Cramps seem to be somewhat random, but getting more fit helps as much as anything.
My theory on the tandem: I pedal however hard I think I should be pedaling, stoker pedals however hard she thinks she should be working, and whatever happens, happens, whether that means going 10 mph or 30 mph. Staying with groups works sometimes, sometimes it doesn't.
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"be careful this rando stuff is addictive and dan's the 'pusher'."