crank spider contacting chain on singlespeed
 

I just had my bike converted to single speed. Crank is a Shimano XT M785 and chain ring is a stainless shimano 32T. I'm running a Surly 18t in back. Love the ratio. I noticed the chain is slightly contacting the crank spider though and has worn off the finish a bit. Is this a problem? I am having no performance issues it appears to be cosmetic at this point but as the chain wears down or the teeth on the chainring could it become a problem? Can I solve this by installing chainring spacers between the spider and chainring? Or am I just making an issue out of nothing? Thanks!





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No, it shouldn't be a problem as long as the chain stays properly seated as it passes over the spider.

It appears to be properly seated as it goes around. No skipping issues. The spider is literally flush with the chainring. It looks like it is getting full tooth engagement when the chain passes over this area.

If it BECOMES a problem, and you like the gear combo, you'll have to swap ring and cog; BikeCalc.com says 36/20 is pretty much identical.

You won't have to swap the cog, just file a chamfer onto the spider where it contacts.

- Joel

The chain will likely wear itself a recess on the spider. If you'd like you could take a Dremel tool with a drum-shaped tool and finish the job yourself. If your chainline permits you could also use "chainring spacers" to shim the ring away from the spider until the chain clears it.

Spacers will foul up your chainline. I'd pull off the crank and spend a few minutes with the bench belt sander.

Maybe consider using an economical chain till it does and really it won't take long...

That's essentially what Ofmega/Avocet did to accommodate a 41T ring on their 144mm BCD spider:

http://www.os2.dhs.org/~john/avocet-crank.jpg

yea, File off the needed clearance, from the end of the crank spider .

Might want to have the crank off the bike to do a good job..

Thanks for the advice! I am going to take it by the LBS and try a set of 2mm chainring spacers between the chainring and spider and see if that gives enough clearance. I have a Surly SS kit in the rear so I can easily adjust the chain line to keep it straight afterwards. This would also benefit me by gaining a couple more MM's clearance at my chain stay for the chain as its a bit close anyways.

some tweaking of axle spacers and wheel re-dish could move the chainline on the hub over ,
were it not a single- speed-on- a- Cassette hub, conversion..
You mean the dropout end, at the back, right?

Update. Went by the LBS and they installed 4mm spacers and new bolts. Worked great! Adjusted the spacers in the rear for the new chain line and all is good now! Thanks guys!!! Hope this helps someone else if they run into this issue.


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