[RicThot]

Hey guys,

Looking to respace an old XT M756 rear hub, from 135mm to 130mm.

Looking at the following diagram: http://tinyurl.com/n968e4s

Is the 4th piece from the left of the (7) Left Hand Lock Nut Unit a spacer? Guessing a 2.5mm one...?

And same for 2nd piece of the (3) Right Hand Lock Nut Unit.

Which would equal 5mm of spacers that I could remove to get to 130mm spacing ?

 

[Andy_K]

You're looking at a fairly tricky task there. I've gone the opposite direction, respacing a Tiagra hub from 130 to 135, and that was a piece of cake. What you're doing, however, presents some obstacles.

Look at the hub:



There are two pieces on the left side in the exploded parts diagram that appear to be spacers, but they may also function as washers. The thing is, even assuming you can remove one of them (and a corresponding spacer on the other side), you've got the problem that part number 9 in that diagram is the dust seal and if you take out 2.5mm of spacers the locknut is going to be receding into the dust seal. That may be OK, but it's not a sure thing.

On the other side, you may have an even bigger problem. It looks like the lock nut protrudes a decent amount there, but whatever you end up with you need it to protrude enough that you can get a cone wrench on the locknut, plus you're moving the frame that much closer to your smallest cog. Again, it may work, but also maybe not.

If it were me, I'd probably give it a try if I already had the hub. After all, the worst case there is that you waste some time and gain some knowledge. On the other hand, if I didn't have the hub I don't think I'd buy it with this project in mind.

 

[RicThot]

Thanks Andy, that really helps.

I already have the wheel so I'll give it a try.

I looked closely at it on my frame, and there is only little missing for the hub to slip right in (aprox 2/3mm). I'm fairly confident that I could get away with it by just removing the disc side thickest washer, which seems to be approx 2mm.

From what I can see, the locknut would still protrude from the rubber seal just enough to touch the dropout without squeezing the rubber seal.

Worst case, I can try eithout the washer on the drive side, which appears to be around 2mm as well and I would still have space for the cone wrench. I may have to play with the derailleur/chainline a little bit and hopefully make it work, that would save me from building another wheel for this budget bike build.

Silly German frame...

 

[Andy_K]

You've probably already thought about this, but if you remove spacers unevenly (i.e. from one side only) then you should theoretically re-dish the wheel. It's probably not critical if you're only taking out 2mm, especially if you're using disc brakes, but it's something to consider.

This is another downside to going from 135 to 130 -- it makes the spoke tension even more unbalanced than it already is for a rear wheel. That may be reason enough to skip the re-dishing for a small change if the tires stay clear of the frame.

 

[J.B. Weld]

Worst case, I can try eithout the washer on the drive side, which appears to be around 2mm as well and I would still have space for the cone wrench. I may have to play with the derailleur/chainline a little bit and hopefully make it work, that would save me from building another wheel for this budget bike build.

Silly German frame...

You need the locknut to protrude far enough from the freehub body so the chain will clear the frame but you don't necessarily need access to that drive side locknut flat. That locknut needs to be locked tightly to the drive side cone before the axle is inserted, and the adjustment is then made from the non-drive side.

Steel frame? It would be a piece of cake to cold set the rear triangle to 135mm if it was.