If you want to run small errands around the neighborhood or have a place to put a purse, a front basket might be all you need. Baskets never have to be removed from the bike or locked up, and they can hold about 10 pounds of stuff. However, going beyond that can make steering hard and could possibly hurt your bike’s handling.

If you’re commuting regularly on your bike, though, we recommend getting a pannier to carry the stuff you need each day and a rear rack to hang it on. The racks we recommend can carry up to 55 additional pounds without having much impact on your ride, and you can use your pannier as a replacement for any number of different everyday-carry bags.

What makes a great bag is really personal, even when you’re talking about bags meant to go on bikes. I often find that no matter how many bags I have, I need (okay, want) them all, and I believe it’s because each one does a slightly different task perfectly. As much as I wish I had one bag that could do everything, when a bag excels at being unobtrusive as you move through your day, it’s because it’s performing a monotask and performing it well.

As such, bag testing is a lot about figuring out exactly what any given bag does best and who would want that bag. We do that in every Wirecutter guide—spelling out who the product is for—but with bags, recommending a good one is all about cracking that code.

So to find the best panniers, we researched 82 different models and then chose 26 to test in person. We rode with these bags for nine months on city streets, and asked these questions:

What can it carry? And how? We laid out 28 different items that a bike commuter might carry, and filled each bag with as many as we could.

Everyday-carry items:

Keys

Phone

Wallet

Transit card

Chapstick

Pen and pencil

Notebook

Water bottle Portable office items:

Laptop and case

Laptop charger

Earbuds

Phone cable

USB wall charger

External mouse and case

Laptop stand Bike accessories:

Patch kit

Front and rear bike lights

Bike lock

Windbreaker

Warm hat Extras:

A change of clothing

An extra pair of shoes

A small lunch

Reusable silverware

Will it stay on the bike? Rescuing a laptop from the middle of the street is not how anyone wants to start their day, so a durable mounting system is important. Also, pannier hooks that are mounted against a crossbar are easier to mount. In addition, a stiff back on the pannier and a bottom hook add additional security and make the weight easier to handle when it’s on the bike.

Will it come off the bike easily? This is the paradox of pannier mounting systems—it must stay firmly barnacled to your bike rack, except of course when you want to take it off. Then, it must release with hardly any effort. Unlike a touring cyclist, who might leave their panniers on for days or weeks at a time, a commuter removes them every time they park.

Will it hit your heel when you pedal? The best panniers are shaped to avoid heel strike and made to keep the load low on the bike. In general, bags that do this well are slightly tapered at the bottom and tend to be taller than they are wide.

We did not look at bags designed specifically for bicycle touring. We also dismissed saddlebag-style panniers (the kind that are attached in the middle with fabric); they’re meant to be left on the bike and are difficult to carry once you take them off.