Guide to Grates
There are a lot of different kinds of sewer drain grates in use in Baltimore, and not all of them are bad! To determine if a grate is bad, you can consult the pictures below, but there is an easy ways to check. I ride on 700C 32mm road tires which are pretty standard for road or hybrid bikes in the city - if you ride on wider tires, you might want to check the grate images instead.
After dismounting your bike, roll the front tire over the grate in the direction of traffic. If the tire falls into the empty space or gets caught, that's a bad grate. If a bike can stand up with a wheel in the grate, it's definitely deadly:
Simple, right? But you can't always tell by looking. For instances, this one has channels that go in the wrong direction, but they're short enough that I don't think they're a problem:
This one looks similar, but the channels are just long enough and just wide enough to grab the tire and send you over your handlebars:
This one seems fine until you look at the edge farthest from the curb - one big long channel for your wheel to get caught - and it's on the East entrance to Druid Hill Park:
The worst of the worst are these ones - long channels and deep holes:
You can also look at the many bad grates on the site for more examples!