For those who aren't strong and fearless cyclists, Strava can be helpful, but be careful and double-check those routes. I've seen some pretty dangerous segments that I have been very scared on, and they show up red-hot on Strava. Why? Probably because some die-hards go that way a lot, or go that way in a group. And those are probably the types of people that use Strava more than the casual commuter.

In my city there's a 5 lane bridge, shoulder just wide enough for drains, and nothing but a 3-ft concrete barrier 60 or 70 feet above the river. The speed limit is 45, but people drive like that's a mild suggestion. This is a very hot cycle route on Strava for some reason, but I think it's frightening.