Chainring wear visualized
03-17-14 | 09:51 PM
#1
Thread Starter
Insane Bicycle Mechanic
Joined: Mar 2008
Posts: 10,158
Likes: 1,124
From: other Vancouver
Chainring wear visualized
On a recent ride, one of my friends commented that my chainring teeth were looking a little pointy. Since they'd lasted through 3 chains, I figured it was time. I ended up with everything new: chainrings, chain, and cassette. See if you agree:
(old on the left, new on the right... duh)
(old on the left, new on the right... duh)
__________________
Jeff Wills
Comcast nuked my web page. It will return soon..
Jeff Wills
Comcast nuked my web page. It will return soon..
03-17-14 | 10:37 PM
#4
Thread Starter
Insane Bicycle Mechanic
Joined: Mar 2008
Posts: 10,158
Likes: 1,124
From: other Vancouver
__________________
Jeff Wills
Comcast nuked my web page. It will return soon..
Jeff Wills
Comcast nuked my web page. It will return soon..
03-17-14 | 10:56 PM
#5
Senior Member
Joined: Mar 2005
Posts: 1,311
Likes: 0
From: NY state
Bikes: See Signature...
Oh, come on! You had at least 5 more years out of that one 
When I finally replaced the cassette on my MTB, I was pretty shocked at how worn the most used sprockets were. Not pointy, but the U was very pronounced compared to new. And the shifting got a lot better...
When I finally replaced the cassette on my MTB, I was pretty shocked at how worn the most used sprockets were. Not pointy, but the U was very pronounced compared to new. And the shifting got a lot better...
03-18-14 | 05:27 AM
#6
Senior Member
Joined: Jun 2010
Posts: 7,579
Likes: 6
From: Pearland, Texas
Bikes: Cannondale, Trek, Raleigh, Santana
Jeff, I nearly posted photos showing the difference in chain ring wear on a recent touring bike rebuild, but I thought nobody would be interested. Good for you.
Brad
Brad
03-18-14 | 07:14 AM
#7
Senior Member
Joined: Feb 2012
Posts: 19,356
Likes: 5,478
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
What I've found interesting is the different wear rate at points around the ring's circumference. BITD of symmetrical toothed rings we would rotate them every time we took them off the crank for cleaning. Andy.
03-18-14 | 08:53 AM
#8
Senior Member
Joined: Aug 2005
Posts: 33,657
Likes: 1,119
From: Pittsburgh, PA
Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!
Good illustration of what truly worn chainring teeth look like. We get so many questions about short, flat or "broken" teeth that are intentional design features, not wear, that it's good to show what wear really looks like.
03-18-14 | 10:44 AM
#10
Full Member
Joined: May 2013
Posts: 204
Likes: 0
Thanks OP! I've always characterized worn rings as "shark teeth." When they get sharp enough like that to cut you, it's time to change them (correction: LONG overdue to change them). In my younger days when I didn't know any better, that's what my mountain bike's chainrings looked like before I replaced them.
03-18-14 | 10:52 AM
#11
Full Member
Joined: May 2011
Posts: 374
Likes: 1
From: Midwest
Bikes: '10 Fuji Cross Comp, '12 Brompton S-Type, '14 All City Mr Pink
I assume that is just because there's more power being applied with the crank arms at say, 8 & 2 o'clock than at 11 & 5 o'clock? Where does the maximum wear tend to be (I can then make a point - ha ha - of checking those spots in particular on my bikes)? And would it make sense (as I think 02Giant was suggesting) to make rotating the rings part of a maintenance routine?
03-18-14 | 11:15 AM
#13
The space coyote lied.
Joined: Sep 2008
Posts: 48,742
Likes: 10,993
From: dusk 'til dawn.
Bikes: everywhere
I assume that is just because there's more power being applied with the crank arms at say, 8 & 2 o'clock than at 11 & 5 o'clock? Where does the maximum wear tend to be (I can then make a point - ha ha - of checking those spots in particular on my bikes)? And would it make sense (as I think 02Giant was suggesting) to make rotating the rings part of a maintenance routine?
But, I flipped the little ring on my 15-year-old Record crankset after chainsuck started occuring. Now it's just like new!
03-18-14 | 11:29 AM
#14
Full Member
Joined: May 2011
Posts: 374
Likes: 1
From: Midwest
Bikes: '10 Fuji Cross Comp, '12 Brompton S-Type, '14 All City Mr Pink
Not flippable, but still rotatable, right? E.g. a five-bolt chain ring can be rotated 20%, to put 'fresh' teeth into the area that sees the most wear?
03-18-14 | 11:55 AM
#15
Senior Member
Joined: Jan 2011
Posts: 2,977
Likes: 780
When I posted the 20-40% comment, I assumed you could, and wear the ring more evenly. Now that I think about it, the last chain rings I swapped were 4 bolt on a mountain bike crank, I am not so sure now without checking.
03-18-14 | 07:33 PM
#16
Senior Member
Joined: Feb 2012
Posts: 19,356
Likes: 5,478
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Many of the current rings have specific shift aid designs like lift pins, ramps and gates. While these features don't preclude rotating a ring around the arm's mounts many of these are "clocked" WRT the pedal position. So rotating many modern rings might result in shifting suffering, especially for those who haven't learned to shift well to begin with. When flipping the inner ring take care with whether the chainring bolts stick out further then before and might scuff the RH chainstay. Andy.
03-18-14 | 08:55 PM
#17
Junior Member
Joined: Mar 2014
Posts: 5
Likes: 0
I have been trying to figure out if my 10 year old 20,000km Dura-Ace chainrings need to be replaced. I have replaced chains before they are worn out most of the time. The inner ring looks fine, but the outer somewhat worn, not nearly as much as the above, but I am not sure how much of it is how the teeth are when new, due to shifting performance design. What are your thoughts? See photos:
Last edited by n808; 03-18-14 at 09:27 PM.
03-18-14 | 09:05 PM
#18
The space coyote lied.
Joined: Sep 2008
Posts: 48,742
Likes: 10,993
From: dusk 'til dawn.
Bikes: everywhere
Oops, sorry, totally misread that post. I've never ******** or advanced chainrings to even out wear but I have done so with Biopace just to see if it was better in different orientations. I guess ******ing or advancing both rings the same amount should work fine, although some shift ramps might be set to work in low power phases of the crank revolution and would then be out of those ranges after rotation.
03-18-14 | 09:07 PM
#19
The space coyote lied.
Joined: Sep 2008
Posts: 48,742
Likes: 10,993
From: dusk 'til dawn.
Bikes: everywhere
I have been trying to figure out if my 10 year old 20,000km Dura-Ace chainrings need to be replaced. I have replaced chains before they are worn out most of the time. The inner ring looks fine, but the outer somewhat worn, not nearly as much as the above, but I am not sure how much of it is how the teeth are when new, due to shifting performance design. What are your thoughts? See photos:
EDIT: when I compare the outer ring with low res photos of brand new outer chainrings, I see that the teeth are shaped much like I see below, but it's hard to compare.
EDIT: when I compare the outer ring with low res photos of brand new outer chainrings, I see that the teeth are shaped much like I see below, but it's hard to compare.
Thread
Thread Starter
Forum
Replies
Last Post
Doctor Morbius
Bicycle Mechanics
19
10-08-17 08:50 PM
David Bierbaum
Bicycle Mechanics
8
07-10-12 04:33 PM
