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Hi, recently I've got myself a Shimano R8000 groupset, but I've got some issue with the front shifting. Sometimes the left shifter is jammed when I tried to change from the small ring to big ring, but most of the time it's doing fine. Later I noticed the reason is that I touched the small lever together when I shift into the large ring, which causes it to jam. But I haven't got any issue with my Sora R3000 & 105 5800 shifters. Is that normal or something is wrong with my shifter?

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SpikeBike [132 posts] 7 months ago
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I know it's a new groupset but no chance its a cable issue? Last time I got a jam on my 105 shifters was about 5mins before my cable snapped inside the shifter. It has frayed and got stuck.

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Philphluter [2 posts] 3 weeks ago
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I have just this problem and suspect it is a front mech limit screw or tension problem.

I have a couple of ideas to troubleshoot and will update if I find the solution.

A big part of the problem is the incredibly poor Shimano R800 adjustment instructions in the installers handbook.

Shimano really needs to employ a good technical writer to make the instructions, and particularly the diagrams intelligible.

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Philphluter [2 posts] 3 weeks ago
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Well I have spent another hour experimenting with the Ultegra R8000 front derailleur.  I have now achieved acceptable operation of the sti lever.

It turns out my 'tension' (a misleading description of cable pull - cable pull is a 'distance' rather than a 'force') was too high or too long a pull.

It seems that Shimano are wanting us to set up the 'tension' as high as possible without causing malfunction.

Originally I set up to Shimano instructions which is to increase 'tension' with the front mech ''barrel' (another misnomer as it is a 2mm caphead screw) or the cable adjuster fitted to the cable run - until with the mech in the "top trim" position the two white lines on the mech line up.  It turns out that on my bike (Felt FR3) this results in jamming and the correct adjustment to get acceptable operation is to set the lines 1mm shy of being in line.

I believe that this setting then allows the mech to reach its fully inward position whereas having the lines line-up cause so much tension/movement they don't allow this.  For some reason the premature stopping of the mech before moving fully inboard causes the lever to jam.

The operation of the lever is now acceptable with a slight catch before it moves the front derailleur onto the big ring rather than locking-up solid.  I wonder if this catch (detent) is designed so that once the mech overcomes the detent it moves rapidly giving a quicker shift?  I have heard that Shimano have said similar things in the past in regard to the 6800 Ultegra (which is a different design entirely).

 

 

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SpikeBike [132 posts] 3 weeks ago
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That line matching up will be directly effected by what tension you put on the cable when you clamp it down. If you follow the instructions to the letter it should match up well. Saying at I am only going off my 105 version.