How Much Bag Volume You Actually Need, by Trip Length

Bag capacity is sold in litres, and litres are a poor way to decide anything. Twenty litres on the handlebar and twenty litres in the frame triangle are not remotely the same bike to ride, and neither of them tells you whether you can sleep out on Saturday.

A more useful question is: how long are you away, and what has to come with you? Answer that and the volume works itself out.

Two hours to a full day

What you actually need is a tube, a pump, a multi-tool, a phone, cards and keys, something to eat, and a layer for when you stop. That is a small volume of quite dense things and one soft item.

The whole lot fits in a small saddle bag and a stem bag, or a half-frame bag on its own. If you commute and want the keys and cards to walk away with you, a hip pack takes that short list off the bike.

The mistake at this end is buying big. A large bag carrying a day's kit is mostly air, and air moves around.

One night out

This is the jump, and it is the one worth planning properly. It is also where bikepacking starts being a different activity from a long day ride: you are adding a sleeping bag, a mat, some form of shelter, more food, and more water.

The sleeping kit is the defining problem: bulky, light, and compressible. It wants a position where volume is cheap and weight barely matters, which means the handlebar or a saddle bag. Everything else you are adding — food, water, a stove, a battery — is dense and wants to be low and central, in the frame triangle.

Most people land somewhere between fifteen and twenty-five litres in total for a mild-weather overnight, split across two or three bags. The total is less interesting than the split. The same twenty litres in one large bag on the bar makes the steering vague and the bike unpleasant on anything loose; spread across a handlebar bag and a frame bag, you barely notice it.

Three or four days

Almost nothing new goes on the list. What changes is how much food and water you carry between resupply points, and that is dense weight.

So the extra volume goes low: a fuller frame bag, a pair of fork bags for water and food, or a rack. Adding it to the handlebar instead is where trips go wrong — you end up with a heavy, wide bar bag and a bike that wants to fall into corners.

This is also the length at which a rack starts to make sense rather than being overkill. A rear rack and a trunk bag put weight over the axle instead of behind it, and they carry it without any of the sway you get from loading the saddle.

A week and beyond

Past a few days the equation stops being about volume at all and starts being about resupply. Two riders on the same route can be carrying wildly different loads depending on how far apart the shops are.

What is consistent is that long trips end up on racks. Panniers and trunk bags carry the most, they sit low and over the axle, and they are the only setup where the bike still handles predictably fully loaded. The frame bag stays for tools and water; the handlebar keeps the sleeping kit; the rack takes everything the trip added.

Buy for the riding you do

The most expensive mistake in this category is sizing for the trip you might take one day. A bag bought for a week is a bag that is two-thirds empty for the other fifty-one weeks, and an empty bag does not sit still no matter how many compression straps it has.

Buy for your ordinary rides. When the longer trip appears, add a bag for it — that is the whole point of a system built from separate pieces rather than one big container. Which pieces, and in what order, is the subject of how to build a bike bag system without overpacking your bicycle, and the other direction — what you can safely leave at home — is in are you overpacking for bikepacking.

Weigh it once, before the first trip

Volume is what people plan and weight is what they feel. The two come apart badly: a compressed sleeping bag is enormous and light, and a bag of tools is small and heavy, and the second one is what makes a bike unpleasant to ride.

Put the loaded bags on a set of bathroom scales once. Weigh yourself, then weigh yourself holding them. It takes two minutes and it tends to end arguments — most people are carrying two or three kilos they would not have chosen to carry if they had seen the number.

It also tells you where the weight is, which is the part that matters. If more than half of it is above the axles or behind the saddle, the bike will tell you about it on the first descent.

A rule that works better than litres

Put the dense things low and between the wheels. Put the bulky light things wherever there is space. Then take the bike round the block loaded before you commit to the route — a setup that feels slightly wrong in a car park feels a lot wrong forty kilometres in.

If you want the bags cut to your bike

We build to measurement, which is most of the reason our bags fill the space they are given instead of nearly filling it. Write to [email protected] with your frame measurements, what kind of trips you actually ride, and what you are carrying now. We would rather talk you into two well-placed bags than sell you one large one.

Questions we get asked

How many litres do I need for an overnight bikepacking trip?

Somewhere around fifteen to twenty-five litres total for most people in mild weather, spread across two or three bags. The spread matters more than the number: the sleeping kit is bulky and light and wants the handlebar or the saddle, while the tools, food and water are dense and want the frame triangle. The same total in one big bag rides much worse.

Is it better to have one big bag or several small ones?

Several. Splitting the load lets you put dense items low and central and bulky items where volume is cheap, which is the whole reason a loaded bike can feel normal. One large bag forces everything into one position, and that position is always wrong for half of what is inside it.

Should I buy for the longest trip I might do?

No, and this is the most common expensive mistake. A bag sized for a week is a bag that is two-thirds empty on every ordinary ride, and an empty bag flaps and shifts no matter how well you strap it. Buy for the riding you actually do and add a bag when a longer trip comes up.

How much room does water take?

More than people plan for. Two litres is two kilos and roughly two litres of volume, and it has to go somewhere low. Bottle cages handle it if the frame bag leaves them clear; a bladder inside a full-frame bag carries more and sits lower. Either way, count it as part of the load rather than as an afterthought.

What if my bags end up half empty?

Compress them. Roll-top closures exist for exactly this, and rolling three or four extra turns takes the slack out. If a bag is habitually half empty, it is the wrong bag for your riding, and the honest fix is a smaller one rather than more compression straps.