Bicycle Mechanics - how do you take apart a cassette?

I'd like to turn my old Trek 800 into a single speed. I removed the Shimano cassette from the freehub but how do you separate out the rings and spacers? thanks!

some are riveted together and some had a three small screws on the back of the largest cog. do you have extra spacers?

Why bother? Just set the chain where you want it and remove the shifter, cable, and derailleur.

looks like there are 3 small rivets on the second to smallest ring holding everything together. How do i get those apart? and yes, I do have extra spacers

Why bother? Just set the chain where you want it and remove the shifter, cable, and derailleur.

You cant just shift the chain over to whichever cog you want on and then remove the components... The rear derailleur picks up the slack on the excess length of chain depending on what cog you're in, so either way, you'd end up with a chain that is WAY too long for a SS/FG.

Many Shimano cassettes are held together with very thin bolts with allen heads, IIRC, a 1.5 mm wrench fits them. If that's your case, just unthread the three bolts and the whole thing will fall apart.

Some cassettes are rivited and you have to grind off the heads. A Dremel tool with a small grinding stone is the best approach to these.

On the last cassette I took apart, the "rivets" were actually bolts with tiny hexagonal heads. Try turning them out with a pair of pliers. You'll want extra spacers to replace the space left from removing gears.

It's not a great idea to take off the derailleurs and shorten the chain. Most modern cassettes are ramped, making for smoother shifting, but if you had a shortened chain on a full cassette, it's not all that hard to accidentally catch one of those ramps and "shift." I had a friend who broke his axle in a situation just like that.

On the last cassette I took apart, the "rivets" were actually bolts with tiny hexagonal heads. Try turning them out with a pair of pliers. You'll want extra spacers to replace the space left from removing gears.
+1. I had forgotten about those. Those bolts take a 4mm socket or open end wrench and the bolt heads are behind the largest cog.

BTW, the allen head bolts I mentioned above require a 1.5 or 2 mm allen wrench depending on the model of cassette.

thanks guys, I'll go see if the little rivet things are actually tiny allen screws or what.

Grind the heads off the rivets and remove them with a pin punch. If it's the OEM cassette on Trek's lowest end 1993 MTB, that sucker is riveted together for sure.

If your bike has vertical dropouts you'll have to buy a singlespeed kit anyway in order to get the chain tensioner, and the kit will come with cogs and spacers.

my Trek 800 has a 7 speed freewheel. Geuss its an older model.

you could scrounge an old cassette from someone. Then break it up for the extra spacers you need.

yep, those are rivets holding the cassette together, guess I will try the dremel grinding stone. or maybe stop by my LBS and see if they have any old cogs around. I'd like a 23t in the back if possible b/c I plan to put winter studs on this bike and I live in a very hilly area and typically ride a 32t/18t combo on my 650B bike w/ very beefy tires for everyday kinds of commuting/riding

If your bike has vertical dropouts you'll have to buy a singlespeed kit anyway in order to get the chain tensioner, and the kit will come with cogs and spacers.

+1 I recommend getting a single-speed kit even if you do have horizontal dropouts. Cogs for multi-speeders are profiled to allow for easier chain engagement/disengagement. An SS cog will have taller teeth with no ramps which will hold the chain on much better.

If you have a cass. with "ramps" on the cass cogs/"gears"... don't bother using them on the conversion.

Why? .. you ask .
Under heavy load, climbing or sprinting out of the saddle. The cog will "shift" the chain to the next gear... ( no matter what the chain tension ) and since there isnt one, the chain will drop.

Same for a derailer-less ( complete not dissasembled )cass ... but worse ! ( if you have old school horizontal dropout. "not a trak fork." See sheldon brown site if needed. )
Under load if you have ramps it will shift to the next larger cog ... and since, your chain will stay the same lengnt it will yank the wheel out of the drop out , right into the chain stay.

Sram seems to use tiny allen bolts that reach the smallest cog with the threaded holes, and some shimono uses rivets, the heads grind off real easy, just like mentioned above ...

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