smilingcat is (once again!) correct. The roads are barren out there, they are narrow, and there can be traffic especially on a weekend. I lived in the mountains north of there (Lake Arrowhead area) and used to travel off the mountain to ride. I take it you won't be with a group?

I used to do a really great loop starting at Cal State San Bernardino. The traffic wasn't all that bad and there were enough hills to make it interesting PM me if you want it but I think it is too far away from you. Hey, you know what...I believe there is a Redlands Cycling Club. I bet they have a website (or maybe Riverside does also) with some bike routes.