Do I need two cassettes

Had my bike serviced yesterday. Needed a new chain which was a bit of a surprise. The LBS said I should replace the cassette as well so they are compatible. He told he to see how it goes with the current one for a week or so but if it jumps about then changing it would be changed.

Went out this morning and it looks like a change is in the cards as when I stood up to climb a small hill it jumped all over the place.

This made me think. Do I then need to change the one on the trainer as well to avoid the same issues.

Hoping this is not the case

Maybe, but depends a bunch on how much you used the bike with the worn chain on the trainer cassette. If it was a bunch, and in a range of gears, the extra worn chain is likely to have worn and “damaged” the cassette.

If you didn’t use the trainer cassette ton, and maybe in just a few gears for ERG, you might be fine. You will probably just have to ride it with the new bike chain and make a call like you did with the bike and your regular wheel.

As a rule, if you replace a chain soon enough, you can get 2 or 3 new chains on the same cassette and front sprockets. Let the chain go too long (which sounds like the case), and you are in for expensive replacements. That’s why a $5 chain checker is worth every penny, as is already having a replacement chain in your possession, so you can swap when the time is right… and save a bunch of cash.


Bummer, the chain and cassette were just over 12 months old but the front chainring was the big issue which have now been changed. Looks like I am going shopping for 2 cassettes.

Never good when you have Campag Record to replace

Bit the bullet and ordered the two cassettes today. Not worth wasting the new chain. Hopefully they come quickly

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I have 2 chains on the go - one for the road wheel and one for the Kickr & swap them over depending on what I’m doing. A bit of a faff but it’s not my main road bike - only gets used for long rides so once every 2 or 3 weeks.

That way the chain should always have compatible wear with the cassette being used at the time.

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That is commitment. Would work well I think

Good choice.
Get yourself a chain stretch tool from PartTools or similar, and always change the chain early at the 0.5% wear indicator, and you can typically get 3 or more chains per cassette.

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That’s what my LBS advise. A royal PITA tho!