Help please with new cassette..

Discussion in 'Bicycle Mechanics and Repairs' started by potsy, 13 Apr 2010.

  1. PpPete

    PpPete Guru

    Location:
    Chandler's Ford
    Well the second one looks like a freewheel (not a cassette) despite what Chain Reaction want to call it.

    The specs on the current 7.1FX are for a 14-34 7 speed cassette, so neither your 1st or 3rd options are exactly the same. They should work though - although your gear ratios will be a little higher.
     
  2. OP
    OP
    potsy

    potsy Birder

    Hi pete,yes I have a 14-34 now which has done over 2500 miles so pretty sure it's due a change,don't really use the 34 now so was going to put a more conventional range on it.
    The freewheel bit was confusing me but after reading Sheldon I now realise I need a 'cassette'.
    Just need to work out how many links to take out of the chain now:wacko:
     
  3. PpPete

    PpPete Guru

    Location:
    Chandler's Ford
    You might need a new chain with a new cassette... although 7 speed chains don't stretch as quickly as the 9 & 10 speed stuff so you might be OK

    Either way, there's a good vid for chain length on bicycle tutor IIRC.
     
  4. OP
    OP
    potsy

    potsy Birder

    Just put a new chain on which has got me thinking whether I should have changed cassette as well,only done a few miles since so chain should be as new.
     
  5. swee'pea99

    swee'pea99 Legendary Member

    You say you're 'pretty sure it's due' on account of the mileage. I'm not saying it's not, but the way to check is to look at the teeth. If they have a sharks teeth look like this, then you do need a change. But if not, and you're happy with it, I'd keep it.

    34te8uv.jpg
     
  6. I also just replaced my chain without replacing the cassette. Foolish, as the chain now skips under pressure in all of my favourite gears. I had no idea it was quite so worn, but now it sounds like a bag of spanners! Closer inspection of the teeth on the cassette shows some pointy andor hooked teeth as expected.

    I am going to have to ride it until the end of the month (probably 100 miles total since fitting), but will I then need another chain to go with the new cassette? Is this also going to need a new chainsetrings as well, or are they a bit more tolerant? <crosses fingers>
     
  7. rh100

    rh100 Well-Known Member

    I'm pretty sure that my GF's Trek 7.1FX has a freewheel rather than a cassette, but I'm sure spec's get changed.
    Does yours have the BIG bottom gear, if so it should have the part number on it MF-T something or other same as the one in the second link you gave, if you search for that you should find it listed and find out if freewheel or cassette.

    My own 7100 FX ( a bit older) also had a freewheel and I changed to cassette when buying new wheels.

    I think the freewheel screws on as a whole block, and the cassettes slot on the hub and locked in place with a lock ring. Different tools required for each.
     
  8. Fiona N

    Fiona N Veteran

    When you replace the cassette, buy a second new chain, fit this one (the first new one won't be that much worn anyway) and ride until you want to clean the chain, then swop back to the first new chain and keep alternating - you'll get double the life of the cassette as you'll be spreading the wear over two chains (or three, if you're keen) and won't suddenly fit a brand new chain onto a half worn cassette.

    The greater number of teeth and bigger radius of the chain rings means they take longer to wear out so you should be OK with them and they tend not to skip so much as change poorly when worn.
     
  9. OP
    OP
    potsy

    potsy Birder

    You're right rh100,just been to look it's a Shimano MF TZ31.googled it and it's a freewheel:blush: £12.99.At least I know now.
    Assume I can fit any 7 speed freewheel now then? If I wanted cassette it would mean new wheel?
     
  10. rh100

    rh100 Well-Known Member



    I'm no expert having only fitted the one :smile: but I found it a bit of a minefield. The cassettes fit onto a freehub, which is like a barrel assembly that comes as part of the wheel, it has grooves on which the cassette slots into and is then locked down with a lockring. I had bought new wheels, found out that my current set of cogs was a freewheel block after looking at Sheldons site, so then bought a cassette and spacer (which is needed if 7 speed - only a couple of quid), which then meant a new chain aswell :biggrin: (new chainrings next :smile: )

    I haven't fitted a freewheel block, but I presume they are interchangeable. Hopefully an expert on here will chip in with more advice.
     
  11. TheDoctor

    TheDoctor Resistance is futile! Moderator

    Location:
    Stevenage
    Any 7 speed freewheel ought to go on, the tricky bit is getting the old one off!
    Be advised there's not much choice in freewheels any more. My LBS has Shimano 14-28, and Zenith in 13-21/24 and 14-28.
    And yes, a cassette would mean a new wheel. Or a new hub, at any rate.
     
  12. OP
    OP
    potsy

    potsy Birder

    The perfect excuse for a new bike then:biggrin:
    I see this bike as my 'hack' now so it's not going to get an awful lot of use bar shopping trips and the odd wet weather commute,so will do what I can to keep it going but not going to spend much on it,bargain bits only.
     
  13. Great idea Fiona, and sorry for impinging on your thread Potsy, but I figured it was relevant.
     
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