I've been riding my Raleigh, equipped with Ultegra 9-speed components, compact crankset, for a year now. When new, I think I had cross-gearing noises on the biggest cog (25), and maybe very slightly on the second-biggest cog (let's call it 1.5 cogs). Then I crashed, and found I had to adjust the derailleur a bit. Since then, cross-gearing noises occurred on 2.5 cogs; my attempts to correct that failed. Over time, the tuning got a little further out of whack, to where on occasion I'd drop the chain when shifting up to my big ring. So this past weekend I fiddled with it again, turning the high limit screw just about as far as it would go (adjusting the derailleur position inwards), which was only slightly farther than it had been already set. I was delighted when, on a quick test ride, not only did the chain drop problem go away, but I had only slight cross-gearing noises on the biggest cog. Problem solved, I thought. Only the next day, on a real ride, when I got into the little-cog/big-ring combination, did I learn that I had merely shifted the problem to the other end. What am I missing? The noises only occur during part of the pedal stroke, so chain ring flex or lateral movement is certainly at play.
When looking into other cranksets this morning, I noticed the following blurb in the promotional description of a 105 FC-5750 crankset:
It features a larger gap between the top and low gear, for less chain rub in small gear combinations.I would have thought that spacing the gears further apart would worsen, rather than improve cross-gearing issues. Am I misunderstanding the mechanics?