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8 speed chain and turbo with 11 speed cassette

navrig2navrig2 Posts: 1,809
in Road general
This should probably go in the Workshop or Indoor Training forums however I suspect I will get a quicker response here.

In summary I am looking to attach my wife's 8 speed hybrid to my Kickr Core which has an 11spd cassette.

What problems will I face?

The situation is a little complex. We are in Vietnam which is now in partial lockdown. Bike spares are in short supply - when I bought the Kickr the shop had to hunt around to get the cassette (105 11spd) as they had none and deliveries were forecasting 4 months ahead.

I do not have any tools other than a basic mulit-tool. I don't have much apartment space for doing repairs etc.

Labour is cheap so getting mods done to the bike at a shop is feasible.

The weather is not conducive to outside cycling for my wife and all her social activity groups are now disbanded. The upside is that the traffic is less intense.

She still cycles outside using her bike to get some outside (not fresh) air and for shopping (a basket bike on a top-end turbo is an interesting concept). However it is very (very, very, very) flat here so gear changing is not a regular thing. For instance I don't change gear on my 5km commute to work.

If the 8 speed chain is too wide could I consider fitting an 11 speed to her hybrid? How would the gear changes go? I could disable the rear derailleur using the set screws and if she wanted a lower gear should drop the chain at the front, so would front changes with an 11 speed chain work?



Posts

  • navrig2navrig2 Posts: 1,809
    edited June 2021
    I should add that I am still using the turbo so need the 11 speed cassette attached.

    There is a lot of useful information on the web. For instance I found the following:



    This suggests that the 8spd chain will snag on the cassette however I would still be keen to hear anyone's views or, even, better, experience.
  • smethleysmethley Posts: 45
    Not only will the 11spd chain be narrower on the outside faces (as your table shows) , but it will obviously be narrower on the inside faces too, so the 8 speed cogs will be too wide (thick) for the chain to sit over them properly.
  • mully79mully79 Posts: 904
    The 8 speed chain is going to interfere with the cassette in every gear except the largest one. Thats one option.

    Another is to effectively single speed it by swapping two smaller sprockets around on the cassette and setting the derraileur to only run on the one thats out of position.
  • MattFalleMattFalle Posts: 11,644
    as above re 8 speed chain deffo, however I'd lob a 11 speed chain on and have a fiddle and see what happens - it may not be perfect but its worth a bash.

    After all, its how I found out 10 speed Red works perfect with 11 speed Campag....

    nothing ventured nothing gained.
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • navrig2navrig2 Posts: 1,809
    Thanks guys.
    MattFalle said:

    as above re 8 speed chain deffo, however I'd lob a 11 speed chain on and have a fiddle and see what happens - it may not be perfect but its worth a bash.

    After all, its how I found out 10 speed Red works perfect with 11 speed Campag....

    nothing ventured nothing gained.

    That's where I got to in my thinking. I guess the biggest risk is the cost and installation of the chain. If it doesn' work I will have a spare chain for bringing home with me when we return.
  • MattFalleMattFalle Posts: 11,644
    Can't you use your current 11 speed chain just to see if it works and if so splash out on a new one specifically for this?

    Saves the time lag between ordering, waiting, fitting, fettling....
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • navrig2navrig2 Posts: 1,809
    edited June 2021
    smethley said:

    Not only will the 11spd chain be narrower on the outside faces (as your table shows) , but it will obviously be narrower on the inside faces too, so the 8 speed cogs will be too wide (thick) for the chain to sit over them properly.

    From here:

    https://bike.bikegremlin.com/3555/bicycle-drive-chain-dimension-standards/

    Single speed chains have inner width of 1/8″ (3.175 mm).
    Multi speed chains, from 5 to 8 have inner width of 3/32″ (2.38 mm).
    Multi speed chains from 9 to 12 speeds have inner width of 11/128″ (2.18 mm).

    and here:

    https://bike.bikegremlin.com/3573/bicycle-cassette-rear-chainrings-standards/





  • navrig2navrig2 Posts: 1,809
    MattFalle said:

    Can't you use your current 11 speed chain just to see if it works and if so splash out on a new one specifically for this?

