countalmaviva 

I'm in possession of two early XT rear hubs, and I'm wondering which to go with:

FH-M732
Decent used condition. Slight pitting on NDS cone and cup.
7s HG freehub (with UG threads)
135mm OLD, 36h
RF to center: 23.3mm
LF to center: 37.0mm
Offset: 6.8mm
390 grams

FH-M730
Like new. Apparently was laced but never used.
7s UG freehub
130mm OLD, 36h
RF to center: 23.3mm
LF to center: 33.5mm
Offset = 5.1mm
352 grams

The wheel is for my commuter and touring rig, a Schwinn Cimarron. I'll space the rear to 132.5mm so it will be, ah...bi-spacial

I'm thinking to transplant the HG freehub to the 730, which has less wear on the NDS, lower offset, and FWIW, weighs less.

Only negative I see: the NDS bearings on the 730 are farther from the dropout, making a bent axle a shade more likely...? Thoughts?

Thanks,
Oliver H.
FH-M730 on top, FH-M732 on bottom. RH flanges are aligned.

blamester

I don't think a bent axle is something you will have to worry about. It isn't common.
And even if it did you have a spare axle.
You might have to swap other parts to make the freehub work. Ds side cones and seals.
Lovely hubs by the way. They will last a lifetime.

Retro Grouch 

Slight pitting on the cup and cone is like being slightly pregnant.

Bill Kapaun

Switch the associated cone, seals etc. with its specific FH Body, since the bearing race is in the body.

What's the spacing on the bike now?
It wouldn't make sense to space the bike at 132 and leave the hub at 130. You'd just squeeze the frame back to 130 when tightening the wheel.
Add 2 mm spacing to the NDS and shift the axle 1mm to that side.
Redish slightly for a slightly stronger wheel.

These are 7 speed hubs, so your dish is less than 8 speed or more. Don't go too crazy over 1mm.Note- your offset will change between 130 & 135.

AnkleWork

Might as well think about it a lot more. Spring is not near.

davidad

If the cup is pitted you are screwed. I would go with the 730 and not look back. You can respace the 730 to 135mm and use the axle from the 732 to have the right length. My wheel build for a tourer back in the 90's started out with an Ultegra hub at 130. When the custom bike didn't work out I bought a Trek 520 and respaced the hub to 135. When the 520 became the Heron I went back to 130. The hub has over 65,000 miles on it. I overhaul my hubs at 2500 miles.

Bill Kapaun

I think you missed the point about the FH body transplant.
UG to HG/UG.
OP wants to use "modern" cassettes, not Uni Glide.
I'm still unsure what the spacing currently on the bike is.
IF 135, make the hub 135.
IF the OP is "widening" the DO spacing, it'd be foolish to space it at 132 and then clamp in a 130 hub. I'd widen the hub as much (up to 135) as I could and still get the wheel inserted reasonably easy.
Keeping the DO's parallel is important for long bearing/cone life.

davidad

The freehub bodies look identical to me, so I don't see the need to change.

Bill Kapaun

It's not in the "looking".
It's in reading the 1st post and noting the differences listed.
Else, it would have been a no brainer.
https://www.sheldonbrown.com/images/...3-stylessm.jpg

countalmaviva 

This made me laugh. My buddy and I were just the other day joking about less-than-ideal weather meaning too much winter "research."

Seriously impressive longevity. When you respaced to 135mm, how much axle did you have on the NDS? (see my comment below)

I think I repack my hubs as often, but I recently realized I may not be careful enough when cleaning them. NYC commuting is DIRTY. I don't necessarily spend a lot of time cleaning the gunk from the outside of the hub before opening it up. I've got pitting on my current front wheel, and I suspect I've let dirt inside without knowing it...

