Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Compact chainrings - anyone swap 50/34's and 50/36's?

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Compact chainrings - anyone swap 50/34's and 50/36's?

Old 07-08-08, 12:16 PM
  #1  
adam
Senior Member
Thread Starter
 
adam's Avatar
 
Join Date: Jan 2007
Location: Toronto area
Posts: 1,124

Bikes: Cervelo, Pinarello, Specialized

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Compact chainrings - anyone swap 50/34's and 50/36's?

I have a range of chainrings for my FSA crank.

I see some of them have a 50(34) stamped on the big ring and know when you buy replacements the big ring is matched with a small ring. I'm assuming that has to do with shifting pins/ramps.

My question - has anyone every mixed these with ok results (shifting wasn't horrible)? ie - a 50(34) paired with a 36T? or a 50(36) with a 34T?
adam is offline  
Old 07-08-08, 12:18 PM
  #2  
merlinextraligh
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Posts: 30,778

Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1135 Post(s)
Liked 264 Times in 143 Posts
I'm pretty certain the 50 ring is the same whether you pair it with a 36 or a 34. It's not like there are 2 50's pinned and ramped differently.

The 50/36 will shift a little better typically because of the smaller gap.

I see where the 50 FSA ring is stamped 50/34. However, There aren't 2 50 rings referenced on FSA's web page, or by people selling them online.

I have Shimano compact with 50/34 rings and it shifts fine.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

Last edited by merlinextraligh; 07-08-08 at 12:36 PM.
merlinextraligh is offline  
Old 07-08-08, 01:17 PM
  #3  
Brian Ratliff
Senior Member
 
Brian Ratliff's Avatar
 
Join Date: May 2002
Location: Near Portland, OR
Posts: 10,122

Bikes: Three road bikes. Two track bikes.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 45 Post(s)
Liked 2 Times in 2 Posts
It has to do with how the teeth are aligned. If they are a "matched set", as the chain crosses from one ring to the other, it will instantly engage the teeth on the ring. If they are not matched, then there is a chance that the chain will ride on the tips of the teeth for half a rotation or so before settling onto the chainring. It's not a really big issue most of the time for general riding.

For racing, where you are shifting quickly and rather violently and the results of the race (and the safety of the peloton) can hinge on whether you drop the chain or not, then having matched rings is well worth the money and effort.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter

Last edited by Brian Ratliff; 07-08-08 at 01:24 PM.
Brian Ratliff is offline  
Old 07-08-08, 01:23 PM
  #4  
Brian Ratliff
Senior Member
 
Brian Ratliff's Avatar
 
Join Date: May 2002
Location: Near Portland, OR
Posts: 10,122

Bikes: Three road bikes. Two track bikes.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 45 Post(s)
Liked 2 Times in 2 Posts
It looks like, from FSA's website, that the matched sets are:

50(34) - compact double
46(36) - cyclocross
52(38) - (undersized) standard double
53(39) - standard double

I don't think FSA makes a 50(36) matched chainring set.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Brian Ratliff is offline  
Old 07-08-08, 02:50 PM
  #5  
Gummy Bear
Member
 
Join Date: Apr 2005
Posts: 45
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Alfred E. Bike lists two different FSA 50T part numbers for 36T and 38T respectively.
Gummy Bear is offline  
Old 07-08-08, 05:24 PM
  #6  
roshea
Señor Member
 
roshea's Avatar
 
Join Date: Sep 2007
Location: Australia
Posts: 751
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I have paired a 36T FSA with a 50T Shimano without any problems (I prefer 36T over 34T, so got rid of that little one).
roshea is offline  
Old 08-25-11, 12:23 PM
  #7  
klam
Senior Member
 
Join Date: Mar 2003
Location: N. America
Posts: 86

Bikes: 04 Specialized Allez Comp SRAM Rival/Ulegra, Giant NRS C1/XTR, Cannondal System 6 Healthnet DA

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I recently had to get a new 50T for my SRAM rival cranks. The shifting ramps are spaced apart differently if you get the 50T for 36 or the 50T for 34. I ordered the wrong one (50T for 36) but I'm hoping it will still work..although not optimum.
klam is offline  
Old 08-25-11, 01:25 PM
  #8  
topflightpro
Senior Member
 
topflightpro's Avatar
 
Join Date: Jul 2007
Posts: 7,417
Mentioned: 54 Post(s)
Tagged: 0 Thread(s)
Quoted: 1797 Post(s)
Liked 583 Times in 364 Posts
My wife complained about her 50/34 set up, so I swapped her 34 ring for a 36. There have been no problems.

Yes, technically, the ramps are slightly different on a 50 ring designed to pair with a 34 vs. a 36, but they are small differences.
topflightpro is offline  
Old 08-25-11, 01:46 PM
  #9  
bobonker
Member
 
bobonker's Avatar
 
Join Date: Oct 2009
Location: Nor Cal
Posts: 825
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked 0 Times in 0 Posts
I have a 38 tooth FSA inner ring on my SRAM Force compact crank (50/38). Shifts great. Super fast and precise largely due to the fact that the 12 tooth jump is relatively small. I love the tighter spacing (paired to a 12-23 cassette) when I'm riding on flat terrain.

Bob
bobonker is offline  
Old 08-25-11, 02:48 PM
  #10  
bbattle
.
 
bbattle's Avatar
 
Join Date: Aug 2005
Location: Rocket City, No'ala
Posts: 12,745

Bikes: 2014 Trek Domane 5.2, 1985 Pinarello Trevisio, 1990 Gardin Shred, 2006 Bianchi San Jose

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Likes: 0
Liked 7 Times in 5 Posts
Originally Posted by bobonker View Post
I have a 38 tooth FSA inner ring on my SRAM Force compact crank (50/38). Shifts great. Super fast and precise largely due to the fact that the 12 tooth jump is relatively small. I love the tighter spacing (paired to a 12-23 cassette) when I'm riding on flat terrain.

Bob
What is meant by "tighter spacing"?
bbattle is offline  
Old 08-25-11, 03:36 PM
  #11  
bobonker
Member
 
bobonker's Avatar
 
Join Date: Oct 2009
Location: Nor Cal
Posts: 825
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked 0 Times in 0 Posts
By tighter spacing, I mean that each gear change results in a small change in pedaling cadence.

With a 50/34, if you're going 18 mph on the small ring and jump to the big ring, you'll have to dump 3 or 4 gears on the rear cassette to maintain a comparable speed. With a 50/38, the jump is less dramatic.

Bob
bobonker is offline  
Old 08-25-11, 04:53 PM
  #12  
scirocco
Senior Member
 
Join Date: Aug 2006
Location: Perth, W.A.
Posts: 935
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I've swapped a 34T on a Shimano crank with a SRAM 36T inner ring. Worked flawlessly, and as people have said, if anything the shifting is better because there's less of a jump between small and big rings.
scirocco is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
delbiker1
Bicycle Mechanics
2
10-17-18 07:14 PM
99Klein
Road Cycling
9
02-05-13 03:28 PM
Ridefreemc
Touring
4
11-09-11 06:22 AM
Handelfan
Bicycle Mechanics
2
12-09-10 01:23 AM
msu2001la
Road Cycling
25
05-04-10 10:08 PM

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.