I’ve never had a problem sorting skipping gears in all my years….until now.

It’s usually just a process of elimination via the most obvious signs of wear or damage.

It’s not rocket surgery usually.
Or maybe it’s harder?

However, the gears on my eeb are doing me nut in. Spent a few hours trying to sort it yesterday, largely due to infernal cable routing I might add which makes everything more faff.

Anyway, this is how my set up is. Maybe someone can think of something I’ve not tried.

*Brand new 12s Sunrace cassette
*Brand new Sram 12s chain
*Brand new inner and outer cable lubed and routed same as original through frame, behind battery. (Battery not fitted whilst checking gears so no pinching)
*Rear mech brand new or original xt 12s same symptoms

What I’m getting is gears skipping up and down with the bike upside down, so no load.

Changing off the biggest cog it’ll often jump two at a time. Going back to bigger up the cassette seems better.
Just doing chilled pedal rotations it’ll skip up and back in random cogs.

What I’ve tried –
*Blown out shifter and re-lubed.
*Changed gear outer once, and inner twice and checked it’s running smooth as.
*Tried a brand new mech instead of original xt that came on the bike, and same symptoms.
*Used a gear hanger alignment tool and checked and adjusted the hanger.
*Visual inspection for alignment. Seems fine.
*Checked all cable ends are well seated.

Can anyone think what else to try?
I’m beginning to think I’m being punished for something I’ve done in a previous life. 😐

b screw tension on the rear mech?

Setting up 12 speed is definitely more faff than 10. I was pretty successful at it after I’d watched an instructional YouTube video. Roughly, the process went, (IIRC)

Check hangar alignment.

Set high gear limit.

Adjust indexing

Set low gear limit screw

Set B screw gap.

Worth triple checking that the cable routing onto the mech is fed the correct way through the pinch bolt. Ask me how i know that double checking isn’t enough and it needs triple checking…..🙄

Next thing I’d check would be the rear hub, I’ve had dodgy shifting as a symptom of a snapped axle in a Hope hub before now.  NB: On XT mechs there may be a B screw setting guide on the top jockey wheel – a little line marked 51T to align with the cassette.

Cheers.
Yes B-screw adjustment has been liberally fiddled with too.

If the cassette has individual cogs, are the spacers and orientation of the cogs themselves correct?

Had an issue last year with a rear mech that had a slight twist in the cage.
Kept thinking it was a hanger/B screw thing and spent ages faffing around.

Check for lateral play in the hub and cassette. Failing that, run a cable straight from the shifter to the mech outside the frame as a test to rule out cable routing as an issue.

Can you post a close up video of it randomly shifting on its own?

If the cassette has individual cogs, are the spacers and orientation of the cogs themselves correct?

It’s one lump then I think the last three or so are individual.
I’m always careful doing this but I thought that the splines made it impossible to fit them the wrong way round?

Had an issue last year with a rear mech that had a slight twist in the cage.
Kept thinking it was a hanger/B screw thing and spent ages faffing around.

Yes, as I say I tried it with my spare brand new mech too. Same symptoms.

Check for lateral play in the hub and cassette. Failing that, run a cable straight from the shifter to the mech outside the frame as a test to rule out cable routing as an issue.

Roger that.
I was going to try a cable from shifter to mech outside the bike but didn’t have any spare (got rid of old outer already)and didn’t want to take the existing outer, out of the bike as I need to use it to rout a replacement….which I don’t have yet.

I agree though that this is the most likely culprit so I will do that test.

You can tell if it’s cable friction because if you shift up then down again you get a loose feeling at the shifter and you can see the mech not move, because the slack hasn’t pulled through.

What kind of skipping is it? Is it the chain being picked up by the next sprocket, or is it actually slipping over the teeth?

I’m afraid you need a new frame. When I built a new bike up with all brand new 12spd components I could never stop the little annoying click and skip in 1-3, then I bought a new frame and put all the same components on and boom, smooth and silent operation.

Enjoy your new bike

Worth triple checking that the cable routing onto the mech is fed the correct way through the pinch bolt

This is often mentioned. I can’t for the life of me see how you’d do it with a rear mech. Some old front mechs it wasn’t obvious, but on my M8000 and M6100 rear mechs there’s only one logical way to feed the cable in and secure it. Anyone got a picture of it done the ‘wrong’ way?

Aside form all the great advice up there. You mentioned gears skipping when upside down?
They never work properly upside down.
Use a stand or jerry rig it the right way up.

I’m afraid you need a new frame….Enjoy your new bike

😂

What kind of skipping is it? Is it the chain being picked up by the next sprocket, or is it actually slipping over the teeth?

Yes it’s not slipping over the teeth, it’s like it can’t settle on one cog.
I’ll start dropping down off the big ring and it’ll jump maybe to the third largest, then as I keep going it’ll tend to ride up, down, up, like it doesn’t want to settle on one gear.

I think it has all the hallmarks of sticky cables but yeah, all brand new and tested for friction before clamping onto the mech nut.

Aside form all the great advice up there. You mentioned gears skipping when upside down?
They never work properly upside down.

Never had an issue before like this on every bike I’ve ever had, but I’ll try it right ways up.
It’s just a total pita to be honest with it being an eeb with internal routing where I’ve had to let loose all the connections etc.

