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

Changing chainring?

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 chainring?

Old 05-06-21, 09:35 AM
  #1  
dkyser
Senior Member
Thread Starter
 
Join Date: Jul 2007
Location: St Louis Missouri
Posts: 347

Bikes: 19 Gunnar Hyper-X Ultegra Disk, 17 Specialized Sequoia Elite

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Liked 9 Times in 6 Posts
Changing chainring?

I have an Ultegra 50/34 Crankset and need more lower gearing. Can I change the 34t for a 32t with out having any issues.
11/32 Cassette and 50/34 crankset. Not sure if changing out the 34t for a 32t will cause any issues when shifting.
Thanks
dkyser is offline  
Old 05-06-21, 09:43 AM
  #2  
cxwrench
Senior Member
 
cxwrench's Avatar
 
Join Date: Jul 2013
Location: Nor-Cal
Posts: 1,666

Bikes: lots

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 737 Post(s)
Liked 888 Times in 509 Posts
Which Ultegra? Not that it matters, it's not possible to put a 32 on either 6800 or 8000. Nor any of the earlier series. It also surpasses the max difference between chainrings spec'd by Shimano. It would shift ok, not great.
cxwrench is offline  
Old 05-06-21, 09:57 AM
  #3  
dkyser
Senior Member
Thread Starter
 
Join Date: Jul 2007
Location: St Louis Missouri
Posts: 347

Bikes: 19 Gunnar Hyper-X Ultegra Disk, 17 Specialized Sequoia Elite

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Liked 9 Times in 6 Posts
Originally Posted by cxwrench View Post
Which Ultegra? Not that it matters, it's not possible to put a 32 on either 6800 or 8000. Nor any of the earlier series. It also surpasses the max difference between chainrings spec'd by Shimano. It would shift ok, not great.
So I would need to go with a new crankset 48/32?
dkyser is offline  
Old 05-06-21, 10:20 AM
  #4  
delbiker1 
Mother Nature's Son
 
delbiker1's Avatar
 
Join Date: Mar 2016
Location: Sussex County, Delaware
Posts: 1,790

Bikes: Early 90's Ochsner road, 2006 Schwinn SS DBX, 2014 Orbea Avant MD30, 2004 Airborne Zeppelin TI, 2003 Lemond Poprad, 1989? Fuji Ace, 2001 Lemond Tourmalet, 2014? Soma Smoothie

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 473 Post(s)
Liked 484 Times in 292 Posts
You could go with a cassette with a bigger spread on the cogs, example 36T. But, unless your present derailleur is a GS, not SS, that would mean changing the rear derailleur. What speed Ultegra do you have? Obviously, a 9 nine speed set up with long cage gives you a wider gap between the gears than an 11 speed system. Some cassettes are not readily available right now.
delbiker1 is offline  
Old 05-06-21, 10:24 AM
  #5  
Barry2 
LRP=HR
 
Join Date: Sep 2019
Location: SF Bay Area
Posts: 858

Bikes: 79 Holdsworth Special, 93 C-dale MT3000 Tandem, 96 C-dale F700CAD3, Two Cervelo R3's 2011 & 2018, JustGo Runt, Ridley Oval, Kickr Bike 8-)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 321 Post(s)
Liked 316 Times in 201 Posts
Spec's are HERE if you've not found them.
Large limits are 46-53T with 16T capacity.

Shimano has R8000 crank available in 46-36T
I do wonder why Shimano dropped to 46T but only used 10T capacity offering 36T


Hope that helps

Barry
Barry2 is offline  
Old 05-06-21, 10:32 AM
  #6  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 3,382

Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 940 Post(s)
Liked 743 Times in 504 Posts
Your real problem is the BCD of our crank. I believe it is 110mm so you can't install anything less than a 34t. Well, I think technically 33t, but finding that is pretty much non-existent.

What I think you should do is run the ratio/speed numbers to see what advantage you will get from going to a wider range cassette and a longer cage rear derailleur, or swapping the crank to a 46/30.

I think a lot of people see a couple tooth change as their saving gear ratio and then find it is not as significant as they had hoped for. Running the numbers, especially with a cadence/speed calculation, may help you get a feel for how much benefit you will gain.

