Take Apart 105 Shifter?

quarkrad

I'm having indexing problems on my rear derailleur - I normally do not have any problems. I have a 105 5800 groupset and can index either 2 - 11 or 1 - 10 but not the full range 1 - 11. Having spend some time at the rear of the bike I have now found out my problem is with the shifter. Comparing to another bike with the same groupset I have discovered the following: Good bike: with cable disconnected I have 10 clicks up and 10 clicks down. With the problem bike I have 9 clicks up and 9 clicks down. Why this has suddenly happened is a mystery as the groupset has been working very well for a couple of years since I first installed it. (I renewed the cables in Jan and adjusted them for stretch since). I'm thinking I'll have to take the lever apart to see why, or rather where, the missing click is. Any advice on what to try before I start or how to take apart would be appreciated. (I'm testing by pulling down the cable with one hand (external cable on down tube) and clicking the shifter. I am making sure the shifter is fully released via the short lever).

veronese68

Have you ever had a cable break? Could be a bit stuck in the shifter.

arlowood

quarkrad wrote:

I'm having indexing problems on my rear derailleur - I normally do not have any problems. I have a 105 5800 groupset and can index either 2 - 11 or 1 - 10 but not the full range 1 - 11. Having spend some time at the rear of the bike I have now found out my problem is with the shifter. Comparing to another bike with the same groupset I have discovered the following: Good bike: with cable disconnected I have 10 clicks up and 10 clicks down. With the problem bike I have 9 clicks up and 9 clicks down. Why this has suddenly happened is a mystery as the groupset has been working very well for a couple of years since I first installed it. (I renewed the cables in Jan and adjusted them for stretch since). I'm thinking I'll have to take the lever apart to see why, or rather where, the missing click is. Any advice on what to try before I start or how to take apart would be appreciated. (I'm testing by pulling down the cable with one hand (external cable on down tube) and clicking the shifter. I am making sure the shifter is fully released via the short lever).

A couple of suggestions although you may have already done this.

Firstly when you flicked the inside paddle to release all the cable tension and get the shifter into it's "start" position ie in the highest gear (smallest cog) position, did you have the cable still attached to the rear derailleur or not. If it was still attached I would go back, release the cable at the pinch bolt and try again to get it to the start position by flicking the inside paddle. If at that point you are still only getting 9 clicks instead of 10 then there must be something internally fouling the ratchet mechanism.

To inspect the mechanism you don't need to fully dismantle the shifter. Have a look at this video which shows how to remove one of the cover plates at the bottom of the shifter.

https://www.youtube.com/watch?v=Znc6pZXN_O0

With that removed you can then inspect the ratchet mechanism to see if there may be some debris which is preventing the shifter from fully releasing

DeVlaeminck

Shimano shifters used to be notoriously difficult to take apart and reassemble, my attempt with a 9 speed dura ace years ago ended in failure whereas I've fixed a couple of Campag shifters where small springs needed replacement following youtube videos.

I don't know about more recent Shimano stuff but I'd make taking it apart the last resort.

proto

Same for me as @DeVlaeminck, I’m pretty handy with the spanner’s and will tackle just about anything on a bike. New hub and freehub bearings, Campag shifter rebuilds, straighten wheels, etc., however, I once took an Ultegra shifter apart, to my regret. Couldn’t fix it, couldn’t get it back together. Binned it.

StillGoing

It's simple. Remove the screw underneath and two sections of the ABS will come away giving you a view of the mechanism. If you see something jammed in there but can't free it, knock the drift pin out to be able to get access.

keef66

Before you do anything drastic, check the cable isn't fraying inside the shifter. I know it was new in January, but I'd still check.

Then remove the cable from the shifter and see how many clicks you get each way. As above, also make sure there's nothing stuck in there from an earlier event.

I did once consider taking apart a failed 5603 lever, but the exploded diagram put me off trying. I picked up a used one off Ebay instead. Now I have one silver and one black lever.

One day, possibly when I retire, I'll see if I can transplant the silver lever from the broken STI onto the working one. I'll need to get my new glasses before then...

ham76

I bet these 2 pdf can help you sort out the issue.....

https://si.shimano.com/pdfs/dm/DM-ST0002-05-ENG.pdf

https://si.shimano.com/pdfs/dm/DM-RD0003-09-ENG.pdf

quarkrad

Thank you all. All fixed now - yes, it was the cable fraying in the shifter. How this happened is a mystery as a new one was installed at the beginning of the year. Just goes to show, even though a new cable is installed it a still trip you up if not checked. Once again, thank you.

keef66

I only suggested it because my 5600 shifters eat cables fairly predictably, and it all sounded so familar