You're correct, Bill. The DO spacing is currently 128mm. I assume that was to accommodate both 126mm and 130mm hubs that were common in 1985. I intend to get my LBS do this spreading to ensure the DO's are parallel (they have the Park tool for this). My reasoning for 132.5mm was so that I'd be able to use the 130mm hub as is but upgrade to a 135mm wheel if needed someday. Are you contending that these intermediate spacings create sufficiently non-parallel DO's to cause premature cone wear?

There's already a 4mm spacer on the NDS of the 130mm hub and a total of 17mm of axle protruding from the hub body. I'd wonder whether extending it by an additional 5mm would be a good idea?

Cheers,
Oliver H.

ThermionicScott 

I don't see the point of respacing the frame to 135mm at this time. Just keep the M730 at 130mm, build it into a wheel and convert it to HG. You can always stretch the frame to 135mm later.

7-speed wheels are plenty strong whether they're at 126mm, 130mm, or 135mm.

Bill Kapaun

I stuffed a 133 hub into 126mm DO's .
Albeit a low end Shimano hub, I was eating DS cones in 200-300 miles.
From that experience, I'm a bit leery at even a 4mm spread without alignment.
IF you are going to have them spread AND align, have them shoot for 135, or as much as you can get and then space the wheel to match.
I think from your other posts is that you want a minimally dished wheel?
Every 2mm wider DO's is 1mm less dish.(offset)
Going "wider" on the DO's means the dish decrease should be easily accomplished by a bit of tightening on the NDS spokes.

countalmaviva 

Thanks, Bill. My parameters are to build a strong wheel with vintage parts. Inasmuch as that means minimal dish, then, yes, minimal dish. I've never built a wheel, but I understand that offset/dish is a big contributing factor to overall strength. It's the reason I'm going with 7s.

I also understand that flange-to-flange spacing would affect lateral wheel strength. The wider the base of the triangle, the more stable it is. The M732 flanges are spaced 5mm wider.

Anyway, I think I'll go with your suggestion and go for 135mm on my frame with aligned dropouts. More options for future that way. One thing I just realized is that the HG freehub results in 2.5mm greater distance from the right flange to the right locknut. I suppose this means I need to get the HG freehub onto the M730 hub body BEFORE I get my wheel built, yes?

Sheldon suggests you can get freehub bodies off unlaced hubs but that you can't get them fully on an unlaced hub. I have yet to obtain a 10mm hex wrench to test this, but I wonder if I could simply place a 2.5mm spacer on the DS of the M730 with original UG freehub for the purposes of wheelbuilding? That would ensure proper centering once I got the HG freehub on there....

Bill Kapaun

You are going to use the "old" hub with the newer body.
Period.
Offsets will be what they will be.
You may see a slight change in hub spacing (1-2mm?) with the body swap. just different generation "stuff".
It is what it is. Quit obsessing.
Your 7 speed wheel w/135mm spacing is going to be far stronger than the same rim laced to an 8 speed hub.
WHEN you have made the swap, I use this method to actually measure my CTF's etc. The "charts" can have errors. An actual measurement will give real results.
You can get the idea from the pic. Holding the camera w/1 hand and the "trapezoidial effect" makes things look wonkier then they are.


You can run your numbers through Spocalc. It gives the DS/NDS tension %'s.
It'll look very good compared to >7speed hubs.

countalmaviva 

Oh, that method makes hub measurements tons easier, thanks! And, yes, I definitely need to quit obsessing. I think the wealth of information available in the Internet age can be a burden. Thanks for your input. I hope this discussion will help someone else down the line.

By the way, I just got back from a week of skiing Bachelor. I had forgotten how beautiful that part of the country is.

NHmtb

This. Avoid running anything already compromised, unless you want run it into the ground and trash it. My experience with commuters is that I want them to work; I don't want to work on them.

davidad

I don't know if spreading the rear triangle on an Aluminum frame is a good idea.

countalmaviva 

Thanks davidad -- it's 4130 steel.

davidad

Sorry, I thought that that frame was Al.