Chain pulling forward slipping

[shankldu]

Back story happening on two bikes both disasembled and shipped to me niether one shows any wear at all on the rings or chain ,weird the chain under presure is sliping up over the casette teeth on one and the crank teeth on the other ,i have looked at all the normal stuf chain tension etc . Sram on shimano on the one ,which i have never had trouble using together and 9 speed shim on all shim 9 speed on the other . crazy!!!!!!

[batman1425]

Are these bikes new to you, or are they yours and were just broken down for shipping? Sounds to me like a classic case of a new chain on a worn cassette and chainring. Wear doesn't have to be visible for slipping to occur.

Unfortunately, I suspect you are looking at new cassettes, rings, and potentially chains for both bikes.

[Blue Jays]

Originally Posted by batman1425

"...I suspect you are looking at new cassettes, rings, and potentially chains for both bikes..."

Agreed. That "catching and dropping" sound would almost certainly be worn chainrings.
At that point just solve everything, treat yourself, and have a completely fresh drivetrain.

[shankldu]

thanks for the info guys thanks unfortunitly what I was thinking , the Jamis Aurora with the 9 speed shimano only does it in mid cassette so im guessing the mid rings are warn im hopin its a multiple piece and I can just replace mid rings .

[ridethecliche]

Originally Posted by shankldu

thanks for the info guys thanks unfortunitly what I was thinking , the Jamis Aurora with the 9 speed shimano only does it in mid cassette so im guessing the mid rings are warn im hopin its a multiple piece and I can just replace mid rings .

9 speed cassettes can likely be found for cheap, no?

[mikehkaiser]

If you replace the cassette get a new chain with it. They'll both last longer. If you get a new chain with worn cassette/rings, the chain will wear faster. The other way, the chain can wear the cogs/chainrings faster or could be stretched slightly and might not align properly with the teeth.