Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

changing Ultegra gear ratio

Notices
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.

changing Ultegra gear ratio

Old 06-17-10, 06:23 PM
  #1  
signalnc
Senior Member
Thread Starter
 
Join Date: Apr 2007
Location: nc
Posts: 225
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked 6 Times in 3 Posts
changing Ultegra gear ratio

I have a 2006 Ultegra group on my bike (except the cranks). I think it's Ultegra 6600. I have Truativ carbon cranks . The cranks are 53/39 and i have an 11-23 cassette. I would like to change the gearing. I was told the 6600 ultegra can only take a 27t cog not a 28. Is this true? what about changing thr chainrings. Can i swap out the 53/39 to a 50/34? thanks
signalnc is offline  
Old 06-17-10, 06:49 PM
  #2  
joejack951
Senior Member
 
joejack951's Avatar
 
Join Date: May 2004
Location: Wilmington, DE
Posts: 12,078

Bikes: 2016 Hong Fu FM-079-F, 1984 Trek 660, 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1, 2016 Islabikes Beinn 20 (son's)

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1229 Post(s)
Liked 76 Times in 55 Posts
A 28T large rear cog will most likely work fine with your current set up. I can't guarantee it but I'm currently using a 27T large cog with my 6600 rear derailler and it clears just fine.

As for the chainrings, the only way you can make a significant chainring change is to get a different crankset. Your 53/39 double almost certainly uses a 130mm BCD for the chainrings (measure to be sure though as there are 110mm BCD 53/39 chainring cranks). The smallest inner chainring you can mount on a 130mm BCD is a 38T. Not worth the effort. To mount a 34T chainring, you'll need a crankset with a 110mm BCD (otherwise known as a compact crank). Depending on how much lower gearing you are looking for, you can change the crank or cassette or both. The cassette is by far the cheapest and easiest swap though so I'd suggest starting there.
joejack951 is offline  
Old 06-18-10, 01:16 PM
  #3  
Zouf
Senior Member
 
Join Date: Aug 2004
Posts: 736
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
joejack951 is correct as far as 39-38 being the lower limit on 130 BCD - and 38T can be a problem, you have to make sure the chain will clear the crank spider. However, there are indeed options on the large chainring, FSA has 50T 130 BCD chainrings that work great with Ultegra. It all depends on what your motivations for gearing changes are (want to spin faster and be more centered on the cassette? want to climb steep hills?), and what your budget is (compact crank replacement ok for you?). I swapped my 53/39 Ultegra rings for 50/39 FSA because the chainrings were dead and needed replacing anyway, and I,m more of a spinner than a masher - but that's me, your mileage may vary.
Zouf is offline  
Old 06-19-10, 12:45 PM
  #4  
signalnc
Senior Member
Thread Starter
 
Join Date: Apr 2007
Location: nc
Posts: 225
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked 6 Times in 3 Posts
thanks for the replies. My motivation is to get an easier gear for climbing. My current setup is fine for hills with max 6% gradient and nothing longer than 1 mile where I am riding now. Changing to a compact crank is not out of the question. I am going to replace the cassette to either a 12-25 or a 12-27. If I get the 12-25 I may change to a compact next year before heading to the Blue ridge mountains. I am just a casual rider (2 or 3 times a week--1000 to 1500 miles a year). Thanks again
signalnc is offline  
Old 06-19-10, 10:38 PM
  #5  
woodway
Squeaky Wheel
 
woodway's Avatar
 
Join Date: Nov 2008
Location: Newcastle, WA
Posts: 1,585
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 51 Post(s)
Likes: 0
Liked 45 Times in 26 Posts
I am running 50-34 on the front and 12-30 on the rear with my Ultegra 6600 deraileur. That's 16+18=34 teeth on a derailluer rated for 27 teeth. Works fine, shifts fine and has done so for the last 8000 miles. I am sure that you'll have no problem going from 27 to 28 teeth on your setup. the derailuers are spec'ed somewhat conservatively.
woodway is offline  
Old 06-19-10, 11:42 PM
  #6  
JiveTurkey
Low car diet
 
JiveTurkey's Avatar
 
Join Date: Aug 2007
Location: Corvallis, OR, USA
Posts: 2,407

Bikes: 2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by woodway View Post
I am running 50-34 on the front and 12-30 on the rear with my Ultegra 6600 deraileur. That's 16+18=34 teeth on a derailluer rated for 27 teeth. Works fine, shifts fine and has done so for the last 8000 miles. I am sure that you'll have no problem going from 27 to 28 teeth on your setup. the derailuers are spec'ed somewhat conservatively.
Hold on a sec, you are describing two things.

"34 teeth" refers to the total capacity: [50+30]-[34+12]=34. The 6600-SS RD is rated at 29T or less and the 6600-GS RD is rated at 37T or less. If you are using the SS (short cage) RD, then, yes, you are exceeding recommended chain wrap capacity of 29T (not 27T).

OP: The major problem with exceeding total capacity with a double crank is that even though you should never actually use the large-large combo, the chain should be long enough to go there, but if this is the case, then the smaller cogs of the cassette won't run as well while using the inner chainring because the RD won't be able to take up all the slack in the chain.

The other limitation of an RD is largest cog. All 6600 RDs are rated at 27T or less. However, most people can get a 28T to work, and some can get a 30T to work by screwing in the b-tension screw.

https://techdocs.shimano.com/media/te...9830616226.pdf

Last edited by JiveTurkey; 06-19-10 at 11:45 PM.
JiveTurkey is offline  
Old 06-20-10, 11:38 AM
  #7  
DMF 
Elitist Troglodyte
 
DMF's Avatar
 
Join Date: Jun 2006
Location: Dallas
Posts: 6,924

Bikes: 03 Raleigh Professional (steel)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time in 1 Post
You sure it's not a 9-speed group (6500)?

12-27 will make a big difference and work with anything in the Ultegra lineup. But if you go to a compact you may want a long-cage road RD.
__________________
Stupidity got us into this mess - why can't it get us out?

- Will Rogers
DMF is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Bugster
Bicycle Mechanics
12
09-12-14 04:17 PM
GoodOmens83
Road Cycling
16
08-09-13 12:00 PM
GRVR6
Bicycle Mechanics
21
01-04-12 05:24 PM
gus6464
Bicycle Mechanics
5
05-09-11 01:17 PM
damnable
Bicycle Mechanics
6
02-09-10 10:45 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.