**Mounting systems: **Think about attachment points—is your sissybar tall enough for the bag? Too wide? Will the bag sit on the passenger seat or does it require a dedicated luggage rack? Also consider a universal mounting system for versatility.
**Rigid vs. soft: **At least some type of structure is a good thing to have in a bag; it makes for easier packing and unpacking. Rigid bags are also more supportive backrests when you flip them forward to rest on the passenger seat.
**Weatherproofing and durability: **Many bags come with their own rain covers, but material construction can make a big difference in surviving the elements. Leather has visual appeal, but heavy-grade nylon is probably a better choice for all-weather durability.
**Capacity: **Bigger is not always better, especially when mounting something tall and heavy on the back of your bike. Cargo can severely affect a motorcycle's center of gravity, resulting in poor handling or, worse, loss of control. Keep the heaviest part of the load low and as close as possible to the bike.
**Convenience: **A host of welcome features are apparent in the latest luggage designs on the market. Two of our favorites are backpack straps (make sure they're padded) and roller wheels (the lower the profile, the better).