Chain Dropping off front ring
Right, don't normally ask questions as I've got about 21 years of road bikes behind me, but...................
I have a new 8 speed rear block, new 9 speed chain rings and until a couple of weeks ago was running on a SRAM PC68 chain. Just replaced it for one of KMC's 8.99 chain (top 8 speed one) and every so often, when changing down, the chain just drops right passed the inner chain wheel (53/39) and onto the bb shell.
Given that I've had no issues with a SRAM 8 speed chain on the 9 speed rings, I've put this down to the chain and possibly it's width. I've ordered a quality 9 speed chain to try instead - that's me thinking that the KMC may be slightly wider externally than the SRAM PC68 and that a 9 speed should drop onto the inner 9 speed ring easier. No adjustments have been necessary with the front and rear mechs.
The sprocket widths between 8 and 9 is a small fraction, and I've read that 9 speed chains will work on 8 speed cassettes (just 8-9 speed chain rings can cause issues)
No issues with an identical KMC chain on my other bike which is running 8 speed chain rings (53/39)
Any other theories ?
I have a new 8 speed rear block, new 9 speed chain rings and until a couple of weeks ago was running on a SRAM PC68 chain. Just replaced it for one of KMC's 8.99 chain (top 8 speed one) and every so often, when changing down, the chain just drops right passed the inner chain wheel (53/39) and onto the bb shell.
Given that I've had no issues with a SRAM 8 speed chain on the 9 speed rings, I've put this down to the chain and possibly it's width. I've ordered a quality 9 speed chain to try instead - that's me thinking that the KMC may be slightly wider externally than the SRAM PC68 and that a 9 speed should drop onto the inner 9 speed ring easier. No adjustments have been necessary with the front and rear mechs.
The sprocket widths between 8 and 9 is a small fraction, and I've read that 9 speed chains will work on 8 speed cassettes (just 8-9 speed chain rings can cause issues)
No issues with an identical KMC chain on my other bike which is running 8 speed chain rings (53/39)
Any other theories ?
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Comments
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The limiting screws on the front mech might need adjusting.0
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Nothing to do with chain size, you need the front mech adjusting.0
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Your front mech stop is set up wrong. Adjust it, the problem will stop, no need for a different chain.
The 9 speed chain won't work with your 8 speed cassette anyway.0 -
Like the others said, look to adjust yr front mech.
Unlike another said, a 9 speed chain works fine with 8 speed cassette.0 -
If you shift your chain on to the small front chainring, then look at the screws on the front mech, one will have H for high and one will have L for low. If you turn the L or low screw clockwise you will see it pushing the front derailer outwards away from the frame. Shift the chain back on to the large chainwheel, then try shifting it back to the small chainwheel, if the chain still comes off then you need to turn the screw clockwise a bit more so that the chain doesn't come off.0
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Update,
Forgot to mention I did adjust the front mech, but it caused the mech to rub the chain in bottom gear, the tollerance was tight.
Was the chain - put on a 9 speed Dura-Ace one and it's dropping straight on to the inner ring without a problem.
It also is running perfectly with the 8 speed block.
With the 8 speed KMC, the chain would just drop right passed the inner ring, even if turning slowly. Saving that chain now for the training bike !
Advantage as well with the 9 speed chain, it that when on the inner chain ring, I've now got better access to the lower sprockets - i.e. the chain isn't rubbing the outer ring on the lower sprockets.
I did later adjust the front mech as the chain is narrower. Thanks for the responses !0
