Gritty feel when pedalling-what could be the cause?

[Globalti]

The big ring is also completely worn out; I'd be surprised if the chain wasn't jumping around the teeth under pressure. The sound and feel is certainly "gritty".

 

[Shut Up Legs]

I can typically get at least 3000 miles out of a drive train. The one in the OP probably could have too, if it had been cleaned more often.

 

[vickster]

It appears the OP hasn't been back to respond, probably out of embarrassment

My Genesis has done 3.3k miles, chain and cassette due a change...but then it's clean and used mostly in dry conditions

 

[night cycler]

I have now completed the reassembly of the chain rings, and crank arms.

The bearings are the sealed type that are not serviceable in the same way that some bottom bracket bearings are on other cycles. The bearings as well as the parts inside the bottom bracket , are all a press fit. The outer seals can be removed but apparently (due to damage if removed) have to be replaced with new ones. Fortunately, when checking the bearings for smooth running they were perfect.

Dismantling the individual chain rings gave me an opportunity to thoroughly clean the areas not fully accessible when on the bike.

Everything now relubricated with clean hypoy.