Back by popular demand, the general all-things Road forum!
Moderator: robbosmans
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Timmy269
- Posts: 243
- Joined: Tue Nov 25, 2014 2:34 pm
by Timmy269 on Wed Oct 04, 2017 11:14 am
grover wrote:I can't think of a circumstance where the chain spontaneously drops off the big chainring to the small except when the chainring is worn, the chain is sloppy side to side and you're in a gear that makes quite a chainline. Say 53-28/25/22. The big ring teeth are no longer tall enough to hold the chain on the teeth against the angle that is pulling it towards the little ring (especially happens if you do half a pedal backwards when shifting your weight cornering/descending).
I don't know your yearly mileage, conditions or maintenance but three years is a long time for a set of rings to last for anyone in my opinion. I'd replace the chainrings and the chain. Given the likely worn chain is not skipping on the cassette, I'd say the cassette is shot too. Again, three years on a cassette is a long time.
Your chains aren't lasting very long now because your putting them on worn chainrings and cassette. You get away with it a few times but now it's just not working. A new chain only will probably remedy the issue for a short period because it will be stiffer laterally. But it will wear quickly.
My vote is to replace your chainrings, chain and cassette. And given the chain has dropped onto the bottom bracket a few times it sounds like your limit screw and chain catcher position need a tweek.
I thought that if the teeth of the cassette and chainrings had points they are worn out
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goodboyr
- Posts: 1487
- Joined: Wed Jan 10, 2007 10:56 pm
- Location: Canada
by goodboyr on Wed Oct 04, 2017 12:41 pm
With all due respect, you’ve got some opinions to act on now. I’m not sure what the point is of further discussion. At least the chain, and in others option the rings and cassette too. When you get your new stuff you can hold it up side to side to compare and see the wear.
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Delorre
- Posts: 967
- Joined: Sat May 24, 2014 12:09 pm
by Delorre on Wed Oct 04, 2017 12:50 pm
grover wrote:I can't think of a circumstance where the chain spontaneously drops off the big chainring to the small except when the chainring is worn, the chain is sloppy side to side and you're in a gear that makes quite a chainline. Say 53-28/25/22. The big ring teeth are no longer tall enough to hold the chain on the teeth against the angle that is pulling it towards the little ring (especially happens if you do half a pedal backwards when shifting your weight cornering/descending).
I don't know your yearly mileage, conditions or maintenance but three years is a long time for a set of rings to last for anyone in my opinion. I'd replace the chainrings and the chain. Given the likely worn chain is not skipping on the cassette, I'd say the cassette is shot too. Again, three years on a cassette is a long time.
Your chains aren't lasting very long now because your putting them on worn chainrings and cassette. You get away with it a few times but now it's just not working. A new chain only will probably remedy the issue for a short period because it will be stiffer laterally. But it will wear quickly.
My vote is to replace your chainrings, chain and cassette. And given the chain has dropped onto the bottom bracket a few times it sounds like your limit screw and chain catcher position need a tweek.
I totally agree here!! I've recently began to have similar issues on some occasions, but it happens only when in the big ring and with cross chain with the third last cog (I don't go higher when in the big ring). And yes, the chainrings have 25.000 km's and the chain is due for replacement also. Never had drops in the past, even when the chain was due for replacement. So, my vote also goes toward changing chain AND chainrings (and cassette if it has already seen a couple of chains)
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glepore
- Posts: 1408
- Joined: Thu Mar 28, 2013 4:42 pm
- Location: Virginia USA
by glepore on Wed Oct 04, 2017 1:52 pm
Not to pile on, but the photos of the big ring show obvious wear. To the point of shards hanging.
Cysco Ti custom Campy SR mechanical (6.9);Berk custom (5.6); Serotta Ottrott(6.
; Anvil Custom steel Etap;1996 Colnago Technos Record
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ddsg
- Posts: 39
- Joined: Sun Dec 08, 2013 10:30 pm
by ddsg on Thu Oct 05, 2017 2:43 am
Have the same problem on my older 10 speed Di2 setup. Chain is fine (checked with chain tool) and chainrings don't seem worn... Will be curious to see what fixes it in your case.
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goodboyr
- Posts: 1487
- Joined: Wed Jan 10, 2007 10:56 pm
- Location: Canada
by goodboyr on Thu Oct 05, 2017 3:31 am
Those chain checkers don’t show pin to pin wear. Take a 12 inch steel ruler and check pin to pin with the chain stretched tight. I bet you’ll see wear of 1/8 or more even though your chain checker says it’s ok.
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Timmy269
- Posts: 243
- Joined: Tue Nov 25, 2014 2:34 pm
by Timmy269 on Thu Oct 05, 2017 12:58 pm
Thanks, in the meantime I have mailed the photos of the chainrings to the Rotor Distributor and according to him there is wear but not so that they need to be replaced.
This evening I will measure the chain wear
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wingguy
- Posts: 4318
- Joined: Thu Mar 08, 2012 11:43 pm
by wingguy on Thu Oct 05, 2017 2:29 pm
Timmy269 wrote:I thought that if the teeth of the cassette and chainrings had points they are worn out
Points?
If your chainrings have points then they are ULTRA worn out
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Ritxis
- Posts: 1119
- Joined: Fri Jun 01, 2012 3:00 pm
- Location: San Sebastian
by Ritxis on Fri Oct 06, 2017 8:20 am
Timmy269 wrote:What's the best choice, Shimano chain or KMC chain
Shimano CN-HG601 (105) Pay more than it costs this, is to waste money