Hi folks,
I’m new to bike wrenching and I successfully indexed my own bike. That said, wife’s bike was having issues shifting on her first ride of the season. Only thing that changed from last summer was that we put in a new fork.
I’ve been playing around with her derailer only tweaking H, L, B screws and the cable tension. I’ve watched all the videos about indexing but I can’t get it to work properly and I’m thinking maybe the derailer has an issue itself?
If I try to turn the B screw to tension the chain, then the chain rubs on the jockey wheel. There’s a sweet spot where it doesn’t but then the thing that holds the cable rubs on the cassette cogs. If I move the H screw it helps a bit but then it just doesn’t align with the cassette and doesn’t shift properly.
If I compare the derailer to my own, this one looks a lot higher up than my own (last picture). I’m kind of at a lost here – any thoughts? The derailer seems properly installed if I look at the hanger…
Side note but related to indexing: I just don’t understand how to reset the cable tension in a way that makes sense, even after watching countless videos. Can anyone simplify the steps for reseting cable tension?
by Vast-Decision-2688
20 Comments
[deleted]
There is no chain tension whatsoever because the chain is way too long. Looks like at least 2 links can be removed.
Can you post a pic of the rear derailleur when it is on big/big?
Why were you playing around with it in the first place? Was something wrong with it?
+1 for your chain being too long.
Have you had the hanger checked to see if it’s bent in any way?
Check b tension screw adjustment before shortening the chain
Is this a RM Growler? I have the same bike, and the arm that holds the shift cable is always close to the cassette. If it is rubbing on the cassette you probably have a slightly bent hanger or derailleur cage. The arm should be close but not rubbing in the largest cog. Also your chain looks too short by at least 1-2 links. The derailleur should be angled much further forward when in the big cog, not down like it is. Lastly, you correct the tension this way: 1. Turn barrel adjustor at the shifter so there is no extra tension (back it off), then shift to smallest cog, loosen the fixing bolt that holds the cable at the derailleur and pull the cable as tight as you can with your finger and retighten the bolt. The cable should be under tension but not crazy tight. At this point you can use the barrel adjuster to index the gears
Looks like the chain is too long on your wife’s bike, probably 2 links or so. Did it come from the shop that way? Looks like your riding an Optic, that chainstay looks mighty familiar.
Maybe the bracket moved backward? If it was working last year and nothings changed, it would be weird that you chain is magically too long now.
The dérailleur is fixed to a bracket that is fixed to the hanger. I think this bracket can shift backward if knocked.
The purpose of the derailer cage is to take the slack off the chain. When you change to a smaller cog, the cage swings back to compensate.
Currently, with the chain in the smallest cog, it cannot swing any further back and the chain is slack. This can only happen when the chain is too long. Either this has always been the case, or the chain has been changed and left too long, or the chainring has been changed to a smaller size.
Looking at the derailer with the chain in the largest cog, you could start by shortening the chain by one pair of links, meaning 1 inch total. But it could be that dropping 2 inches would be even better.
So your h and l screw adjusters don’t have any effect on chain tension. Think of them as a stop when shifting into high or low gears. They stop the derailleur derailing the chain off the low gears into your spokes and the same for your low gear derailing off the smallest cog. Btension can help a little with tension.
If you remove your derailleur there is a slot on your hanger that the derailleur fits in when screwing it back in. You have to manually put tension with your hand to align it properly when screwing it back into the frame.
Your chain can stretch over time causing this issue too.
Hope any of this info helps. If in doubt I’d try bring it to your local bike shop as these things can be tricky for beginners to get perfect
Def chain too long….or…is that chainstay …bent??
When you replace a chain, hang the new chain next to the old chain and adjust its length to match and (if the old chain was correct), you should be golden.
As others have said , looks like the chain is wrong.
Also, rather than tinkering till it’s “fixed” , check out Park Tools YouTube video on setting up a derailleur. Follow every step, and you’ll have a great shifting machine.
Resetting cable tension/adjusting derailleur: Park tool video on derailleur adjustment is good.
To summarize
0: fix chain length (Park tool video on chain sizing is good) and verify hanger and derailleur are aligned
1: fully de tension derailleur cable (righty tightly at shifter (and derailleur)) if super slack, undo cable nut on der and pull cable until not slack and retighten nut
2. Set high limit (guide/top wheel about .5mm outside center of smallest cog)
3. Try to shift up one, add tension to cable until able to shift to second smallest cog with one “click”
4. Shift to big-middle refine tension until wheel is centered or slightly inboard of chain roller center. Verify by quiet operation (for now)
5. Set b tension to around 4mm gap between guide wheel and biggest cog while in big-2ND BIG (as small as possible without feeling like binding when shifting into low (or looking like first picture in small-small, but that is two other problems)
6. Carefully shift to small-big and set lower limit (wheel centered on chain roller, quiet operation, shifter hard stops at last gear position)
7. Refine tension (usually only 1-2 notches on adjuster) to alleviate any balky shifting-more tension (lefty-loosey) if slow to shift onto larger gear or less tension if slow to shift to smaller gear
There are more precise ways, but that should get you very close
As far as setting proper cable tension for indexing: shift to the smallest cog and unbind the cable at the cable binder bolt. Dial out your barrel adjuster (probably at the shifter on your set up) two or three full turns. Set the high limit so the top jockey wheel is parallel with the smallest cog and the chain doesn’t make undue noise when pedaling. Pull the cable tight and re-bind it with the binder bolt. Shift to the biggest cog, set low limit by turning the screw until is barely touching the limit tooth on the parallelogram. Shift one click at a time down the cassette, then back up on click at a time. If you get chain noise, dial that barrel adjuster in or out until the noise goes away.
This is all assuming the derailleur hanger is straight btw
Chain is way too long. You can’t index anything like that, it’s pointless man. Look at how the derailleur is all scrunched up at the small cog and barely extended at the big one.
The B-screw is for setting the approx 5-6 mm distance between the derailleur top pulley and the big cog, it’s a subtle tweak that should be done at the end.
**Never play around with the limit screws to try to make your bike shift well.** They’re only there to retain your derailleur and stopping the chain from dropping over/under you cassette if your cable fail or whatever. It’s the last thing you double check.
Stop playing with the screws: put back your derailleur without the chain and zero tension on the cable.
Set back the limit screws to allow your derailleur to move to your big and small cogs. Set the B to something reasonable looking. (Push your derailleur around with your hands)
Look at what a 10sp Deore should look like under chain tension at the lowest and highest cogs; replicate that chain length, put that chain back.
Now read this article and follow that video https://www.parktool.com/en-us/blog/repair-help/rear-derailleur-adjustment steps by steps. Make sure that you understand what is exactly happening every-time you touch your derailleur/cable barrel adjuster/limit screws, take your sweet time, confusion is the biggest enemy. Sleep on it if necessary.
btw it might just be the picture but that outer cable routing seems a bit funky, if that’s a 90° angle I’m seeing right out of the chainstay.
*** it was the chain as most of you said. I had taken out both our bike’s chains in the fall and put the wrong ones back (I will label them next time)***
Now I will index the drivetrain but THANK YOU SO MUCH for taking the time to respond in such detail, i’m quite flabbergasted at how good this community is. Its a silly mistake on my end but I learned a lot about the system altogether by your comments, so it won’t have been in vain.
RIDE ON!
Wrong chain I’d say