    Saves the time lag between ordering, waiting, fitting, fettling....

    I don't have a splitter and am trying to avoid accumulating more belongings here (although my wife is trying to do the opposite). Not sure how the chain lengths would vary either - although for a quick test that would not matter.
  • smethleysmethley Posts: 45
    Navrig2, re sprocket thickness, I'm not sire which point you're making? From your table the 11 speed chain will be expecting 1.6mm, but you are going to offer it 1.8mm. Given that the chainline is not parallel on all sprockets, I'd be wary. Of course as others have said, you can simply suck it and see.
  • MattFalleMattFalle Posts: 11,644
    negatron - he's using 11 speed cassette, 11 speed chain, 8 speed shifter

    the whole sprocket/chain thang is a red herring.

    its the shifting he's thinking about.
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • shirley_bassoshirley_basso Posts: 6,194
    what about the front chainrings?
  • darkhairedlorddarkhairedlord Posts: 7,180
    Just swap the cassette over and stop faffing about.
  • MattFalleMattFalle Posts: 11,644
    shirley_basso said:

    what about the front chainrings?

    fairly moot point i'd say - may work, may not.

    give it a bash and see what happens...
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • navrig2navrig2 Posts: 1,809
    darkhairedlord said:

    Just swap the cassette over and stop faffing about.

    The idea is to be able to use the turbo for both bikes and the idea of swapping cassettes each time we swap a bike? That's a faff.

    Thanks for your useful contribution.
  • navrig2navrig2 Posts: 1,809
    MattFalle said:

    negatron - he's using 11 speed cassette, 11 speed chain, 8 speed shifter

    the whole sprocket/chain thang is a red herring.

    its the shifting he's thinking about.

    It's not the shifting that's the issue. It's the fit and compatibility between chain (8 or 11spd) and the 11spd cassette on the turbo.

    If my wife's hybrid runs with the 8spd chain there is a potential clash with the 11spd cassette. If it runs with an 11spd chain there may be an issue with the chainring thickness.

    Out and about she rarely changes gear so if, with an 11spd chain, the gear change is clunky that's not an issue as long as it doesn't result in the chain dropping and getting jammed.

    Looks like I'll have to try the 11spd chain option.
  • darkhairedlorddarkhairedlord Posts: 7,180
    navrig2 said:

    darkhairedlord said:

    Just swap the cassette over and stop faffing about.

    The idea is to be able to use the turbo for both bikes and the idea of swapping cassettes each time we swap a bike? That's a faff.

    Thanks for your useful contribution.
    You have an eight speed and eleven speed. You can either make both bikes 11, both 8, or change the cassette. Happy to help.
  • MattFalleMattFalle Posts: 11,644
    navrig2 said:

    MattFalle said:

    negatron - he's using 11 speed cassette, 11 speed chain, 8 speed shifter

    the whole sprocket/chain thang is a red herring.

    its the shifting he's thinking about.

    It's not the shifting that's the issue. It's the fit and compatibility between chain (8 or 11spd) and the 11spd cassette on the turbo.

    If my wife's hybrid runs with the 8spd chain there is a potential clash with the 11spd cassette. If it runs with an 11spd chain there may be an issue with the chainring thickness.

    Out and about she rarely changes gear so if, with an 11spd chain, the gear change is clunky that's not an issue as long as it doesn't result in the chain dropping and getting jammed.

    Looks like I'll have to try the 11spd chain option.

    ok

    8 speed chain won't work on 11 speed cassette

    11 speed chain won't work on 8 speed cassette.


    8 speed chain will work on 8 speed cassette

    11 speed chain will work on 11 speed cassette

    done.
    .
    The camera down the willy isn't anything like as bad as it sounds.
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