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

Potentially warped chain ring - what are my options?

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.

Potentially warped chain ring - what are my options?

Old 01-04-21, 01:33 PM
  #1  
Herzlos
Senior Member
Thread Starter
 
Join Date: Sep 2020
Location: Glasgow, Scotland
Posts: 112

Bikes: Voodoo Limba, Planet X Fat Baz

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 91 Post(s)
Liked 55 Times in 37 Posts
Potentially warped chain ring - what are my options?

Hi all,

So I've got a Voodoo Limba adventure bike, with a Prowheel 48/32t chainset. On the 48t ring I can see the chain move side to side by maybe 1-2mm when pedalling on a turbo trainer, at the outermost point it hits the derailleur and causes a rubbing noise. There doesn't seem to be any play in the bracket to I suspect it's the chain ring, confirmed by a gap being visible when a straight edge is placed beside it. I've yet to take the chain rings off as I want to avoid that if possible since I haven't done it before.

Am I ok to use a disc bending tool to try and reshape it, or will it need replaced?
If I'm replacing it, is it worth getting an upgraded part? Should I be replacing both chainrings or the crankset?
Herzlos is offline  
Old 01-04-21, 01:45 PM
  #2  
masi61
Senior Member
 
masi61's Avatar
 
Join Date: Oct 2005
Location: SW Ohio
Posts: 2,932

Bikes: Puch Marco Polo, Saint Tropez, Masi Gran Criterium

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 740 Post(s)
Liked 163 Times in 125 Posts
Originally Posted by Herzlos View Post
Hi all,

So I've got a Voodoo Limba adventure bike, with a Prowheel 48/32t chainset. On the 48t ring I can see the chain move side to side by maybe 1-2mm when pedalling on a turbo trainer, at the outermost point it hits the derailleur and causes a rubbing noise. There doesn't seem to be any play in the bracket to I suspect it's the chain ring, confirmed by a gap being visible when a straight edge is placed beside it. I've yet to take the chain rings off as I want to avoid that if possible since I haven't done it before.

Am I ok to use a disc bending tool to try and reshape it, or will it need replaced?
If I'm replacing it, is it worth getting an upgraded part? Should I be replacing both chainrings or the crankset?
A lot of old school LBS mechanics used to have a chainring bending tool which is probably quite similar to the disc bending tool you are referring to. I'm not sure if the thickness of a brake rotor is close enough to the thickness of the chainring to where you can use the disc brake straightening tool. If it doesn't fit, I would think you could use a large adjustable wrench (one of the American made ones where it can be adjusted for tight tolerances and actually hold its adjustment) might also work. If in doubt take it to a trusted bike mechanic at your LBS. If the chainring is not particular on how the chainring bolt holes should line up in relation to the crank arms, you could try orienting the chainring differently on the spider. Sometimes this will cancel out run-out and make things more in line. Worth a try. Also, you did not say there were any missing chainring bolts or anything but one obvious thing to check is that all the chainring bolts are there, that they are installed correctly with some light grease on the threads and torqued to spec.

PS: If you do try to bend the chainring straight, don't overdo it. Aluminum fatigues quite easily so only a very small bend should be attempted. If it is way out and you try to bend it back, it may well crack in which case you will then most definitely need to just replace the warped chainring.

Last edited by masi61; 01-04-21 at 04:22 PM.
masi61 is offline  
Likes For masi61:
Old 01-04-21, 01:55 PM
  #3  
HillRider
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 32,861

Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!

Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 1671 Post(s)
Likes: 0
Liked 530 Times in 397 Posts
Since this is the outer chainring it's likely it has a pin on the outside face opposite the crank arm to prevent a spilled chain from wedging between the arm and the ring. If so, you don't want to change its orientation. As noted, a good quality adjustable wrench can be used as a straightening tool.
HillRider is online now  
Likes For HillRider:
Old 01-04-21, 02:17 PM
  #4  
Iride01
Hits [ENTER] b4 thinking
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 7,678

Bikes: '20 Tarmac Disc Comp '91 Schwinn Paramount '78 Raleigh Competition GS

Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 3009 Post(s)
Liked 1,601 Times in 1,167 Posts
2 mm is only .079 inches. An that is only a little more than 1/16 inch. So if 2 mm is the full range of movement from one to the other, then it's only little more than 1/32" out of kilter.

Is that causing you any problems?
Iride01 is offline  
Likes For Iride01:
Old 01-04-21, 02:23 PM
  #5  
Herzlos
Senior Member
Thread Starter
 
Join Date: Sep 2020
Location: Glasgow, Scotland
Posts: 112

Bikes: Voodoo Limba, Planet X Fat Baz

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 91 Post(s)
Liked 55 Times in 37 Posts
Originally Posted by Iride01 View Post
Is that causing you any problems?
It's causing the chain to hit the derailleur when in the highest gear, which I'm assuming will cause wear/damage over time as well as being annoying.
I can't adjust the derailleur out any further to avoid it either.
Herzlos is offline  
Old 01-04-21, 02:25 PM
  #6  
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 9,609

