I currently only have a mountain bike in the “stable” (which I bought with the proceeds from all of the Dura Ace 7800 parts that used to be on my road bike). One of the local city parks now has a series of trails. Super well built, they manage through intense curving to eke out a good few miles of constantly up and down singletrack action within only a few acres. I’m always on the rivet, but probably never going more than 20mph.
As I found in Baltimore (where much of my mtb riding took place on a similarly constrained spatial scale), it is surprisingly easy to convince myself on the mtn bike that I could quickly get some fitness again and maybe even race. But, then I look at pictures of real mtn bike racing and remember that you have to descend in these races as well.
This shit would give me nightmares: