indexing issues either high or low

jlloyd
jlloyd Posts: 131
edited June 2019 in Workshop
Hi all,

Have just changed the inner and outer gears cables on my Road bike (105 5800 system). The front derailleur is working fine, however the rear is driving me nuts.

I set it up in the usual way but when I clicked down the gears, it wouldn’t reach the largest sprocket. No problem, I just gave the barrel adjuster less than a turn and it moved on to the largest sprocket. However, I then went back up to the block, but this time it wouldn’t reach the smallest sprocket. Again, slight adjustment and it drops in.

I went back up down the gears and now I’ve lost the largest sprocket again. Slight adjust (qtr turn), drops in. Go back up again and I’ve lost the smallest sprocket. Slightest of adjustments, drops in.

Basically, I can’t get the 2 extreme gears to work at the same time, it’s either one or the other and no amount of micro adjustment is working.

Any ideas?

Comments

  • whyamihere
    whyamihere Posts: 7,698
    Quite possibly a bent mech hanger. You can get an alignment gauge quite cheaply. They're useful to have because sometimes even brand new hangers aren't perfectly aligned. Otherwise, any bike shop will be able to check it and fix it for you.
  • keef66
    keef66 Posts: 13,123
    As above; bent mech hanger would be my bet. It doesn't need to be far out to muck up 11 speed shifting.

    Other things to check: Is the cable correctly routed / clamped at the rear mech?

    If it's externally routed, did you do as Shimano recommend and temporarily clamp the cable then pull hard on an exposed bit to bed in the outers, ferrules etc before finally clamping it properly?
  • StillGoing
    StillGoing Posts: 5,211
    Have you ensured that the cable inner has been pulled all the way through with the shifter changed up to the small sprocket before attaching? If you're one shift out, it could explain why it's effectively working as 10 speed rather than 11 speed.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • jlloyd
    jlloyd Posts: 131
    Cheers all

    Have double checked my routing

    Made sure shifter in right position

    Reattached cable with a little more tension

    Thoroughly cleaned and re oiled derailleur and jockey wheels

    I can now shift across all the sprockets. However it will shift up thru the block to the biggest ring smoothly, but sticks on the way back down. Normally I would say that this is friction in the cable, but have just installed new inners and outers.

    The hanger does look like it's bending in slightly and have ordered a tool to hopefully fix this.

    If it doesn't will go back and check /redo cables

    Anything I've missed here?
  • pilot_pete
    pilot_pete Posts: 2,120
    JLloyd wrote:
    Cheers all

    Have double checked my routing

    Made sure shifter in right position

    Reattached cable with a little more tension

    Thoroughly cleaned and re oiled derailleur and jockey wheels

    I can now shift across all the sprockets. However it will shift up thru the block to the biggest ring smoothly, but sticks on the way back down. Normally I would say that this is friction in the cable, but have just installed new inners and outers.

    The hanger does look like it's bending in slightly and have ordered a tool to hopefully fix this.

    If it doesn't will go back and check /redo cables

    Anything I've missed here?

    Cable run is smooth throughout? Loop at the rear is not too tight a bend? With the cable removed I assume the derailleur parallelogram moves inboard/ outboard smoothly with no restrictions when pushed with your hand? Spring loading allows the derailleur to move back outboard freely? B tension set correctly (top jockey wheel is set as close as possible to the biggest sprocket without trapping the chain)? These can all affect shift quality as you describe.

    Hanger alignment is the next obvious candidate to check, but it could be that you have it indexed with the chain too close to the next biggest sprocket if it shifts up the sprockets easily but hesitates to drop down the block. Last thought is to just ensure that the cable is clamped correctly as it is possible to clamp the cable the wrong side of the clamp/ bolt which affects the cable pull. Check the dealer manual for your particular model for exact correct positioning (free to download if Shimano).

    PP
  • jlloyd
    jlloyd Posts: 131
    Cheers all,

    Fixed now, Combination of rechecking the cables and straightening slighly bent mech hanger

    Ta