Retfor

ive had a 700c wheelset lying around for a few years from and old road bike that the frame cracked and became useless. i think i tried selling them once or twice, but parts are a hard sell. so instead i figured id pick up a bike that was missing the wheels, slap in these and sell the full bike, which should be easier to sell. i picked up a trek hybrid the other day with 700c wheels, but when i went to put in my wheels just now, the back one doesnt align properly, its off center, and theres a lot of extra spacing between the hub and the dropouts. im guessing hubs/axles meant for road bikes and hybrids are different...? is there an easy way to get this to fit and align properly? perhaps washers to fill in the space?

thanks.



(in the pic i had tightened down the nut on the right, there was more space there initially.)

HillRider

I think you installed a 126 mm hub in a 130 or 135 mm frame.

Retfor

Could definitely be. Can I just put washers or something for spacers or do I need a new hub?

Bill Kapaun

The "correct way"-
Add the needed spacers to the NDS under the lock nut.
Redish the wheel, which is relatively easy for this scenario.
Just equally tighten the NDS spokes until the rim is "centered".
This also results in a more symmetrical, stronger wheel.

The usual problem is corroded nipples.

Retfor

Thanks. The wheel is already true, though, is it still necessary to mess with the spokes further?

Bill Kapaun

Assume the wheel is dished correctly for its current spacing.
The new dish will be off by 1/2 of the amount of spacing you add.
It's possible the dish has "migrated" in your favor to some extent and you end up very close to correct.
It seems a lot of generic, machine built rear wheels shift that way as they settle in.
You can only tell by measuring.
Flipping the wheel in the drop outs and see if the rim is the same distance from some convenient ref. point on the chain stay will get you quite close.

Retfor

Hmmm, maybe im not getting what you mean by wheel dish. Isn't that just the truing of the wheel?

I adjusted the nds nut out so that I could sit it in what seems to be the proper spacing once I get spacers to keep it there, and that seemed good. Pedaled and looked like the brakes would hit it evenly. Anything else to be concerned about?

WizardOfBoz

So let's refer to the locknut surfaces that touch the inside of the dropout as your "reference surfaces". Ideally, the bike rim and tire is centered between those surfaces.

As you know, if a wheel has a small section that is out of true - too far left or right - you can tighten a spoke to bring the rim closer to the reference surface on the side of the hub that the tightened spoke is on. Or you can loosen a spoke to let it move away from the side the spoke is on. What if you tightened all the spokes on the left side of a wheel? The rim would move left. If it had started out perfectly between the references surfaces, now it will be off. Still true, but too far left or right.

For the back wheel, you have a freehub or cluster. This means that the hub flange is moved toward the centerline of the hub on that side. If you centered the rim between the hub flanges, it would be too close to the non-drive-side reference surface, and too far away from the drive side ref surface. So you typically leave the non-drive side spokes a little loose, and tighten teh spokes on the drive side. This moves the rim towards the drive side. By adjusting the relative spoke tension on the left and right, you can center your rim. This process is called dishing.

If you add spacers under the locknuts, you are moving the reference surface on that side, and so if your wheel is dished properly (e.g. centered) initially, after you add the spacers you will a have improperly dished wheel. So you need to tighten all the spokes on the side you add the spacer to. (A little bit, then check. And if the DS spokes are already a bit taut, you could loosen the NDS spokes. )

Andrew R Stewart 

Is it lens distortion or is that axle bent? Andy

Bill Kapaun

Stand behind the bike.
Look at the angle of the spokes between the rim and the hub.
Notice the DS spokes don't have as much angle?
7 speed & less, dish isn't too bad.
When you go to 8 speed & more, it is more pronounced because the stack of cogs is wider.

Retfor

Ok, thanks for the explanation, I get what you're saying now. I've never taken a really close look at that angle of a wheel before, but I had always thought that the wheel was basically centered over the hub with the spokes on both sides pretty much evenly angled. It never occurred to me that you could/ should move it off center. Wouldn't it better, if necessary, to shift the hub on the axle in order to get the wheel centered? (And then add spacers to both sides if needed. ) I would think that having the spokes at different angles wouldn't be as secure.




I did notice that too, that the axle looks bent in the pic, but I think it's just the angle, I don't think it's actually bent.

JoeTBM 

You have a very sharp eye...

dedhed

https://commons.wikimedia.org/wiki/F...sh_diagram.svg

mrrabbit 

The "correct way" is to have some specs to follow:

https://www.mrrabbit.net/docs/freewhe...OLD_sizing.pdf

I've posted this here several times now, surprised people haven't book marked it yet to save time when answering.

=8-