Two final workouts for trainer:
Who says trainers can't be good workouts- I think they are better. look at the structure:
Workout one- pick a gear- ride it for ten minutes, then upshift- repeat, upshift, repeat, until destruction! This works the legs and kicks up aerobic threshold:

(p/s the joke here is cadence- the blue line- look in how zone "7" marked in pen the cadence is all over the place- at that point I was out of the saddle sprinting trying to maintain power- I couldn't sit anymore)
Two:
Intervals- strong medicine. one minute on. one minute off. look how the HR goes anearobic, recovers, then up//down again, on a slightly increasing sloping until destruction!!!! ps- destruction occurs when recovery (in areobic) climbs to anearobic- so everything is anearobic-look at the bottom of the peaks and how it comes up to the anearobic horizontal red line
These are two great workouts which you can't reproduce on a group road ride (remember the one all over the place).... Think in terms of how the road rides go up and down- and how the structured rides have a horizontal HR. THINK HORIZONTAL!!!!!!