Loose chain

[George Hetrick]

Wow! That's a lot, George, and troubling. Hmm. D'you mean when the chainring is mounted on the arms, there's a 1.5mm gap between the inner edge of the 'ring and the crank spider's mounting flanges?

Just curious: Will or does the 'ring center on the chainring bolts? Or does it sort of rattle around on the sleeve nuts/bolts? Does your 'ring mount to the outer or the middle (inner) position on your crank?

I think it matters that the Surly ring is intended for a single-speed, rather than a double/triple crank; they may very well have slightly different standards.

But the ring bolts are not counter-sunk, and slightly smaller, which allows the slack.

And, yes about the flange-spacing.

[Danneaux]

<nods> Thanks for the additional details, George. Boy, that is troubling. 'First I've heard of the problem and very sorry it hasn't worked out for you.

All the best,

Dan.

[Andre Jute]

I don't quite see how there could a different standard in a chainring for a half-inch chain which has been standardized for half a century and more. "Single speed" chainrings don't have gear-chainging ramps and pins, true, but that follows from their function.

I think that it's likely that what will be discovered about this particular rogue chainring is that the Surly steel chainrings are essentially a custom job, cut one by one in the shed out back. I too have the 38T Surly chainring, and in 2500km have not noticed anything odd about it, so mine is a good one, which implies there is no design fault with it, just a manufacturing glitch. There are more owners of the 38T chainring on the forum who might chip in even if their contribution is "nothing to report in [distance]".

Sounds to me like a straight-up case of Surly owing you a new, correctly cut, chainring.

[julk]

I too have fitted a Surly 38 tooth 5 arm chainring.

It was not an exact fit onto the spider and I used this to tweak the ring into a position where it ran perfectly centered before giving the bolts a final tighten.

It has continued to work fine since being fitted.
Julian.

[mickeg]

I worked in a bike shop in the 1970s.  A lot of components back then were manufactured with less precision than many of the computer aided manufacturing tools accomplish today.  Thus, I am used to making minor tweaks when I build up a bike.

I am using a 110mm BCD chainring that cost about $10 USD with no manufacturer name on it.  It fits a bit sloppy on the 5 arm crank of a different manufacturer.  Instead of buying a high end high quality alloy chainring, I am buying cheap chainrings and cheap KMC chains.  It was listed as a "Alloy BMX Chainring 3/32" 44T x 110mm" and supplied by a wholesaler in Seattle.

I do not know how much gap I have between the arms and ring, but the chainring was not perfectly centered on the crankarms with a bit of sloppiness.  All it needed was a few minutes of adjusting, then I tightened the the chainring bolts once I got it centered.  I did this when I first built up the bike.

And once I had that set, then I set the eccentric. 

[geocycle]

I too have fitted a Surly 38 tooth 5 arm chainring.

It was not an exact fit onto the spider and I used this to tweak the ring into a position where it ran perfectly centered before giving the bolts a final tighten.

It has continued to work fine since being fitted.
Julian.

I've done a lot of fiddling with my 42 tooth surly and have yet to find a sweet spot on the Thorn 110BCD spider.  It just doesn't line up very well at all giving the uneven chain tension mentioned above.  I think I have exactly the same problem as Hetrick with gaps at the spider.  It is just about acceptable for the moment to ride on but is a pain to adjust the tension accurately.  I need to find another ring that will work under the chainglider (which I appreciate more and more!).