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Changing a 9 speed cassette for a 7.

craftycrafty Posts: 85
edited October 2008 in Tour & expedition
Is it a relatively straight forward proceedure to swap a 9 for a 7? My wheel was built for a 9 but I need to run a 7 for a short time. I'm wondering if things will still line up properly. The mech will be changed for a 7 as well.

Thanks.

Posts

  • nicklousenicklouse Posts: 81,520 Lives Here
    well you will need to change the brake/gear changer and the chain, and add a spacer to the freebody before fitting the cassette. the Mech can stay as it is.

    I have to ask why as it is a fair cost and effort.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • craftycrafty Posts: 85
    I didn't explain correctly in the first post. It was a little early. :oops:
    The wheel is being used on a 21 speed bike for the winter. It's curently running on a 27 speed bike.
  • maddog 2maddog 2 Posts: 8,114
    just use a spacer on the freehub, that's all

    seven speed cassettes are narrower than 9 by approx one sprocket.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • nicklousenicklouse Posts: 81,520 Lives Here
    as above just the spacer. 4.5mm thick IIRC.

    Again presuming that the drop outs are the correct width apart.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • andymillerandymiller Posts: 2,856
    nicklouse wrote:
    well you will need to change the brake/gear changer and the chain, and add a spacer to the freebody before fitting the cassette. the Mech can stay as it is.

    Would you need to change the shifter? Presumably once the derailleur had reached the largest sprocket the limit screws would stop it moving further over, so the shifter wouldn't be able to go the two clicks further.
  • nicklousenicklouse Posts: 81,520 Lives Here
    andymiller wrote:
    nicklouse wrote:
    well you will need to change the brake/gear changer and the chain, and add a spacer to the freebody before fitting the cassette. the Mech can stay as it is.

    Would you need to change the shifter? Presumably once the derailleur had reached the largest sprocket the limit screws would stop it moving further over, so the shifter wouldn't be able to go the two clicks further.

    yes (if shimano type and indexed) as the spacing between the cogs is different.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • andymillerandymiller Posts: 2,856
    nicklouse wrote:

    yes (if shimano type and indexed) as the spacing between the cogs is different.

    Ah right. Good point. Another good argument for non-indexed shifters.
  • craftycrafty Posts: 85
    Thanks guys.

    Really helpful.
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