Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Bikes: Some silver ones, a black one, a red one, an orange one and a couple of titanium ones
Mentioned: 18 Post(s)
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Originally Posted by DMF
Shimano locates the ramps and pins differently on different crank sets. In addition, the spacing between the rings is nominally the same between 9-spd and 10-spd, but like different groups within each generation the spider face plus the ring thickness (plus the odd spacer) determines the actual centerpoint. Mix groups or even models within groups and the spacing is not guaranteed.
You took the wrong option for improving shifting. Rather than change rings you should have changed dérailleurs.
No need to change the derailer. This sounds like a cabling/stops issue. It shouldn't matter if what kind of derailer or rings the crank has, if you move the derailer far enough the chain has no where else to go but up onto the gear.
Downshift the front to the small cog. This should be the lowest tension point on the cable. Check to see that the cable is taut. It should have a little play in it but not much. Now spin the crank and see where the derailer is positioned in relation to the inner cog. It should be positioned so that it doesn't rub when you are in the lowest gear in the back but just barely. If you have significant daylight between the chain and the inner plate on the derailer, you can fiddle with the low limit screws. You shouldn't have to move it very far.
Check the cable again. If it is loose, either adjust the slop with the barrel adjusters or reposition the cable.
Now shift outward to the big ring (in a middle range gear on the rear). If the derailer won't throw far enough to make the shift, you can fiddle with the high limit screw to move it outboard. Once you get it onto the big ring shift from the middle of the cassette to the high gear on the cassette. Check to see that you don't have chain rub on the outer plate and adjust the cable tightness and/or limit screw accordingly.
You may also want to check the crank on the spindle (perhaps before you go messing with the derailer
) to make sure it is properly seated. If the bike shifted up to the big ring before, it should do so now.
Another thing to check (again perhaps before you go messing with the derailer) is the ring itself. You did
reinstall it in the proper direction, didn't you? If the outer face is now the inner face, that could move it too far outboard.