Rear cassette compatability

I’m looking into replacing some parts on a friend’s MTB before we go to BPW. It’s an old Trek 810 and has a shimano tourney group set, it has “FC-TY30” stamped on the crank arm. The middle chain ring is very worn and is causing problems.

I’ve found new crankset and chain very cheaply (£25 for both), and i’m happy with that, rather than trying to upgrade.

Since I’m replacing both of those I thought I should probably replace the cassette too. I think from the documentation here:
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Tourney/SLTY22-7/SI_TY220B_EN_v1_m56577569830607240.PDF

I’m looking for a cassette with the model name: MF-HG37

I can’t seem to find any UK sellers for that part, does anyone know if I could buy any 7 speed shimano cassette eg:
http://www.wiggle.co.uk/shimano-cs-hg50-7-speed-cassette/
..or will there be something special about the HG37?!

Thanks,

That’s a freewheel not a cassette.

BPW on a Trek 810 ? Rim brakes ? He won’t be a friend by the time you get back…

Any 7 speed should work as long as it is same fitment and ratio.

You’ll need something like… http://www.sjscycles.co.uk/freewheels-7-speed-dept79/

Thanks all.

So, assuming I go for one off the link from simondbarnes
eg: http://www.sjscycles.co.uk/shimano-mf-tz21-7-speed-screw-on-freewheel-14-28-prod18964/

I have limited mechanical experience as I have clearly already demonstrated(!), but will I be able to use my standard HG freewheel extractor tool/chain whip/spanner combo to remove the old and fit the new one?

As regarding BPW: I’ve got the impression from people on here that as long as I don’t lead him down a black or pro-line, then he’s not going to die. But it if he does die, at least his drive-train will be in immaculate condition.

I think that the freewheel remover is deeper than a cassette lockring remover, and that’s if the splines are the same
Ring SJS (if you’re buying from them) they’ll advise you. The remover is <£3
You won’t need a chain whip, just a vice or big spanner ParkTools

Cassette lock ring tool is not the same as the free wheel tool you will need to remove that old screw on free wheel.

But to save buying a tool you maybe able take apart the free wheel to remove the cogs leaving the part with the paws on the wheel. Ten clamp this in a vice and turn the wheel to unscrew this remaing part

There are two little dimples on a ring just inside the smallest cog tap this round to get into the free wheel

You won’t need a tool to fit the new freewheel just a little grease

Used to work in a LBS,a TREK dealers and we were always at the 810 bike as we hired them out and they got a hammering. Never really minded changing a freewheel as it is easier than a cassette to do. Most people woould bring in their wheel with the tyre still on,it gives you much more grip to spin the wheel. Favourite tale is one clever lad who rocked up wanting his freewheel removed to rebuild his wheel. All well and good you think but he had cut the hub out of the wheel,just little stub of spokes left on the driveside!. Not happy when we told him we could not get the freewheel off!. Major fail,mojor laugh for us though…… 🙂

Thank you – I’ll talk to SJS on ordering to confirm, but that Park article clears it up a fair bit too. Great resource, thanks.