Rival 1 shifting issues

Jterrier

Am looking for anyone with perhaps personal experience of this. My cx bike has a 38t ring with 11spd rival 1 on an 11-36 cassette.
It used to (from the shop) have 44 at the front and 10-42 at back. I have shortened the chain. The cassette and chain are sram, the single ring is not.


I now seem to have incurable shifting issues, only at the top 3 gears (i.e the 3 smallest sprockets, 9th/10th/11th). It shifts uphill on the block (i.e me pushing the lever through) perfectly, and it taps back ok until it gets to 9th. It then hangs, noisily, and requires a double shift, at which point it makes two changes in one. Bah.

I have reset the cable position and lubed the inners, and have made sure the hanger is straight. If i index it, it just moves the problem around and never sorts itself; the symptom above is the best i can get it to; it doesnt need a gear tune as it is only that one specific sprocket and shift combination that is an issue.

I have never moved the b screw and some advice states that this has quite an effect (in which direction i wonder? Wind the jockey wheels further away from the block to increase tension...?). I also wonder if maybe the spring tension in the rear mech is going, as it has had 2 years of hard cx racing.

If i cant find anything obvious i think i will have to basically rebuild and recable and go from scratch.

whyamihere

Jterrier wrote:

I have never moved the b screw and some advice states that this has quite an effect (in which direction i wonder? Wind the jockey wheels further away from the block to increase tension...?).

This, but in the opposite direction to what you mention.

Jterrier

whyamihere wrote:

Jterrier wrote:

I have never moved the b screw and some advice states that this has quite an effect (in which direction i wonder? Wind the jockey wheels further away from the block to increase tension...?).

This, but in the opposite direction to what you mention.

As in, wind the b screw outward so the jockey wheels get closer to the sprockets. Ok. Will try. That might make sense actually as the previous cassette was much larger at one end and smaller at the other.

tgotb

Let me guess - you've mounted the single chainring on the inner position?

Sounds very similar to the issue I have on my bikes, which is all about chain line. Things you could try include:
- Adjust B screw, as discussed
- Move chainring to outer position (but drivetrain may be noisy/less efficient/harder to shift on the inner sprockets)
- Depending on bottom bracket type, move chainset out slightly
- Switched to a dished chainring (to get it to a more "central" position)
- Experiment with different chain length

Bottom line - on a 2x10 or 2x11 setup you wouldn't expect shifting to work well on the inner ring and outer sprockets, so it's never an issue. By shifting to 1x10 or 1x11 you're suddenly expecting it to work. I've a suspicion that the narrow/wide chainring actually makes the situation worse by holding onto the chain for slightly longer.

In my case I improved the situation a bit by adding a couple of chain links. Because I spend most of my time at the lower end of the cassette I didn't want to compromise drivetrain efficiency in low gears, so I just accept that shifting won't be brilliant at the other end of the range. Bizarrely, one of my supposedly identical bikes is consistently better at shifting into the top couple of gears than the other. This has been the case through multiple seasons, and replacement hangers/mechs/chains/cables. If I'm doing a race with fast sections that require the full range of gears, that's my bike of choice...

I have 10-speed SRAM road shifters and X9 type 2.1 mechs, which should be an equivalent setup to yours.

I haven't tried it, and it might not be very useful anyway, but I wonder whether shifting might work a bit better with an old (ie worn) chain with more sideways play...

Edit: My default setup is 38 x 12-32, but I occasionally race with 34 x 11-36 (eg for 3 Peaks), and shifting is much the same.

Jterrier

TGOTB wrote:

Let me guess - you've mounted the single chainring on the inner position?

Sounds very similar to the issue I have on my bikes, which is all about chain line. Things you could try include:
- Adjust B screw, as discussed
- Move chainring to outer position (but drivetrain may be noisy/less efficient/harder to shift on the inner sprockets)
- Depending on bottom bracket type, move chainset out slightly
- Switched to a dished chainring (to get it to a more "central" position)
- Experiment with different chain length
.

problem is the bike was always 1x, and the chainring is direct mount so only goes 1 way, and the bb cant be adjusted as it is a PF30 system with a set spacer etc. the only thing i have to play with are either the cable, chain, hanger, or mech adjustment.

tgotb

Have you checked that both old and new chainrings give you the same chainline? Is it possible that your 44t was dished and your 38t isn't?

