Advertise on Bikeforums.net



User Tag List

Results 1 to 9 of 9
  1. #1
    Senior Member buddy's Avatar
    Join Date
    Jul 2007
    Posts
    306
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Compact crankset?

    My chainrings on my bike are 34/50. Is this consider "Compact Crankset"?

    What is the differece between a compact and a double?

    Could I change my chainrings to something different without changing my cranks, let say 42/54?

    Thanks.

    buddy

  2. #2
    Biker looking for a ride!
    Join Date
    Nov 2006
    Location
    Edmond Oklahoma
    My Bikes
    Kuota Kreedo...looking for something different.
    Posts
    1,480
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Yes that is a Compact...

    The double is refering to the fact that it has 2 chain rings...

    You can change the rings if they make some in the same bolt pattern.....it will be closer to your 36/50 like a 36/51 maybe.....not sure though...the options on my campy compact crank are 34-48, 34-50, 36-50....any combo within that....

    A compact is what you have.....a standard double would be a 39-53 or a 39-52..the differances are the chain rings and the bolt pattern..

  3. #3
    Senior Member
    Join Date
    Aug 2005
    Location
    New Hampshire
    Posts
    845
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It sounds like you have a compact double, as you can't fit a 34 inner ring on a standard road double. 34/50 and 36/50 are fairly common sizes for compact doubles.

    The difference between a compact and a road (or racing) double crank is the "bolt-circle diameter" (BCD) of the crank. This is the diameter of the circle formed by the chainring bolts On a compact, the bolts sit in a circle 110mm in diameter. On a road double it is more like 130mm (135mm for Campy). With a 130mm BCD, you can't have an inner chainring smaller than, I think, 39 teeth, hence the need for the compact setup. I don't think there's any prohibition on running larger chainrings on a 110mm BCD crank (assuming someone makes them in the sizes you want). I suppose stiffness could be an issue with really large rings on a small BCD crank.

  4. #4
    Senior Member buddy's Avatar
    Join Date
    Jul 2007
    Posts
    306
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I have a FSA SLK CARBON COMPACT 50x34T W/ ISIS BB. I ride primarly on flat land and I feel that the 50 is too easy and the 34 is a total waste.

    I see on the FSA web site they offer a standard 39-53 for the FSA SLK Crankset. Could I change my 50 -30 Chainrings to the FSA 53-39 Chainrings?

    Or should I change my Crankset to ULTEGRA like I have on my other bike.

    Many thanks.

    buddy

    My CASSETTE is SHIMANO DURA-ACE 10-SPEED 12/25T if that helps.

  5. #5
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,072
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by buddy View Post
    I have a FSA SLK CARBON COMPACT 50x34T W/ ISIS BB. I ride primarly on flat land and I feel that the 50 is too easy and the 34 is a total waste.

    I see on the FSA web site they offer a standard 39-53 for the FSA SLK Crankset. Could I change my 50 -30 Chainrings to the FSA 53-39 Chainrings?

    Or should I change my Crankset to ULTEGRA like I have on my other bike.

    Many thanks.

    buddy

    My CASSETTE is SHIMANO DURA-ACE 10-SPEED 12/25T if that helps.
    You can change the rings on your compact but only if the replacement chainrings have the same BCD as the FSA compact crankset, probably 110 mm.
    Your current high gear, 50/12 is good for at least 33 mph so I find it hard to believe that you need a bigger chainring for flatland riding. Perhaps you could replace the 34 ring with a 36, making it more useful and possibly improve shifting and reduce chainrub.

    Al

  6. #6
    Senior Member buddy's Avatar
    Join Date
    Jul 2007
    Posts
    306
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Al1943 View Post
    compact crankset, probably 110 mm.
    Your current high gear, 50/12 is good for at least 33 mph so I find it hard to believe that you need a bigger chainring for flatland riding. Perhaps you could You can change the rings on your compact but only if the replacement chainrings have the same BCD as the FSA replace the 34 ring with a 36, making it more useful and possibly improve shifting and reduce chainrub.

    Al
    Thanks good advice about changing to a 36.

    I'm just use of my other bikes and I am having a hard time getting use to the smaller chainring. Maybe I need to give it more time.

    buddy

  7. #7
    Senior Member RockyMtnMerlin's Avatar
    Join Date
    Sep 2005
    Location
    Laramie Wyoming
    My Bikes
    Merlin Extralight Topolino Wheels Campy Record
    Posts
    2,972
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Compact gearing should not be too hard to get used to. I switched a while back and have faired well. Many of the gear ratios overlap the standard ones. Good excuse for learning to pedal at higher RPM if you feel you need to go faster.

  8. #8
    Biker looking for a ride!
    Join Date
    Nov 2006
    Location
    Edmond Oklahoma
    My Bikes
    Kuota Kreedo...looking for something different.
    Posts
    1,480
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by buddy View Post
    I have a FSA SLK CARBON COMPACT 50x34T W/ ISIS BB. I ride primarly on flat land and I feel that the 50 is too easy and the 34 is a total waste.

    I see on the FSA web site they offer a standard 39-53 for the FSA SLK Crankset. Could I change my 50 -30 Chainrings to the FSA 53-39 Chainrings?

    Or should I change my Crankset to ULTEGRA like I have on my other bike.

    Many thanks.

    buddy

    My CASSETTE is SHIMANO DURA-ACE 10-SPEED 12/25T if that helps.
    Just change your rear cassette to something smaller....I run an 11-23 on mine....I am sure Shimano has something close to that....that would be cheaper than getting a new set of cranks as well...

  9. #9
    road rash/tree burn
    Join Date
    May 2005
    Location
    Chapel Hill, NC
    Posts
    726
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by buddy View Post
    Thanks good advice about changing to a 36.

    I'm just use of my other bikes and I am having a hard time getting use to the smaller chainring. Maybe I need to give it more time.

    buddy
    I'd say give it some time. I bought a bike with a compact in February and was certain for the first week or two that I would pull it off and replace it with a standard crank. Within a month, not only had I decided not to do that, but I had ordered another compact to put on one of my other bikes.

    Compacts rule, even for flatlanders- what happens when you travel somewhere and get to climb hills? A 50/11 gear is actually slightly bigger than a 53/12, so you're not really losing out as far as gear ratio goes. At most you might want to swap your 34 for a 36 as previously suggested. If I didn't go out to western NC to climb a fair amount, I would do that.

    Good luck!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •