Indexing problems
Discussion
I'm having a bit of a problem here. My Lapierre Zesty isn't changing gear very well. It's a 2016 with 1 x 11 Sram GX. I'm finding that on the bike stand, I can tune it perfectly I've got the high & low stops spot on & it runs up & down the gears faultlessly but as soon as I ride it, it will only change down as far as about 7th or 8th gear.
Clearly, my weight is increasing the sag & that's causing the effect but how to fix? The rear shock is sitting about 150psi. I've pumped it up to about 170 & it;s helped a bit. When I undo the clamp bolt & hold the cable in my fingers & change up & down the gears, I can feel it's a little sticky on those last few gears, so new cable?
Is there anything I'm missing?
Clearly, my weight is increasing the sag & that's causing the effect but how to fix? The rear shock is sitting about 150psi. I've pumped it up to about 170 & it;s helped a bit. When I undo the clamp bolt & hold the cable in my fingers & change up & down the gears, I can feel it's a little sticky on those last few gears, so new cable?
Is there anything I'm missing?
Sram mechs seem quite sensitive to cables which aren't running smoothly so a new cable would be a cheap and easy first step. Shifting can be horrible with a poorly routed or gritty cable.
Sitting on the bike shouldnt change the indexing setup but check that the cable end isn't coming out of the stop, either ar the shifter or mech, causing extra tension on the cable. Check for kinks too.
Sitting on the bike shouldnt change the indexing setup but check that the cable end isn't coming out of the stop, either ar the shifter or mech, causing extra tension on the cable. Check for kinks too.
The diameter of SRAM cables is slightly less rhan Shimano - I had indexing issues which weee caused by an LBS using the wrong cable - after many attempts by them to correct the issue they then told me the problem was caused by a worn out rear derailleur or an issue with the frames internal routing....
After lots of head scratching, google and a micrometer I diagnosed the cause and replaced the cables with the correct type and everything has worked fine ever since - another LBS added to my growing list of bicycle shops that I won't visit...
After lots of head scratching, google and a micrometer I diagnosed the cause and replaced the cables with the correct type and everything has worked fine ever since - another LBS added to my growing list of bicycle shops that I won't visit...
I've got the high & low stops dialled in, the B screw is dead on & I've ruled out a bent mech hanger or bent cage. When I started on it, the cable was frayed at the clamp, so I changed it for one I had in the tool box & I'm pretty sure it was just a Clarks generic from Halfords, so I'm feeling sure it's that. I'll change it for a Sram one this week, see if that sorts it.
Back to this. I changed the inner & outers last night to oem spec & tried again. I'm getting the same issues. On the stand it's fine, on the road, it won't change up to the smaller cogs.
I've reset (again) the high & low stops, so I know they're fine. I wind off all the tension on the barrel adjuster & then wind it on a whole turn for leeway before clamping the cable, which is working fine & still I can't get it to shift up sufficiently.
The closest I've managed to spec is to put the bike into highest gear on the stand then wind tension into the adjuster until it changes down from 11th to 10th, then unclamp the cable & reclamp it with in effect a ton of tension applied. This allows the bike to shift up to top gear on the road, but causes problems on the lower gears, most notably high tension in the shifters on the bigger cogs.
I've read that GX is very sensitive to any adjustment & B screw can really aid or hinder things but as far as I can see, I'm doing everything I should be but still it won't settle?
I've reset (again) the high & low stops, so I know they're fine. I wind off all the tension on the barrel adjuster & then wind it on a whole turn for leeway before clamping the cable, which is working fine & still I can't get it to shift up sufficiently.
The closest I've managed to spec is to put the bike into highest gear on the stand then wind tension into the adjuster until it changes down from 11th to 10th, then unclamp the cable & reclamp it with in effect a ton of tension applied. This allows the bike to shift up to top gear on the road, but causes problems on the lower gears, most notably high tension in the shifters on the bigger cogs.
I've read that GX is very sensitive to any adjustment & B screw can really aid or hinder things but as far as I can see, I'm doing everything I should be but still it won't settle?
Not sure I understand your method of cable tensioning.
