I posted a similar thread on the old forum and got a couple of ideas I still use.

Warm up then 1 min hard 1min rest 2mins hard 1min rest up to 5 and back down to 1 again then cool down time.

Or I try to keep my cadance above 180 in various gears for a 20 min effort.

Or 5min easygear fast feet 5min hardgear above 85% HR for a 40 minute session.

I do like it in winter just for a change but I sweat buckets.

Hope this helps.