Compact chainset / cassette options

jonrb101
jonrb101 Posts: 86
edited February 2010 in Road buying advice
I’m currently building a lightweight road bike and want to go compact, but need climbing gears to equal my current triple set up. My current smallest gear on the triple is 30/26, which equates to approx 30 ins and I think the smallest I can achieve on a compact would be 34/27 or approx 34 ins – the limiting factor being the cassettes available and the capacity of a standard road rear mech.

Can anyone please advise if and how I can achieve a smaller gear than this using a road compact set up (shimano based)? Are there any other options to consider?

Thanks

Jon

Comments

  • skyd0g
    skyd0g Posts: 2,540
    AFAIK you can't get a smaller combo on a compact than 34/27 that you've already mentioned.

    Limiting factor available? Your legs.
    Other option? Do more hill training. :wink:
    Cycling weakly
  • keef66
    keef66 Posts: 13,123
    SRAM cassette with a 28 sprocket? Read many times on here of folk running these on Shimano compact doubles with standard rear mech.
  • markos1963
    markos1963 Posts: 3,724
    You should be ok with a Sram cassette11-28 and I think that the new Ultegra 6700 comes with a 28 bottom option. You should get away with keeping your current rear mech but you might need to adjust the B screw to makes sure the jockey wheels don't foul on the bottom cog. With a 23mm rear tyre that would give you a 31.9 inch bottom gear which is pretty low enough for most. Any hills steeper than that then I suggest you take some crampons with you! :wink:
  • Cheers all, I'll try the 28 tooth option, but it may still be a struggle. I'm surrounded by 20% hills so there's no such thing as a 'recovery' ride!


    Jon
  • 11-28 works fine
  • Road Red
    Road Red Posts: 232
    I'm looking to build a bike also but have the same concerns about leaving my triple behind.

    I see Campag do a cassette with a 12-29 in the Athena set. I presume this with a 34 ring will narrow the gap even further? I currently have a 30-27 as by bottom gear.
  • skyd0g
    skyd0g Posts: 2,540
    jonrb101 wrote:
    Cheers all, I'll try the 28 tooth option, but it may still be a struggle. I'm surrounded by 20% hills so there's no such thing as a 'recovery' ride!


    Jon

    Aye, but think o' t' ride down again. :wink:

    ...nowt but flat fields & crosswinds here. :cry:
    Cycling weakly
  • keef66
    keef66 Posts: 13,123
    @ Road Red

    I currently ride a triple with a 12-25 cassette and like it. I think I'd be annoyed by the bigger jumps between some of the sprockets on a 12-29 cassette. I'm also not sure about the possibility that I'd be constantly switching from one chainring to the other.
  • Mister W
    Mister W Posts: 791
    My wife has a compact with a 13-29 cassette (Campag). That's almost low enough to ride up walls.

    If you need lower than that you could use an MTB rear mech, although you then have the issue of getting a 10 speed cassette. They do exist but they aren't cheap. If you go for 9 speed then you'd have loads to choose from.
  • markos1963
    markos1963 Posts: 3,724
    jonrb101 wrote:
    Cheers all, I'll try the 28 tooth option, but it may still be a struggle. I'm surrounded by 20% hills so there's no such thing as a 'recovery' ride!


    Jon


    How about avoiding the 20% hills until you're strong enough to get up them! :wink:

    Seriously though why do you want to change to a compact if you are ok with a triple. The weight difference is very little and as you can see the hassle factor of changing over is immense. I do have a compact on my race bike but to be honest I will change it for a standard soon as I hate the lowness of the inner ring, I don't get any cruising gears on it when riding in a bunch and I rarely go below the 21 cog when climbing(I run a 12-25 cassette)
  • Thanks again folks, forgot to mention that I'm an old git and as fit and strong as I'm likely to get.

    Cheers

    Jon
  • Have to say that i don't get the whole compact chainset thing. I've just recently got back into road cycling and thought that, given that i'm neither as fit nor as young as i was, going for a compact and making sure that i kept my cadence up woud be the way forward.
    But it's just a pain in the butt with a massive leap between front cogs. Should have gone with a standard i reckon as it's much more useable in 90% of normal conditions.
    Given the slopes you've got round your way i'd stick with a triple and still keep a good range of useable gears.
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