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If you still think swinging a heavy bat is the way to faster bat speed read this: Warming up with a weighted bat does not increase swing speed.

Good research and I'm going to have to do my own. On face value, I don't buy it but the only backup I have is that 99% of pro baseball players can't be wrong.
As far as bikes are concerned, I'll admit you can train as hard on a geared bike as you do on a FG/SS but you probably won't. You would have to be very disciplined not to kick it down a notch when things start to hurt. Something most of us couldn't do. There is no option on a FG/SS.