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Compact Chaniset- What ratio for a fatty in a lumpy area

jerry3571jerry3571 Posts: 1,532
edited October 2017 in Workshop
As above, got a few more pounds that I used to have. I got a Compact Chainset (not sure on teeth yet). Some others are riding 32 tooth bottom. I am on a 28 bottom. In the olden days, if it went more teeth than a 28 (on pre compact 53-42 chainrings) then a long arm mach is needed; is this the same with a compact? (34 or 36 tooth inner chainring on a compact I guess??)
Sorry Compacts are still a bit modern for me :P
Any help please. :)
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  • Ben6899Ben6899 Posts: 8,979
    I think it's the same. 28T cassette on a compact (50/34) chainset is long cage mech territory.

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  • It depends on the rear mech you have. normally what is classed a medium cage is required for a 32T rear sprocket. Why is it people with a bit of weight talk about themselves in a derogitory way "fatty" it is never a positive term.

    Many who are slim use a 32T rear cog in hilly areas so it is nothing unusual. -wheel building and other stuff.
  • Gearing is so personal, it depends not only on your fitness levels, but also the terrain you are riding.

    When not training to push your personal boundaries, I believe current thinking is along the lines of choose a gear that you can spin at a cadence of at least ~80+rpm on the flat and ~75+rpm up an incline.

    I have a compact chainset on the Cube, 50/34 on the front, with 11-32T cassette (the default setup). My easiest gear gets plenty of use when I climb the final ~0.6 miles of Harvesting Lane ... /4391/4690 and more recently on the evil local discovery of Dell Road's steepest section ... is/367/509
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  • lesfirthlesfirth Posts: 1,206
    Just have what suits you.If you have low self esteem and you need to prove something to others, a 32T rear sprocket is not for you.However for the rest of us it is better to have a low gear you never need than to need one you do not have.
  • To confirm what's stated above, my BMI is ~23 and my Castelli Perfetto is size M. I ride a compact crankset on an 11-32T, and 34x32 will see usage for anything over 11% longer than 100m. My next cassette will have a 32T, too, as will my next road bike. No shame in that.
  • Nick PayneNick Payne Posts: 288
    edited October 2017
    lesfirth wrote:
    [snip...] However for the rest of us it is better to have a low gear you never need than to need one you do not have.
    That's been my motto for many years. The bike I rode today was equipped with a Middleburn crank using 38x27 chainrings and an 11-32 cassette.

    For a bike that I'm not going to race, I set it up so that at an easy flat ground cruising speed I'm in the middle of the cassette on the "big" chainring, and on the steepest large hill I'm likely to encounter I can still maintain a cadence of around 80 at only a moderate level of effort. My 38x27 and 11-32 meets that criteria for the terrain around here.

    p.s. The latest Campagnolo Centaur rear derailleur just comes in a single cage length that is designed to be compatible with cassettes up to 32t.
  • i.bhamrai.bhamra Posts: 178
    In my experience a 28T sprocket with a compact chainset (34, 50T) works fine with a standard shortcage rear mech (experience with tiagra 4600, ultegra 6600, 6700 and 6800 mechs).

    A 32T sprocket will also work although you will have too short a chain on the big/big combo or slightly too long a chain on small/small. Obviously you should avoid these combinations anyway but I tend to go for the latter (ie slightly too long a chain for the small/small combo) so you don't make a mess of the rear end of your divetrain/frame/wheel when you inevitably select the biggest sprocket when in the "big" ring.

    I think the length of the chainstay and/or the mech hanger will play a role in how well this works on your frame (my experience is with small to medium frames with relatively short chainstays. A medium cage mech will probably give you a bit more wiggle room re chain length and spocket clearance but I've never had to resort to this.
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