Shifter only uses first 4 gears

Question

I've got a Shimano trigger shifter on an 8 speed derailleur. It only allows me to use 4 of my 8 gears. I can adjust the derailleur so that it is the top 4 or the bottom 4, but the shifter just won't click through the rest. It clicks 3 times and then acts like the rest of the gears don't exist.

I've tried adjusting the derailleur. Seems to work fine. I can even get the bike to shift by pulling the cable manually.

I've sprayed a ton of WD-40 into the shifter. That definitely improved the shifting speed and smoothness, but no affect on clicking through the rest of the gears.

Does anyone know what is happening or to fix it? When I opened up the shifter case, it does not look easy to mess with...

Thanks for the help.

Answer 1

If you pull the inner wire by hand while spinning the pedals, does the rear derailleur move the chain to all 8 cogs on the rear cassette? (suspend the bike in a workstand or hang from something with a rope to make this easier)

Does the shifter (the part on the handlebars) click through 8 different positions as you press the buttons? Can you feel it pulling the inner-wire a little on every click?

Sounds like the shifter unit is pogged up and some of the pawls inside are not latching into the teeth. You could try disassembling it, clean all the old lube out with a degreaser/petrol and then re-lube and reassemble. I've done this with brifters and it was hard work but fixed the problem.

If that doesn't work, you're probably up for a replacement 8 speed shifter... not too expensive new. Your local bike coop might be able to help too.

Fit a new inner cable while you have the chance - they're cheap.

Answer 2

Old post but might help someone. There are 2 sets of teeth inside the shifter, inside and outside. There are two latches, one is on a post and it is spring loaded. It pushes the first set of larger teeth from the end (they latch elsewhere) and the second smaller set it uses the spring to latch onto each tooth. If the latch doesn't turn you will only get the first set. Either the spring is broken or the latch post doesn't rotate. Pull the cover off and replace the spring if it is broken or spray with WD40 while you rotate the latch. Fixed one half an hour ago.

Answer 3

I will update this post as I had a broken SRAM x4 8 speed shifter for over a year and I decided I would find the problem and fix it. This may be the same issue with similar Shimano shifters. My shifter would only shift the 4 highest gears and then would do nothing. I disassembled it and compared piece by piece with a new shifter.

This was the damaged part:

You can see the top of the edge is worn out. As I have left and right shifters, and the insides are symmetrical, I just swapped these pieces and voila, both shifters work as new.

I disassembled a few more broken shifters and they all had this problem. As for how to disassemble the shifters, there are some good videos on YouTube that will explain you how to do it.

Hope this will help anyone out there!