John
70sSanO is offline  
Likes For 70sSanO:
Old 05-06-21, 10:32 AM
  #7  
dkyser
Senior Member
Thread Starter
 
Join Date: Jul 2007
Location: St Louis Missouri
Posts: 347

Bikes: 19 Gunnar Hyper-X Ultegra Disk, 17 Specialized Sequoia Elite

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Liked 9 Times in 6 Posts
Originally Posted by delbiker1 View Post
You could go with a cassette with a bigger spread on the cogs, example 36T. But, unless your present derailleur is a GS, not SS, that would mean changing the rear derailleur. What speed Ultegra do you have? Obviously, a 9 nine speed set up with long cage gives you a wider gap between the gears than an 11 speed system. Some cassettes are not readily available right now.
I have an 11 speed with medium cage derailleur.
dkyser is offline  
Old 05-06-21, 11:03 AM
  #8  
dkyser
Senior Member
Thread Starter
 
Join Date: Jul 2007
Location: St Louis Missouri
Posts: 347

Bikes: 19 Gunnar Hyper-X Ultegra Disk, 17 Specialized Sequoia Elite

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Liked 9 Times in 6 Posts
Originally Posted by 70sSanO View Post
Your real problem is the BCD of our crank. I believe it is 110mm so you can't install anything less than a 34t. Well, I think technically 33t, but finding that is pretty much non-existent.

What I think you should do is run the ratio/speed numbers to see what advantage you will get from going to a wider range cassette and a longer cage rear derailleur, or swapping the crank to a 46/30.

I think a lot of people see a couple tooth change as their saving gear ratio and then find it is not as significant as they had hoped for. Running the numbers, especially with a cadence/speed calculation, may help you get a feel for how much benefit you will gain.

John
Thanks John, that may be a better option if I can find a 11/36 cassette.
dkyser is offline  
Old 05-06-21, 03:16 PM
  #9  
delbiker1 
Mother Nature's Son
 
delbiker1's Avatar
 
Join Date: Mar 2016
Location: Sussex County, Delaware
Posts: 1,790

Bikes: Early 90's Ochsner road, 2006 Schwinn SS DBX, 2014 Orbea Avant MD30, 2004 Airborne Zeppelin TI, 2003 Lemond Poprad, 1989? Fuji Ace, 2001 Lemond Tourmalet, 2014? Soma Smoothie

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 473 Post(s)
Liked 484 Times in 292 Posts
The medium cage will work with a 36T just fine. If you think that is not enough additional low gearing, a 46/30 crankset could be the way to go.
delbiker1 is offline  
Old 05-06-21, 05:23 PM
  #10  
jp911
Senior Member
 
Join Date: Feb 2017
Location: San Francisco Bay Area
Posts: 197

Bikes: Trek Madone 5.2 Dura Ace, Niner RLT9 aluminum, Santa Cruz 5010 CC

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 53 Post(s)
Liked 22 Times in 20 Posts
SRAM makes an 11-36 11-speed cassette that I've used on Ultegra 6800 (with a Wolftooth Roadlink) on my gravel bike. Gives you a good bailout gear for long climbs.
jp911 is offline  
Old 05-07-21, 08:48 AM
  #11  
oldbobcat
Senior Member
 
oldbobcat's Avatar
 
Join Date: Jul 2005
Location: Boulder County, CO
Posts: 3,397

Bikes: '79 Gios, '80 Masi, '06 Felt, early '60s Frejus

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 143 Post(s)
Liked 104 Times in 77 Posts
Originally Posted by dkyser View Post
So I would need to go with a new crankset 48/32?
Yes. There is no way 32 t will clear the 110 mm bcd.
oldbobcat is offline  
Old 05-07-21, 08:54 AM
  #12  
cxwrench
Senior Member
 
cxwrench's Avatar
 
Join Date: Jul 2013
Location: Nor-Cal
Posts: 1,666

Bikes: lots

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 737 Post(s)
Liked 888 Times in 509 Posts
Originally Posted by delbiker1 View Post
The medium cage will work with a 36T just fine. If you think that is not enough additional low gearing, a 46/30 crankset could be the way to go.
You don't know this. OP still hasn't said exactly which GS derailleur he has. The 6800 will work w/ a 32, the 8000 a 34. I'd normally be comfortable w/ using a 36 w/ the newer 8000 derailleur, but not necessarily the 6800.
cxwrench is offline  

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.