Grinding from Derailler

[Wetdog]

Hi guys, on a ride the other day I noticed a grinding noise from the rear. I was hoping that someone had a clue what it was seeing as though I haven't ruled out everything nor do I know what they are called
It only happens in top gear and when the right pedal is down and about to continue the cycle to the top. Change down and it goes.
I'm riding a Cannondale Synapse Aluminium 2014 model.

 

[winjim]

Is the chain possibly rubbing on the front mech cage? This can happen when in the big chainring / small sprocket combination and can manifest as a regular grinding once per crank revolution. If so, the high limit screw just wants adjusting to move the front mech maybe half a mm or so outwards when on the big ring.

 

[Wetdog]

Cheers Winjim I'll try it when I've a bit more breath, just come in

 

[bonsaibilly]

Bring it round mine we'll have a look. It could be that but we can stick it on the turbo and have a play. Bb