Freehub Body Compatibility

[gremlint]

The freehub body attached to my Shimano Ultegra hub (c. 2005) seems to be on its last set of revolutions.  The wheel clatters intermittently with a horrible sound, and the hub sometimes refuses to spin backwards momentarily.

So I thought I could replace the hub with an FH-RM30, which sells for only $15-20.  But a mechanic at our local bicycle shop (in which I don't have much faith) is telling me that I need a freehub body that would cost $55.  (He also recommends that I buy an entire new wheel for over $200 to replace my Mavic rim, etc.)

Can anyone offer some sound advice on freehub body compatibility?  Would the inexpensive part do just fine?  I have 8 gears on the cluster.

[Alex Ramon]

I'm not entirely sure about this, so a second opinion would be good, but I do believe the FH-RM30 freehub body is compatible with both the Altus FH-RM30 and Ultegra FH-6700 hubs. It is a lower quality so it may not last as long as the $50 freehub, but I can't see there being any functional problems if you want to save the cash.

If your freehub alone is the problem you have no need for an entire new wheel. The only reason you'd need to replace the wheel would be if the hub's bearing races or rim surfaces are worn or damaged.

[gremlint]

Thanks for the quick reply.  I hope you're right.

The rim surface seems to be in good shape, and I didn't see hairline cracks anywhere — even after more than 10,000 miles.  (I love Mavic A719 rims.)

The bearings also seem fine, as there's no give when I put some sideways torque on the hub.  I think it's crazy to put parts into a landfill that still have some good life in them.

[nfmisso]

From: http://www.sheldonbrown.com/k7.html

Quote:Body Transplantation.
Virtually all Shimano Freehub bodies are interchangeable. The exceptions are:

Very early Freehubs (sometimes identifiable by the absence of the typical bulge on the right end of the hub barrel) which have non-interchangeable bodies. The Freehub body of these hubs is held on only by the axle bearings, and will slip off once the axle is removed.
Hubs that use the "silent clutch" mechanism.
Pre-1997 Dura-Ace Freehubs, which only take pre-1997 Dura-Ace bodies.
FH-7800 and FH-7801 Dura-Ace bodies, which have a cartridge bearing inside the Freehub body and use a ratchet inside the hub shell. These bodies are removable using a 5 mm Allen wrench at each side. The fixing nut on the right side unscrews clockwise. Shimano information.
FH-7850 and FH-7900 Dura-Ace bodies, which have returned to a splined attachment between Freehub body and hub shell, but it is larger than the usual one. It is similar but not interchangeable between these two models.
Some disc brake Freehubs including the Saint series have a Freehub body that threads into the hub shell. Disassembly is by unscrewing counterclockwise using a 15 mm Allen wrench; Shimano exploded diagram; assembly/disassembly information

[Joe_W]

Does the hub clatter only when coasting? Before you replace the freehub body, inspect the bearings for damage. If you never did that before, you might want to do that anyway... I usually try to overhaul my bearings at least once a year, more often on the bikes I use in the mud / rain.

[gremlint]

Thanks for the replies, everyone.

Yes, the hub only clatters while coasting.  As soon as I apply force through the chain (turning the gear cluster), the sound vanishes.

[Joe_W]

Some freehub bodies can be overhauled, though I am not sure about Shimano hubs. A new freehub body is less messy, though.