Compact Cranks and climbing

Discussion in 'Cycling Equipment' started by Jeffonyourleft, Jan 29, 2006.

  1. Jeffonyourleft

    Jeffonyourleft New Member

    Joined:
    Jul 13, 2004
    Messages:
    23
    Likes Received:
    0
    Hello,

    First off, it is a shame to read that a fellow cyclist has lost their life to an irresponsible driver. I have been run off the road by someone on a cell phone, and it freightens me to know that people don't give a hoot about us on the roads.

    My question is regarding compact cranks and climbing. How much of a difference does it make to switch to a compact crank when tackling hills. I am not the greatest of climbers, and I was wondering if it would make a difference. Normally, I hang a twinkie off the front of my helmet and try to get it. Any help would be appreciated

    Thanks

    jeff (onyourleft)
     
    Tags:


  2. buckybux

    buckybux New Member

    Joined:
    Jul 14, 2005
    Messages:
    227
    Likes Received:
    0
    The compact crank is going to help with keeping your cadance higher while climbing. Do you have a problem with your cadance dropping too slow on the hills? I am 50, and still able to keep up the cadance, although a number of my friends have gone to the compact crank to make the hills easier.
     
  3. achtervolger

    achtervolger New Member

    Joined:
    Dec 31, 2005
    Messages:
    46
    Likes Received:
    0
    Jeffrey, I had the same questions and created a Word doc with a bunch of gear ratios and configurations if you want to have a look. PM me if you (or anyone else) is interested. Maybe I can post it somewhere, but for now just PM me if you want to have a look.
     
  4. jsull14

    jsull14 New Member

    Joined:
    Nov 26, 2005
    Messages:
    244
    Likes Received:
    1
    achtervolger,
    I'd like to have a look if you don't mind. I currently have a triple with a 30/27 bail out gear. I am thinking of going to compact as I am getting better at climbing but would like to know what the gearing differences would be. I am assuming one fewer crank will also take some weight off but i'm not sure how much.
     
  5. Postie

    Postie New Member

    Joined:
    Sep 25, 2003
    Messages:
    241
    Likes Received:
    0
    Compact cranks will make a big difference to the ease of your climbing vs a regular double. However, the granny gear on a triple is still that much easier.

    I don't want a triple, but lots of people love them.
     
  6. hd reynolds

    hd reynolds New Member

    Joined:
    Nov 15, 2005
    Messages:
    813
    Likes Received:
    0
    The concept of a compact crankset has been around since the 70's. With a 110mm BCD it enables the fitment of a 33t inner ring (although 34 & 36 are more popular). The advent of 9speed and later on 10speed systems mean that a 50/34 compact can virtually match all the range of gears available with a triple. The advantages are obvious - lighter weight, narrower thread and a much lower gear versus a regular double.
     
  7. jjiam25

    jjiam25 New Member

    Joined:
    Jun 29, 2005
    Messages:
    49
    Likes Received:
    0
    So compact cranks are OK to use in races?
     
  8. artmichalek

    artmichalek New Member

    Joined:
    Sep 15, 2004
    Messages:
    2,010
    Likes Received:
    0
    Depends on the race. A lot of pros use compacts for mountain stages. If the race is flat, you may find yourself shifting rings more often than with a standard double. You also won't have enough high end to win many sprints.
     
  9. hd reynolds

    hd reynolds New Member

    Joined:
    Nov 15, 2005
    Messages:
    813
    Likes Received:
    0
    Perhaps hilly races or for sportive events. Also depends if one can push the highest gear in sprints. In my case, the only time I get to use the 53x13 is downhill. In sprints I use the 14 coz I just cant push the 13 hard enuf.
    :D
     
  10. RapDaddyo

    RapDaddyo Active Member

    Joined:
    May 17, 2005
    Messages:
    5,088
    Likes Received:
    41
    FWIW, I switched to a compact crank last September on my Campy 10s double. I changed cranks after looking at my options for a 17.5 mile hillclimb race with some grades >6% where my cadence was too low for my preferences. I went to the FSA carbon 34/50 and also changed my cassette to 13/29. I ran a bunch of numbers before making my decision, but my numbers wouldn't be very useful to you unless we climb at the same power/weight ratio (~4.0 w/kg). My suggestion is to figure out what your climbing power is and then use the tools at analyticcycling.com to figure out what your speed will be on climbs of the different grades you encounter on your rides. From speed, you can compute cadence in each gear in your drivetrain. I built a spreadsheet for this purpose, where I plug in a speed and it computes my cadence in every gear combination (even though some of them are not practical due to the chain crossover).

    What I like about the compact crank is the ease with which I can make drivetrain changes for different courses, by simply changing the cassette (cassettes are both cheap and easy to change). Campy has a wide range of cassettes and I'm sure Shimano has a comparably wide range. So, I could ride a criterium on Saturday and a hillclimb on Sunday and can swap cassettes in ~15 minutes to give me the desired gearing for each event. BTW, my 34/29 gives me about as low a gear as most triples. My 50/13 is a bit low for downhills but is fine on the flat. I use that drivetrain for training now as well, because I care more about getting my desired cadence on climbs than I do about being geared out on descents. Bottom line, I'm happy with my compact crank.
     
  11. jsull14

    jsull14 New Member

    Joined:
    Nov 26, 2005
    Messages:
    244
    Likes Received:
    1
    Great post Rap! I have been thinking about the 34/29 combo as this seems very similar to a 30/27 triple. I'm not sure if Shimano makes this combo. I might have to go with Campy.
     
  12. achtervolger

    achtervolger New Member

    Joined:
    Dec 31, 2005
    Messages:
    46
    Likes Received:
    0
    jsull, you have a PM.

    I used this site:

    http://sheldonbrown.com/gears/

    to generate the numbers. If you generate some additional ones on your own, it would be awesome if you could add to my .doc and resend, but at your own discretion--you may not want to bother.

    Note that my calculations are for my wheels, cranks and Campy cassettes.
     
  13. RapDaddyo

    RapDaddyo Active Member

    Joined:
    May 17, 2005
    Messages:
    5,088
    Likes Received:
    41
    Glad it's helpful. I did hear that about Shimano, but isn't there a Shimano compatible, non-Shimano brand cassette available? I don't run a Shimano drivetrain, but I think I saw something about that in another thread -- you know, one of the many threads on Campy vs. Shimano which end up with equal numbers of rabid advocates on both sides of the question. And who said cyclists aren't passionate?
     
Loading...
Loading...