Wheels or straps: the ground decides the bag

These are listed in the order worth acting on, which with choosing luggage is not the order they are usually presented in.

The physics is the whole argument

A wheeled bag puts its weight on the floor, so a twenty-kilogram case is nearly effortless on smooth tile and nearly immovable on a staircase. A backpack puts the same weight on your hips and spine, which is constant work but entirely indifferent to the surface. The decision is therefore a question about the ground between the station and the door, not about the bag.

Anyone who has dragged four wheels across cobbles at night has done this calculation the expensive way.

Where wheels win comfortably

Modern airports, business hotels, conference centres and rail stations with lifts are designed for wheeled luggage and reward it. Four-wheel spinners glide alongside you and take the load off your arm entirely, which matters on long terminal walks. Anyone with a back, shoulder or knee problem should treat wheels as the default and work around the exceptions.

For heavy loads on good surfaces there is no contest at all.

Where straps win

Old city centres, unpaved streets, stations without lifts, ferries, minibuses and anywhere with more than a flight of stairs punish wheels immediately. A backpack also frees both hands, which matters for tickets, doors, children and handrails. It fits overhead lockers and luggage racks that a rigid case does not, because fabric deforms and a shell does not.

The cost is that you feel every kilogram, which is a useful discipline and a genuine burden.

The hidden weight of the mechanism

Wheels, axles, a telescopic handle and a rigid frame together weigh roughly one to three kilograms depending on the bag. On a carrier with a strict cabin weight limit, that is a meaningful share of the allowance spent on the bag rather than the contents.

Frameless backpacks are the lightest option but transmit awkward loads straight to your back, which is why an internal frame is usually worth its weight. Compare bags by empty weight as well as by capacity, since the figure is published and rarely looked at.

Failure modes differ

Wheeled bags fail mechanically: a sheared axle, a jammed telescopic handle or a cracked shell, none of which is repairable on a Sunday in a foreign city. Two-wheel bags with recessed wheels survive rough ground far better than four-wheel spinners, whose external castors snap on kerbs. Backpacks fail at zips and buckles, both of which can be bodged with a cable tie or a safety pin.

The working rule: neither is fragile in normal use, but only one leaves you carrying it.

Allowances vary by fare class more than by airline.

Hybrids and the honest compromise

Wheeled bags with stowable shoulder straps exist and carry the penalty of both systems: the weight of the wheels and a harness that is rarely comfortable. They work well for trips that are mostly smooth with one difficult section, and badly for trips that are mostly difficult. A duffel with backpack straps is the lightest genuinely versatile option and the least comfortable when full.

On a long trip, choose for the hardest hundred metres of the trip, because that is the section that decides how you remember the bag.

Everything above, in order of what to do first

1. The physics is the whole argument. A wheeled bag puts its weight on the floor, so a twenty-kilogram case is nearly effortless on smooth tile and nearly immovable on a staircase.
2. Where wheels win comfortably. Modern airports, business hotels, conference centres and rail stations with lifts are designed for wheeled luggage and reward it.
3. Where straps win. Old city centres, unpaved streets, stations without lifts, ferries, minibuses and anywhere with more than a flight of stairs punish wheels immediately.
4. The hidden weight of the mechanism. Wheels, axles, a telescopic handle and a rigid frame together weigh roughly one to three kilograms depending on the bag.
5. Failure modes differ. Wheeled bags fail mechanically: a sheared axle, a jammed telescopic handle or a cracked shell, none of which is repairable on a Sunday in a foreign city.
6. Hybrids and the honest compromise. Wheeled bags with stowable shoulder straps exist and carry the penalty of both systems: the weight of the wheels and a harness that is rarely comfortable.

The takeaway

Map the worst surface on the route, then choose. Everything else follows from that.

Every kilo you leave behind pays you back at the third connection.