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Rear Wheel... Oblong?
#1
So this is a new problem for me -

Picked up a Giant RS930 from a Goodwill the other day and was checking it over. Both wheels are perfectly true (the bike was hardly ridden, sadly) and all spokes are tight. However, the reel wheel seemed odd - it rotates like the bearings are bad, though they're fine, but upon spinning the wheel and watching it from the side, it appears slightly oblong. The wheel isn't tacoed, the hub seems fine, and it really is perfectly true, so I'm guessing this probably happened from improper storage. Is there a way to repair this, or should I nix the rim? They're practically brand new Araya 700c wheels, so if I could fix it, I'd like to.

Thanks for the help!
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#2
I don't really understand you: Either the wheel is true (no lateral or radial deviations) or it is not. What do you mean with "oblong" and "rotates like bearings are bad"?
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#3
(08-11-2010, 03:38 AM)Aeyoqen Wrote:  So this is a new problem for me -

Picked up a Giant RS930 from a Goodwill the other day and was checking it over. Both wheels are perfectly true (the bike was hardly ridden, sadly) and all spokes are tight. However, the reel wheel seemed odd - it rotates like the bearings are bad, though they're fine, but upon spinning the wheel and watching it from the side, it appears slightly oblong. The wheel isn't tacoed, the hub seems fine, and it really is perfectly true, so I'm guessing this probably happened from improper storage. Is there a way to repair this, or should I nix the rim? They're practically brand new Araya 700c wheels, so if I could fix it, I'd like to.

Thanks for the help!

So are you saying the wheel does not deviate to either side laterally when viewed from the back when spinning. But when you look at it from the side it is slightly oblong in shape?
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#4
(08-11-2010, 04:40 PM)RBurrelli Wrote:  So are you saying the wheel does not deviate to either side laterally when viewed from the back when spinning. But when you look at it from the side it is slightly oblong in shape?

Yes, it seems so. I looked at it a bit more last night, and I'm thinking that it might be an illusion caused by the rim being slightly displaced or off center, which makes a bit more sense than it being oval in shape, which would really just mean a good re-spoking and checking over the rim might fix it.
(08-11-2010, 06:14 AM)Joe_W Wrote:  I don't really understand you: Either the wheel is true (no lateral or radial deviations) or it is not. What do you mean with "oblong" and "rotates like bearings are bad"?

Oblong as in oval shaped, very slightly. I guess "spins like the bearings are bad" is a better description for it. Basically, on any bike I've worked on that had a wheel with bearings that needed help, the wheel wouldn't spin for very long on its own, it would just creak to a halt. But on a good wheel, it takes a good while to slow down and finally stop. Not so much with this back wheel.
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#5
Could it be the tires them self are bad or not on the rim just right.
My dad always told me a Sledge a matic can fix any thing.
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#6
(08-11-2010, 09:18 PM)Surly LHT Wrote:  Could it be the tires them self are bad or not on the rim just right.

I checked - it's definitely a wonky rim :/
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#7
Well, if it is not true, you have to true it. From what you write it seems to me that the radial trueness is off. Try to
- find the highest spot
- tighten the spokes in that area (the pairs (drive/non-drive side) closest about 1/2 turn, the adjacent pairs only 1/4 turn (though you would want to tighten the drive side a bit more, otherwise you'll end up with lateral bumps)
- find the lowest spot and loosen some spokes (as above)

Oh, and if the wheel turns as if the bearings were bad, you should check them first. Makes no sense to work on a wheel with a shot hub (well, only as a learning experience).
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#8
(08-12-2010, 07:05 AM)Joe_W Wrote:  Well, if it is not true, you have to true it. From what you write it seems to me that the radial trueness is off. Try to
- find the highest spot
- tighten the spokes in that area (the pairs (drive/non-drive side) closest about 1/2 turn, the adjacent pairs only 1/4 turn (though you would want to tighten the drive side a bit more, otherwise you'll end up with lateral bumps)
- find the lowest spot and loosen some spokes (as above)

Oh, and if the wheel turns as if the bearings were bad, you should check them first. Makes no sense to work on a wheel with a shot hub (well, only as a learning experience).

I'll give this a try, though it might take me a while to get it rideable again! I don't mind doing it just for the learning experience, since I'm still new to working on bikes. And really, I'm not quite sure what's up with the bearings, but I have a few spare hubs that I know for certain are good, so I can always respoke it.
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#9
Well, if it cup and cone bearings you can overhaul them (cf. tutorial on this site).
Rebuilding a wheel with a new hub: well, if you can do that you can fix the flat spots... if you cannot fix the flat spots I'm not sure how lucky you will be with building a new wheel (though it is a bit easier as you start with a reasonably round rim).
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#10
(08-16-2010, 09:16 AM)Joe_W Wrote:  Well, if it cup and cone bearings you can overhaul them (cf. tutorial on this site).
Rebuilding a wheel with a new hub: well, if you can do that you can fix the flat spots... if you cannot fix the flat spots I'm not sure how lucky you will be with building a new wheel (though it is a bit easier as you start with a reasonably round rim).

I have a few spare rims lying around, so I might just resort to that :]
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#11
*g ok, here is what you should do:
- Get Roger Musson's book, it is really great http://www.wheelpro.co.uk/wheelbuilding/book.php
(and inexpensive, too, and has free updates)
- Check your spare hubs until you find one that is still ok (cf. tutorials on hub overhaul)
- Get the correct spoke length for one rim / hub combination, maybe you're lucky and have the correct spokes lying around somewhere (highly unlikely, though). Get good spokes, double butted ones, they build more reliable wheels
- Get a good spoke wrench (the Spokey-type, the non-professional is good enough)
- Build or improvise truing stand (and dishing gauge)
- Build your first wheel
Good luck! If you have questions, don't hesitate to ask here, some wheelbuilders (non-pro, I believe, but quite knowledgable) are active here.
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#12
(08-17-2010, 07:47 PM)Joe_W Wrote:  *g ok, here is what you should do:
- Get Roger Musson's book, it is really great http://www.wheelpro.co.uk/wheelbuilding/book.php
(and inexpensive, too, and has free updates)

What an awesome book! I'm definitely going to download it. I know a few veteran shop owners and participate in a bicycle fixing volunteer programs, so I'm sure I can find someone who can help me if I get stuck. I have the materials to build a truing stand, so that won't be a problem. Really, the only thing I'll need are spokes!
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#13
If you relace the wheel with a new rim: get one with the same ERD (distance between the surfaces where the nipples sit). Then you don't need new spokes.
If you build a new one: get good spokes (I like DT double butted, but there a many other brands), but go for double butted ones, the wheel will be much more reliable (yeah, I don't get tired repeating that). Also (cause I haven't mentioned that in a while) since rims are consumables when you ride on rough ground: you'll then know how to fix a bent rim.
Have fun!
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