I have some friends that have a cabin up there, right near Snow Summit (where the MTB Park is), so I ride up there with them a reasonable amount.

My favorite trail in Big Bear is Skyline Trail. There’s a number of ways to get up there but a good route from Snow Summit is to take the doubletrack road called Bristlecone east from the Snow Summit parking lot. From that climb Fern trail up to Skyline and then ride east to west on Skyline and get off at the intersection of Skyline, Pine Knot and Grandview. Descend the upper part of Pine Knot to Knickerbocker fireroad to Town Trail, which will dump you back into the Snow Summit parking lot. It’s a 15ish mile loop.

Pine Knot all the way to the bottom is also a really nice trail but it kicks you out a little distance from Snow Summit and you’d have to ride back to meet your friends on the road. Nice trail but not worth it in your context.

On the other side of the lake, in Fawnskin, I like Grout Bay and Hannah Flat as an out and back. You can ride there 20 min or so from the Snow Summit area, mostly on the bike path. But it’s hotter and drier over there, not fun if you want to sleep in til 10.

I don’t know much about the trails in the bike park. I climbed up Fern once and down Pirates & Fall Line (in the bike park). Those trails were so chewed up that I found it no fun. So I’ve never ridden in the park since.

You can ride around the lake on a road bike (I guess on a mtb too but that would be a slog). There’s not really any shoulder on the roads though, and lots of vacation-headed drivers. I personally don’t care much for the road riding options and would avoid it during prime summer season. Just too hairy.

Have fun, I love the mtb trails in Big Bear.