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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

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  • Welcome, I suggest to take the tour. It is not necessary to write "my first post", we can all see that. Similar with greetings. Similar thing happened to me mid-ride, but with a much cheaper shifter. It was harder and harder to shift up and suddenly impossible. Somehow I managed to get it moving again by trying repeatedly on the roadside, so that might have been some debris. – Vladimir F Oct 27 '20 at 9:29
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    Consider checking your inner cable for damage - could be one single strand is broken and catching somewhere. – Criggie♦ Oct 27 '20 at 9:39
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    I had this issue on a Shimano 105 5700 Brifter when I had excessive cable friction (and not enough cable tension) and not enough pulling force from the derailleur spring arrived at the Brifter. Are you sure you’ve installed the cable correctly and everything is seated properly? In my case the cable itself kind of got stuck inside the Brifter because it was not properly pulled around the ratcheting mechanism. – Michael Oct 27 '20 at 10:55
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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.

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I would suggest a very simple solution. New cables have a breaking in period, they stretch out a little bit. But the amount could be so small that you only feel it in one gear, and the top gear would be the most likely.

Ok, Ok...do the cables really stretch? it is really more the housing settling in, getting compressed a little bit, and the ferrules getting pulled on a little bit tighter.

I would simply shift into the smallest cog and repeat the process of adjusting your cable tension. There are a handful of other things it could be, but trying to diagnose them before checking the cable tension is moot.

Bike repair and maintenance is sometimes a guessing game. When that is the case, it is best practice to start your troubleshooting with the simplest solution and work your way up from there.

Good luck.

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