Gears not driving/ slipping on road bike

[biggs682]

every time i apply a bit of pressure in any gear it lost drive for a moment on and off no matter what gear , replaced wheel and no problems with my spare wheel (good old fashion screw on block type) , fitted new freehub on to original wheel re fitted in to frame and went for a spin , still slipping but no where near as bad as origanally , so swapped on to another free hub equipped wheel and that only jumps in 6th gear not any others , any ideas at all .

gear system is basic shimano 12 sis , but has got 7 cogs on back so should now be 14 but not getting to smallest cog , have not tried adjusting rear deraileur to see if it can get there , as night fall arrived .

any ideas ie are chains differant on for 6 & 7 speed set ups ?

i cant see any tight spots on chain

 

[rusty bearing]

When did you last replace the chain and cassette? Sounds like they're completely knackered.

 

[biggs682]

they both look ok , but might swap chain over for another 1 have that i know is low miles

 

[Maz]

i was thinking the same as RB, i.e. when was the chain last changed?
Could be that the chain/cassette are worn out, hence the 'skipping' you are experiencing.