It's funny. I get way worse of burn in my quads from just riding around the adjoining neighborhood, because it's all hills, so quick downhill, and then constant grind back up. But, the rest of me is actually sore from having to constantly fight to stabilize and keep control of the bike. It's a definite whole-body workout.
Junior described it as "fun but terrifying". We didn't even make it onto the actual trail before she had already rear-ended me. She has no concept of progressive braking to scrub speed. She starts rolling, has an "oh shit" moment, then locks them up and slides, exacerbated by the fact that she doesn't think to shift her weight back to let the rear tire have any real bite. She literally had to bail and went face first into a tree about 2/3 into the loop. I looked back over my shoulder, and it looked like the Coyote had hit a phone pole going after the Roadrunner. I am wondering if I should just pay the $100 for the kit and convert her to hydraulic brakes, which have way more initial bite/progressive grip than her mechanical discs do, and maybe a little more confidence.
For our next outing, I will definitely stick to the nicer areas of town and go with something known to be a little easier. The Whitewater Center has some really good easy ones (more mileage but much flatter/hard packed dirt), and the local membership-only greenway does also, but both were closed due to all the rain we've had. I think we may try the greenway next, and hopefully on a weeknight where there won't be much of any other bike traffic. There were only two other people on the loop we went to, and we never saw them other than in the parking lot. I think if a lot of experienced riders go whizzing by her, she'll get intimidated by it.