MTB Rear Mech Indexing Problems!

[JoeKF]

Hi. I'm trying to sort out the rear mech action on two of my sons bikes and hoping someone might be able to help! Both bikes are old hardtails; a Kona AA and a Specialized Rockhopper.

The Kona has an original Shimano Deore XT rear mech 8spd with recent replacement Shimano Alfine shifter. Its shifting from highest to lowest gear, but skips every other gear on the way up and down! Don’t know how to stop it shifting too far so it’ll index to each gear (by loosening the cable), without stopping it shifting into the highest gear?!

The Specialized has a new SRAM X5 rear mech 9spd with original Avid shifter. I’ve managed to get it shifting between gear 1 and 7, but can’t get it up to 8&9. And its not the adjustment screw stopping it.

In both cases I’m wondering if it’s a compatibility issue of old and new kit from different brands. Or if it’s just case of better, different adjustment.

Any help or ideas appreciated. Thanks

 

[fossyant]

Do you have new cables (inners and outers). Start there first.

 

[Spiderweb]

Hi. I'm trying to sort out the rear mech action on two of my sons bikes and hoping someone might be able to help! Both bikes are old hardtails; a Kona AA and a Specialized Rockhopper.

The Kona has an original Shimano Deore XT rear mech 8spd with recent replacement Shimano Alfine shifter. Its shifting from highest to lowest gear, but skips every other gear on the way up and down! Don’t know how to stop it shifting too far so it’ll index to each gear (by loosening the cable), without stopping it shifting into the highest gear?!

The Specialized has a new SRAM X5 rear mech 9spd with original Avid shifter. I’ve managed to get it shifting between gear 1 and 7, but can’t get it up to 8&9. And its not the adjustment screw stopping it.

In both cases I’m wondering if it’s a compatibility issue of old and new kit from different brands. Or if it’s just case of better, different adjustment.

Any help or ideas appreciated. Thanks

If the Avid shifter is a 9 speed then I’d think it requires more cable tension?

 

[Ming the Merciless]

Do you have a barrel adjuster anywhere between lever and mech? You could add in the missing tension that way.

 

[JoeKF]

For the Specialised: There is barrel adjuster on the Avid shifter. Its very stiff and can only turn with pliers! I'll try adding more tension to see if that helps. If that doesn't help, I'll try new cables.

 

[JoeKF]

Any thoughts on the Kona mech problem anyone?

 

[Ming the Merciless]

Make and model number of the Alfine shifter?

 

[JoeKF]

Make and model number of the Alfine shifter?

Shimano make. Dont know the model number. 8spd variant I guess!

 

[C R]

Shimano make. Dont know the model number. 8spd variant I guess!

Alfine would be for hub gears, do they have the same pull as required by a derailleur system?

 

[JoeKF]

Alfine would be for hub gears, do they have the same pull as required by a derailleur system?

It reaches top to bottom, but skips every other gear as it goes. I got that one because there aren’t many on the market for 8spd anymore. I didn’t notice that it was only for hub gears!

 

[Big John]

You need to source at least a right hand shifter. The net isn't short of 8 speed shifters. Try Tredz.

 

[C R]

It reaches top to bottom, but skips every other gear as it goes. I got that one because there aren’t many on the market for 8spd anymore. I didn’t notice that it was only for hub gears!

Range is not necessarily the issue, from what you say it sounds like each click of the shifter moves the derailleur twice as far as it should.

According to Sheldon Brown, alfine 8 speed pull is about 5mm whereas a derailleur 8 speed shifter pulls about 2.8mm of cable per click, which would explain what you are seeing.

This page explains how it all works https://www.cyclinguk.org/cyclists-library/components/transmission-gears/derailleur-gears/shimergo

 

[JoeKF]

You need to source at least a right hand shifter. The net isn't short of 8 speed shifters. Try Tredz.

Thanks. Sounds like I’ve bought the wrong shifter!

 

[JoeKF]

Range is not necessarily the issue, from what you say it sounds like each click of the shifter moves the derailleur twice as far as it should.

According to Sheldon Brown, alfine 8 speed pull is about 5mm whereas a derailleur 8 speed shifter pulls about 2.8mm of cable per click, which would explain what you are seeing.

This page explains how it all works https://www.cyclinguk.org/cyclists-library/components/transmission-gears/derailleur-gears/shimergo

Thanks for all the detail. It sounds like I’ve bought the wrong shifter and will have to replace it!