Matt from profitgreenly.com
Matt is a retired engineer, current full time dad. He's been biking for transport for decades now in cities all over the country. These days you'll find him riding his kids around his small PA town in a Madsen bucket bike and blogging about biking and other ways to save energy and money at profitgreenly.com.
1. Niterider Mako 200 USB light. This is the light that gave me the confidence to finally ride at night. After I got it I started riding poorly lit suburban roads back from work late at night and really decreased my car use. It also let me ride in the winter when there's less sun, and to evening music shows, parties, and evening grocery trips. It's old enough that it doesn't seem like they actually sell my exact model any more. The Makos now look like they run on regular batteries which will quickly cost more than the light itself but the Swift 500 seems like an upgrade to my Mako that is still USB chargeable. Any USB rechargeable headlight that provides 200 lumens or more of light and can easily be put in your pocket would be fine. Lights like these used to cost hundreds of dollars, but now you can find them under $40. Honestly, I think new bikes should be required to have lights built in just like cars, they're so important to safety.
2. Third Eye Pro Helmet Mirror. Honestly I owned this mirror for years before I started regularly riding with it. The problem was that the double sided tape it came with did not hold to my helmet for long and it kept falling off. I finally solved this by wrapping electrical tap around it and the a plastic strip in my helmet. Having a mirror while riding now has honestly been a revelation. Instantly seeing behind you without having to physically turn around is really nice, particularly when biking a cargo bike filled with children. I have grown so accustomed to the mirror now that I find myself looking for it when walking even. I don't think this model is the best mirror and honestly I'd like to see a helmet maker actually integrate one instead of them all being add ons, but even a bad helmet mirror is a million times better than no mirror at all.
3. Ortleib back roller classic panniers. I think of these as another essential item for making a bike truly useful (of course you'll also need a rack to mount them on). I hate the feeling of wearing a heavy backpack while riding, so panniers are my go to way to transport stuff. These roll up to be totally waterproof so you can keep your laptop and phone dry in a rain storm. You can also leave them open and fit a ton of groceries in each, I've hauled 40 lbs of groceries with them without issue. The best thing about these for me is how they secure to your rack. Other panniers I had in the past would sometimes fall off my bike while riding. Luckily they were filled with books, not groceries or electronics, but falling off is just inexcusable. These are always secure, but when you get where you're going a simple pull on a strap removes them instantly. Their shoulder carrying straps let you easily carry them around for short distances and double as extenders to their tie down straps to help you secure huge loads. They're also super durable, mine have been going strong for nearly a decade now.
4. DIY GPS Bike Tracker. My main ride for years has been a 1989 Cannondale touring bike I got used for $300. I used a u-lock and locking wheel skewers to keep it safe, but mostly relied on it being cheap and old to avoid theft. When I bought an expensive Madsen bucket bike to haul my kids I decided that I needed to up my security game. Even my beefy fahgettaboudit lock could be cut by a battery powered angle grinder in a few seconds and the huge Madsen bike is hard to fit on a bike rack for locking. I decided I wanted to add GPS tracking to it, but all the trackers I found online cost a lot per month and I don't have faith that the companies that sell them will keep supporting them for years to come. I decided to DIY my own GPS tracker out of an old android phone I had laying around and connect it with a Google Fi data only sim card. This costs me about $1/month for data and I'm confident that Google will keep supporting the software I power it with for a very long time. Now I just lock my Madsen with the front wheel lock right where I'm going and don't worry about it being stolen. It hasn't been taken yet, but if this happens I'll be ready.
The full instructions on how he made his GPS bike tracker are at Matt's website, along with an analysis comparing the emissions/costs of ebiking to driving and regular muscle biking.