Ultegra R8020 STI shifter sticking I have an Ultegra R8020 lever and I recently did a cable change. Everything worked fine for a few moments then on the first ride the left shifter wouldn't click up into the big ring. After a few attempts it crunched into place. After investigation I found that if you ever so slightly touch the paddle to shift down gear then the upper shifter will not work. This isn't the same on the right hand shifter which shifts fine.
I've taken the lever and hood off, degreased, greased and it works slightly better, but it feels like a mechanical issue instead of dirt or grit stuck in there.
Are there any tips on how I could rectify the problem? The shifter was in otherwise good condition before the cable change. It is nothing to do with the derailleur or cable, I can confirm its the shifter that is sticking.
Thanks for your help,
Brad
It’s possible the shifter mechanism has some material in it that is obstructing the proper operation, maybe a bit of wire from the cable, maybe dirt or grit. Unfortunately it may also be that something broke in the shifter.
You’ll have to systematically track down the issue. I’d start by removing the cable completely so you can check for damage to it.
Next, work the shifter without the cable installed just to check that the leavers are not jammed.
If the cable was not damaged re-thread it through the derailleur and out of the housing on the handle bar, or even the back of the shifter without going through the housing if you can manage it. Make sure the cable head is seated in the shifter properly. Put a little tension on the cable and work the shifter to check it’s operation. You may be able to get a better sense of what’s going on with it.