hilltowner

I've got a V.O. Grand Cru triple chain wheel . When I run the chain on the middle ring and second smallest cog the pins on the big ring try to upshift the chain. Not successfully but enough to make the chain jump as it is picked up momentarily and falls back onto the middle ring. I recently bent the side plate of my now-replaced chain and haven't figured out how it happened except perhaps through the process just described. I run with old Campy friction shift levers. I don't need the indexing-friendly feature of the pins. Any idea if I will solve my problem and/or cause more problems for myself if I file the pins a bit? P.S. Too much cross-chaining if I run the chain on the smallest cog/ring. Not interested in that, just the second smallest cog on middle ring. P.P.S. Nine-speed IRD cassette rear.

alcjphil

https://velo-orange.com/products/gra...kset-24x34x48t
Is this your crank? The recommended bottom bracket spindle length for it is 124 mm JIS which is quite long. Is that what you have? I am only asking because your question didn't include this information. Also, you don't say what rear cogset you are using and what chain you are using with it. A solution might be as simple as using a narrower chain with flush pins rather than laboriously filing pickup pins on your chainrings. If you are using friction shifting you can use as narrow a chain as possible no matter how many cogs you have in back

hilltowner

Yes, that's the crankset. IRD nine-speed rear. I didn't set up the bottom bracket for this bike so I'm not sure of the spindle length and as you say the recommended length is quite long. I told the mechanic who put the BB in the bike to shoot for the best chain line and that is what he did. The old, now-bent, chain was a Shimano 9-spd. I just put a SRAM 9 -spd on there. Brand new chain so I'm actually inclined toward filing the pins now rather than pulling the chain and experimenting with something narrower.

Andrew R Stewart 

"Dr. How do I make it not hurt when I drink from my coffee cup with the spoon in it" asked the patient. "Take the spoon out" replied the Dr.

Current wide rear cogset widths, short stays and lift pinned rings rarely play nice in as many cross combos then was the case BITD. My suggestion (besides confirming chainlines are within reason) is to avoid that near cross over combo. Andy

Drew Eckhardt 

Get some 0.5mm chainring spacers from Wheels Manufacturing, Origin 8, etc. and move the big ring outboard a hair. You'll keep the pins for shifting and avoid problems from a crankset which was probably made for a narrower chain to go with fewer cogs.

alcjphil

Your crank is compatible for up to "10 speeds" Since 11 speed chains have the same internal width as 10 speed chains, that is what I would try out. Much easier than fiddling with very thin spacers or filing pins on your outer chainring. Chains wear out anyway, so if you need a new one, buy one that provides the best clearance

dsbrantjr

This a solid fix which is easy to do, especially since you are using friction shifting. It addresses the root cause and it also avoids trying narrower and likely more costly and shorter-lived chains, which may not be narrower enough to solve the problem. The 0.6mm size should suffice.

2_i 

You could put a spacer to push the BB a bit out to the drive side, giving the chain less chance to catch the pins.