Reddit mentions of SHIFT Racing Enforcer Adult Knee/Shin Guard Dirt Bike Motorcycle Body Armor - Black/One Size

https://www.amazon.com/Shift-Racing-Enforcer-Motocross-Motorcycle/dp/B005M16QY6/ref=sr_1_7?ie=UTF8&qid=1524477489&sr=8-7&keywords=Motorcycle+Knee+pads
Wear these under my pants, surprisingly effective for the cost.

I ride from San Pedro to Sherman Oaks 4 days a week year-round, splitting on the 110 and 405; about 38 miles each way. There are plenty of us who commute on a regular basis - I see a lot of the same guys out every day. I've never been down, and even the few close calls I've experienced really haven't been that close. It takes me around 45 - 60 minutes door-to-door. By car it's anywhere from 1:15 to 2 hours, and that doesn't include anomalous events like major accidents and lane closures.

Personally, I'd go mental if I had to do it in my car every day. Every now and then I cage it when I have to make a Costco run on the way home or whatever, and it's a miserable experience.

I ride a Ninja 1000 (less extreme ergos than ZX Ninjas). Commuting mods I've made are bar risers, a Russell seat (https://www.day-long.com/), and Givi tail trunk. As for gear, I wear kevlar lined jeans with hard shin guards underneath (http://www.amazon.com/Shift-Racing-Enforcer-Motocross-Motorcycle/dp/B005M16QY6), a textile jacket with armor, weather-appropriate gloves, and boots. I carry my work clothes with me on the bike and change in my office when I get to work, and again when I leave for the day.

If you become a regular 2-wheel commuter, I think you'll probably want a more comfortable bike. But if you can tolerate it for 45 minutes or so, you can give it a try and see if motorcycle commuting is for you. Hope to see you out there, and be safe!

The extra denim will add protection in a slide, but won't do much to pad you in an impact. You could pick up some cheap motocross knee pads for $20-$25 like these. I have a similar pair for dual sport riding. Another impact point is your hips and butt, not much you can do to pad those other than wearing an adult diaper, but as a bonus, you won't need to hit the rest stops as often.

Depends on what you're going for. If you want it to look like the comics, see KirbyW's comment. But if you want it to be 'realistic', I recommend something like this over a black turtleneck, with the proper blue (or red for current continuity, I guess) paint applied. For the pants, slim-fit cargos with shin guards, perhaps?

The mask is pretty easy, 'night mask', or if you want realism, maybe tactical goggles.

"Ninja" stuff might also be a nice touch (grappling hook, throwing knives etc.)

His traditional weapon is 2 eskrima sticks (buy a dowel rod from Hobby Lobby, cut it in half, paint), but collapsible batons could be an interesting alternative.

edit: added a link for goggles.

edit 2: added links for shin guards and knives.