Changing Chainring

FishFish
FishFish Posts: 2,152
edited September 2017 in MTB workshop & tech
I'm getting a new Boardman MTB (29 pro if you are interested). It has a Sram GX crankset and a 32 T 1*11 setup. I currently run 38 T or 36T and it was my intention to fit one of these - say the 36 and get rid of the 32 as it is too undergeared for me. My instinct is that this will not require a new chain and the back is 10 to 42 and I doubt I'll use the lowest gears.


Will I need a new chain because of the larger front? My instinct is to use a larger ring around here - Thetford forest and put the smaller one on when going to mountains, trails but was wondering if I needed a chain for each setup.


....Halfords is offering bike discounts and a trade in for any bike against a new one - 10%.
...take your pickelf on your holibobs.... :D

jeez :roll:

Comments

  • fenix
    fenix Posts: 5,437
    Are you riding a 29 at the moment ?
  • cooldad
    cooldad Posts: 32,599
    You will need a longer chain.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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  • The Rookie
    The Rookie Posts: 27,812
    If the current chain is correctly sized, as CD says you will need a longer chain (another pair of links for 36T and one or two pairs for 38T), it may be its too long and you don't need to add any, if its too short the rear mech gets pulled into the cassette and wrecked so it's not a good idea.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • nobby_chobbly
    nobby_chobbly Posts: 3
    I got the same bike new from Halfords last year, and also replaced the 32T ring with a 36T. The chain that came with it had 114 links which was plenty long enough to cope with the 36T/42T combo.
  • FishFish
    FishFish Posts: 2,152
    Fenix wrote:
    Are you riding a 29 at the moment ?


    Yes, a Bizango 1*10
    ...take your pickelf on your holibobs.... :D

    jeez :roll:
  • FishFish
    FishFish Posts: 2,152
    I guess you are right! I suppose that as the pitch size of the chain is still half an inch then the difference between 32 and 36 is 4 teeth = 2 inches. Certainly don't want to wreck the rear mech or worse - the cassette which is ridiculously expensive.

    I presume that it has a clutch mech too which adds to the chain tension.

    I'll but another chain and use it with a larger ring or find out where nobby_chobbly lives and steal his.
    ...take your pickelf on your holibobs.... :D

    jeez :roll:
  • The Rookie
    The Rookie Posts: 27,812
    Right idea, poor application, the chain wraps round half the chainring, so the current 16t becomes 18t for the 32 to 36.

    The clutch adds no chain tension, it just controls the spring.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cooldad
    cooldad Posts: 32,599
    I'd just measure it properly.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The Rookie
    The Rookie Posts: 27,812
    Of course, as its not uncommon for OE chains to come out too long.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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