Bike Forums - Locknuts and freewheels

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Locknuts and freewheels

I recently bought a used bike which has 120mm rear dropout diameter, but the hub is spaced at 126mm. The locknuts are about 7mm, is it possible to get 5mm locknuts or thereabouts, so I can bring the overall hub width down to 122mm?

Also, if I bring the hub width down to around 122mm, will I be able to fit a 6 speed freewheel. There seems to be a lot of room between the 5 speed freewheel and the frame, enough that another sprocket and reduced hub width wouldn't seem to make a difference. But then everyone says 6 speeds=126mm dropout, is this always the case in practice?

The hub is threaded for British standard 1.370" x 24 tpi, will a current shimano freewheel fit ok?

There were Ultra-6 freewheels made by Sun Tour that had 6 cogs in the width of 5 and were intended for 120 mm dropout spacing. You may be able to find an NOS one if you search. They didn't shift very well but did give the extra cog. Regular 6-speed freewheels were intended for 126 mm dropout spacing.

If you remove spacers to get your hub to fit the frame, be sure there is sufficient clearance on the drive side for the smallest cog and chain to clear the dropout face.

Quote:

Originally Posted by HillRider

I can only see what I assume to be one spacer on the drive side of the hub, a thin black disc with a tab that fits into a notch in the axle, is this a spacer?

Hence why I was asking about thinner locknuts, do they exist?

Check the pic...

That tab washer is a spacer. AFAIK, there are no thinner locknuts. They have to be thick enough to engage sufficient threads on the axle to tighten sufficiently without damaging the threads.

So, I can't narrow the hub o.l.d down then?. I suspect if I take the tab washer out, it'll put the wheel off centre in the dropouts...

Quote:

Originally Posted by Mothra

If you change OLD, you will always throw of the dishing of the wheel and need to get it re-trued. If this is a steel frame, I'd say just cold-set the rear-end out to 126mm and use a 7-speed freewheel. Tonnes of Suntour and Shimano 7-speed freewheels out there. The last generation Shimano freewheels even had Hyperglide for great shifting performance.

To get maximum-strength and consistent shift-indexing, I'll always juggle the spacers between the left & right sides to place the smallest cog 3.5-4mm away from the drop-out. This creates a wheel with mimimal dish for best strength. With the smallest cog in the same position on all my wheels, I can swap wheels without having to adjust the shifting in any way.

Yeah, what he said.

See: http://sheldonbrown.com/frame-spacing

Sheldon "TwoByFour" Brown

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