Ive tried allsorts but can’t get it to stop. It only happens when putting power through them. It’s the smaller 2 on the rear

If you answer this it may save me taking a hammer to it 🙂

It’s worn. New cassette time.

new chain on old sprocket?

No ware on them. All fairly new.

Should also note I tried a different wheel and got same result!

The lock nut definately done up tight enough?
As its normally the last two that are loose.

Incompatible parts? Maybe a 7 speed chain with a 9 speed cassette….. or suchlike.
I also would have went with worn cassette/chain, classic symptoms. Are the front chainrings also new-ish?

I’ve had exact same was down to slightly bent mech hangar and the shifter was worn also, I’d bought new cassette and chain and it was still doing it, so it was a process of elimination

Yup whole set up fairly new. Lock nut is tight took cassette off to check it all over.

It’s a 9 speed with a 9 speed chain. If baffled. Might have to give in and take it to a shop 🙁 not done that for long as I can remember.

Ah cool hanger could be it. I’ll check in day light! Cheers!!!

did you put new cables & outers on ? – last 2 cogs are where the spring is “weakest” so feels the effects of crappy cables a bit more

(or b screw setting is out)

Yup high quality ones too. I checked the screw. I’m hoping it’s the hanger now… Hope it’s not expensive.

I had similar symptoms – it ended up being a loose mech hangar!!

Check the shifter, if it is old an the spring strength of the ratchet inside is going then that can cause an issue

How old are the front rings? Mate had a similar issue with a new chain, took us ages to figure out it was the front rings as it felt like the rear slipping. On the two small cogs the torque was high enough to cause it to slip, while on others it would still run.

I had the same thing and found a small piece of wood jammed inbetween the two small cogs that I didn’t notice when checking the mech and hanger etc.

Might be worth a check if you haven’t already.

Sounds really obvious, but check how you’ve clamped your cable to the mech. I once ran mine the wrong way round the bolt (because it seemed intuitive to me) and at one end of the cassette, it didn’t want to play – obviously having set my cable tension perfectly at the other end! I bought a new hanger and even had the cage plates off to check they were straight before someone pointed out what I’d done wrong

Bottom stop. Unwind it a little. Probably find that under tension itju ping due to misadjustment

SRAM rear mech? Some came with pretty feeble springs that meant they don’t always return cleanly into the outermost rings… Leaving it parked in the highest gear usually sorts it though.

bent mech hanger or mech. In my case I could get it so one end of the gears worked but not both at the same time. Replaced mech hanger and no more banging knees on the stem when it slips. 🙂

Is B-tension correct?
It can bring the mech closer and further round resulting in more chain being in contact with cassette

i had this on new chain and cassette replaced jockey wheels made sure cassette lock nut was tight readjusted mech indexing all is ok now i think it was the indexing out a bit

bent mech hanger 🙂