Impossible to adjust Apex 1x
 

I have a gravel bike with a SRAM Apex 1x RD and a 11-42 SRAM Apex cassette that has never worked that well, but lately it's becoming exasperating: it refuses to upshift from the 4th to the 5th sprocket. If I adjust it so that it barely upshifts, then, when on the 2nd sprocket it will randomly fall down to the 3rd, and when on the smaller cogs, it will not downshift. Also, when on the smaller cogs, if I downshift more than one cog, it simply refuses to downshift all of them (if I click twice, it downshifts once. If I click 3, it downshifts 2). It's specially frustrating because the shifters being doubletap, it's impossible to "nudge it" to force it to shift, as that clicks for an upshift inevitably. Sometimes it shifts better than others for no apparent reason, sometimes it even (almost) works for a while.

Things that I have done:
- Checked the hanger alignment (that seemed like the most obvious thing) with a hanger alignment tool.
- Replaced all cables and outers TWICE. First time with Jagwire, second time with SRAM cables. I don't want to do it again since each time I have to replace 2 layers of bar tape and that's costly.
- Checked that the routing is good, with large radius curves, and that the cable moves smoothly (it does when pulling by hand).
- Checked that the shifter is releasing and pulling cable properly.
- Checked that the derailleur moves freely from side to side.
- Checked that the derailleur has no play anywhere.
- Checked for B screw proper adjustment (it improves if I move it closer than what SRAM recommends, but the downshift to the first cog is not ideal then).
- Replaced the chain. I'm using original SRAM 11sp chains.
- Replaced the BB cable guide just in case...

I'm about to trash the whole groupset, I have a Rival 1x11 in the road bike that is not as nice as the 12sp on my mountain bike, but at least it works. I've even had bikes with Shimano SIS and Microshift, and I never found I bike that shifted as bad as this one.

Any idea?

The first question that comes to my mind is - exactly what shifter and what derailleur are you using? Also, how many miles on your cassette?

I've never had any serious trouble with three NX 11 bikes that are essentially the same except for the shifter, and the cable clamp bits on the derailleur. My kid has an Eagle bike that I recently had to do a serious un-tweak to the hanger to get working right. Have you done the Park Tool procedure? Put it in top gear, smallest rear cog, by letting out all the cable with the small trigger on the shifter. Make sure it's lined up in top gear.. make sure the first shift actually shifts and you're not one click off... Make sure the first shift is lined up... then the next one... then the next one...

Intermittent problems often have intermittent causes. Something settling (like a cable endcap), or something coming loose (pinch bolt). I once had an overtightened bearing in my wheel that was making the thru axle unscrew, and when it came un-cinched, the indexing went out of whack.

i'd be checking the Derailleur hanger first. and then looking for a twisted or Worn Out/loose Derailleur... the SRAM products i've had similar issues with seem to be extremely loose in the pivot pins... i mostly see the MTB lines, but still.. Look for slop in the Derailleur. Shot pulleys/bushings have been found too.
a worn chain can also cause really annoying, changing shift hassles.... side-to-side, wet noodle wear, not length wear.
none of what you list as symptoms points to cabling...

and, there's a chance you've run into a mismatch between the shifter and derailleur... SRAM just loves re-inventing the wheel for no reason whatsoever.... :rolleyes:
what exact models of the der. and shifter are you fighting?

personally, i advise against using SRAM derailleurs and shifters.... others seem to stick by it even while they cuss at it.

Apex 1 was very similar to NX 11 speed but it had different cabling bits on the underside of the derailleur knuckle so it would match the SRAM road, not MTB cable pull. Right brifter, left is just a brake lever.

There's a newer 12 speed version (XPLR & Eagle) but dude hasn't replaced any of those pieces.

Another question because often the descriptions are confusing. Usually "upshift" means to a higher gear,iOW a smaller sprocket. But often people confuse rear "upshift" with going "up" to a larger sprocket, a lower gear. Which way on the cassette is causing problems?

They certainly like to make it seem that way but it's an act once you dig into the details.

I ditched double tap after just a few months of riding. I didn’t like much about it, from the super straight brake levers to the imprecise shifting. Mine was 11sp Rival and I haven’t missed it.

It should work though.

You’ve replaced the cable. That’s good. Are you sure you didn’t cause any kinks in the ends? When you rerouted the cable, did you get it properly through the little whoop de doom in the derailleur?

When you changed the chain, did you possibly route the chain outside the little tab on your pulley cage? I did that with Campagnolo and just about drove myself crazy.

Your der hanger is straight, how’s your chain line?

Is the shifter smooth and reliable with just finger tension? Before you connect it?

Is the shifting bad on the work stand or only while riding?

It seems like it should be fine with what you’ve done.

And in the future, don’t wrap the bars until the bike is shifting exactly how you want.

Some folks don't understand that you have to check hanger alignment all the way around, not just vertically.

Also, the cable has a very specific path through the rear derailleur. Check it.

Apex 1x11 mechanical shifters and Apex derailleur. Cassette has around 3000km. Chain is almost new.

The cable is ok. Alignment has been checked in all directions.

The rear derailleur is not worn. It doesn't have play, and neither does the cassette.

I would suggest unhooking the cable so it isn't pulling on the derailleur, and pull on it as if your hand is the derailleur while you run through the shifting. You should be able to feel the shifter taking up or releasing cable in even increments. If not, and you can feel the cable stuttering, that lays the blame somewhere between your hand and the shifter mechanism.

Also, lube the shifter mechanism. I like spray Triflow, but WD40 works fine.

There is a possibility that you have consistently screwed up how the cable housing runs into the shifter - I have seen that where people tape stuff down before actually running the cable all the way to the RD and adjusting it. A small gap between the housing and shifter body will screw everything up. Also with SRAM, I have seen people kink the cable when they feed it into the housing at the shifter and pull it down to a sharp bend, rather than run the housing onto the cable as it naturally exits.

Dunno what bike this is on. What is the cable routing? Examine every cable stop and guide for how the cable moves through it.

Some of those are probably duplications, but you either have a shifter problem, a cable problem, a derailleur problem or a set up problem. Isolate each and test.