Old 01-28-24, 12:26 PM
  #31  
Kontact
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Originally Posted by oldbobcat
I can see that you're getting plenty of chain wrap, but any way you cut it, the jockey pulley is way too far forward of the axle to get close enough to the cogs for crisp shifting. I think this might be due to the shape of the hanger. Normally, on a triple I'd discount using the small ring with the fast end of the cassette (the smallest 2 or 3 cogs), but the positioning is still too far forward on the largest cog. That would suggest that the chain is too long. But your big-big photo shows the chain pretty much at its limit. Shimano specs the unit for a 20-tooth spread on triple chainrings, but we can see this pushes it close to the limit.

I've worked with 4700 plenty of times and never had issues with it. In fact, that's what's on the Trek Emonda 3 that I bought my daughter a few years ago. But that was with double chainrings.

As a penultimate to the last resort measure I'd take the derailleur to a shop and ask if there is anything wrong with it. As a last resort, I'd try removing one more link-pair from your chain. I believe it will still be long enough. You can test before cutting by folding over a pair of links on the slack side. I used to be doubtful, having cut my chains slightly loose for years, until I tried shortening one for some reason that I can't remember. It was on my own SRAM Force 10-speed. And presto, the rear shifts were noticeably crisper because the jockey pulley was was in better line with the cogs.
There is nothing wrong with the bike or the parts - they just don't work well together because the cassette is small.

Removing links is going to make the problem worse, not better, because the upper pulley will rotate further down.


Personally, I would use a short cage derailleur and leave the chain long enough that the small/small is slack. That's how we ran short cage Deore XT derailleurs with triples on MTBs in the early '90s. It won't break anything and the small/small with a granny is easy to avoid.
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