Drivetrain change... how often and to what?

accountdeleted Posts: 31
edited February 4 in Commuting general

Hello fellow commuters.

How often do you change your chain, chainring, cassette and what do you replace with (OEM or cheap alternative) on a commuter?

My commuter is Triban RC500 with factory:

  • Sora chainring (50, 34)
  • Microshift 9 speed cassette (11, 13, 15, 17, 19, 21, 24, 28, 32).
  • KMC X9 chain.

I've done just over 3,200miles in 2023, all commuting miles. It's had one chain change (approx. 1,600miles) at 0.75 stretch and I'm due for another one as the indicator is almost falling at 0.75. 52t chainring is showing mild sharkfin. I couldn't spot any sign of wear on the cassette (hard to see).

The internet's general rule seems to be to change drivetrain every third chain change; so it is due for replacement. Cheapest Sora 50t (only, I hardly use 34t) is £30ish on eBay. Cheapest cassette is around £14 on eBay (Microshift 11-28, which I don't mind). So that's around £45.00 + new chain. Not bad, I've got the tools and the skill.

But then I thought, I only use the bike to commute, why not just keep changing the chains at 0.75 stretch until the drive train starts skipping (and then change the chainring and cassette).

For a commuter, is it false economy (and lazy) to just change chains and mash the teeth to ground before the whole drivetrain change?

Do you buy cheap non-branded cheap Chinese drivetrain (can you get cheaper 110BCD 4 bolt chainring?) on commuter?


  • Mad_Malx
    Mad_Malx Posts: 5,005

    Cassette change approximately every third chain (if there is skipping after chain change) but chainrings much less frequently - more like three time that. Shimano chainring teeth are different shapes around the ring, to help the shifting - are you looking at this and thinking they they are worn?

    Distance travelled is no guide at all because of the effects of weather, cleaning, shift frequency etc.

    I find cheap replacements are hit & miss. I assume if they run smoothly they aren’t eating the chain.

  • Thanks @Mad_Malx.

    I'm familiar with spotting sharkfins on chainrings from riding single speed for years (teeth look like skewed bell curve). I also recognised the tall/stubby teeth pattern (what's this called?) on the chainrings. Nevertheless, it's still mild, and the chain isn't skipping on the ring or the cassette.

    Cassette wear, on the other hand, isn't something I'm familiar with so I find it much harder to spot.

    I judge the wear dominantly using the chain wear indicator (0.75), not by mileage alone, for the reasons you mentioned.

    Thanks for your thoughts on cheap replacements. Quick search on eBay returned 'brands' like Bucklos, Bolany, and Sunrace. Bucklos or Bolany (never heard of them) sound like side-hussle brands of Chinese factories that make components for the genuine brands. Sunrace I'm familiar with from single speed and retro bikes. Price difference between these and Microshift/Shimano aren't as big as I thought so I don't feel saving few £ is worth taking the punt on cheaper ones. Or I might just try a set and see what I think.

    As it's a commuter bike (and yes, it gets absolutely abused by the British elements and roads), I'm interested in finding out what it feels like grinding the drivetrain to the ground. I'll get a whole Shimano set to replace now so that I've got spare ready to swap over completely.

    Happy commuting.

  • pep.fermi
    pep.fermi Posts: 333

    I change chain whenever it's too elongated, as measured it with the proper tool.

    I spent tons of sweat asking myself "when should I change the cassette?". Ultimately my conclusion is the following:

    At first I change only the chain, if I then on my 1st ride I notice the new chain with the old cassette slipping, then that very day I change also the cassette, otherwise the "old" cassette is still good for the present new chain.

    This is the method a pro bicycle mechanic told me, according to him you can't recognize a old cassette just by looking at it, though I know of course many people say otherwise.

    Good luck.

  • pep.fermi
    pep.fermi Posts: 333

    Some more, price of chain and cassette can vary much, which one to buy from the many compatible ones....?

    I know some would say "if it's too cheap, it probably last short, therefore it ultimately costs more". Fair enough but not my approach. Everything I know about the more expensive chains and cassettes is that they are more expensive. Nothing else. "They cost more, sure they got therefore to be better, right?...." is something I just don't subscribe to.

    Have fun.

  • seanoconn
    seanoconn Posts: 11,407

    I’m in a similar boat. Chain wear is past 0.75. Didn’t measure until last week. Bike two years old with no change of cassette or chain. As it’s not skipping I’m thinking I’ll run in until spring/summer and then change the chain and cassette. If running a stretched chain is likely to damage the chainring? I’d change straight away as they are more expensive to replace.

    Pinno, מלך אידיוט וחרא מכונאי
  • I've got Campagnolo 9 speed on my commuter/winter bike and I fitted it 8 years ago. I do about 4,000 miles a year on it and change the chain about twice a year. The cassette usually gets changed when it skips after I put a new chain on. I think it's had about 3 cassettes over the past 8 years, and I recently put a new large chainring on, I rarely use the small ring when commuting so it still has plenty of life in it. I also changed the cassette to give me a complete new drivechain, at least while I'm on the big ring.

  • If you continue to use the chain for too long you will definitely have to change the cassette, and it will accelerate the wear on the chainring. Given that cassettes are significantly more expensive than chains it makes sense to change the chain according to the recommendations to extend the life of the cassette.

  • This guy is a hyper-nerd when it comes to drivetrain wear, he has built test machines and come up with a testing procedure that will find the differences between the various OEM and aftermarket options. More expensive is not always better, but the best chains generally cost more. If you want to nerd out yourself he has written several articles on the subject of chains and lubes which can be found on his website, or else you can just skip to the test results.

  • Thanks @pep.fermi, I'll go with this rule.

    Thanks everyone for your tuppence.

    Happy cycle commuting.

  • paulbnix
    paulbnix Posts: 631

    My commuter (when I used to commute) was a triple but I found I was only using the middle ring so I ditched the lot and bought a cheap 38t so I'm now a fashionable 1x