All of the above. I'm a lot faster on my road bike, but nothing whips you into shape better than participating in group rides a couple times per week with the except of being coached. I've noticed since stopping a lot of my recreational riding and just commuting that I have lost some speed despite the fact that I'm getting a lot of hours in on the bike. I guess part of it is that I just run myself into the ground commuting as often as possible which contributes to poor recovery.