I’m really starting to loose my rag with this.

Shifts up cassette fine, but then unpredictable going down the cassette.
Or (after I adjust the cable tension screw on rear mech)
Shifts down cassette fine, but then unpredictable going up the cassette.

Drivetrain: Force 1, 1×11.
Frame: On One Bish Bash Bosh
Wheels: Hunt 4 Season Disc.

I have swapped the rear wheel and cassette , no difference.
Whatever I do I cant get it shifting perfectly in both directions.

Any ideas? I really need some help! Technically and mentally as I’m getting a touch angry with this. 😈

I assume the only adjustment to help this is cable tension, as the limit screws play no part in shifting up/down the cassette.
Do I need to add a spacer to the rear cassette maybe? Are all frame/hub spacing the same?

B screw? My rear mech was doing something like that, and was perfect after twiddling that (shimano M8000).

Checked spacing between granny and jockey wheel?

B screw is something that has a correct setting (1.5 plates between exit from big cog to pulley is normal).

Assuming this is set and limits are correct , then indexing should be normal, i.e. Wind barrel full in then back out three turns, install cable, install correctly sized chain, and testing should find it within a couple of clicks of cable tension adjustment at worst. I haven’t changed anything about how I set up a SRAM 1×11 drivetrain over a standard x10.

Since you’re using drops and STI’s, have you checked the outer routing under the tape? If cable tension was set correctly then a binding cable on release would be my first port of call.

Usually a sticky cable or bent mech hanger when it does that.

B screw yes.. I have wondered and tinkered with it a bit. But maybe not enough.
Any advice as to how far in/out it should be?
The top jocky wheels is about 2cm below the cassette, in both 1 and 11.

Since you’re using drops and STI’s, have you checked the outer routing under the tape?

Interesting, what would I be looking for here?

I had this problem with Rival22 that I’d switched to 11*1. Symptoms were like a sticky cable, despite all being new. The route out of the shifter was causing it. Their are two possible routes so I went with the route that caused the least bend out of the shifter, and was careful to minimise bends under the tape. And tinkered with the b-screw, but I am not too sure what I ended up doing, maybe it was dialling it out more than I might normally do

most likely cable friction somewhere along the line – the cause of most indexing problems so check to see if the cable runs smoothly. You can also look at adjusting the screw that sets how far the upper jockey wheel is from the cassette sprocket – you basically want it close without actually touching.

I now remember, importantly, I also removed a cable-end ferule from where the cable exits the shifter. The ferule was causing friction

Have you checked the hanger??

Hangers get bend so easily and can cause what you’re describing. I had similar problems with 1-11 XT and new hanger fixed it

My money is on the hanger

Yeah, and don’t assume the hanger is straight if its new, get it checked on the frame. Hanger might be straight but frame might not be.

Had this with a brand new frame with brand new hanger.

Some further testing shows that the problem only occurs after gear 6-7, any lower on the cassette and its pants. Moving down the cassette from 1 to 6 is super fast and nice.

The spring on the mech gets weaker closer to gear 11 so there is not as much pull force the further you get from the 1st cog.

I now remember, importantly, I also removed a cable-end ferule from where the cable exits the shifter. The ferule was causing friction

OK, progress,..

Removed cable from mech… downshifted and then pulled the cable (like the mech spring would)
Hmmmm, that felt a bit grabby… repeat…. Yes!!! Found something!! deffo some friction somewhere.!!

So removed cable from rear internal route, and tested the same, still grabby.
Removed cable from underneath the BB route. Still the same…
Pulled enough cable from the front downtube entry point and tried again.. Still the same!!

So there is friction somewhere between the downtube and shifter.
Removed bar tape, got to the gear cable and tested. A little better, but still not good.
There is deffo some friction around the shifter area.

I think JamieP is bang on..!
I thought the worse and assumed there was some nasty carbon inside the internal routes causing some fouling.

I’ll get to the shifter later and check out the exit path.
Although on first look I cant see any different exit routes, just the one its using.
I’ll also check the ferrule out.

Sticky cable outer before the RD. Replace. It won’t be the shifters and unlikely to be hanger. Replace.

Sticky cable outer before the RD. Replace. It won’t be the shifters and unlikely to be hanger. Replace.

Its not that, silky smooth from new. I dont think it has even had a wet ride to get gummed up too..

Got inside the shifter and removed the inner cable..
It deffo does not move very freely along the channel that it takes to exit the shifter unit…
I would say there is far too much friction there for the rear mech spring to pull through when it gets to the lower part of the cassette..

Next question, how do I fix it?

OK, I have fixed it.

Without being able to fix the excessive amount of friction coming from somewhere in the shifter housing, I tried to remove as much friction (not much at all) from the rest of the cable path.

So.
Removed the 1st cable bend as it exits the sifter and routed the cable diagonally across the bars. This keeps the cable in the same direction as it exits the shifter.
When I re-tape the bars I will exclude the gear cable.
I did 55 miles last night without tape and with the cable like that and it did not hinder me at all.

Secondly I removed the BB cable guide and installed a new piece of outer cable instead, this is something I have been wanting to do anyway as its much better than having an exposed inner cable in that area. No mud issues now.

Thirdly, I fully wound the B screw out, just to see. The mech is now approx 0.75cm from the cassette, too close for my liking but its work fine.

I now have super slick shifting, what I would expect from a Force 1 setup with 500miles on it..

All of the above has not removed the friction from inside the shifter but possibly compensated for it.
I am going to do some further testing tonight with the cable taped to the bars, maybe just the BB mod and b-screw fully out is enough.

does the shifter not have an alternative exit port for the cable outer ? Shimano ones certainly do, on the outside, to let the outer run smoothly along the line of the bars.

replace the cable outers with a full length of new outer. Even if it has meant drilling out inbuilt guides I have found this makes gears more workable and good shifting longer-lasting.

Cut the outer’s ends crisply. Put on nice new ferrules. Replace the cable. Give it a light lubing before slipping it in.

Nice that you’ve managed to improve it already.

Unlike Force, the Rival shifter has two cable exit routes – one like above, exiting diagonally. This caused stickiness issues for me. The second exits in line with the bar, which removed the skickyness issue

does the shifter not have an alternative exit port for the cable outer ?

Not that I could see.. Just one.
Pretty sure of that as the only way you can thread a new cable is from the inside, and it exits in one place. There is no other exit point visible, or any way I can influence the route it takes as its all hidden.

Like this you mean?
No the Force 1 Hydro does not have this option.

yes, like that. I’m not familiar with Sram, hence the question as they are normal on Shimano to avoid the issues you are having.