Drivetrain help

RustyMTB

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
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

E*POWAH Elite World Champion
Subscriber
Feb 14, 2019
829
1,031
Brazil
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

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
Far as I can tell it is?

_ryFy-Lr.jpg
 

RustyMTB

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
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

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
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.

x-1HsNiq.jpg
cGI34Hsl.jpg
 

Meepmeep

Member
Oct 3, 2020
10
5
Scotland
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

E*POWAH Elite World Champion
Subscriber
May 2, 2022
1,943
1,874
Chichester, W.Sussex, UK
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.

Screenshot_20230306_170007_Xodo Docs~2.jpg
 
Last edited:

RustyMTB

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
Good shout - the cassette is definitely correctly assembled.
 

irie

E*POWAH Elite World Champion
Subscriber
May 2, 2022
1,943
1,874
Chichester, W.Sussex, UK
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.
 
Last edited:

RustyMTB

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
Which would imply I have the chain on backarsewards? Hmm that could explain a few things.
 

Snrbrtsn

Active member
Apr 7, 2021
204
158
Uk - Scotland
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
A2C53F7A-7957-4445-913A-6B8F33BF89BB.png
 
Last edited:

RustyMTB

E*POWAH Elite World Champion
Jul 22, 2020
2,494
6,103
UK
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

E*POWAH Elite World Champion
Subscriber
Feb 14, 2019
829
1,031
Brazil
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.
 

discdigger

New Member
Dec 29, 2022
10
5
Worcester MA
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

Active member
Apr 7, 2021
204
158
Uk - Scotland
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

E*POWAH Elite World Champion
Subscriber
May 2, 2022
1,943
1,874
Chichester, W.Sussex, UK
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

Wedding Crasher
Nov 5, 2018
8,362
8,589
Lincolnshire, UK
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).
 

RustyIron

E*POWAH Elite World Champion
Jun 5, 2021
1,477
2,347
La Habra, California
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.
 

EMTB Forums

Since 2018

The World's largest electric mountain bike community.

518K
Messages
25,448
Members
Join Our Community

Latest articles


Top