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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 08-20-06, 06:49 PM   #1
kendall
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bent fork, realigning?

recently picked up a '94 bridgestone rbt, everything except wheels factory, switched around to aluminum 27's from the steel 27's on it.

problem is that when I slip a wheel in the forks it's offset at the crown by about half the tire width, and the only way to make sure it's right is to tilt the wheel. (rides perfectly like that though)
When I throw a junk steel rim in it with narrow hubs it comes fairly close to centering itself, but the aluminum rims with wider hubs stay off set

measurements seem to show that it's straight, but the bike looks like it hit something once, handlebar bent in slightly, and tape's messed up on that side, also the offset is 'away' from the hit as though it was pushed over, so I figure it is bent at least a little, LBS says they can straighten it out with a bit of grinding, but would prefer rebending it to correct postion.

How would I do this without overbending it? and could overlywide hubs be a problem? I've never ran into issues with that, but think it may be a possibility, the aluminum rim is a perfect fit in the rear, (slight issues with the axle being too thick, have to make sure the slot is aligned right) and the front actualy slips right in perfectly without spreading or squeezing the fork legs.

at present my plan is to turn a bar down to the ID of the steerer tube, insert that in the tube, then measure off it to check measurements, and use a chunk of padded PVC to bend them to the proper postion,(has great paint with only a few mild scuffs) unless others have a better way to measure and straighten?

did a google search, but no real info came up.

Thanks
Ken
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Old 08-20-06, 07:12 PM   #2
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I'm having a real tough time imagining what the problem is. The fork is bent? The handlebars are bent? The fork steerer is bent? What?

Please take a picture if you can.
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Old 08-20-06, 07:58 PM   #3
kendall
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Sorry, I like to give as much info as possible when asking advice, and tend to get carried away with it, so end up confusing the issue.

Definately the forks, in order to make the tire sit straight you can't fully seat the axle in the drops. LBS mechanic said to just grind the one pocket deeper so the tire sits right, to me that seems like a 'fix' and not a repair

It seems as though the whole fork is tipped to one side, bike rides fine when you tilt the wheel, it just doesn't feel right when riding.

visualize a front rim laced like a rear and you'd have the offset showing when the tire's installed.

Bet ya that's not a lot clearer is it?

ken.
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Old 08-20-06, 08:27 PM   #4
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Does it make any difference if you put the wheel in with the axle reversed? If so, then the wheel is not dished correctly and needs to be centered. Also check that the hub is exactly parallel to the fork crown. If not, then one side of the fork is bent back more than the other. If it looks like both fork blades are bent sidways, then yo need to straighten them. Something else to try; tighten the wheelwith one of the axle ends not seated and th etire centered and see how it rides no hands. If it rides straight, maybe the mechanic's "fix" is the best way to go.
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Old 08-21-06, 04:28 AM   #5
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Assuming that the dish on your wheel is correct (I'd check that first), my bet is you have one or both fork legs that's pushed over to one side. Some bike shops have a tool for checking that alignment.
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Old 08-21-06, 12:36 PM   #6
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Dish is correct, same effect either way I put it on, I think I'll run it to the LBS with a request not to grind it

It's a very nice smooth riding bike, so I don't want to hack it.

thanks for all the responses!

Ken.l
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Old 08-21-06, 03:22 PM   #7
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wouldn't it be easier to pick up a used front fork for it ?
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Old 08-21-06, 08:11 PM   #8
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new fork

May be an option, right now I have zero in the bike, and would like to keep it low buck if possible.

Besides, I haven't found a fork in the 'junk' bin that would work well!

Ken.
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Old 08-22-06, 11:04 AM   #9
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I might be just one fork longer than the other or it might be offset forks (offset to one side) or it could be a combination of both. Is it affecting how the bike tracks (can you ride no-handed pretty easily?) If not, I wouldn't really worry about it.

About 20 years ago I really wanted a bike I could not get locally. So I mail-ordered it and had it shipped UPS. When it arrived the front fork spacing was ~95mm so I pulled them apart to 100mm. The problem is I think I bent the wrong one. The wheel was very nearly centered but the bike pulled pretty hard to the left when i would try to ride no-handed.

Earlier this year I figured that since the bike is 20 years old, I don't really care if I mess it up so I worked on bending the fork. I took the front wheel out, laid the bike on it's right side, stood on the seat tube and seat post, and pulled up on the forks one at a time. After a few trials and checks by putting the wheel back in, I got it to where the wheel was slightly off center, but to the other side. I took it out and rode it and it actually tracked pretty good no-handed. Still a slight pull to the left that I can live with.
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Old 08-22-06, 11:43 AM   #10
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Are you sure the fork legs are bent or is it possible that the dropouts were not mounted to the fork legs the same. Had one like that once.
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