Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 03-10-11, 11:03 PM   #1
mdbrown
Newbie
Thread Starter
 
Join Date: Feb 2008
Location: Cupertino, CA
Bikes: 2009 BMC SLT01, 2009 Trek District, Broken 2006 Orbea Opal :(
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Swapping different sized chainrings

I'm looking to swap out some 175 FSA SLK cranks I have for 172.5 FSA cranks that I found a good deal on. My 175 is 46/36 and the 172.5 cranks have 52/38. Both have a BCD of 110 so are the two chainrings interchangeable? I'm looking to keep the 38 on the 172.5 cranks, but swap over the 46 from the 175 cranks to the 172.5 cranks so in the end I'd have 46/38. I feel like swapping over shouldn't be an issue, but I'm not 100% so I figured I'd ask.
mdbrown is offline   Reply With Quote
Old 03-10-11, 11:27 PM   #2
ScottNotBombs
Senior Member
 
ScottNotBombs's Avatar
 
Join Date: Mar 2008
Location: Joliet, IL
Bikes:
Posts: 405
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It'll be fine, just move your derailleur down so there's a 1mm gap between the cage and new chain ring.
ScottNotBombs is offline   Reply With Quote
Old 03-10-11, 11:45 PM   #3
mdbrown
Newbie
Thread Starter
 
Join Date: Feb 2008
Location: Cupertino, CA
Bikes: 2009 BMC SLT01, 2009 Trek District, Broken 2006 Orbea Opal :(
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Awesome, thanks for the quick reply.
mdbrown is offline   Reply With Quote
Old 03-11-11, 01:02 AM   #4
FastJake
Constant tinkerer
 
FastJake's Avatar
 
Join Date: May 2010
Location: Madison, Wisconsin
Bikes:
Posts: 7,574
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It'll be fine. Any reason why you want such a close ratio up front? Just curious..
FastJake is offline   Reply With Quote
Old 03-12-11, 05:52 PM   #5
Chris_W
Gear Combo Guru
 
Chris_W's Avatar
 
Join Date: May 2007
Location: Switzerland
Bikes: Spec' Tarmac (road), Ridley Fenix (commuter & fast tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder)
Posts: 2,241
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Agreed that the chainring swap will be fine. Plus, there may be no need to move the front derailleur. If I understood you correctly, the large ring is going to stay the same (46 teeth), and it is that normally determines the front derailleur position. Try it as it is, and only if the inner cage of the FD contacts the inner chainring when you try to shift to the big ring, then move it up, but if it doesn't then leave it.

Last edited by Chris_W; 03-13-11 at 08:51 AM.
Chris_W is offline   Reply With Quote
Old 03-12-11, 09:04 PM   #6
Burton
Certified Bike Brat
 
Burton's Avatar
 
Join Date: Jan 2011
Location: Montreal, Quebec
Bikes:
Posts: 4,251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Another confirmation

An easy switch and no reason to change the position of the front derailleur. Correct installation requires a 2mm clearance between the large chainring and the ouside face of the front derailleur as it passes over it.

Since your large chainring will remain unchanged the front derailleur calibration should be unaffected.
Burton is offline   Reply With Quote
Old 03-13-11, 02:57 PM   #7
ScottNotBombs
Senior Member
 
ScottNotBombs's Avatar
 
Join Date: Mar 2008
Location: Joliet, IL
Bikes:
Posts: 405
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Oops. I didn't realize he was changing the smaller chainring.. On the park website it says 1-2mm or about the thickness of a penny
ScottNotBombs is offline   Reply With Quote
Old 04-07-11, 04:19 PM   #8
Kevinative
Senior Member
 
Kevinative's Avatar
 
Join Date: Jan 2011
Location: Cherry Hill, NJ
Bikes: GF Level Betty FHO, GF Paragon, Raleigh Tomac, DB Interval, Scott CR1 Team
Posts: 76
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
ok so I did the search function to avoid starting a new thread. I've got a slightly different angle on this same question. My new carbon bike (CR1) came with a CD, 50/34. I recently purchased an older 105 octalink crankset that has a 53/43. I want to simply put the 53/43 rings on the new crankset. both are 105, don't see any fit issue, may have to slightly raise fr der. question is, what about chain length? are 3 extra teeth going to require an extra link?
Kevinative is offline   Reply With Quote
Old 04-07-11, 04:37 PM   #9
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 18,913
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 236 Post(s)
Probably.. may be time to put on a fresh chain anyhow..
fietsbob is offline   Reply With Quote
Old 04-11-11, 11:58 AM   #10
mdbrown
Newbie
Thread Starter
 
Join Date: Feb 2008
Location: Cupertino, CA
Bikes: 2009 BMC SLT01, 2009 Trek District, Broken 2006 Orbea Opal :(
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Kevinative View Post
ok so I did the search function to avoid starting a new thread. I've got a slightly different angle on this same question. My new carbon bike (CR1) came with a CD, 50/34. I recently purchased an older 105 octalink crankset that has a 53/43. I want to simply put the 53/43 rings on the new crankset. both are 105, don't see any fit issue, may have to slightly raise fr der. question is, what about chain length? are 3 extra teeth going to require an extra link?
Just an update, everything worked out well on my end. But for you, I feel like you're in the same position I was in. 53 tooth rings only fit on BCD 130 spacing cranks so they wouldn't fit on a BCD 110, which is compact.
mdbrown is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 08:06 PM.