Drivetrain help

[RustyMTB]

Little help? Just swapped out all my old drivetrain. Now I'm running a 12spd SLX cassette, XT Deore derailleur, Deore 12spd chain & Raceface 34t chainring. Everything is brand new except the derailleur, like three rides old.

The chain is skipping in top gear and only top gear Even moderate pressure through the cranks will see it do this. Why?

 

[B1rdie]

Are you using quick link? check that its fully seated. I first changed the chain on the 12s cube last week, and it was very difficult to make the link get correctly placed.

 

[RustyMTB]

Far as I can tell it is?

 

[RustyMTB]

Obvs it's hard to say exactly where it's slipping when I'm riding it but it feels like on the chainring which doesn't necessarily make it so. I did adjust the B screw when I changed everything over but will put it in the stand & take a pic soon. I also sized the chain to match the original, taking stretch into account, so I'm sceptical that the chain is over long but will provide pictures for the jury.

 

[RustyMTB]

You think the derailleur looks bent? It's crossed my mind but I've also read Shimano stuff doesn't sit perpendicular. I certainly don't remember bashing it & there are no marks on it.

 

[Meepmeep]

Quick link looks in the wrong orientation, theres an arrow on it that should point the way the chain moves when pedaled
cant see the arrow on the pic

 

[irie]

Do you have a pic side on of the deraillier in top gear ?

Is the pulley touching ? Or too far away and not getting sufficient wrap (new chain so may need adjusting ?)

Or something else is weirdly out of alignment. Is it defo the chain skipping on the teeth and not the 11t spinning on the hub ?

It is indeed very easy to misalign the sprockets on Shimano 12 speed cassettes and that would be what I'd first examine. Remove the wheel and have a close look at the cassette, particularly the spacing of the individual smaller sprockets and the spacers.

Edit: the Quicklink also looks the wrong way around.

 

[RustyMTB]

Good shout - the cassette is definitely correctly assembled.

 

[irie]

Good shout - the cassette is definitely correctly assembled.

My edit says "the Quicklink also looks the wrong way around". Both sides of the Shimano Quicklinks I use have arrows on them, but the side you see must face chain direction.

 

[RustyMTB]

Which would imply I have the chain on backarsewards? Hmm that could explain a few things.

 

[Zimmerframe]

Which would imply I have the chain on backarsewards? Hmm that could explain a few things.

I doubt your that daft. I think the chain's correct, you've just got the bike the wrong way round.

 

[RustyMTB]

So, if I turn the bike around the other way, then only ride fakey, I'm all good again?

 

[Zimmerframe]

So, if I turn the bike around the other way, then only ride fakey, I'm all good again?

If you pedal backwards and there's no chainslip - you've proved it ....

 

[irie]

Quick link looks in the wrong orientation, theres an arrow on it that should point the way the chain moves when pedaled
cant see the arrow on the pic

The pic is very blurry but the arrow may be pointing to the right which is the wrong way.

 

[Zimmerframe]

The pic is very blurry but the arrow may be pointing to the right which is the wrong way.

Hey, you can put a man down about his mechanical incompetence, but never diss his photographic abilities ! :-D

 

[B1rdie]

Far as I can tell it is?

View attachment 108465

Yep, properly seated, just facing the wrong way

 

[Snrbrtsn]

Something doesn’t look correct here
rear mech wrap appears wrong and chain appears too long

Hard to see, what with the high resolution picture, is the jockey wheels in correct position,
Both are directional also

 

[irie]

@RustyMTB

1. Please count the number of links in the chain you took off.

2. Also, put the bike in the lowest gear and take another pic.

 

[RustyMTB]

Something doesn’t look correct here
rear mech wrap appears wrong and chain appears too long

Hare to see, what with the high resolution picture, is the jockey wheels in correct position,
Both are directional also
View attachment 108483

Nah, the mech is all good. Sorted now, swapped the chain around the right way & off we go.

 

[B1rdie]

He’s just changed the whole drivetrain from 11 to 12 speed I guess, so properly sizing (cutting) the chain would be the way to go.

 

[irie]

He’s just changed the whole drivetrain from 11 to 12 speed I guess, so properly sizing (cutting) the chain would be the way to go.

If it's 116 links and hasn't been shortened it's gonna be f*****g long!!!

 

[RustyMTB]

It was sized correctly when it went on. the chain length is a nothing burger boys.

 

[irie]

Nah, the mech is all good. Sorted now, swapped the chain around the right way & off we go.

The Quick link was also on backwards so at least that's consistent.

 

[discdigger]

Little help? Just swapped out all my old drivetrain. Now I'm running a 12spd SLX cassette, XT Deore derailleur, Deore 12spd chain & Raceface 34t chainring. Everything is brand new except the derailleur, like three rides old.

The chain is skipping in top gear and only top gear Even moderate pressure through the cranks will see it do this. Why?

Did you check the limit screw adjustment ?

 

[Snrbrtsn]

If it’s any consolation.
I just replaced my chain, thinking, knowing I was pushing the limits on the chain wear, having cleaned the cassette jockey wheels and chain ring, happy as pig in 5hite, I set off!
Horrid Shifting, gear skipping so curtailed my ride.

On return home, the axle nut that keeps the freehub on had backed off….
Non drive side has a push cap, Drive side is threaded.
Initially pretty pissed on the premise my rear wheel is removed often and I’m normally meticulous!

Nevertheless, I striped the wheel, replaced the Rotor & Cassette, (recent Magura MT7 upgrade with Xt rotors didn’t cut It & cassette as I was pushing the chain wear) adjusted the cable tension at the shifter and set off!

Today has to have been one of the best rides, bike felt so crisp & fresh!

So maybe worth checking axle nut - though sounds as if your issue is behind you!
Im of the thinking the Slx chains only last 7-800kms & I get 3 chains to a cassette with frequent cleaning and lube!

 

[irie]

Typically about 3 chains to a cassette as long as the chain is replaced when wear hits 0.5. Put simply, if a chain gets more worn than 0.5 it increasingly rapidly wears the cassette. As also does riding at lower cadence and higher gears (smaller cassette sprockets).

 

[steve_sordy]

It's always hard to tell with pics, but the mech arm seems to be deviating away from the bike. It is an easy bend to happen and well worth checking with a mech hanger alignment gauge. The gauge is not cheap but is worth every penny for anyone with 11 or 12-speed. The use of it is low tech and anyone can do it. It is a ten-minute job to set up, check, adjust and refasten the mech to the hanger.

Often, the mech hanger is fine but the lower mech arm is bent. That takes a bit more technique to straighten. If you suspect the mech arm, try that first and then the hanger (because you might bend the hanger while trying to straighten the mech arm).

 

[RustyMTB]

Bike's tip top & has been for a week Steve.

 

[RustyIron]

You think the derailleur looks bent? It's crossed my mind but I've also read Shimano stuff doesn't sit perpendicular. I certainly don't remember bashing it & there are no marks on it.

Always start with the things that are definitely wrong. Fix them one at a time, from biggest to smallest.

From your picture in Post #6, it looks as if either the chain is too long or the B Screw is maladjusted. Fix this first, and then go from there.

 

[RustyMTB]

Post #29 dude.