Just completed a new build – full suss – mix of new components and old. All seems to work really well in the bike stand, but two annoying issues on first test ride. Any thoughts welcome!

Btw… Cranks old, chain new, rear derailleur almost new. 2×10

1/ when in big ring, the minute I try to put serious power down the chain skips – appears to try to dive into smaller ring
2/ when in small ring, regular chain skipping from jockey wheels – it runs ok but is quite annoying

Can not recreate either problem in the bike stand.

Thoughts? Thank you!

Is the chain the only new part on the running gear ?
if so ,it’s going to be chainrings,cassette or both.

chain correct length?

Big ring issue sounds like worn teeth, and maybe stiff chain links for the other?

Stiff chain links often become obvious in the workstand when you turn the pedals backwards, so worth a try to see if it is that.

new chain on worn chainring is a recipe for chainsuck. Not quite sure what you’re describing but that’s my bet

1. Check chainline also.

2. Tough to say

I had what sounds like a similar problem, when I built my bike from old bits and put a new chain on.

I found one problem that was my rear QR Skewer wasn’t gripping the frame enough, it kept sliding out, only slightly! When I looked the teeth on it had worn, a new skewer fixed it for me.

I still had a bit of skipping about though, but after about 50 miles or so of riding it seemed to sort its self out, I guess the chain or cassette wore into each other.

Thanks guys

Suspect worn chain rings for first – can’t work out why I can’t replicate jockey wheel on stand – could it be a different chain length when the rear suspension is active?

i had a similar problem, 2×10 set up and always seemed to skip on higher gears in the cassette when under load…..swapped new cassette and solved it.

Depending on the frame, the chain length will grow as the rear suspension compresses. I unbolt one end of the shock and pull the rear wheel up to find the longest chain point on my bike.

Movement in the bottom bracket under load which would then screw the chain line?

New press fit bb – how do I prevent chain line moving under load?