Assuming the stops are set correctly as you say, undo the cable and make sure the shifter is clicked all the way down to the smallest cog and the adjuster is backed off all the way, then add maybe a turn to give a little leeway. Pull the cable reasonably tight so there is a tiny amount of slack and clamp it up. Click the shifter twice and rotate the pedals to see where you are. Adjust the tensioner until you're on the correct cog for this (two up from the smallest cog) and the chain is running quietly. That should be pretty much all you need to do. Check and fine tune through the range. If this isn't working there's another problem somewhere. It sounds like your cable is too tight. Usually rear mech adjustment is the same on the stand as on the road.
Assuming the stops are set correctly as you say, undo the cable and make sure the shifter is clicked all the way down to the smallest cog and the adjuster is backed off all the way, then add maybe a turn to give a little leeway. Pull the cable reasonably tight so there is a tiny amount of slack and clamp it up. Click the shifter twice and rotate the pedals to see where you are. Adjust the tensioner until you're on the correct cog for this (two up from the smallest cog) and the chain is running quietly. That should be pretty much all you need to do. Check and fine tune through the range. If this isn't working there's another problem somewhere. It sounds like your cable is too tight. Usually rear mech adjustment is the same on the stand as on the road.
TwilightJohnny said:
Not sure I understand your method of cable tensioning.
Assuming the stops are set correctly as you say, undo the cable and make sure the shifter is clicked all the way down to the smallest cog and the adjuster is backed off all the way, then add maybe a turn to give a little leeway. Pull the cable reasonably tight so there is a tiny amount of slack and clamp it up. Click the shifter twice and rotate the pedals to see where you are. Adjust the tensioner until you're on the correct cog for this (two up from the smallest cog) and the chain is running quietly. That should be pretty much all you need to do. Check and fine tune through the range. If this isn't working there's another problem somewhere. It sounds like your cable is too tight. Usually rear mech adjustment is the same on the stand as on the road.
Cheers, done all this. Barrel adjuster wound off to slack, wound on 1 turn, cable clamped, per the book. My problem is when I follow the Standard way of tuning a mech, it's not working. Assuming the stops are set correctly as you say, undo the cable and make sure the shifter is clicked all the way down to the smallest cog and the adjuster is backed off all the way, then add maybe a turn to give a little leeway. Pull the cable reasonably tight so there is a tiny amount of slack and clamp it up. Click the shifter twice and rotate the pedals to see where you are. Adjust the tensioner until you're on the correct cog for this (two up from the smallest cog) and the chain is running quietly. That should be pretty much all you need to do. Check and fine tune through the range. If this isn't working there's another problem somewhere. It sounds like your cable is too tight. Usually rear mech adjustment is the same on the stand as on the road.
Works fine on the stand, not on the road, what I'm saying about winding the barrel on a gear is it's getting me close but not really close enough to normal. I can't see how simply changing a cable has left me struggling to tune it in. Clearly my weight on the bike is tensioning the cable somewhere along the line from the pivot back & causing the problem. I think the next step is to check the routing forensically against the spec, sooner rather than later, it's essentially unuseable right now.
Insert Coin said:
My Sram 1x11 was doing the same, ok on the stand and crappy on a ride. Took it to my LBS who diagnosed a new cassette, along with a chain and it's been fine ever since.
Circa 1500 miles out of the first cassette and chain.
500 on this one, I might get the LBS to check the chain & cassette Circa 1500 miles out of the first cassette and chain.
Finally, sussed it. The shifter cable routes through the down tube & through a guide which is designed to stop the outer riding up against the frame. It had popped out of the guide & so when I sat on the bike, the cable was tensioned, stopping it from changing up.
The guide is hidden behind a carbon fibre bash pad & so wasn't immediately obvious & was the only bit of outer I didn't change. It's also got a bit of damage to it but since the bike's now changing ok, I've left it for the time being.
The guide is hidden behind a carbon fibre bash pad & so wasn't immediately obvious & was the only bit of outer I didn't change. It's also got a bit of damage to it but since the bike's now changing ok, I've left it for the time being.
Eddie Strohacker said:
Insert Coin said:
My Sram 1x11 was doing the same, ok on the stand and crappy on a ride. Took it to my LBS who diagnosed a new cassette, along with a chain and it's been fine ever since.
Circa 1500 miles out of the first cassette and chain.
500 on this one, I might get the LBS to check the chain & cassette Circa 1500 miles out of the first cassette and chain.
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