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Swap chainrings to create compact chainset?

Discussion in 'Bicycle Mechanics and Repairs' started by Star_Rover, 3 Sep 2007.

  1. Star_Rover

    Star_Rover New Member

    Location:
    Hackbridge
    My double chainset (shimano 105, 53/39) is a bit overgeared for me and I wouldn't mind swapping it for a compact.
    Would I need to buy a whole new chainset or could I just swap the chainrings (to say 54/30)?
    If so, is this a relatively straightforward job, or should I get the LBS to do it? Would I need a new (shorter) chain as well?
    thanks in advance for any advice
     
  2. Tim Bennet.

    Tim Bennet. Entirely Average Member

    Location:
    S of Kendal
    Unfortunately, 39 (38?) is the smallest you can get for a conventional double chainset. 'Compact' chainsets have a smaller spider to take the smaller rings.

    What is your largest sprocket at the back? Swapping the block is the most cost effective way of getting lower gears.
     
  3. Star_Rover

    Star_Rover New Member

    Location:
    Hackbridge
    Ah, I see.
    Already swapped the cassette and it's fine on all but the steepest hills, but I came across one yesterday (20% gradient) and I nearly had to get off and push and I was half dead when I eventually reached the top.
     
  4. Tim Bennet.

    Tim Bennet. Entirely Average Member

    Location:
    S of Kendal
    Yep, that's cycling for you!

    If you feel do do want lower gears then a new compact chainset (or triple) is your only option. The bike shop should be able to let you know your options including non Shimano ones from Bontrager or other manufacturers. Some might be compatible with a present Bottom Bracket and some may not. Get some advice and if they don't seem to be offering you enough choice (ie, we have this one - take it or leave it), then leave and try somewhere else.
     
  5. alecstilleyedye

    alecstilleyedye nothing in moderation Staff Member

    the cheapest way will be to go for 38 on the front, with something like 25 on the back. that way you will avoid needing a new rear mech. a good lbs will be able to tell you what you can get away with. get a new chain as well, if you are changing the cassette.

    i went through this last year and decided to go triple as i still wanted 52/42 with 25-12 but also some lower gears. ended up cheaper to buy a complete groupset upgrade, which is what i did in the end.
     
  6. Star_Rover

    Star_Rover New Member

    Location:
    Hackbridge
    thanks chaps.
    no cheap solution by the looks of it!
    guess I'll have to make do with the double for now and hope the muscles grow . . .
     
  7. MichaelM

    MichaelM Veteran

    Location:
    Tayside
    no cheap solution by the looks of it!

    Would it be inappropriate of me to mention that in a box in the garage there's a 9 speed 12-27 Ultegra cassette and a 38T and a 50T chainring?

    Not that I'd want to advertise things I have for sale in your post you understand....
     
  8. Star_Rover

    Star_Rover New Member

    Location:
    Hackbridge
    MichaelM, not inappropriate but my set up is 10 spd. And I already have a 12-27 cassette, and a 39T inner chainring so there wouldn't be much advantage in a 38T.
    thanks for the offer though.
    I think I only need the extra lower gears for biggest of hills (well the biggest in Surrey/Sussex). If I was hitting the Alps I'd definitely be getting shot of the double!