SRAM APEX INDEXING PROBLEM

exlaser

Hi all, just query to make sure I haven't missed something stupid.
I have just developed a indexing problem. If I decrease the tension in the system, the chain won't drop on to the smallest cog ( 11 teeth ). If I increase the tension, it will drop onto the 11 cog and works fine in the 32 to 11 direction but when working the 11 to 32 direction it jumps 2 cogs at a time.
Am I bring stupid? Has anyone go any ideas before I take to my local bike shop.

StillGoing

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19706448#p19706448]exlaser[/url] wrote:

Hi all, just query to make sure I haven't missed something stupid.
I have just developed a indexing problem. If I decrease the tension in the system, the chain won't drop on to the smallest cog ( 11 teeth ). If I increase the tension, it will drop onto the 11 cog and works fine in the 32 to 11 direction but when working the 11 to 32 direction it jumps 2 cogs at a time.
Am I bring stupid? Has anyone go any ideas before I take to my local bike shop.

The throw on SRAM rear shifters is capable of changing several gears at once. If you only want to go back one cog, use a smaller throw of the shift lever. This is a useful option for climbing.

exlaser

Cheers, but I did know this. The problem is what ever the amount the lever moves, it changes up two cogs.

StillGoing

It is very sensitive, could it be your dexterity in how little you think you're moving the shifter?

exlaser

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19706768#p19706768]philthy3[/url] wrote:

It is very sensitive, could it be your dexterity in how little you think you're moving the shifter?

That's exactly what I thought at first, that it was me just being to rough with it shifter when riding. But I have had the bike on the stand in the garden and still couldnt make it change one cog at a time. How ever far I operated the shifter it changed up two cogs. It's driving me mad

andrewjoseph

bent the mech hanger? will loosening the tension all the way i.e. undo cable pinch bolt, allow chain to drop to smallest cog? if so it may be the high limit screw is the problem.

exlaser

Have checked the hanger, but will still check again and then do what you suggested.

paulbnix

I have SRAM Apex on both my bikes.

I find that after a few months the indexing becomes less reliable. Basically the tension to change from smaller cog to larger cog needs to be set too high to allow it to change from larger to smaller.

This always seems to caused by the section of outer cable leading from the chainstay to the derailleur.
This outer cable needs to be clean and the correct length of 36 cm.
Sometimes cleaning the outer and relubing works but other times it needs a new inner and a new section of outer cable to fix the problem.

exlaser

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19707754#p19707754]paulbnix[/url] wrote:

I have SRAM Apex on both my bikes.

I find that after a few months the indexing becomes less reliable. Basically the tension to change from smaller cog to larger cog needs to be set too high to allow it to change from larger to smaller.

This always seems to caused by the section of outer cable leading from the chainstay to the derailleur.
This outer cable needs to be clean and the correct length of 36 cm.
Sometimes cleaning the outer and relubing works but other times it needs a new inner and a new section of outer cable to fix the problem.

Cheers for the advice, I will check this next. Have double checked the rear hanger and its fine.

andrewjoseph

i've had the same outer on my apex system since put on bike in jan 2014 (about 5000km) without needing a change or cleaning or any other maintenance. I had to change the inner cable last week due to fraying at the pinch bolt.

svetty

Another vote for the outer casing at the rear mech needing replaced here - assuming your inner isn't obviously frayed/damaged somewhere along it's length....

paulbnix

Last time I was out on my dry weather bike I noticed that a couple of the lower (bigger sprocket) gears were noisy when I changed from a bigger sprocket to them but not when I changed the other way.

It looked like the spring in the derailleur was not pulling the gear cable through enough.

This is one of the symptoms of a clogged up rear derailleur outer cable. I fitted a new 36 cm bit of outer and a new inner and perfect functionality was restored. It was over a year since the previous time - probably about 4000 dry(ish) weather miles.

exlaser

Cheers guys, will check this out and get back to you all.