Rear hub service

[colin54]

Sheldon Brown's hub adjustment article..
https://www.sheldonbrown.com/cone-adjustment.html

[rjb]

Sheldon's method is a good first approximation but it isn't exact as the in service compression of the axle and cones is caused by the compression of the locknuts being transferred through the cones and axle.
One idea is to use a pair of spanners acting as dropouts with the qr tightened but this makes adjustment of the cones difficult.
It's always the final adjustment which can be a bit of a compromise.

[Brucey]

as I mentioned earlier the cones don't move appreciably differently on the axle between when you load the axle using the hub vice and when you put the wheel in a frame, provided the locknuts are tight. Hence the biggest variable in the final adjustment is how tight the QR skewer is.

cheers

[fausto99]

Sheldon Brown's hub adjustment article..
https://www.sheldonbrown.com/cone-adjustment.html

Thanks for the link. I've almost got it now. The picture of the skewer lever end is clear but what about the other end and why is it called a hub vice? Where's the vice?

[Brucey]

I call it a hub vice because it loads the hub and clamps the hub in position. The other end of the Sheldon tool can be almost anything that will allow the skewer to be tightened and the load passed through the axle, including

- a 'dummy dropout' i.e. a lump of metal with a hole in it (which can be clamped in a bench vice if you want) with a QR skewer nut
- a 10mm open ended spanner and a QR skewer nut
- a stack of washers and a QR skewer nut
- just a QR skewer nut (without the spring of course) bearing against the end of the axle.

In any of the above the QR skewer nut can be substituted for any M5 x 0.8mm threaded fastening that will accept the load and transfer it into the axle assty without damage.

I recommend that the RH locknut is held in a bench vice (or similar) whilst the hub is being adjusted.

BTW I already posted that link upthread.

cheers

[fausto99]

Sorry, my bad re the link. Down to skimming rather than reading -life is short.

I guess I’m doing the same thing by doing the final adjustment with the wheel in the truing jig. Probably no need to do the spacer thing or clamp a single dropout in a vice.

[Brucey]

if you don't have the axle under compression then the adjustment is much more 'trial and error'. If you don't clamp the RH side of the axle as you make the adjustment you

a) need three hands or
b) start forcing locked cones around (bad) (*) or
c) more easily lose track of what you are doing

if you use the hub vice method then bearing adjustment becomes rapid and precise. The final step is to leave the axle under compression, and to release the bench vice. If you turn the axle in your fingers, you will feel just how much (or hopefully how little) drag there is in your precisely adjusted/representatively preloaded bearings.

(*) I forgot to mention this before, but most older hubs (and some others) use tab washers and axles with features (e.g. grooves) in them. Forcing partially locked assemblies around without tab washers is bad enough, but with them is a surefire way of wrecking the tab washers.

cheers

[nigelnightmare]

I start by setting the RH cone+ lock nut to 5.5mm from the end of the axle and locking it there.
QR axles are 11mm longer than the OLD of the hub so you should find the amount of axle protruding to be equal after you've finished.

Then I use a stack of M5 penny washers clamped to the axle (5-6 each end) using the QR skewer so that it's pressing on the end of the axle not the locknut's. Tightened the same as when the wheel is fitted to the bike.

Then adjust the LH cone to remove the play.
Whilst holding the cone STILL, tighten the locknut down to it.

Easy quick and cheap.

[offroader]

I remembered this post today when servicing the hub.

I just wanted to say thanks to all for the tips. Cone preload was bob on first time using the axle compression setup, it's a real revelation to me!

[Brucey]

when I started doing it this way, I couldn't help but think of the many hours I spent faffing about and mostly doing it wrong before.....

cheers

[Popolof]

Apologies to tag onto this thread. Can anyone help me with rear hub choice??

I have an old steel Trek mtb with 130mm drop outs, that I’d like to use a 9/10 spd drivetrain on. I don’t want to cold set the frame or faff about prising the rear wheel in and out by squeezing in a 135mm mtb hub. I know I could use a road hub which seems the simplest solution, I’ve been looking at a Tiagra FH-4600, but to be in keeping with the MTB Group heritage, I think I’d like to use the Deore FH-T610. Not sure if these have the same silver finish?

My question is, can I re-space the T610 easily by swapping the axle to 141mm and swap the left hand spacer to a 5mm to reduce the OLN to 130mm? Are there any specific differences between the two hubs mentioned which would make one better or worse for the job in hand such as wider flange spacing? Better sealing? Stronger for XC use Etc. It’s going to be a 36h 26” wheel, 3 cross lacing, probably using Sapim D-light spokes. Many thanks!

[Brucey]

you can do what you want to a Deore hub (and it isn't difficult to cut the axle down BTW) but IMHO you have missed the point; 135mm is used for MTBs because 'road' hubs at 130mm build into wheels with more dish that are not really strong enough for the task in hand. There may also not be a lot of clearance (between the chain and a fat tyre) when using bottom gear if you use a 130mm/8s hub.

If you want to use (mostly) modern equipment but don't want to reset your frame, I'd suggest using a 130mm 7s hub, and using a shortened cassette on it, i.e. 8 from 9 or 9 from 10.

cheers

[fausto99]

you can do what you want to a Deore hub (and it isn't difficult to cut the axle down BTW) but IMHO you have missed the point; 135mm is used for MTBs because 'road' hubs at 130mm build into wheels with more dish that are not really strong enough for the task in hand

+1 even if you are prepared to put up with the weakness of a very dished wheel, don't underestimate the difficulty of building in a lot of dish. It requires a large difference in spoke tension from one side to the other and therefore hard to true. It's a major PITA.

[Popolof]

Thanks guys. I like the 9 of 10 sprockets suggestion. Am I correct in thinking from your advice that 130mm OLN dimension with a 7 spd hub builds into an adequately strong wheel (albeit well dished) for XC/gravel type abuse?

I guess there’s a reason why the spacing evolved to 135, because off-road riders were discovering the limitations of a weaker wheel! Also as the Freehub body was lengthened to accommodate 8/9/10 spd cassettes then the OLN was forced to increase to 135 in order to maintain the correct wheel geometry?

Maybe a cold set to 135 is the best way to proceed, would I have to reset the dropouts to vertical as well? As a final thought, do you have any recommendations for a fairly well sealed 7 speed hub? I have some old RM-40s, cheap n cheerful, look quite nice but only a metal cup seal.

Cheers

[Brucey]

AFAICT few if any 7s freehub bodies had a rear seal, or can be fitted with one easily, so it is a question of keeping up the lubrication of the freehub body (eg with SFG) and not pressure-washing that area too enthusiastically. However the RH seal can be made of a newer type in almost any freehub, and the left seals likewise. An easy conversion for FH-RM40 is to use a cone with a seal built in to it on the left side, and to use a RH seal which bears against the cone directly.

The 7s freehub body is a fair bit shorter than a 8s one but the 7s freehub body is not perfectly optimised for dish; it is possible to machine back the shoulder on the body so all the sprockets are ~1mm further leftwards, and to similarly diminish the clearance between the sprockets and the dropout, by modifying the spacing. Whatever change in the RH spacing you make, you can add those spacers back into the LH so that there is the least wheel dish possible. The dish in a standard 7s/130mm setup is about the same as a 8s/135 but you can improve this yet further.

If using an 8-from-9 shortened cassette then you can omit one of the smaller sprockets or one of the larger ones. However if using a 9-from-10 cassette you ought to aim to lose the smallest sprocket (because the largest sprocket is dished), which will require some attention to lockrings and spacers.

cheers