velociraptor

Right now, I swap one cassette between 2 wheels for either riding on the trainer, or taking the bike out.

This cassette and the chain on the bike have worn together and have approx 3000 miles on them.

For the sake of efficiency, I'd love to have both wheels with their own cassettes so I can just swap them out at will.

However, I know this may present a problem because the used chain won't ride quite right on a new cassette.

Or am I overthinking and it doesn't really matter?

How do others address this situation?

If it's no big deal, which wheel would be recommended to put the new cassette on, the wheel for the trainer or the other? Does it matter?

FBinNY 

You're either overthinking this or you're not.

At 3,000 miles odds are that the older cassette and chain aren't that badly worn. If this is the original chain, take a moment to measure it and that will tell you the story. If the chain is worn but OK, I'd replace it now because worn chains are harder on sprockets than new ones, but don't discard it. Run the new chain on both cassettes, and monitor the stretch. When it wears beyond the condition of the old chain, switch back, and thereafter play leapfrog running the chains alternating and you should be able to run both cassettes as long as you don't let them get too mismatched.

BTW- if the new chain skips on the old cassette, which it may if the old chain is overly worn, then replace the cassette, and switch back and forth often enough to keep everything decently matched.

hueyhoolihan

if it were me, i'd buy a new cassette, try it out, and then determine whether or not i had a problem.

if skipping occurs on the new cassette, i'd buy a new chain and again, test it out to see whether or not i had a problem. if new chain skipped on the old cassette, the only reasonable fail type situation left, i'd probably buy another new cassette.

BTW, i've only ever had one cog set, and it was probably an 8-speed xtr freewheel at that, ever wear to the point it skipped. that was about 20 years ago now. for some reason my single speeds never give me any trouble. not sure why. and i'm not asking either.

fietsbob

New chain And cassette .. paired together chain wear imparts its wear Pattern in the teeth.

bag the old cassette and chain together.

ljsense

I think the notion that a chain and cogset wear together and should be replaced together is based on old corncob 5 or 6 speed freewheels.

Now freehub cassettes sometimes have different materials for different cogs (titanium and steel) and a wider range, and chains are much narrower and less durable and people are always swapping wheels. It just doesn't seem credible that the 15t cog and the 21t cog, which are made from different materials, are all magically calibrated to the wear on a 10-speed chain. If someone has evidence to back this up, I'd like to see it because in everyday life I've never seen evidence that modern cogsets and chains are magically connected by wear patterns.

FBinNY 

I don't think anybody said anything like all the sprockets wearing evenly. They don't.

The most used sprocket will wear faster than the others, but the wear rate and wear pattern are determined by the condition of the chain. You get the classic hook pattern as each roller sweeps in on an arc, leaving that in the next tooth.

It's that wear pattern which reflects the longer pitch of a worn chain, that causes new chains to skip on sprockets that ran worn (stretched) chains for any length of time.

I hope this helps, but if not your free to believe what you want until a skipping chain tells you otherwise.

BTW- the use of Ti on larger sprockets on some cassettes reflect the reality that larger sprockets weigh more so the cost is justified. It also assumes that larger sprockets will see less use, so the softer Ti will still hold up. That second assumption makes sense, since IME the skipping sprockets are almost always on the outer third or so of the cassette.

velociraptor

Thanks guys for the helpful answers.

I'm thinking I'll just buy a new chain with 2 new cassettes - and then make sure I'm getting even wear between them.

hueyhoolihan

good idea.