Beats per minute stuff

That depends (ya hear that a lot here).

What are your goals?

What's your current fitness level?

IMHO if you are an experienced athlete, want to excel at sprints and be competitive for a top spot you're likely training too long too low. That's not many people on this board, however.

If you are just starting out you're likely training a little too long a little too high. Long slow distance is a good mantra, particularly for beginners. It helps build a solid foundation, keeps injury away, gets your body accustomed to the stresses of exercise, and allows for more aggressive training once your muscles/tendons/ligaments/lungs have had an opportunity to adapt. Most people will focus on attaining distance before trying for speed.

What method did you use for determining your zones?

Something that has helped me tremendously is doing 2x20s on the turbo (spinner). I use the sufferfest videos, if you haven't seen 'em, check 'em out. They give you cadence recommendations and perceived effort which you can translate into your HR zones. There's a thread on here talking about improving bike speed and wattage, and one of the main things I got from it is a workout as follows:

Day 1: 2x20 (with a warmup, break in between, and cool down) sufferfest = Hell Hath No Fury

Day 2: 1x20 (w/u well, get after it hard, cool down ) sufferfest = the hunted 

Day 2 option 2: VO2 max work (w/u, 5x4min or something similar, cool down) suferfest = a very dark place

Day 3: light spinning or active rest

REPEAT