RD skipping under pressure

[nickobec]

Just built up a new FM066SL, took for test ride, if I put pressure of pedals, ie climbing a slight hill, accelerating the chain would skip around on the cassette.

Ended up changing the RD, the gear cable, cassette and rear wheel and the skipping is still there.

Any suggestions of likely cause, all I have left is misaligned RD hanger

[Mulger bill]

If you haven't mixed used components in and the setup and tension is right then it does sound like something is out of shape

EDIT Is it happening right across the stack or in one particular gear?

[nickobec]

Components - Slightly used SRAM Red shifters, new SRAM red cranks, used SRAM red & rival RD, used Force FD, 1070 and OG 1090 cassette, new KMC X10 SL chain. So basically light used SRAM drivetrain.

Occurs anywhere in the range, though less frequent when on the biggest or smallest cog on the cassette.

[Mulger bill]

New chain and used cassette? If you've still got the old chain, whip out the ruler and measure it...

[nickobec]

New chain and used cassette? If you've still got the old chain, whip out the ruler and measure it...

New frame, so no old chain.

I have three wheelsets which get moved around between bikes (training/commuter bike - about to replace one chain as it hit 0.75%, race bike chain 3,0000km and still good and poseur bike - brand new chain 200km)
Training wheelset, with 11-23 1070 cassette that has seen 3,000km on 3 different bikes/chains - no issues
Racing wheelset, with 11-23 OG 1090 cassette that has seen 1,500km on a single chain (race bike) this is what caused me grief on Thursday.
Climbing wheelset with 11-26 1070 that has seen 500km on a single chain (race bike)

Have a lightly used chain from another project , I will try to see if that is an issue with the chain

[ytd]

in my experience skipping is nearly always a compatibility problem between the chain and cassette, assuming neither is worn. Once had really bad skipping with new components. Realised that I had put a mislabelled 8 spd chain on a 9 spd cassette.

[jules21]

old chain on new chainset could possibly cause slipping. i have had this problem several times and i always end up solving it with new drivetrain (chain, cassette, rings) across the board. one day i will learn