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 102 Post(s)
Tagged: 0 Thread(s)
Quoted: 2940 Post(s)
Likes: 0
Liked 1,495 Times in 996 Posts
Does the gap between the outer and inner rings change as you rotate the pedals? Often the issue is with the crankset itself; very likely at the fit to the BB spindle. (If so, the crescent wrench fix will work to improve things, but you are only fixing the symptom. But slightly out of true cranksets have been ridden for as long as bikes have existed and generally haven't caused issues to anything except between the ears of certain people.
79pmooney is offline  
Likes For 79pmooney:
Old 01-04-21, 02:46 PM
  #7  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,105

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 28 Post(s)
Tagged: 0 Thread(s)
Quoted: 1349 Post(s)
Liked 857 Times in 600 Posts
I have found that a small long-nose Vise-Grips® works well for truing chain rings.https://www.amazon.com/VISE-GRIP-Ori.../dp/B0000BYD9A
dsbrantjr is offline  
Likes For dsbrantjr:
Old 01-04-21, 03:03 PM
  #8  
alcjphil
Senior Member
 
alcjphil's Avatar
 
Join Date: Jun 2002
Location: Montreal, Quebec
Posts: 4,458
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1159 Post(s)
Liked 563 Times in 371 Posts
Before trying to bend the chainring, check to see if it runs true when not under load. Drop the chain off the crank and spin the pedals slowly to see how true the chainring is. This bike has a relatively inexpensive square taper crank that probably flexes a bit under load. If flex is causing the chain rub, bending the chainring to compensate could cause rubbing on the inside of the derailleur cage when there is no pedal load
alcjphil is offline  
Likes For alcjphil:
Old 01-04-21, 03:19 PM
  #9  
blamester
Blamester
 
Join Date: Dec 2011
Location: Ireland
Posts: 898

Bikes: Peugeot teamline

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 208 Post(s)
Liked 74 Times in 61 Posts
Does it drop the chain?
if it doesn't I would try and adjust the fd first to get rid of the noise that way. No harm can be done by doing that.
​​​​​​
Sorry missed the bit where you tried to adjust it

Last edited by blamester; 01-04-21 at 04:28 PM.
blamester is offline  
Likes For blamester:
Old 01-04-21, 07:09 PM
  #10  
veganbikes
Clark W. Griswold
 
Join Date: Mar 2014
Location: ,location, location
Posts: 8,659

Bikes: Foundry Chilkoot Ti W/Ultegra Di2, Salsa Timberjack Ti, Cinelli Mash Work RandoCross Fun Time Machine, 1x9 XT Parts Hybrid, Co-Motion Cascadia, Specialized Langster, Phil Wood Apple VeloXS Frame (w/DA 7400), Cilo Road Frame, Proteus frame, Ti 26 MTB

Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 2388 Post(s)
Liked 1,388 Times in 933 Posts
If you didn't want to try bending a probably low grade aluminum chainring, Prowheel stuff is pretty cheap stuff so is not a bad candidate for replacement but you also have to consider the quality of the rest of the bike and see how much you like the bike and how much you would want to put in it.
veganbikes is online now  
Likes For veganbikes:
Old 01-05-21, 09:06 AM
  #11  
Herzlos
Senior Member
Thread Starter
 
Join Date: Sep 2020
Location: Glasgow, Scotland
Posts: 112

Bikes: Voodoo Limba, Planet X Fat Baz

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 91 Post(s)
Liked 55 Times in 37 Posts
Originally Posted by veganbikes View Post
If you didn't want to try bending a probably low grade aluminum chainring, Prowheel stuff is pretty cheap stuff so is not a bad candidate for replacement but you also have to consider the quality of the rest of the bike and see how much you like the bike and how much you would want to put in it.
It's definitely a cheap bike (£450 so maybe $600) so I don't want to spend a fortune on it. I'm already debating upgrading it to a Giant Contend AR 4 or a Cannondale Topstone 4 soon, so I really just want to get it to a state where I can (a) use it and (b) sell it on to someone else without feeling bad about it being damaged. It does a pretty decent for my needs though (very casual cyclist in pretty bad shape).
Herzlos is offline  
Old 01-06-21, 09:51 PM
  #12  
veganbikes
Clark W. Griswold
 
Join Date: Mar 2014
Location: ,location, location
Posts: 8,659

Bikes: Foundry Chilkoot Ti W/Ultegra Di2, Salsa Timberjack Ti, Cinelli Mash Work RandoCross Fun Time Machine, 1x9 XT Parts Hybrid, Co-Motion Cascadia, Specialized Langster, Phil Wood Apple VeloXS Frame (w/DA 7400), Cilo Road Frame, Proteus frame, Ti 26 MTB

Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 2388 Post(s)
Liked 1,388 Times in 933 Posts
Originally Posted by Herzlos View Post
It's definitely a cheap bike (£450 so maybe $600) so I don't want to spend a fortune on it. I'm already debating upgrading it to a Giant Contend AR 4 or a Cannondale Topstone 4 soon, so I really just want to get it to a state where I can (a) use it and (b) sell it on to someone else without feeling bad about it being damaged. It does a pretty decent for my needs though (very casual cyclist in pretty bad shape).
Then I would probably bend it slightly and carefully and be done with it save the money towards a bike you want. If it isn't perfect and you sell it just let the buyer know.
veganbikes is online now  
Likes For veganbikes:

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.