cskasofia Posts: 34
edited March 2014 in The workshop
Can someone explain the significance of the chain ring ratios quoted for a chainset, I need to replace mine.

The existing one is a Suntour SR and has a ratio 48/38/28. I've seen a Shimano advertised with a ratio 42,34,24. (both are square taper)

Comparing the 2 granny rings 24 teeth to 28, how would they both perform, what one is easier to pedal when climbing


  • wongataa
    wongataa Posts: 1,001
    Lower numbers on the chainset mean lower gearing and therefore easier to get uphill.
  • cskasofia
    cskasofia Posts: 34
    Was looking at Shimano's budget chainset FC-M171

    There are 2 options, 42/34/24 and the 48/38/28.

    Does this mean the 42/34/24 is more suitable for climbing hills , or is there more to it than that?
  • The Rookie
    The Rookie Posts: 27,812
    A lot more, a smaller granny ring only makes hills easier if you are already using the very lowest gear available (smallest front, largest rear) which unless you are climbing a very steep and long hill (and I doubt you are), in which case to make hills easier you need to get fitter, lose weight, select the right gear or some combination of those, changing the crankset wont help!
    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.
  • andrewc3142
    andrewc3142 Posts: 906
    The triple on my Dawes tourer is 48/38/26 and that's about right for me when loaded/towing, both on the flat and for hills (26-30 got me up a 30% hill in Brittany with full panniers and towing an Extra-wheel, also loaded to the max - hard work, mind)

    I suspect that with 42 as the largest you'll run out of gears on the flat all the time.