Bicycle Mechanics - XTR rear deraileur adjustment
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04-23-03, 03:53 AM
ok, i've been able to do it in the past, but for some reason i can't quite get the adjustment right (i bought a new cassette and chain).
so to adjust the system:
first set the cable length - does it matter what the front deraileur is set to? and does it matter is you "zero" on the smallest or biggest cog side? (i have regular, not rapid-rise)
then for the limit screws: which one goes to which? and how exactly do you know to set them? if i remember right, there is one screw that limits the max and one that limits the min --- so this means that the limit screws have no effect when the middle cogs are used?
Nathank, it's true the limit screws stop the chain falling off to the wheel or dropout. The spacing between the cogs is equal so once you've got the limit screws adjusted by line of sight and checking by shifting gear then you don't need to play with them further. Usually that is. Any adjustment you make to the screws will have an equal effect throughout the cogs, so it's best to make the final adjustments to the indexing using the cable adjustment on the shifter barrels. I found that by tweaking the limit screws I could eliminate mechanical scraping and scratching of the chain on my XO rear mech. Since I realised that, my shifters are now extremely smooth and quiet.
I can't remember which screw does what, but if you remove the chain, you'll quickly see which way the screws move the rear mech. On my XOs, the smallest cog required the limit to be set so that the guide wheel inner side was inline with the outer face of the smallest cog. For the biggest cog, the XO required the guide wheel to be in line with the teeth of the largest cog. I can't say if XTR uses a similar line of sight adjustement though?
If anything, I found adjusting the front mech to be a bigger pain in the butt even though it looks like the simpler of the two mechs.
04-23-03, 12:34 PM
1. Completely disconnect your shift cable. (Important)
2. Turn the crank to put your chain onto the smallest cog.
3. Look at your rear derailleur from the back of the bike. Does the upper derailleur pulley line up exactly with the smallest cog? If not turn the high gear limit screw, usually the upper one, until it does.
4. Pull your shift cable taut with needlenose pliers and anchor it to the derailleur.
5. Try to shift down 1 gear. Adjust the cable tension until the chain doesn't make any noise.
6. Repeat step 5 until you can shift into each gear.
7. Shift into your biggest cog. Adjust the low gear limit screw in until it starts to move the derailleur, then back it off about 1/4 turn. Check up and down shifts on the biggest cog.
04-23-03, 12:48 PM
If you disconnect the cable, and sight from the rear you can line up the upper jockey pulley with the small cog using the Lower set screw. If you do not have the chain on, you can manually grab the derailleur and push it left (when looking at the bike from the rear), and line up the upper jockey pulley with the largest cog.
Install chain, cable, shift the rear shifter to the lowest gear, and turn the barrel adjusters (on rear derailleur AND the shifter) all the way in, then back it out 1 full turn. Pull slack out of cable and retighten. Oh yeah, I also shift the front derailleur into the middle chainring. Check lower limit again to make sure it's not rubbing the frame,if it is adjust the limit screw in just a bit more. Now, while pedalling, shift 1 time. This should shift the bike into the 2nd gear. Using the barrel adjuster, turn counter clockwise until the upper jockey pulley is directly below the 2nd cog. This sets the cable in the proper alignment for the clicks on the shifter. Go through all the gears and adjust the barrel adjuster in 1/8 turns to fine tune it.
When you do shift into the big cog, try to overshift and throw the chain off to the inside. If you can, obviously you need to turn the limit screw in a bit. If the chain doesn't want to get into the big cog, you've adjusted it too far and need to back it off a bit.
Also, did you remember the spring tension screw available on the XTR? Where the cable clamp is, toward the rear pivot of the derailleur there is a phillips head screw. If you turn that 1/4 turn, you increase the spring tension on the derailleur which makes downshifts quicker and more crisp!
04-23-03, 12:59 PM
Originally posted by a2psyklnut
Using the barrel adjuster, turn counter clockwise until the upper jockey pulley is directly below the 2nd cog. This sets the cable in the proper alignment for the clicks on the shifter. Go through all the gears and adjust the barrel adjuster in 1/8 turns to fine tune it.
An easy way to remember how to turn the barrel adjuster on the rear derailleur is that you turn it towards the bike (counter clockwise) to move the chain travel in (left) and away from the bike (clockwise) to move the chain travel out (right).
The barrel adjusters on the levers and/or cable stops also have the same effect on the rear derailleur when you turn them counter clockwise (out = left) and clockwise (in = right).
04-23-03, 03:25 PM
One other tip, front barrel adjuster on your shifters themsleves..
Make sure it is not turned all the way in, if you have it out 2 turns, you can adjust on the fly to fine tune things, without having to stop the bike. It especially helps during a race.
There is a reason I know this!! :cry:
04-23-03, 03:28 PM
Aren't you too old to race Scooby?
04-23-03, 03:30 PM
Originally posted by WorldIRC
Aren't you too old to race Scooby?
Does that answer your question?
04-23-03, 03:39 PM
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