Brompton owners

This is part of the issue i'm having with mine at the moment. I guess better to wear out the jockey wheels than the 'derailleur'.

It’s just normal wear and tear. A steel derailleur cage vs a plastic pulley is only ever going to result in one winner. You can buy pulleys as a pair or just replace the whole tensioner.

Make sure your limits on the DR are set, most people who have issues with the top idler wheel wearing is because the limits mean the idler wheel is rubbing the DR the whole time...

Is it just me, or has anyone else with a 2 (or 6) speed set up worn out their jockey wheels to the point that they can no longer change gear? The gear change mechanism seems to wear the outer lip as it pushes the wheel across, to the point that the lip is worn down so much that the mechanism has nothing to press against.

Can be something as simple as adjusting the screw limiter on the chain pusher*, other factor is the cable slack, weakened spring, or the chain pusher being screw in too tight**.

*If it's not set correctly, the chain pusher will rub on the jockey wheel rather, you'd hear the little ticking sound, put it on the stand, spin the crank, and put an allen keys in the chain pusher, turn it until you no longer hear any ticking/rub of the jockey wheel rubbing against the chain pusher.

Also not just the derailleur jockey wheel that get worn, but the chain pusher can also get worn, check the metal plate on the inside to see if it worn into a small lips.

**the last three would contributed to needing to really push and hold the shifter in order to push the chain to the biggest sprocket, thus increase wear on the jockey wheels.

Lastly, as it's technically a derailleur, and obviously I know you know this, always ease a little pressure off the pedalling when chaining gear.