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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) http://farm4.staticflickr.com/3676/1...b3186c67_b.jpg http://farm8.staticflickr.com/7382/1...8b3508e7_b.jpg |
Nice. I saw many folks asking just for that.
You definitively waited way too long before replacing it lol How long it lasted and on what kind of bike? |
You got your money's worth out of those chainrings...
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Originally Posted by lopek77
(Post 16587580)
Nice. I saw many folks asking just for that.
You definitively waited way too long before replacing it lol How long it lasted and on what kind of bike? |
Oh, come on! You had at least 5 more years out of that one :D
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... |
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 |
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.
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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.
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Rotate it 20-40% and run it another chain or two.
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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.
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Originally Posted by Andrew R Stewart
(Post 16588187)
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.
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I usually wait until they are perfectly smooth.
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Originally Posted by Earl Grey
(Post 16588899)
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! |
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?
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Originally Posted by Earl Grey
(Post 16589016)
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?
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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.
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2 Attachment(s)
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:
http://i.imgur.com/Hy5clw1.jpg http://i.imgur.com/uiNjDS1.jpg |
Originally Posted by Earl Grey
(Post 16589016)
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?
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. |
Originally Posted by n808
(Post 16590661)
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. http://i.imgur.com/Hy5clw1.jpg http://i.imgur.com/uiNjDS1.jpg |
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