Changing cassette

Dave1441
Dave1441 Posts: 96
edited March 2014 in Workshop
Hi, I'm planning on changing my cassette, I'm currently on a 10spd and will be keeping it as a 10spd. Will I need to change anything in order to fit the new cassette? Will I need to get a different sized rear derailleur hanger? I plan on changing from an 11-32 to a 16-25 if that is helpful.

Comments

  • e999sam
    e999sam Posts: 426
    Using a 32 you've probably got a long cage mech which you won't need with a 25 but it will still work fine. The only thing you may have to change is your chain if it's worn.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    aa your rear mech will be long cage which you don't need for a 25 max and you will need to shorten your chain going down from max 32 to max 25 - you could shorten the one you have if its in good nick or fit a new one.

    Chain Sizing - Largest Cog and Largest Chainring Method

    An alternative method for determining chain length for new chains is to use the largest size sprockets on the bike. It is easiest to size the chain without threading it through the derailleur.
    1. Remove the old chain.
    2. Shift the front derailleur over the largest chainring, and the rear derailleur on the smallest cog.
    3. Thread the new chain through the front derailleur. It is not necessary to thread the chain through the rear derailleur at this point. Simply wrap the chain around the largest front chainring and around the largest rear cog.
    4. Pull the chain tight, and note the closest rivet where the two could be joined. Keep in mind a chain can only be joined by mating inner and outer plates.
    5. From the closet rivet, lengthen the chain by counting over an additional two rivets (two links), which is a distance of one-inch. Cut the chain at this point.
    6. Remove the chain from the bike and thread it through both derailleurs and join the ends.

    MASTER LINK NOTE: If the bike chain uses a "master link", it is necessary to account for the link. Install one-half of the master link on one side of the chain. Size the chain by cutting the other end of the chain.

    http://www.parktool.com/blog/repair-hel ... gth-sizing
  • lesfirth
    lesfirth Posts: 1,382
    wishitwasallflat wrote:
    aa your rear mech will be long cage which you don't need for a 25 max and you will need to shorten your chain going down from max 32 to max 25 - you could shorten the one you have if its in good nick or fit a new one.

    Chain Sizing - Largest Cog and Largest Chainring Method

    An alternative method for determining chain length for new chains is to use the largest size sprockets on the bike. It is easiest to size the chain without threading it through the derailleur.
    1. Remove the old chain.
    2. Shift the front derailleur over the largest chainring, and the rear derailleur on the smallest cog.
    3. Thread the new chain through the front derailleur. It is not necessary to thread the chain through the rear derailleur at this point. Simply wrap the chain around the largest front chainring and around the largest rear cog.
    4. Pull the chain tight, and note the closest rivet where the two could be joined. Keep in mind a chain can only be joined by mating inner and outer plates.
    5. From the closet rivet, lengthen the chain by counting over an additional two rivets (two links), which is a distance of one-inch. Cut the chain at this point.
    6. Remove the chain from the bike and thread it through both derailleurs and join the ends.

    MASTER LINK NOTE: If the bike chain uses a "master link", it is necessary to account for the link. Install one-half of the master link on one side of the chain. Size the chain by cutting the other end of the chain.

    http://www.parktool.com/blog/repair-hel ... gth-sizing

    If you are fitting a new chain you can use the above procedure. If you are using your existing chain you do not have to do anything.
  • slowbike
    slowbike Posts: 8,498
    I have two wheelsets for my do-it-all bike - one has a 32-11 cassette on (original) the other has a 23-12 cassette - both 9 speed.
    I didn't change anything about the chain when i changed - only checked to see that it wasn't worn.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    lesfirth wrote:
    wishitwasallflat wrote:
    aa your rear mech will be long cage which you don't need for a 25 max and you will need to shorten your chain going down from max 32 to max 25 - you could shorten the one you have if its in good nick or fit a new one.

    Chain Sizing - Largest Cog and Largest Chainring Method

    An alternative method for determining chain length for new chains is to use the largest size sprockets on the bike. It is easiest to size the chain without threading it through the derailleur.
    1. Remove the old chain.
    2. Shift the front derailleur over the largest chainring, and the rear derailleur on the smallest cog.
    3. Thread the new chain through the front derailleur. It is not necessary to thread the chain through the rear derailleur at this point. Simply wrap the chain around the largest front chainring and around the largest rear cog.
    4. Pull the chain tight, and note the closest rivet where the two could be joined. Keep in mind a chain can only be joined by mating inner and outer plates.
    5. From the closet rivet, lengthen the chain by counting over an additional two rivets (two links), which is a distance of one-inch. Cut the chain at this point.
    6. Remove the chain from the bike and thread it through both derailleurs and join the ends.

    MASTER LINK NOTE: If the bike chain uses a "master link", it is necessary to account for the link. Install one-half of the master link on one side of the chain. Size the chain by cutting the other end of the chain.

    http://www.parktool.com/blog/repair-hel ... gth-sizing

    If you are fitting a new chain you can use the above procedure. If you are using your existing chain you do not have to do anything.

    Point is OP is making a big change to cassette so even if reusing the same chain they would need to shorten it.
  • Moonbiker
    Moonbiker Posts: 1,706
    Why 16-25 won't you you will spin out downhill?
  • mamba80
    mamba80 Posts: 5,032
    http://www.machinehead-software.co.uk/b ... hcalc.html

    technically you do not need to shorten it all, as you use the range 16 to 25 on your existing cassette, but I would do so, if this is a permanent change.

    also, un screw the b screw on the RD, to bring the top jockey wheel closer to the cassette, if you are using a junior 16-25 for racing, then fit a new chain (you might need one anyway) - don't want it to break as you sprint for your first win, bring down the bunch :)

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