Bouncing at high cadences

What frame are you using Dammit? It's a Fuji track, isn't it?

I get this bounce now that I've got the Charge but I'd put it down the the steel frame. Old bike didn't do it but it is 501, which is a bit stiffer I think and it's HEAVY. Like MTB heavy.

I guess if you hit the resonant frequency of anything then you will get a bounce effect (take the Tacoma Narrows bridge - that famous old B&W footage of the suspension bridge wobbling and ripping itself apart). But I thought an alu frame would be stiff enough to resist that.

Bounce and flex from the saddle rails? Mine is noticeably less bouncy since I changed the saddle from a Charge Spoon to a wide Specialized Alias.

lower your saddle