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Cassette compatibility question

MharfMharf Posts: 6
edited November 2017 in Workshop
Hi all, this may be a dumb question but I’ve tried to research & can't find the answer. I’m new to cycling since July & bought myself a second hand cx bike. I quickly got the cycle bug :D Due to having kids & not being able to get out as much as I wanted (& not being confident enough to ride in the dark) I invested in a direct drive Turbo which I love & an extra cassette. It’s a 10 speed HG500 11-32

This week I found a cracking deal on a new carbon di2 11 speed Ultegra road bike which I couldn’t resist :lol: It is currently being built :P It is also 11-32

My question is, could I mount this new bike onto my Tackx flux with the 10 speed cassette & loose a gear? I mainly use it in ERG mode for workouts so I rarely have to change gear. Would this work or are they just incompatible?

Thank you :)


  • mfinmfin Posts: 6,724
    A 105 11-32 11-speed is only about £33, so why not buy that and sell the 10 speed one to get a few quid back then it will all work properly?

    I don't get why you'd buy a £600 turbo and a bike that's what? £2000? and then fuss over avoid spending a net of probably less than £20 to have everything spot on.

    Unless you wanna run both bikes on the turbo? In which case just try it and see if it sits in the gear(s) you want, if not, just have two cassettes and swap them on the turbo each time. Takes only a couple of mins to swap.
  • MharfMharf Posts: 6
    Thanks, the Turbo was a present & the bike was just shy of £1,600 :o

    If I need to buy a new cassette then I will but as I have spent quite a lot on the bike & will be keeping the second, I’d rather not if I don’t have to. I will run both on the turbo.

    It’s not just the money, it’s time & ease. Yes cassettes are easy to remove, not the easiest to attach to the turbos multi freehub tho (took me ages). If I could use the same for both bikes it would be great. Anything that saves time is a bonus for me as I squeezie my training time into the nap time of my son.

    My knowledge is just limited; I don’t know whether I would potentially cause damage to the chain/if the chain would fit/if the chain/rear derailleur would work on the cassette spacing etc.
  • kingdavkingdav Posts: 416
    I lurk about, but haven't posted much before.

    I like mixing things up, I run shimano cranks and sram gears on my commuter including 10 speed shifters with 11speed deraileurs... this works fine because the pull ratios are the same. The shifters and the cassette do need to match really though.

    I think what you are doing here is a step too far. I don't think your 11sp di2 will shift cleanly across a 10sp cassette and it's worth losing that cassette and replacing with an 11sp.
  • Alex99Alex99 Posts: 1,407
    If you rely on erg mode and don't have to change gear, then I can't see why it would cause a problem sticking with the 10s cassette. You just need one gear to be working, right? Or if you need two for some reason, you've got big ring, and small ring. Choose one with a straight chain line and tweak the barrel adjuster on the rear derailleur if you need to.

    Why spend more money if you have a solution?
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