Converting MTB hubs to 9 speed\130mm OLD

[kaysee]

Hi all,

Has anyone here tried respacing older Shimano hubs? I want to build up a nice retro set of road wheels, and was hoping to use older XT hubs. I know that a 9 speed cassette body will fit, and I can get a 130mm axle easily enough, but is there then enough room to fit on the cones and locknuts, and still fit it in the frame?

And before it's suggested, respacing the frame is not an option...

Any ideas or advice will be appreciated.

Cheers!

 

[one-eyed_jim]

XT 737 hubs are quite easy to respace. There's a 5mm spacer on the left that comes off, and the rubber seal sits quite comfortably around the base of the cone locknut. You need to trim the axle too of course, or replace it with a shorter one.

XT 732 hubs are another option - they were made in a 130mm option, but only in 7 speed (or 8 of 9).

 

[kaysee]

one-eyed-jim

How strange - Just a few minutes ago I sent you a PM as I found a previous post from you about a 130mm hub. Do you still have a spare one?

 

[one-eyed_jim]

Re: one-eyed-jim

How strange - Just a few minutes ago I sent you a PM as I found a previous post from you about a 130mm hub. Do you still have a spare one?

I've actually decided to hang on to it - sorry.

The 135mm 732 hubs are simple to respace as well, but the 130mm version actually has a different shell with the flanges spaced closer together. That gives better spoke tension balance.

Another option if you're willing to bend the retro thing a little is to use a modern road hub. 9-speed Ultegra hubs are really pretty nice, and the seals are actually better than most mountain bike hubs of the pre-parallax period.

 

[kaysee]

No worries - I do have hubs here I could possibly play with, but I don't want to scrap anything nice...

If I swap a 7 speed cassette with an 8\9 speed, does the OLN increase as well?

 

[one-eyed_jim]

If I swap a 7 speed cassette with an 8\9 speed, does the OLN increase as well?

An 8/9 speed cassette body is about 4mm longer than a 7-speed, so either the OLN will increase by about that amount, or you need to remove spacers from the other end of the axle to compensate. Obviously that increases the dish (asymmetry) of the finished wheel.

 

[kaysee]

one last question then, if you don't mind.

if I have a 7 speed 135mm OLN hub, will I be able to remove enough spacers AND fit an 8 speed freehub, and still end up with 130 OLN?

 

[one-eyed_jim]

if I have a 7 speed 135mm OLN hub, will I be able to remove enough spacers AND fit an 8 speed freehub, and still end up with 130 OLN?

Probably not, for a couple of reasons.

I'm looking at a 135mm XT 732 hub here. It's got a spacer of about 3.5mm, and a 1.5mm washer between the cone and the locknut on the left hand side. If you remove them both, you're at 130mm, but changing the freehub body adds about 4mm to the other end.

If you had a hub with 9mm of spacers on the left, you could get the spacing down to 130mm with an 8-speed body, but you could run into dishing problems.

Briefly, a symmetrical wheel is a strong wheel, because the tension in the left and right hand spokes is equal. As the freehub body gets longer, the tension in the drive-side spokes rises, while the other side falls. The further apart the hub flanges, the bigger the disparity. When Shimano went to 8-speed with XT, they also moved the flanges 5mm closer together.

So if you take a 7-speed 135mm hub with wide flange spacing (about 61mm) and respace it to 130mm with an 8-speed freehub body, you have a very asymmetric wheel, with very low tension in the left-side spokes. If your hub has narrower flange spacing (around 56mm) you should be alright.

 

[kaysee]

That's about what I suspected. I guess I'll dig around for some proper 130 OLN hubs instead.

Thanks for all your help.