Originally Posted by
smashndash
TrainerRoad should have a lot of stuff about this. But my uneducated advice is to try some polarized training. 80% really easy and 20% really hard. Don’t do a bunch of medium pace riding. That fatigues you but doesn’t force much adaptation.
This isn't what 80/20 is. 80/20, as popularized by Seller, means 80% of your training sessions are easy, 20% are hard. I.E., out of 10 rides, eight of them are easy rides, two of them are hard rides. That is a HUGE difference.
And in any case, it's kind of pointless unless you really don't like going hard.
Tempos and threshold work (all that "mid-range" intensity) is going to give you the biggest return for time investment if you don't have a lot of it. For 6-7 hours a week, you can conceivably work up to 3-4 hours of tempo and threshold. That gets you fast way faster, especially in terms of "cruising speed".