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Chainset and cassette sizes

El DiegoEl Diego Posts: 440
edited October 2009 in Commuting chat
I am about to purchase a new Ribble Winter Training Audax 7005 105 Black 10 Double. This will be my first road bike and will be used for commuting and longer weekend rides. My usual ride was a pretty standard Ridgeback Hybrid with 3 rings on the front and 8 on the cassette. I never used the smallest ring on the front.

There are several options for chainset and cassette sizes, which I am a bit confused about.

The options are:


Compact 170 34/50
Compact 172.5 34/50
Compact 175 34/50
170 39/53
172.5 39/53
175 39/53

Any help would be much appreciated.


  • _Brun__Brun_ Posts: 1,740
    Assuming you don't live in the Alps and are reasonably fit...


    Maybe get the 27 cassette if there are any significant hills that worry you.
  • redddraggonredddraggon Posts: 10,862
    50/34 with 11-25 would be the best bet
    I like bikes...

  • il_principeil_principe Posts: 9,152
    +1 to Brun. Although if you are relatively new to cycling a compact may be a better bet.. so 50/34
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  • redddraggonredddraggon Posts: 10,862
    I don't see why the dude would want a full size chainset. A compact really is a better option for the average newcomer.

    50-11 is bigger than 53-12 anyway.

    Perhaps the dude lives somewhere with hills,
    I like bikes...

  • I'm running 50/34 with 170mm and a 12-25 cassette and reckon that it's pretty good for a beginner (on a road bike) like me.

    Provided your happy to spin up above 100rpm, the top gear will see you well over 30mph (I have hit >40mph while still pedalling on a sharpish downhill - my bike computer reckons I was pedalling at 132rpm!). On the other end, I've not needed to resort to 34/25 yet but it's good to know that it is there.

    However, I guess that it depends on your fitness and terrain...

  • wgwarburtonwgwarburton Posts: 1,863
    Underscore wrote:
    I'm running 50/34 with 170mm and a 12-25 cassette and reckon that it's pretty good for a beginner (on a road bike) like me.

    I'd reckon 34/50 and 12-25.
    50x12 is high enough- if you spin that out before you'd be better off freewheeling then you need to work on your technique, anyway!!
    If you plan to ride somewhere hilly then take the 12-27.

    Crank length should be related to leg length. 170 is traditional, usually only going longer for a particularly leggy rider, but I'm not well-informed on current bike-fit theory to advise!!

  • El DiegoEl Diego Posts: 440
    I was leaning towards a compact actually. It's not too hilly in Manchester, although will be taking it to the lakes quite a bit.

    Cheers for the advice.
  • MonkeypumpMonkeypump Posts: 1,528
    I'm a recent convert to road bikes, and use a compact 50/34 11-25.

    It takes some getting used to - simply because the whole bike is so different to mtb - but seems to suit me well so far. I find it's about right for the hills I ride and I'm certainly not spinning out on the flats.

    Haven't felt the need for anything bigger that 25 on the cassette yet, but maybe I'm not riding up 'proper' hills!
  • prawnyprawny Posts: 5,426
    I'd go 50/34 12/25

    I've got a 9sp 12/25 and there's a noticable jump between 2 ratios that would be filled nicely with a 10sp (I checked)

    I hardly ever use 50/12 and I regularly get up to the high 30's-40mph.

    I was impressed with myself yesterday I spun away from the lights up to 27mph in 36/15 :D
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  • biondinobiondino Posts: 5,990
    50/34 and 12/27 for me. Very happy with it, though the 18-tooth sprocket which would be perfect for cruising isn't there (and I don't know on which of the alternative cassettes it would be).

    I like having the 27-tooth sprocket as (mostly) insurance, and the times I use it are the times I am so so grateful to have it!
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