Shifter jumps up a lot of gears

[smilejos]

My bike has a Shimano SIS Index shifter.
Has a lever to go down gears and a "+" button to go up a gear.
When I push the "+" instead of going up only one gear, it jumps up as far as the cross tension in the chain lets it - normally 3 gears. It is as if the ratchet in the shifter just lets go.

[Drew g225]

(02-18-2011, 05:25 AM)smilejos Wrote:  My bike has a Shimano SIS Index shifter.
Has a lever to go down gears and a "+" button to go up a gear.
When I push the "+" instead of going up only one gear, it jumps up as far as the cross tension in the chain lets it - normally 3 gears. It is as if the ratchet in the shifter just lets go.

Hi i had the same problem check the cable , 1 if the cable to see if it's kinked .2 check the derailer adjustment if you have the derailer adjustment set wrong then that means you need to reset the screws on the derailer there's a stopper screw. there's a video on here that can help you with setting the derailer good luck.

[smilejos]

(02-25-2011, 11:45 PM)Drew g225 Wrote:  

(02-18-2011, 05:25 AM)smilejos Wrote:  My bike has a Shimano SIS Index shifter.
Has a lever to go down gears and a "+" button to go up a gear.
When I push the "+" instead of going up only one gear, it jumps up as far as the cross tension in the chain lets it - normally 3 gears. It is as if the ratchet in the shifter just lets go.

Hi i had the same problem check the cable , 1 if the cable to see if it's kinked .2 check the derailer adjustment if you have the derailer adjustment set wrong then that means you need to reset the screws on the derailer there's a stopper screw. there's a video on here that can help you with setting the derailer good luck.

I have watched the videos and adjusted the deraileur. (improved the shifting as that was overdue.) There are no kinks in the cable, but still jumping up three gears - it think it must be the shifter. I hope it just needs a clean, but not looking forward to opening it up and risk losing parts.

[cyclerUK]

Some shifters do allow more than one gear to be shifted at a time.
My Lx right shifter does this.
Obviously depends how hard you press the trigger
Perhaps as you say it needs a clean/lubrication.
On some shifters you can remove a cover and see the internals which may help.
I would undo the cable from the derailleur and, using one hand to pull the cable, operate the shifter with the other to see if it moves normally.