Damage to chainring
#1
Damage to chainring
I was cleaning my bike yesterday, as I had been riding in the wet and had kicked up loads of sand. As I was cleaning, I noticed a number of the teeth of the largest chainring were broken/worn down. There were a significant number of teeth that were rounded off. This is pretty surprising to me, as my bike is roughly 2 months old. Though, I have put roughly 350 miles on it already. I have an appointment scheduled with the LBS I bought it from, as they give a free check-up and tune-up for all new bikes.
Is there something I'm doing wrong? What could be causing it? How can I prevent it?
Is there something I'm doing wrong? What could be causing it? How can I prevent it?
#2
Prefers Cicero
It doesn't make much sense to me. I know some mtb riders grind over logs and sometimes the big ring might bite into them, but even that shouldn't do too much damage as I understand it.
#3
Banned
You may be mistaking engineered changes to speed the shifting from 1 chainring to another ..
The designed ones come at a point where the pedals are at Bottom center on each side , so 180 apart on the chainring.
then again do you have to drag your bike up Concrete stairways ?
Bash guard rings are made for intentional thrashing.
The designed ones come at a point where the pedals are at Bottom center on each side , so 180 apart on the chainring.
then again do you have to drag your bike up Concrete stairways ?
Bash guard rings are made for intentional thrashing.
#4
Senior Member
Over the last decade or so there has been an introduction of engineered sprocket teeth to help aid with shifting, and perhaps also prevent chain suck.
So, a NEW sprocket will have a few short teeth (almost appearing broken), and the back side of the teeth may be rounded while the pulling side is square.
Post some photos of your sprockets, but it is possible they are NORMAL.
Beware of stretched chains, but 350 miles is short for that too.
So, a NEW sprocket will have a few short teeth (almost appearing broken), and the back side of the teeth may be rounded while the pulling side is square.
Post some photos of your sprockets, but it is possible they are NORMAL.
Beware of stretched chains, but 350 miles is short for that too.
#6
Senior Member
I don't see anything particularly concerning about the tooth profiles.
The short tooth in the middle of the 2nd photo is right next to a shifting ramp, and was there from the factory.
As you pedal, the chain pulls to the right end of the channel, or the left side of the tooth (from the view of the photos). Any rounding to the back side of the teeth (right side of the tooth, left of channel) would be by design and not affect your riding.
The short tooth in the middle of the 2nd photo is right next to a shifting ramp, and was there from the factory.
As you pedal, the chain pulls to the right end of the channel, or the left side of the tooth (from the view of the photos). Any rounding to the back side of the teeth (right side of the tooth, left of channel) would be by design and not affect your riding.
#8
apocryphal sobriquet
I agree with the above, although some of the finish has worn off, the tooth profile looks like a design feature rather than wear-and-tear. Is the chain slipping or anything?
#9
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Dirty, slightly worn, not damaged.
#10
I've been having some shifting issues, but not between the front gears. I'm taking the baby in this week for the free check-up and cleaning. The roads here are over salted and then covered in sand in the winters, so my ride to and from work is pretty grimy. I need to do a better job on keeping the gears/chain clean.
Thanks for the help! It's good to know I was freaking out over nothing
Thanks for the help! It's good to know I was freaking out over nothing
#11
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#12
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As long as you can clearly tell the difference between the "normal" and "sculpted teeth on the ring, it's fine. It's when all the teeth look pretty similar that you need to worry.
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FB
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
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I've been having some shifting issues, but not between the front gears. I'm taking the baby in this week for the free check-up and cleaning. The roads here are over salted and then covered in sand in the winters, so my ride to and from work is pretty grimy. I need to do a better job on keeping the gears/chain clean.
Thanks for the help! It's good to know I was freaking out over nothing
Thanks for the help! It's good to know I was freaking out over nothing
#14
Senior Member
If you look at your bike's cassette in the rear, you'll see a similar thing. You will also see ramps cut into the side of the cogs or rings. If you put the bike up into a stand and turn the pedals very slowly while shifting the gears, you will notice the chain only shifts at these ramped portions. Not only that, the chain can physically engage both the cog or chainring it is shifting off of, and the cog or chainring it is shifting onto. These features are why drivetrains shift so quietly. It also allows for less finessing; you don't have to "soft pedal" nearly as much when changing gears compared to pre-CAD drivetrains.
#16
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>>>>Turning the barrel in the direction that screws it outward, (counter-clockwise, looking from the top) lengthens the housing, which has the same effect as shortening the wire, and moves the derailleur inward.
>>>>Turning it so it screws inward, does the opposite and moves the RD outward.
Adjust the RD trim in the direction that solves your problem, ie. inward for crisper shifting to larger sprockets, outward for crisper upshifting to smaller ones, looking for the most neutral balance between the two.
Assuming all was correct, and you suspect cable "stretch" that would have moved the trim outward (the same way as shortening the housing) so bring the adjuster out to correct.
If your friend simply remembers that the adjuster changes the housing length, which is exactly opposite to changing wire length he'll never go wrong.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.