Bicycle Mechanics - warped rims

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justme23
01-16-10, 11:38 AM
i don't know if this is the place to post this. i have a All Terra gt that was given to me on freecycle. i am totaly new to riding(15 years off a bike. i inflated the tires and found out they are warped. i have read a few guides and watched a video on truing but i am afraid i will screw it up. i was laid off thanksgiving and can't afford to pay anyone to fix it. is there anyone near fairpark that could help me out?
thank you
just me
JohnDThompson
01-16-10, 11:57 AM
Are the tires the problem, or are the rims? Tire casings can degrade over time so that they develop bulges and distortions when inflated. Rims can go "out of true" through damage or loss of spoke tension. How you approach this problem depends on the nature of the problem, which isn't clear yet.
justme23
01-16-10, 12:13 PM
the tires look fine. the rims aren't straight. when you spin the back one it rubs on the right brake pad (part of the tire) the front one seems to be alright.
justme23
01-16-10, 12:34 PM
i forgot to say thank you for the reply john.
cnnrmccloskey
01-16-10, 01:15 PM
Truing isn't that hard just go slow 1/8th of a turn at a time
http://www.sheldonbrown.com/tooltips/truing.html is an excellent guide.
make sure your wheel is actually out of true before trying (as opposed to just misaligned in the dropouts)
bikinfool
01-16-10, 01:22 PM
That first truing can be a bit scary, but it really isn't that hard if you take your time and think about what you're doing (and use a proper spoke wrench at least). Hopefully the wheels don't have more problems than just needing truing. You might look for a bike shop that holds classes, maybe you could volunteer your wheels for a lesson. Maybe look for a bicycle coop where tools and help can be provided for inexpensively. You might indicate where Fairpark is so people who are near you might help you out in more detail.
justme23
01-16-10, 01:39 PM
hi Bikinfool,
thank you for the advise. Fairpark is in Dallas Tx. i forget that this is a national(and international) forum. contrary to belief the world doesn't revolve around Texas. i have a tendency to make bad situations worse mechanically.
justme23
01-16-10, 01:44 PM
thank you for the reply and link cnnrmccloskey.
the tires look fine. the rims aren't straight. when you spin the back one it rubs on the right brake pad (part of the tire) the front one seems to be alright.
Does the brake pad actually hit the tire or the rim? It should never hit the tire, if it does the pad needs to be adjusted before riding the bike.
If the brake is consistently hitting one side of the rim the brake caliper needs to be adjusted.
http://www.parktool.com/repair/readhowto.asp?id=20
justme23
01-16-10, 03:01 PM
the back one is hitting the tire. the front one is hitting both tire and rim. the back rim is warped. it hits the brake part of the time. i don't know any other way to describe it. when i spin it you can see it is warped. it doesn't spin straight like the front tire. it wobbles. thank you for the advise and link.
bikinfool
01-16-10, 03:34 PM
That link Al1943 provided for a dual pivot brake isn't likely the one you need, you more likely have either a cantilever or vbrake on there, but there are links at parktool.com that address those specific types as well. Canti link http://www.parktool.com/repair/readhowto.asp?id=19, vbrake (linear) here http://www.parktool.com/repair/readhowto.asp?id=21
the back one is hitting the tire. the front one is hitting both tire and rim. the back rim is warped. it hits the brake part of the time. i don't know any other way to describe it. when i spin it you can see it is warped. it doesn't spin straight like the front tire. it wobbles. thank you for the advise and link.
Understood. It is critical that the brake pad must not contact the tire, this will lead to a blowout. The wobble in the rim can probably be fixed by truing the wheel. Truing includes centering the rim. A plane through the center of the rim should be half way between the frame dropouts, chainstays, and seatstays. A multi-speed derailleur type bike will have much higher spoke tension on the driveside of the rear wheel due to the asymmetry of the hub flanges to make room for the cassette or freewheel.
You can true a wheel good enough to ride without a truing stand if you work the spoke tension slowly with small turns at the spoke nipples with a good spoke wrench. A drop of oil on the spoke threads can make the job easier and smoother.
Al
justme23
01-16-10, 03:53 PM
i will fix the brake pads. but the truing scares me. all that info mostly went over my head. i will have to spend some time researching the terminology. once again thank you and Bikinfool.
bikinfool
01-16-10, 04:20 PM
If you can adjust the brake pad you can adjust the wheel...they just seem more complex. My recommendation is that right now you probably have no cheaper way to learn, and it's a wonderful skill to have especially if your finances are minimal. I remember when I thought wheels were mystical at one point until being shown otherwise (by an excellent pro mechanic who not only was my vendor at one point but eventually a roommate and all the time great friend). I build all my own wheels now and I'm no wheel genius. If you can learn to true a wheel there's no reason you can't build one (to further keep your options open as to costs). Lots of nice people have worked out all the hard parts of wheelbuilding (calculations and databases), leaving really mostly tedious/methodical manual labor. I'd be glad to show you how easy, but, while I bought an unmoved-into condo in Grapevine once, not close at all....
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