I'm a fairly keen (fair weather) cyclist and have never ridden a tandem bike. It does strike me though that (in my atrophied mechanical engineering mind) that it would be "better" if the front and rear pedals were off set by 90 degrees. Now I'm sure I'm not the first person to think this but as all the tandems I've seen the pedals are in synch there must be a good reason why.

I can only think of one possible reason: when starting off only one cyclist can apply pressure to a pedal i.e. starting at half power.

Any tandem riders out there?