I'm just now getting back into riding after about 15 years off. I got ahold of a 95 GT BMX cruiser frame and built it up, but I'm having a strange problem with the drivetrain.

Aside from the frame, everything on the bike is either brand new or NOS. The cranks (Redline Monster 3-piece), chainwheel (Rennen 44T 3/32), chain (KMC 410H 1/2 x 1/8"), freewheel (ACS Claws 1/2" x 1/8"), and wheels (Tuff Wheels), are all brand new.

The problem is that the chain doesn't seem to match the pitch of the freewheel teeth. As the chain goes around, the rollers on the chain are hitting the edge of the teeth and it grinds/clicks as you pedal. The clicking/grinding is from the roller hitting the teeth of the freewheel and slamming into place over the teeth. Obviously, instead of hitting the rollers, the teeth on the freewheel should be going up in between the rollers in the empty space and run smoothly, but it doesn't.

FWIW, I also tried another new 1/2" chainwheel and another new set of Redline cranks but it does the same thing. I have no idea what could be causing this. The alignment between the chainwheel and freewheel is okay because the teeth are landing in the center of the side plates of the chain like they should, but it's as if the pitch on the freewheel is out of whack or something.

My only idea is that it's either the freewheel or the chain and being that they're brand new, I'd rather figure out how to fix this instead of buying more parts.

Any idea whats causing this or how to fix it?