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Compact v double

snedden9485snedden9485 Posts: 57
edited June 2009 in Workshop
My cervelo has a FSA 34/50 compact crankset on it. I am currently running a 12/25 cassette on it. It is fine for normal riding, however i run it out easily on fast sprints and downhills. I have just ordered a 11-23 cassette which i hope will give it that right amount of legs for the sprints. My question is, how many guys run compact cranks or do most run doubles for racing? Most of the racing i do over here is fairly flat, with the hilly courses not very hilly at all. I want to start doing some 2 day races next year and i wonder if a double would be ok for the hilly courses mated with a 11-23. I think a 53 with a 11 on the front would be great for sprinting! Am i worth going to a double?
2009 Cervelo S1
2008 Specialized Allez Elite

Posts

  • softladsoftlad Posts: 3,587
    Most gearing decisions are made on a realistic appraisal of your own ability to ride the terrain in question. Realistically, I think the only person who can answer these questions is you...
  • dennisndennisn Posts: 10,496
    snedden9485 wrote:
    My cervelo has a FSA 34/50 compact crankset on it. I am currently running a 12/25 cassette on it. It is fine for normal riding, however i run it out easily on fast sprints and downhills. I have just ordered a 11-23 cassette which i hope will give it that right amount of legs for the sprints. My question is, how many guys run compact cranks or do most run doubles for racing? Most of the racing i do over here is fairly flat, with the hilly courses not very hilly at all. I want to start doing some 2 day races next year and i wonder if a double would be ok for the hilly courses mated with a 11-23. I think a 53 with a 11 on the front would be great for sprinting! Am i worth going to a double?

    ".... I run it(50-12)out EASILY on fast sprints...."??????? I'd join the pro tour if I were you.
  • peanutpeanut Posts: 1,373
    edited June 2009
    if most of your intended races are going to be pretty flat and fast i would say a 53x38t with a 12-27 cassette should be more than adequate you'd have approx 120" top which is the equivalent of using a 11tooth sprocket with your existing 50t chainring
    At the other end a 38t small ring with a 27t sprocket would give you 37" which is almost the same as your existing 34x25t
    That should get you up anything .

    If you stick with your compact then get a 11t -27t cassette which will give you the spread you need .A Deore or XT MTB cassette will give you the sprockets you need just mix and match with your existing cassette. Don't forget you'll need to use the special size 11t lockring with the 11t sprocket :wink:

    sorry just noticed you have already ordered the 11-23 well that will give you the increased top end you need 50x11 is about 122 " an additional 10" but you have lost 3" at the bottom end which is the equivalent of losing one gear shift :cry: If its not enough you could remove a small sprocket like your 14t and add a 25t or 26t sprocket after the 23t
  • peanutpeanut Posts: 1,373
    ..........50 .........34
    11 119.5... 81.2
    12 109.5 ... 74.5
    13 101.1 ... 68.7
    14 93.9 ... 63.8
    15 87.6 ... 59.6
    17 77.3 ... 52.6
    19 69.2 ... 47
    21 62.6 ... 42.5
    23 57.1 ... 38.8
    25 52.6 ... 35.7
    easier to show than explain.(This is in gear inches ) if you have a look at Sheldons site there is a niffty gear calculator there.
    http://sheldonbrown.com/gears/
  • snedden9485snedden9485 Posts: 57
    ".... I run it(50-12)out EASILY on fast sprints...."??????? I'd join the pro tour if I were you"

    Well not super easy, but i mean that i get a high cadence sprint if its on the flat and i need another gear.
    2009 Cervelo S1
    2008 Specialized Allez Elite
  • snedden9485snedden9485 Posts: 57
    If you stick with your compact then get a 11t -27t cassette which will give you the spread you need .A Deore or XT MTB cassette will give you the sprockets you need just mix and match with your existing cassette. Don't forget you'll need to use the special size 11t lockring with the 11t sprocket

    Will i need anything special to add the 11/23 compared to the 12/25 thats on there now or will i need a special lockring?
    2009 Cervelo S1
    2008 Specialized Allez Elite
  • C-S-BC-S-B Posts: 117
    I recently upgraded to a 53-39 with an 11-23 from a 50-36/ 12-25 for racing. For flat races this is obviously great, but for hills I reckon this makes me go faster aswell-

    Knowing that I am in the lowest gear of 39-23 on a steep hill, the only thing you can do to be able to pedal at a comfortable rate is push harder (+ hence go faster), whereas on the training bike with a 36-27 lowest gear, I would simply reach for an easier gear and spin up the hill.. at lower speed.

    So for racing I dont think you need a tiny gear to spin up hills since you want to keep speed high- unless hills are something you struggle with -?
  • snedden9485snedden9485 Posts: 57
    No i tend to be pretty strong on hills. Thinkning maybe sticking with the compact cranks, but changing chain rings to 36 / 52. That would give it a bit more legs for top end, and still have the low end bail it gears if required.
    2009 Cervelo S1
    2008 Specialized Allez Elite
  • peanutpeanut Posts: 1,373
    snedden9485 wrote:
    If you stick with your compact then get a 11t -27t cassette which will give you the spread you need .A Deore or XT MTB cassette will give you the sprockets you need just mix and match with your existing cassette. Don't forget you'll need to use the special size 11t lockring with the 11t sprocket

    Will i need anything special to add the 11/23 compared to the 12/25 thats on there now or will i need a special lockring?

    you'll need a special 11t lockring which has a smaller dia but the right lockring will come with your 11-23 cassette .
  • snedden9485snedden9485 Posts: 57
    peanut wrote:
    snedden9485 wrote:
    If you stick with your compact then get a 11t -27t cassette which will give you the spread you need .A Deore or XT MTB cassette will give you the sprockets you need just mix and match with your existing cassette. Don't forget you'll need to use the special size 11t lockring with the 11t sprocket

    Will i need anything special to add the 11/23 compared to the 12/25 thats on there now or will i need a special lockring?

    you'll need a special 11t lockring which has a smaller dia but the right lockring will come with your 11-23 cassette .

    ok thats great its included, i was hoping i wasnt goign to have to buy one. Hopefully the 11 - 23 should be a good mix with the 34/50. Looking at the rollout calculators, the 39/53 doesnt really offer that many advantages, just a closer gap between the big and little ring and a little more top end roll out. So is that the main advantage with going to a 39/53 over compact (a closer ratio between the little and big ring)?
    2009 Cervelo S1
    2008 Specialized Allez Elite
  • peanutpeanut Posts: 1,373
    its a pretty minimal advantage to be honest. 50x34 is still a big jump .You develop your own way of minimising the impact of this when changing rings whilst climbing hills . You could always change the 34 for a 36t if it is an issue

    I have always used 53x38 chainrings but after a 4 year layoff due to lumbar problems I have been forced to use a compact because of the excess weight I'm carrying.I have now changed both my bikes to compacts .

    If you are considering raceing you must be pretty fit so the solution you have chosen is probably the best one and certainly the cheapest option.
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