Mountain Bike Reviews Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Hi everyone, first post so please direct me somewhere else if this is in the wrong place or has been answered already...

I'm in the process of building a Soma B-Side 650B with a 1 x 10 drivetrain.

Zee 10 sp shifter
XT direct mount derailleur
XT 10 sp chain
XT 10 sp cassette with Kore 42T big ring.

I can't shift into the large cassette ring for some reason. It's puzzling because I can manually shift the derailleur into lowest gear by pushing the derailleur with my hand, and it seems to be happy enough. The low limit screw is unscrewed all the way so it is not interfering.

Pulling on the cable either by hand or by shifter will not produce enough movement in the derailleur to force it to shift up onto the large ring. I'm tensioning the derailleur cable as usual by shifting into the smallest ring, tightening the cable and securing the nut. All the other gears work fine.

First time trying to build this set up, so maybe there is a compatibility issue with the big ring that I'm not familiar with. I will try swapping out the 42T ring and seeing if I can get that setup to work tomorrow, which will show if it is the problem or not, but I really want to use it.

Any help greatly appreciated.
 

·
damned rocks...
Joined
·
2,624 Posts
What is the model number of your XT derailleur?

At one time, I had a similar setup, but my cassette was a Sunrace 11-42 and my derailleur was a XT M786 GS, to make it work I had to use a longer B-screw. Then I got a new derailleur, a XT M8000 SGS, and a new chain, and the setup works flawlessly.

The usual suspects are; your hanger is bent, or your cable and outer cables setup is old and need to be replaced.

Can't help you more than this.
 

·
Registered
Joined
·
3,782 Posts
Shift all the way down to the small cog and tension the cable by pulling on it by hand and click a couple more times. Now if you shift, does it go up one cog OK?
Usually when I do the initial tension of the cable, I'll shift a couple of cogs from the small cog and then tension the cable. This makes sure all the slack is out of the cable and the final adjustment can be done with the adjuster.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #5 ·
Rear derailleur is XT M781 Shadow long cage. I'm not familiar with the differences between that and an M8000.

Set up works fine if i reassemble the cassette as an 11-36 10 sp. everything is new except the housing so i checked that, replaced one questionable section and put low friction grease on the cable.

I reassembled the cassette with the 42T cog and put a spacer behind the back of the cassette to move it out 1mm or so and it works better but definitely struggles.

I had maxed out the B screw so I turned it upside down to get more space between the jockey wheel and large sprocket.

It feels like I need just a tiny bit more tension in the cable, but using the adjuster barrel on the shifter messes up the indexing. Still perplexed why I can push the derailleur in by hand to shift into the big cog but I can't pull it with the cable.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #6 ·
OK, finally figured it out. the M781 is not a dedicated direct mount derailleur, it has a B-Link which needs to be removed before it is mounted onto the hanger. which changes all the angles and makes my set-up work.
It's been a few years since I built a bike so I hadn't seen the direct mount up close, and it screwed right on to where i thought it should go and worked fine with the smaller cassette. Live and learn, thanks for your help.
 
1 - 6 of 6 Posts
Top