Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 35 Post(s)
Tagged: 1 Thread(s)
Quoted: 1388 Post(s)
Originally Posted by Retro Grouch
I can't tell for sure from your description but I suspect that your derailleur hanger is mis-aligned. .... If the arm seems to be pointing toward the rear wheel, that's it.
The hanger may be bent so the lower end of the RD is inboard from the vertical position. That would mean the chain leaves the upper pulley at an angle toward the inside cage plate.
But, it would have to bent at a pretty severe angle for you to see the difference at the top pulley. I suspect that you have a floating upper pulley (moves horizontally on it's shaft) which is standard on Shimano index derailleurs. Some of these are also slightly asymmetric, so what you're observing may SOP for your derailleur. It's possible that you might float the pulley outboard by adjusting the trim inward a bit (tighten cable at the barrel adjuster) but don't do it for this reason. Adjust the trim for best shifting in either direction, and let the chips fall where they may.
BTW- rule number one of bike repair --- don't fix what ain't broke. You didn't say whether your "problem" was affecting shift performance. If it isn't and shifting is good on both directions, your best bet is to leave it alone and stop obsessing about your bike.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
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