Repeated chain dropping - Praxis works chainrings

[langy]

I've been using a set of Praxis Works 52/36 chainrings with my Quarq dzero power meter and have had numerous chain drops when chaning from the outer to inner chain ring.

Had an issue with a previous quarq power meter using the same chainrings and I had a similar problem.

Between power meters I reverted to using the standard shimano ultegra 6800 52/36 chainrings / crank with no issues whatsoever.

Went out for a gentle ride this evening, chain came off and it went between the frame and chainring and twisted a chain link.

Gears are adjusted OK, I don't currently run a chain keeper (although I do have one on the way).

Any thoughts?

[Bobley]

Is the chainline exactly the same between the two cranks? Are you making any changes to the front mech when you switch cranks?

[lastofthev8s]

Double check they're mounted correctly as installation guide (see link) mentions being matched and incorrect setup will affect smoothness.
https://praxiscycles.com/wp-content/uploads/CHAIN_...

[langy]

Bobley said:

Is the chainline exactly the same between the two cranks? Are you making any changes to the front mech when you switch cranks?

I have found out (prior to yesterdays chain drop) that the Quarq crank arm sat approx 1mm closer to the frame than the standard Ultegra, I've changed this by introducing a spacer, so crank arms are sitting in the same place (i'm using a Wheelsmfg BB). I've adjusted the H & L screws on the front mech to suit the Praxis rings, so there must be a discrete difference between the alignment of respective chainrings.

Must admit, I don't have a reference measurement for respective positions for the actual chainrings themselves.

lastofthev8s said:

Double check they're mounted correctly as installation guide (see link) mentions being matched and incorrect setup will affect smoothness.
https://praxiscycles.com/wp-content/uploads/CHAIN_...

Yes, they are mounted as per instructions.


Chain catcher is due today, so will replace the twisted link, fit the catcher and double check positioning of front mech (height, angle and H/L screws). If the chain drops again, a) I won't be best pleased, b) will end up taking to LBS, and c) consider selling the power meter and rings and reverting back to the Ultegra and continue riding on heart rate / feel.