Midlands Grimpeur

I put rival 1 x on a bike a couple of weeks ago and have had some issues with fine tuning gears including the double shift like yourself. Obviously I can't say for sure that we have had the same problems but my issue was the b screw, I needed a larger gap. Once I had got that dialled (and increased cable tension a little) it fixed the problem. There is a good GCN video which covers RD adjustments which I found handy. https://www.youtube.com/watch?v=XagBY9LLI7c

devhads

TGOTB wrote:

Have you checked that both old and new chainrings give you the same chainline? Is it possible that your 44t was dished and your 38t isn't?

It could be this. The direct mount chainrings from Absolute Black are specific to Sram chainsets. I have Force CX1 and bought a flat chainring by mistake when I actually needed a dished one. I also think you can play around with spacers a bit. I have the big Sram one on the drive side and a few small ones on the NDS and could put them on the drive side if I needed to push the chainline further towards the smaller sprockets.

Jterrier

So today i took a link out of the chain, and wound the b screw out a bit to bring the pulley in closer; it seemed to improve the shifts a bit, as in they snap in a lot harder now, but there is still that hesitancy going up (down ) from 9th into 10th. Its like the spring tension at the end of the rear mechs travel isnt enough to push it over the edge down onto the next sprocket.

Tomorrow i plan to recable it and go from there. I also tried to take a look at the chain line to see if there is anything obviously wrong, but its quite tricky to really tell. The problem with trying to compare whether the old ring was/wasnt dished etc is that in any case, the metal thickness might be different on the two rings....so even if they were both dished, or one wasn't, the chances are that the teeth arent in the same position anyway.

imposter2.0

Check your cable fixing at the rear mech, might be running on the wrong side of the bolt..

Jterrier

I think i can see the issue. And i think its an incurable thing. Basically you always get a compromised chainline at the back with 1x, whereas in the past with 2x all the compromise was at the front mech with cross chaining. Couple of other people here have said the same thing.

I looked at my chainline and it falls sweetly right in the middle of the block. When you get it to either end it is quite angled, and there is bags of noise, which i can see is coming entirely from the chain trying to straighten itself onto the cassette off of the top pulley, with the link plates striking the teeth.

So its a compromise with some unintended side effects, mine being that the shift from 9-10 doesnt work well. Its no wonder sram and shimano are working on oscillating chainrings.

tgotb

Jterrier wrote:

Its like the spring tension at the end of the rear mechs travel isnt enough to push it over the edge down onto the next sprocket.

One thought, given your statement above, and confirmation that chainline is a factor:

Rear mechs work on the basis of a spring pushing the mech outwards, working against a cable pulling the mech inwards. Release the cable, and the mech moves outwards. You've stated that it seems like there isn't enough spring tension at the far end of the range, which is exactly what I felt when I was playing with my setup. However, this spring isn't just working against the cable, it's also working against the chain tension. The compromised chainline means that the chain pulls slightly inwards aswell as forwards, and because it's a 1x mech, the chain tension is quite high. The further out the shifter gets, the more the chain's trying to pull it towards the centre, working against the spring.

If your mech has a clutch, you can probably test this by releasing the clutch and seeing whether shifting improves. Do this with the bike in a workstand; riding with the clutch released tends not to go well.

Lengthening the chain should decrease the chain tension somewhat, which will reduce the amount by which it's pulling the mech inwards. Whether that's enough to sort out the shifting is something you'll have to find out by trying it, but it definitely worked for me. A longer chain will also be easier to shift into the lowest gears. The flipside is an increased tendency to drop the chain, but my experience is that, with a narrow/wide chainring, there's normally plenty of tension to spare.

Jterrier

...i might buy a new chain anyway, an actual sram one, as it may be the case that the current kmc doesnt like feeling its way onto the cassette teeth, whereas a sram one could have edges designed to hit the.shift ramps better.... Maybe.

Also considering a drive side spacer. :roll:

Jterrier

Have recabled it, but even more crucially i noticed whilst doing so that the shifter mechanism was completely full of grit and gunge. Shift seems ok now but i still feel like i might change the chain too as the season is coming...