Replacing a Shimano 8 speed cassette

stephenjohnkuhn
stephenjohnkuhn Posts: 4
in Workshop
I tried to replace my Shimano Sora 8 speed cassette (12-26) with an Acera 8 speed (CS-HG41) 11-34. I can't get the new locknut to tighten (I can if I only try to fit 7 of the gears). Are they not compatible? Or am I doing something wrong?

Comments

  • reaperactual
    reaperactual Posts: 1,185
    edited August 2020
    The CS-HG41 8 speed cassette is for MTB or touring and are narrower than road cassettes.

    The problem is usually the locking nut bottoms out before the cassette is tightened?

    Wider road freehubs require a 1.85mm freehub spacer fitted between the hub and an MTB cassette to make them work?

    Something like this for example:-

    https://www.planetx.co.uk/i/q/HUALFBS/alloy-freehub-body-spacer-185mm-silver

    Not a road biker myself but my MTB wheelset has a road freehub and needs the spacer for my 11 speed cassette to tighten properly.

    Try downloading a picture which may help you get an answer Pal.

  • stephenjohnkuhn
    stephenjohnkuhn Posts: 4
    Thanks. I've ordered the spacer and will give it a try.
  • reaperactual
    reaperactual Posts: 1,185
    Just double checking Mate. Is your problem the same as I described, sounds like you have the opposite issue of the cassette being too wide and only fits with 7 cogs? If this is the case a spacer is not the solution.
  • stephenjohnkuhn
    stephenjohnkuhn Posts: 4
    Yes, I did wonder that. It does seem like the cog is too wide, rather than too narrow to me. I don't know if the spacer might work with 7 gears (although this might mean chain keeps coming off on bottom?). Spacer was only 99p so happy to try-but yes I think you're probably right.
  • reaperactual
    reaperactual Posts: 1,185
    Very difficult know what the issue is. Never heard of this problem before and shouldn't be any issues you described with this set up.

    Don't think your cassette will lock properly without the small cog, it as it has a serrated pattern that the lock nut grips onto for instance.

    A picture of freehub, cassette etc. will be helpful to see the problem more clearly and may be more obvious to work out where it's going wrong.
  • N0bodyOfTheGoat
    N0bodyOfTheGoat Posts: 6,067
    Everyday's a school day, for some reason I thought cassette width was universal across MTB and road until at least 10-speed.

    The recently fitted 11-speed 11-34 cassette on my Cube road bike comes with a spacer, which isn't needed to fit on an MTB 10-speed freehub.
    ================
    2020 Voodoo Marasa
    2017 Cube Attain GTC Pro Disc 2016
    2016 Voodoo Wazoo
  • reaperactual
    reaperactual Posts: 1,185
    edited August 2020
    N0bodyOfTheGoat said:

    Everyday's a school day, for some reason I thought cassette width was universal across MTB and road until at least 10-speed.

    The recently fitted 11-speed 11-34 cassette on my Cube road bike comes with a spacer, which isn't needed to fit on an MTB 10-speed freehub.

    You could be right about same widths up to 10 speeds, N0bodyOfTheGoat I'm not sure on that just my initial thought.

    Only found out about different freehub widths when I bought my Hope Hoops with Pro 4 hubs that use road freehub standard. 🤔 Wondered why my 11 speed mtb cassette was loose until I found out about why it needed a spacer.👍

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