Thorn Cycles Forum
Technical => Transmission => Topic started by: geocycle on December 14, 2008, 04:26:15 pm
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Well anyone like to guess how this happened? How do you lose every other plate?
(http://farm4.static.flickr.com/3151/3107810812_6f0ae91d6d.jpg)
On returning from a ride a noticed I had lost 4 plates from the inside of the chain! It had been a rough-stuff type ride along the sea front and I suppose I could have hit a rock but I don't recall anything. I must have ridden a good few miles home and not noticed. Another advantage of not having to derail the chain I suppose. For the record it was a PC68 with about 5000 miles on the clock.
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Now THAT is bizarre!
Was it left or right side of the chain that lost the plates?
Does your chainset have a chain guard/ bash ring type thingmebob as well as the chainring fitted?
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Those are INNER plates!!! when I chain brakes it is (nearly) always an outer plate that 'springs' off a pin shortly followed by it opposite number. Have you checked you chain ring or spur gear for damage. Best guess is that one or other has a damaged tooth that is scoring the inner plates - but this is clutching at straws.
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Now THAT is bizarre!
Was it left or right side of the chain that lost the plates?
Does your chainset have a chain guard/ bash ring type thingmebob as well as the chainring fitted?
It was the side facing into the bike, so I think that would be left! I don't have any chain guards fitted, maybe I should.
Those are INNER plates!!! when I chain brakes it is (nearly) always an outer plate that 'springs' off a pin shortly followed by it opposite number. Have you checked you chain ring or spur gear for damage. Best guess is that one or other has a damaged tooth that is scoring the inner plates - but this is clutching at straws.
I know! I have only ever had outside plates ping off before, usually while changing a gear on a derailleur bike. I didn't notice anything obviously wrong with the chain wheel/sprocket when I put the spare on last night in the dark and it rode ok this morning. I'll definitely check out the scoring hypothesis. [had a look this lunchtime and there is no sign of any damaged teeth on front ot back]
Alternatively, I must have bottomed out the chain wheel on a rock, but why would this break just the inner links?
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What is the current favourite for a replacement chain? It seems the PC68 is discontinued and SJS only list the Rohloff ST-99 in gold plate (I joke not) at £174.... Anyone using the PC890 which I think looks like the latest version of the PC68???
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That is odd, e-mail Sram and see what they say.
As for replacement:
As standard we now fit: http://www.sjscycles.co.uk/product-KMC-KMC-Z51-Chain-116l-bagged-7-8-speed-14135.htm
You can get a rust free version: http://www.sjscycles.co.uk/product-KMC-KMC-Z51RB-Anti-Rust-Chain-116l-7-speed-15269.htm
These are a nice nifty chain for perfect adjustment: http://www.sjscycles.co.uk/product-Gusset-Gusset-Slink-Chain-3-32-1-2-x-3-32-100L-Slotted-Cranked-Links-(made-entirely-of-half-links)-18265.htm
The Rohloff chains (other than gold!) are indeed currently out of stock, Rohloff are having production problems, staff illness etc and should have some more to us early next year.