Recently purchased the DRT 1.1 (loving it so far!) and am looking for recommendations on a child bike seat that is compatible with my DRT. I'm newer to biking so I'm not 100% what I should be looking for so any help would be much appreciated!
Welcome to the community and thanks for the question! We're stoked to hear that you're loving your Co-op Cycles DRT 1.1. The correct child carrier will depend on the age and weight of your kiddo, so you'll want to make sure to check the specs on the seat for compatibility.
You have a couple of options for mounting a child seat on your bike. Two considerations you want to think about are your wheel size and brake style. Because your bike has 27.5" rims and tires, the circumference of the wheel comes in to play when choosing a child seat, particularly if you go with a rack mounted system. This is the same for the disc brakes on your bike. You'll want to keep that in mind if you go with a rack mounted system as the disc brake rotor makes the spacing at rear hub a little bit wider.
As such, we recommend a system like the Topeak BabySeat II Rack Disc which gives you a rack system and a child carrier together. You could also go with a rack like the Thule Ridealong Child Bike Seat, which attaches to the seat post of your bike and does not require a cargo rack on the back for support.
Lastly, we encourage you to check out this conversations, DRT 1.2 and Thule Yepp Rack, and read about @HaveKidsWillTravel's epic journey to get their bike rack to work. They managed to persevere and get it set up, but it came with some challenges to put it mildly. That thread has some great information that could help make your process easier.
Hopefully this helps, feel free to reach out with any other questions!
Depending on the type of riding you're doing and your comfort level, you could also check out some of the "mid-mounted" or "non-traditional front-mount" seats that have come out recently specifically designed for mountain bikes to actually go off road. The kid sits between you and the handlebars. Their main advantages are that the child's weight is more centered over the bike and so the handling doesn't feel so off when riding with a kid, and they do not require a rear rack so brakes and tire size don't really matter, there's wide compatibility. The most obvious negative is that they are literally just seats/saddles with some foot pegs attached: the child is not strapped in in any way, and they must have the necessary balance to stay seated on their own.
That can be a scary prospect, and there are safety arguments for and against it since it's a bit different to a car seat where you're inside an external frame. It's something you'd have to decide for yourself if it's for you. For my part, I have actually crashed a few times with my daughter on ours and we've been okay due to a combination of slower speeds and they are cradled between your own arms so you can sort of shield them with your body. She cries briefly but more that she's no longer on the bike than ever having been injured. We have used it since she was about 20 months old, now 25m, and they're typically rated for kids up to 5 years old/size 5 clothing.
Although I don't believe REI carries either one, the two major brands are: