I've got a 97' Trek 8200 and I will be replacing the crankset and bottom braket soon. I'll need/want to replace the front derailleur becasue it mounts to the bottom bracket. I need a bottom pull, but I've seen a SRAM online that says "twin pull (top and bottom)", is that either way or both? None of the others I've seen so far have indicated whether they are 7/8 speed or 9. Any help and/or input would be appreciated. Specs don't seem to be available on the manufacturers' websites for low end componenets. Seat tube is 31.8mm.

Thanks, Bill