Cassette queries..

dai_t75
dai_t75 Posts: 189
edited June 2013 in Workshop
Hi all,

I realise you probably get a lot of questions on this area - I have tried to do my own research, but can't seem to find a definitive answer.

I am looking to change the cassettes on both mine and the OH's bikes...

I have got a Triban 3 which came with 25 as the largest rear sprocket - from what I have read I will just about be OK to put a 28 on there without having to change the rear mech (came with shimano 2300). Does this sound right?

My OH has a 'Norco Valence' or something like that. It came with a Sora 8 speed and the largest sprocket at the moment is 30 (I realise this is quite large already). Now, I had a look at the techdocs for the Sora and from what I can see it says 27 is the max... so 30 seems to be pushing it already. So I am guessing I will need to put a MTB rear derailleur on the back if I want to go above the 30? Any cheap recommendations for MTB mech and cassette?

Thanks as always.

Comments

  • dai_t75
    dai_t75 Posts: 189
    Shameless bump... forgot to ask - would I need a bigger chain in either case?
  • smidsy
    smidsy Posts: 5,273
    Without knowing the exact models in question your assumptions seem reasonable.
    Yellow is the new Black.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    Don't know if you would class it as cheap but SRAM Apex long cage and 11-32 is nice.
  • dgunthor
    dgunthor Posts: 644
    28 should be fine any you may get away with a 30 too. I did with my shimano ultegra rear mech
  • dgunthor
    dgunthor Posts: 644
    as regards chain length you need to check that the chain will support smallest chainring + smallest cassette sprocket, largest chainring + largest cassette sprocket as that's the full extent it needs to cover.

    There are various sizing techniques to achieve this but that's what they are doing - ensuring all the gears work ok.
  • smidsy
    smidsy Posts: 5,273
    Technically you should avoid large/large and small/small combinations.

    Shimano size their chains with largest front/smallest rear.
    Yellow is the new Black.
  • dgunthor
    dgunthor Posts: 644
    ^^^ yes, valid point, but this is an alternate chain sizing method to the largest front / smallest rear which checks that the chain can cope with the extreme gears
  • Cretan Steve
    Cretan Steve Posts: 27
    Hi,
    You don't mention whether both bikes are running doubles or trebles? but if they are doubles you can fit the latest 9 speed Sora medium cage rear which will take a 32 sprocket. Also Sram do an 11-32(MTB) 8 speed cassette that works fine with this derailleur. It all works with the 2300 shifters as well. I use this set-up as a cheap alternative to Wi-Fli and it works a treat. Hope that's useful!
    Steve

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