Finicky Shimano 12 speed question

O

Oey12

Active Member
I have a year old 12 speed SLX rear derailleur with 12 speed SLX shifter that constantly needs adjusting. It works nicely for about 3-5 rides then starts miss shifting. Requiring double clicks to shift gears and it skips until it’s fully in gear.

I recently waxed my chain and upgraded the cassette and chain to XT which got rid of this odd clicking sensation I had with the KMC chain. The drivetrain operates very smooth when it’s in gear. I am about to take the bike in for another adjustment which is getting pricey (because I have to do it so often).

My Shimano Deore drivetrain is much less finicky on my 2nd bike. Is this common for the SLX line? What am I missing here?
 
I have had the hanger straightened before. Everything seems to look good on the chain and cassette m. I did look it over before installing. Does it get to a point where the hanger can’t get realigned?
 
Sorry I don’t mean to ask such basic questions but I am trying remedy this…very frustrating but at least it’s getting better.
 
One question how did you figure out chain length? I watched a you tube video to cut chain length on the micro spline 12 speed. You wrap chain around front ring and around the 51 cog and 4 to 5 links past cut the chain works perfect. Just giving another thing to look at.......
 
Did you check the bolt that secures the cable to the derailleur? That will slip if it isn’t tightened enough.
Sometimes the coating on the cable needs to be stripped off there.
 
Oey12 said:
It works nicely for about 3-5 rides then starts miss shifting. Requiring double clicks to shift gears and it skips until it’s fully in gear.
Click to expand...
Is it requiring double shifts to go down to a lower (easier) gear? If so it might a cable tension issue, too much slack in the cable. If that's the case try backing out the barrel adjuster a few turns to remove cable slack.

Also, like mwlikesbikes said the cable could be slipping, which would also make it lose tension.
 
sundaydoug said:
Is it requiring double shifts to go down to a lower (easier) gear? If so it might a cable tension issue, too much slack in the cable. If that's the case try backing out the barrel adjuster a few turns to remove cable slack.

Also, like mwlikesbikes said the cable could be slipping, which would also make it lose tension.
Click to expand...
On my 10 or 11 speed I will use a KMC chain but I prefer a shimano chain on my 12 speed.
 
sundaydoug said:
Is it requiring double shifts to go down to a lower (easier) gear? If so it might a cable tension issue, too much slack in the cable. If that's the case try backing out the barrel adjuster a few turns to remove cable slack.

Also, like mwlikesbikes said the cable could be slipping, which would also make it lose tension.
Click to expand...
Upshifting to a higher gear…
 
Oey12 said:
Upshifting to a higher gear…
Click to expand...
Hmmm, if that's the case it's possible there's not enough slack in the cable but I doubt it. If it's not a cable tension issue I'd check to make sure the derailleur is snugged to the hanger. If it's loose even a little bit it might wiggle around under load and cause shifting weirdness. Happens to me about once per season, just gotta snug it up.
 
Another issue that a lot of people miss is the fact that the smaller cogs have spacers that have to go in a particular order because Shimano thought it was wise to make some of the smaller cogs offset.

Go to 1:40 mark of video. Hopefully this should help.

 
Last edited:
sundaydoug said:
I'd check to make sure the derailleur is snugged to the hanger. If it's loose even a little bit it might wiggle around under load and cause shifting weirdness. Happens to me about once per season, just gotta snug it up.
Click to expand...
This for sure. Happens to me and affects my 12 sp. also check to make sure the cage itself isn’t bent. I was having an issue where in all but the larger cogs everything was fine but once I got to the larger cogs it wanted to shift up into the next larger cog. After maddeningly trying to adjust cable tension, derailleur stops and B screw to no avail, and seeing that the hanger wasn’t bent, I gave the cage itself a tug outward and viola, issue solved.
 
You must log in or register to reply here.
Back
Top Bottom