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New Cassette

Im looking to get a new cassette for my bike, mine is looking a bit worn.

Just looking for advice on the range.... Im thinking 12-27 to give me the full range. Prob going to get the Shimano 105.

What does anyone think?

Also, I need a new chain.... any suggestions or should I just stick with Shimano 105 for that too?


  • For the rear cassette it depends where you use the bike, and how strong you are up the hills. I have a 12-27 on the back, and a compact chainset. I run out of gears down some of the hills, but will trade that for the get me up the hill gear when i'm tired....
  • husslerhussler Posts: 237
    The 105 cassette is a good buy, although if you can stretch to the Ultegra thats even better....

    I run an 11-21 on the TT Bike when its not a hilly course... on a hilly course I will switch to a 11-23 or 25 depending on the severity of the hills.

    Ill always use an 11t though!:)
  • treefrogtreefrog Posts: 1,242
    Generally when you go to a 27 you will also have to fit a medium cage rear mech. lengthen the chain and possibly change the front mech to the longer arm version. Also if your bike is not set up correctly or if the frame is old you may have trouble actually shifting into the 27 cog when in motion.

    You might get away with a 25 and the only alteration is to lengthen the chain
  • sfullersfuller Posts: 628
    Thanks for the responses.

    The reason I ask is that Im buying some new wheels and need a new cassette (as my old cassette is worn and Im leaving on my 'Turbo trainer wheel/tyre setup') to fit to them, Im currently running 12-27, so thats why I decided on this to stick with it.

    If I did go down to 12-25, would I need to shorten the chain? Change any of the components?

    Treefrog, you are a fountain of bike maintenance knowledge so please impart if you will. No curses this time though.
  • BopomofoBopomofo Posts: 980
    Go for the 12-25, or even a 12-23.

    Dunno about the mysteries of chain shortening but I guess it will be bloody obvious if you need to do this.

    You mentioned getting a 105 or Ultegra cassette and a new chain... are you currently on a 10-speed set-up? I think there may be compatibility probs between 9 and 10 speed, so you couldn't bung a 105/Ulty/Dura cassette and chain on a bike with a Tiagra/Sora chainset. Probably.
  • MrSquishyMrSquishy Posts: 277
    I asked my LBS about the "upgradability" (today's new word!) of Tiagra to 105/Ultegra etc, and was told the amount of components I would have to replace it wouldn't be worth it - may as well take the money and get a bike with 105 (or better) already in situ.
  • sfullersfuller Posts: 628

    Im on a 10-speed (old) Ultegra set-up so assuming a 10-speed 105 or Ultegra will work with it fine.

  • agent_tiagent_ti Posts: 306
    Just a quick warning, if you get a new cassette, then you will likely need a new chain as well otherwise it will just slip non stop

    And old 10 speed and new should mix fine
  • BmanBman Posts: 442
    I agree with agent_ti, ive had a slipping chain for days since getting a new chain and the guy at my LBS took one look this morning and said I needed to change the cassette too. Seems to be the norm.

    Seems when an old chain stretches with age, it wears the cassette differently to when its new, so swapping either one will mean the they will be out of sync with each other slightly. And thats when you get that annoying slipping when you apply a little extra force.
  • sfullersfuller Posts: 628
    So what about at the front of the bike? When you get a new chain.......
  • If the front is worn, then you will need to change that too. They don't wear as quick though, unless you ride a lot it really crap weather (or it's a moutainbike and its muddy, I change chains and cassettes far to often on the mountianbikes)

  • shadowone1shadowone1 Posts: 1,408
    as i consider myself a complete novice, you's are talking double dutch to me with the 12/25, I assume its to do with teeth on the cogs...... need input..
  • shadowone1shadowone1 Posts: 1,408
    so then the less gears on the back then the less teeth. I only have a sixteen speed... yes entry level.

    Having just finished cleaning the rear cassette and chain I am now intrigued. cheers for this.
  • Okay, cos I cant be arsed to work it out..........

    I have a 12/25 on the rear and a 53/39 at the front. When I am on the small front ring and 12 or 13 at the back, this feels harder to pedal than when I am on the big ring and either 25 or 23 ring on the back. Is this right?
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