Never had an issue before like this on every bike I’ve ever had

I can’t find it but I swear I read a shimano or sram doc that mentioned this..

I can’t see how it would be, but could it be that the chain is incompatible?

Your description of it riding up & down the cogs sounds odd & not really something I’d associate with a sticky cable run. It sounds more like the chain isn’t meshing with the cassette teeth correctly. Can you try the old chain?

Never had an issue before like this on every bike I’ve ever had, but I’ll try it right ways up.

Was just going to post along the lines of i had similar problems when setting up an 11 speed system on my eeb.
Turned it the right way up and a little cable tweek and it was running sweet.
No idea why but it didn’t like it one bit being upside down.

this is EXACTLY how i found 12speed to be all the time with a variety of mechs. The SRAM ones never worked from new and i was sooo happy when i smashed them to pieces. the Shimano mech actually worked at shifting gears but still was not great. i even bought a hanger alignment tool and everything!

I`ve now bought a Microshift 10sp setup for the same price as teh 12sp cassette! sooo much nicer and i feel i can pedal into a jump without risking the old favourite – stem/nadgers interface to lip faceplant.

i did read somewhere that you need to use only sram quicklinks with a sram chain (and shimano with shimano etc) so if you have mixed and matched this may be the culprit.

Was the b tension set under SAG? I’m sure with SRAM mechs you need do it sagged. Have you a hanger alignment tool to check the mech hanger is straight? even new ones can be bent.

I had a similar frustrating issue, spent hours trying to figure it out. Gave up, and went to LBS, took him all of 20 seconds to straighten a tooth on the chainring. Worth checking all those teeth are straight.

Was the b tension set under SAG? I’m sure with SRAM mechs you need do it sagged. Have you a hanger alignment tool to check the mech hanger is straight? even new ones can be bent.

Not Got as far as sag. It’s upside down and not working. Shimano mech.

Yes, checked hanger alignment and seems good.
Got a new one on order anyway just in case.

Worth checking all those teeth are straight.

True dat. I’ll get on it.

Can I ask, what bike/frame is this?

Orbea Wild fs

oceanskipper

Worth triple checking that the cable routing onto the mech is fed the correct way through the pinch bolt. Ask me how i know that double checking isn’t enough and it needs triple checking…..🙄

Well, full disclosure. I’m not too proud to admit that sometimes I’m an idiot and I’m laying my idiocy bare for all to see here just in case it should help someone equally distracted in the future! 😂🙄😂
I can honestly say I’ve never had this issue in all my biking years so I’m stoked to break new ground…

Top marks go to Oceanskipper who correctly advised that I check the cable routing into the mech.

It turns out that I had NOT got it the right way.
I’ve fixed it the other way now and everything is working perfectly…

Here are the two variations.

Firstly, this is the wrong way and it’s the way that I had it.
In my defence, the bike was upside down and to me, it actually seems like the more obvious routing as it’s straighter from the cable stop to entry.

And this is the correct way, which has cured the skipping.
You see, to me, it doesn’t immediately look like the natural route but there you go…
Looking closer at it, you can actually see a tiny little curved lead-in channel. I expect this might be in the documentation that comes with it that nobody in history has ever read…

So thanks to everyone who tried to help but the biggest shout going out to @oceanskipper who gets 12 points, one for each speed I now have, and a lovely warm feeling! 😂
I owe you a cup of tea. 👊

Most of all though, to me, I give a 🙄

Result ! Top marks for sharing your success !

Holy 12speed Batman! First time I’ve ever got the correct diagnosis for a fault on here!

Nice one OP. I did exactly the same as you. The most natural looking way is actually incorrect.

Pleased you have it sorted and pleased that I was able to help. 👍😎

Pleased you have it sorted and pleased that I was able to help. 👍😎

Yeah man. Cheers for your thoughts. It certainly had me confused for a while.
Sooo frustrating when something seemingly so simple just will not work 😊

Been there!

No shame in it

Well, maybe a bit eh…. 😂

The most natural looking way is actually incorrect.

Nae shame there kayak.
That cable line is so crap,no wonder you rigged it up wrong,I would have done the exact same.

Nice one OP. I did exactly the same as you. The most natural looking way is actually incorrect.

Absolutely weird and counter intuitive…do you think they designed it to be used the other way and realised it didn’t work ?

Yeah man. Cheers for your thoughts.

No worries mate. Happy shifting. 😁

Wow! Great detective work.
The way the cable exits the stop looks like a fairly crappy angle, and I notice the you are mid-way through the cassette. I’m guessing when you’re at right at the biggest gear it exits at a terrible angle?
Q What’s going to wear out first, the cable or the stop?

Here is the illustration in the Shimano xt manual.
It looks nice and straight in their illustration. Not so much like my reality but…meh, it works.

Literally nobody reads them though…

Try doing it with the bike the right side up, SRAM or get a southern hemisphere spec chain, such as those found in antipodean bike shops

😂

RTFM – every flippin time.

Oh look the manufacturer tells you axactly how to do it

RTFM – every flippin time.

Do you read the manual of things you’ve done lots of times before for years with no issues?
No, thought not. 😉

Easy to say RTFM now, but where were you earlier bro? 😂

No shame in this, I did exactly the same when setting up my girlfriends newest bike! Amazing how much better it shifts when it’s routed properly…