it goes around.

what is 'truing'? does it mean just straightening out the wheel? can they do this at the bike shop?

i bought the bike at a local bike shop just a few weeks ago.

You're local bike shop can do it, truing a wheel is just adjusting the tension on the spokes to make the rim go straight again.. basicaly...

Is Diamondback sold in true bike shops anymore? Seems like I only see them for sale at my local sporing goods store anymore. If that's where you bought it, well-good luck finding somebody to repair it there!

kindbud - see,ms that as you did not pay so much for the bike then it stands to reasons the wheels are going to be cheap ones to replacement. Get it checked first and it should qualify for statutory rights replacement.

Truing? Think of the hub as the centre of your wheel's 'universe'. Truing does achieves two things: one, it makes sure the rim does not follow an eccentric orbit. The rim does not have to be bent for this to be the problem. I think you might have answered this yourself.

Two. If the rim runs in a straight orbit around the hub, that is each point of the rim is equidistant from some reference point, then truing will also ensure that the rim is not too far to the left or right of the centre of the hub. That is usually true but is not gospel on all types of wheel.

well i took the bike to the shop today. the guy took out a little spoke wrench or something and tightened/loosened a couple of spokes and that was that. when i spin the wheels, even my contact lens wearing eyes can detect that it's not making perfect revolutions, but the back wheel is no longer rubbing against the brake pad on every turn.

thanks to everyone for all your help/time/input

i guess i shouldn't sweat the fact that my wheels are perfectly round, not until i pay more for a better bike, or learn some more on my own.

again, great forum!!

-kindbud

This is a useful sitew for learning about bicycles and how to look after them.

http://www.sheldonbrown.com/articles.html

You dont have to own an expensive bike to enjoy cycling. Read the articles and it will help you when you look for your nexr bike.