I had two reasons to head out to where the bike path passes the north end of Coal Canyon.
First, I'm trying to stack up as much time as I can on the bike to complement the strength work I'm doing. 90 minutes at 140BPM/100RPM is perfect for that.
Second, I wanted to check out access to the climb up Coal Canyon through Chino Hills State Park.
By the time I got there, it was dark and drizzling. Access to Coal Canyon seems to be via an underpass under the 91 FWY there, but the terrain looked a little chunky for my road bike, and I just didn't want to go stumbling around in my road bike shoes, alone, in wet weather 45 minutes from home. Should be fine in good weather on a mountain bike, though.
When I have time, I'll take a mountain bike recon ride to scout access to Coal Cyn and Chino Hills State Park from near that point where the Santa Ana River Trail bike path meets Green River Rd.