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Transmission Upgrade Advice

grantusgrantus Posts: 690
edited May 2008 in Workshop
Hi folks,

Was looking for some advice/opinions please: -

I have an 8 speed roadbike with 39-53 double and 12-26 cassette set-up.

I want to increase the range of gears as simply and cheaply as possible.

I had narrowed it down to two options: -

Fit a Sora compact chainset (marketed as 9 speed but will this suit 8 speed also?) I can get one online for under £30 delivered.


Fit 11-32 cassette and swap the Tiagra short cage mech that is fitted at present for a Deore. The cost of this would be around £30 also.

Would it also be feasible (and cheap!) to fit a triple or would this mean a new front derailleur and bottom bracket?

Alternatively, could I get away with a 28 or even 30 tooth rear cog with the Tiagra short cage mech? I know the limit is supposed to be 27 but I've read that you can get a good bit more than that with careful adjustment.

If so, how do you make this adjustment! as at present the top jockey wheel is only millimetres below the 26 tooth cog?

Cheers in advance for any tips, etc.




  • SDPSDP Posts: 665
    all the options above ...yes you will need poss new STis/BB/f.der if you go triple

    do you need the 53 ring ???

    you could go 12-27 with 50/38 rings ???

    i have done that & its a good spread & gets you up most things...& shifting is fine..

    i find a 50/34 a big drop & find i am dbl changing a lot ...
  • grantusgrantus Posts: 690
    I didn't actually consider reducing the size of the double chainrings.

    Yeah, I'd kinda ruled out the triple just because of the hassle of BB and front derailleur compatability.

    Don't want to go down the road of changing shifters as too expensive - I only paid £140 for the bike to start with! I don't think I'd need to anyway as they are Sora shifters and the left one is three speed as it is.

    I think maybe squeezing on a 12-28 and a 38 inner at the front could be an option

  • Monty DogMonty Dog Posts: 20,614
    You may find fitting a cassette with anything bigger than a 27 tooth sprocket tricky with a short-arm mech - you may also find that having swapped the cassette, you'll end changing the chain because it skips i.e. worn. Easiest option is therefore to swap to the compact chainset initially and maybe swap to a 11or 12-25 cassette when funds allow.
    Make mine an Italian, with Campagnolo on the side..
  • grantusgrantus Posts: 690
    Will plump for mtb cassette and long mech - sorted.

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