I chose to test these four levers after eliminating everything out there that’s not appropriate for a roadside emergency kit. That includes metal levers. They’re durable, but according to touring cyclist Ramona Marks, “Metal tire levers are trouble. It’s possible to rip your tube even with the plastic ones if you’re not careful, so metal is out of the question, and you don’t want to put pressure against the wheel rim with a metal lever.”
Writer Peter Flax, the former editor-in-chief of Bicycling magazine, rode over 1,000 miles and tested 15 tools for our full-length guide to multi-tools, and he concluded the Topeak Mini 9 is the best for casual cyclists. It’s tiny, it’s light, it’s easier to get some leverage with than other tools that have different designs. It’s not meant for serious wrenching on your bike, but it’s good for on-the-fly adjustments.
A pair of disposable latex gloves:  Not absolutely necessary, but good for keeping grease and grime off your hands during a repair.  Also, nice to have in an emergency when it starts raining and the temperature drops 20 degrees and you don’t have a pair of regular gloves.   Just keeping your hands dry and the wind from directly blowing on them makes a huge difference in comfort.
If you’re going to use the chain whip you just made, you’ll also need a way to get that cassette off. A lockring remover is a must-have; unless you use one of the shady removal methods I’ve seen on the internet—which I wouldn’t necessarily recommend unless you don’t care much about the condition of the wheel after you use them. I recommend Park Tool’s iterations here that cost about $6, but you’ll need to buy the specific one for your brand/type of cassette. (By the way, I’m assuming you already have an adjustable wrench laying around somewhere to use with this tool. If you don’t, well, you’ll need one of those too.)

That’s a reality of all hand pumps—it’s really hard to get a tire up to pressure with these things. So another reason Lezyne pumps are so good is because you can actually keep pumping longer than any other brand we tested. With excruciating effort, we could get the Sport Drive HP to pump tires to 90 or 100 psi. It still wasn’t easy, but it wasn’t impossible the way it was with some other models.

Brakes come in a variety of designs depending on the age and style of your bike. Rim brakes offer more modulation but have less stopping power, so are more suited to riding on the roads. Disc brakes can provide huge amounts of stopping power so are best suited to off road riding, although ‘V’ rim brakes are also well suited to mountain biking. All brakes use a friction system to stop the movement of the wheel, so regular checks of the contact pads should form part of your regular cycle maintenance.