SRAM 12 speed set up - chain skipping

[peter-h]

My two wheels have no letters at all. Both are symmetrical although the upper one can go in only one way round, due to the design of the central hole and washers. The lower one has every 2nd tooth smaller and it goes both ways.

 

[fossyant]

SRAM and Shimano 12 speed is great, and you should be more than fine with GX. It's SX that's a bit cheap and doesn't last too well (rear mechs).

There is a 'tool' for setting the B screw and the distance of the top jockey from the sprockets for SRAM, this does seem a key point. Also, chains, don't buy from Amazon or Ebay - too many fakes. Buy from a bike shop or 'bike shop ebay page.

Another point, I've found from 10 speed up, having a really good quality shift cable (inner and outer) is essential. If the indexing isn't so good, and you've had the cable on a couple of years, I'd recommend changing it. Makes a world of difference !

 

[chriswoody]

I've popped my jockey wheels out for clarity so you can see. It can be a little hard to see, but hopefully you can see the location on mine, which are the exact same as yours. They only have one letter on one side, so if that can't be seen then there is a chance that it's the wrong way around.

The top Jockey wheel will go in the wrong way around, it just needs the bearing cover plates to be swapped around. It's probably worth checking, it's only a few minutes job to remove them.

 

[mickle]

Have you checked your derailleur hanger alignment? If its had a bash it could be the cause of your chain 'skipping'

 

[peter-h]

I did eventually find those tiny letters. Amazing that matters because no matter how close I look, I cannot see any assymetry on the upper wheel. If it really makes a difference, it's no wonder this system does weird stuff, when the tolerances are so tight.
If I wanted to replace those wheels, can anyone recommend a source?
Yes; much of amazon and ebay is counterfeits.
The derailleur has never been bent AFAIK. That said, the lower wheel is not in line with the upper one. It "leans" slightly to the centre, and I thought that is intended because it helps to feed the chain off the front gear. It's always been like that.

 

[silva]

Having put the old chain back on, I get frequent skipping on the smallest gear and much less frequent on the next one up. Moving that link around has not changed this; unsurprisingly since it looks exactly symmetrical.

So suddenly the bike has become hard to ride. So I am going to change the whole lot now (cassette, chain and the front gear). Not sure I have all the tools needed so could be off the road for a while while waiting for stuff to turn up. Is there anyone near Brighton who could help if I get stuck, for some £££?

But I wonder what the cause might be of the old chain suddenly skipping. The only other thing I did was to remove, clean up and replace the two derailleur gears. Their bearings seem ok but I wonder whether a slight wobble (in the upper gear, which directs the chain onto the appropriate cassette gear) might cause chain skipping? I can get new ones; they are not expensive. They have ceramic bearings which don't need lubing.

Sometimes some patience allows such problems to go by themselves.
At the moment, the wear states of the individual drivetrains parts are different, but further wear will bring them back in line, since the surfaces that mate with other, will wear, and those that don't mate, won't.
The result is that gradually more teeth again start to share the load, reducing the load per tooth, and thereby stopping the skipping.
A file (alu) or an angle grinder (steel), may accelerate the process, but you need a good eye and watch out to keep it good.
And bonus: the patience solution doesn't cost bucks.

 

[Moderators]

Mod note. Thread temporarily closed awaiting clean-up and removal of some members.

Edit. Thread tidied and civility hopefully restored. Reopened.

 

[fossyant]

Mod note. Thread temporarily closed awaiting clean-up and removal of some members.

Edit. Thread tidied and civility hopefully restored. Reopened.

You've missed removing a certain person who talks rubbish ?

Leaving 'alone' won't fix the issue by the way. Fit a motorbike chain and you'll be 'reet'.