jimmay2000 said:
Hi
I have a relatively cheap hybrid that I use as a commuter and to carry my son around on the weekends. Due to a problem with my rear derailleur, I asked LBS to upgrade it.
The old derailleur was a 7-speed Rapid Rise with Revo twist shifters. The new one is a Shimano Tourney, which is high-normal as opposed to low-normal. The shifter was not changed.
Now I can cope with the reversal of gears from 1 to 7, but now the indexing is screwed:
7 gives cog 1
6 gives cog 3
5 gives cog 4 or 5
4 gives 5 or 6
3 gives 6
2 gives 7
1 gives 7
Is this a problem I can easily fix? Can I remove indexing completely?
Thanks for your help
jimmay
Hi Jimmay,
Your hand shifters don't care how the rear derailleur works. Rear derailleur indexed shifting is pretty much tried_and_true at this point in time and I'm pretty sure you just need to properly tune your rear derailleur and you'll be happy as a pig in what_they_like_to_lie_in. You really don't want to remove indexing for a rear derailleur. Trust me.
First, I'll give you a reference to the Park Tool Repair site blurb:
http://www.parktool.com/repair/readhowto.asp?id=64
And, now I'll tell you how I do it ...
1. Shift your rear derailleur to the high gear (i.e. the small cog).
2. Shift the front derailleur to the big chainring (on a double) or the middle chainring (on a triple).
3. Loosen the bolt that locks the shifter cable.
4. Turn the crank (bike should be up on a stand or on a trainer) and the chain should move smoothly on the small cog. If it does not your "H" limit screw is out of adjustment. Look at the relationship between the small cog and the jockey wheel from behind the bike. They should be in line with each other. If they are not, turn the "H" limit screw until they are directly in line. Now turn the crank and the drive train should operate smoothly. If not, turn the "H" limit screw a quarter of a turn (you pick which way - but remember!). Do this a quarter turn at a time until the drivetrain cranks butter smooth. Now your "H" limit setting is done.
5. Now you will set the "L" limit screw. This is the setting which prevents your chain from passing the largest cog and jumping into the spokes.
The RD cable is still loose. Turn the crank using the pedal and push in on the bottom of the rear derailleur - be careful of your fingers!!! While you are pushing in on the bottom of the derailleur and cranking the chain will move up to the larger cogs. If it does not move all the way to the largest cog then your "L" limit is too tight - turn the "L" limit screw CCW a half turn at a time until you can "push" the RD to get the chain to move to the large cog. Once you can get to the large cog, back off a quarter turn and see if you can still get there. You only want enough to just get you on the large cog. If, when you first push on the bottom of the RD, the chain moves up to the large cog and past it onto the spokes (or spoke protector), then your "L" limit screw is too far "out" (or "loose"). In this case, turn the CW until the chain does not jump off the big cog when you push hard on the bottom of the RD. Adjust the "L" limit screw as necessary until you can push the RD bottom and move the chain onto the big cog - but not past it - smoothly.
6. Now your high ("H") and low ("L") limits are set.
7. If your RD has a barrel adjuster on it, turn it all the way CW until it is in all the way (look at the aluminum sleeve on the inside and see when it stops moving). Now, turn it four complete turns CCW. If there is a barrel adjuster at the shifter, turn it all the way CW. If there is a barrel adjuster on the downtube, adjust it all the way CW.
Keep in mind, CW adjustments shorten the cable (i.e, reduce tension), and CCW adjustments lengthen the cable (i.e. increase tension). This is an important concept. The simplest adjustment to get correct indexed shifting is to just slightly increase the tension with the barrel adjuster at the RD.
8. Ok,
NOW, it's time to lock down the shift cable. Make sure it's routed correctly, pull it through the lock down clamp (just take a pair of pliers and pull the slack out of the cable), and then tighten down the locking bolt. This is almost always a 5mm hex bolt, but sometimes it's a 9mm nut. Once you've got it tight - it does not need to be deathly tight - pull on the exposed RD shifter cable where it travels along the down tube and see if it moves the RD towards the 2nd cog. If it moves a little in that direction you are good to proceed. If you feel excessive slack in the cable then you did not get it tight enough - go back and do so.
9. Turn the crank arm with the pedal and tug on the RD cable a little. It should initiate a shift to the 2nd cog. If it does, try cranking and shifting with the hand shifter.
10. If shifting one position with the hand shifter while cranking accomplishies a one_gear shift, then shift back and forth between the high gear (the smallest cog) and the 2nd highest gear (the next biggest cog). If this is working fine then shift to the next gear, and so on. Odds are that you will reach a point where the chain is hesitant to move "up" to the next larger cog. This means you need more cable tension. You get this by turning the barrel adjuster on the RD CCW. Do this in small increments, no larger than 1/2 turn at a time. Usually it only takes a few "clicks" to complete this adjustment. You should now be able to down shift (to progressively larger cogs) with the hand shifter one click at a time.
11. Once you get to where you can
down shift properly, you should fine tune to make sure the indexed shifting is done. You do this by checking that the
up shifting (to progressively smaller cogs) works correctly and smoothly. Up shift (large cog to smaller cogs) one gear at a time and insure that each gear is hit properly. If you find that some gear is skipped then you may have put a little too much tension on the cable during the down shift index adjustment. If you miss a gear then back off 1/4 click on the RD barrel adjustment. Do this until your up shifting is correct. Re-check the down shifting. Go back and forth between the down shifting adjustment and the up shifting adjustment until the indexed shifting is perfect.
12. If, after you do your RD adjustments and you are out on the road and your indexed shifting gets balky, then you likely need just a bit more tension in the cable. In this case, turn the adjuster 1/4 click CCW (remember, you are lengthening the cable!). You can do this with a barrel adjuster at the hand shifter, on the down tube, or at the RD (if you don't have any other barrel adjusters). This is what the hand shifter barrel adjusters and down tube barrel adjusters are for. You can fix your indexed shifting on the fly. Just take the time to learn what you are doing and then you can be confident that you are going in the right direction.
12. Most rear derailleurs have a "B" adjustment screw and I advise using the proceedure outlined on the Park site for that. If you have a situation where you are cranking and the chain seems to be "lumpy" going over the small cog, this is very possibly the "B" adjustment. The big chainring and small cog combination should be very smooth. If it is not, then either the "B" adjustment is off or the "H" limit needs a tweak.
I took the time to write up my proceedure because I have always found that there is a lot to be desired from any written proceedures I have come across. I hope that my comments will make RD adjustments easier for those of you that want to master this proceedure.
In the end, it's really pretty easy and just takes a little practice. I hope this helps. Good luck and good riding!
Cheers,
fish156
