I've got a 9 speed chain thats brand new. I also have a bunch of 7 speed cassette cogs. My road bike is 10 speed, so I have no use for 7 speed or 9 speed stuff.
I want to go to a larger cog on my singlespeed, but the chain that is on there is too short. so, I wanted to use the 7 speed cog with my 9 speed chain. Is there any reason why this wouldnt work? remember folks, this is a SINGLESPEED. no shifting will be done here.