Chain derailment

[HLaB]

Chain Derailment, it seems to be happening a lot since I put a new chain/ cassette on as far as I know its the same chain set up but the cassette (previously a 12-25) was replaced with a 11-25. The chain now comes off at the cranks once a ride I think when I'm in the small (38t) chainring, shift down (up) I can never remember what is correct (from a large cog to a smaller cog) and then shift rapidly to the big (52t) chaining. Its probably hard to form an exact opinion but what do folk on the forum think, have I worn the front ring out a bit or is it just my bad shifting, compounded by rapidness and I should just tighten the limit screw since I have a smaller cassette.
And taken with Macro mode

 

[RecordAceFromNew]

You did not say how does the chain derail, does it always go outboard over the 52T ring? If so is the high (outer) limit screw set so that the gap between the front mech and the chain is only 1mm or so when the chain is on the 52T in front and the smallest cog at the back?


Hard to tell from the pics because I think either a) the camera is too close to the chainset so although big the pics are out of focus for the particular focal length used, or b) the camera is too far from the chainset if the macro mode requires the lens to be closer to the object to be in focus.

 

[HLaB]

Yip, the chain is occupationally jumping over the 52 t chaining, I think I'll see if tightening the high limit screw cuts it out.

I'd never make a photographer, those pics are cr@p when they are large they looked OK on the camera screen. I'll maybe try again with another camera (a bad workman blames his tools ) or try different distances.

 

[HLaB]

Results aren't much better with the focal length increased


and the macro mode is just pants at any distance.

The Mobile phone camera without a flash is too dark.


But I think the overshifting was the cause of the problem hopefully limiting that will solve things; I'll see on tomorrows club run either that or I'll stay in the one chainring.