Gear Ratios

jogger2000 Posts: 19
edited August 2009 in Workshop
Hi, I've just bought a used steel road bike with a 52/42 chainring and a 23/13 nine speed block which I find hard when climbing. If I were to make it easier on the hills would it be best to change the chainrings or the rear block? I don't want to change the rear mech so what would be the best combination? All your suggestions would be greatly appreciated. Many Thanks Ian.


  • maddog 2
    maddog 2 Posts: 8,114
    depends on how much life there is in the current stuff

    both options will lower the gearing

    without seeing the bike....

    rings - Shimano go down to 38t, Campag 39t

    cassettes - you could go 12-25, 12-27 and so on

    for how it influences gearing see

    cheapest option is probably just a s/hand 39 ring. Best option is to probably change both.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • Thanks, I think I will take you r advice and start with a 39 tooth chainring. Cheers Ian.
  • Diogenes
    Diogenes Posts: 1,628
    Front 42 38 42 42 38
    Rear 23 23 23 27 27
    Gear (in) 154.9 140.1 154.9 131.9 119.4

    The table above shows what happens if you replace your 42 with 38 and if you change your cassette? to give you a 27, the final column shows what happens if you do both.

    You get a bigger change per number of teeth changed by changing the cassette so if only one of them is an option then the cassette change has the bigger effect. Whether your rear mech will support such a large cog you will have to determine. Your lbs should be able to advise.

    D :D
  • rickhotrod
    rickhotrod Posts: 181
    Just change the 13-23 for a 14-25. The 14-25 comes in HG50 quality ie. Tiagra