I've got a gritty freewheel. No idea how, it's never been this gritty before.

– lent my bike out, came back a bit dirty, (short cleaning effort with jetwash?) sandy, gritty noise on spinning the wheel backwards, thought it was sand between the nuts at the top of the cones and the lockring (which doesn't make sense now I come to think about it).

Took all that off, cleaned out the sand from the recess for the lockring at the outside end of the freewheel, then realised the freewheel wasn't moving. Gave it a bit more of twist, and it freed up, then stuck. Lots of grit in there. It moves, but it's not pleasant to feel or to listen to.

Can you take the freewheel off the hub and take it apart to clean? I can't see anywhere for a tool to get any purchase.

Thanks,

Ed

right.

I've done what I should have done before posting (googled for more than 90 seconds). It turns out that:

1) I don't have a freewheel at all
2) I need a new freehub body*
3) I can remove my freehub body with an allen key, after having removed the axle and bearings

* Or do I? Is there a way to dismantle and clean the freehub body once it's off the rest of the hub?

No, most freehubs aren't servicable. And those that are can be too much faff to bother.

Don't let jetwash waving numpties borrow your bike!

And the winning hub is…?

what hub is it? If it's Shimano, you can buy a replacement, if it's anything else, buy a new hub (ome have spares but they're not easy to find) or, if there's a seal on the back, lift, rinse with some degreaser and then flush with a heavy chain lube before replacing the seal. Most will come out with a 10, 11 or 12 mm hex key.

Shimano, £20-£25. done.

I was worried it was going to start off an "if X needs replacing, I should/may as well get Y at the same time" chain that would start with a freehub body, move to hub (rim to disc), wheel, disc brake, frame to builder for disc tabs, respray in an all or nothing spendy extravaganza!

You may find an entire hub is cheaper than a freehub body on its own. Then you get a nice new set of bearings and cones to boot!
Try google shopping for the M code number on the hub

bikewhisperer. just ordered the body in the end. the whole hubs were a bit pricier, especially from this place: http://www.petracycles.co.uk/product_info.php?language=en&currency=GBP&products_id=22684&source=googlepbs

Haha!

Presumably you got exactly the right freehub? Very few are interchangeable.