How to Keep Your Backpack Dry While Cycling to Work

You've checked the forecast, decided to risk it, and halfway through your commute the sky opens up. By the time you lock up at the office, your backpack is soaked through. Your laptop's fine (you hope), but your spare shirt is damp and your lunch bag is sitting in a puddle of rainwater. Sound familiar? A decent waterproof backpack cover solves this problem for under twenty quid, and it takes about five seconds to fit.

The UK averages around 156 rain days per year. If you cycle commute even three days a week, you're going to get caught out regularly. Here's how to keep your bag and everything inside it bone dry.

Why your backpack isn't as waterproof as you think

Most everyday rucksacks are marketed as "water-resistant," which really means they'll handle a light drizzle for ten minutes. The fabric might repel surface moisture, but water finds its way in through the zip seams, the stitching, and anywhere the material is under tension from a heavy load. Once water gets through the outer layer, it soaks into the padding and takes hours to dry out.

Cycling makes this worse. You're moving at 15-20mph, so rain hits your bag at an angle and with more force than if you were walking. The airflow pushes water into gaps that would stay dry at walking pace. And if you're riding behind traffic, road spray from below adds another layer of soaking your bag never signed up for.

The simplest fix: a cycling backpack cover

A dedicated cycling backpack cover is the fastest and cheapest way to waterproof the bag you already own. You don't need to buy an entirely new bag. Just stretch the cover over your existing rucksack, tighten the straps, and ride.

Good rain covers use a waterproof membrane (typically PU-coated nylon or polyester) with sealed seams. They weigh next to nothing, usually under 100g, and pack down small enough to live permanently in your bag's side pocket. When the rain starts, you pull it out and fit it in seconds.

What to look for in a rucksack rain cover

• Sealed seams: taped or welded, not just stitched. Stitching creates needle holes that let water through
• Secure attachment: a single elastic opening won't cut it on a bike. Look for a three-point strap system or hook-and-loop fasteners that stop the cover flapping or blowing off at speed
• Hi-vis or reflective material: if you're commuting in poor light, a bright hi vis backpack cover doubles as a safety feature. Reflective strips catch headlights from behind, right where drivers need to see you
• Size range: covers are sized by bag capacity (usually 20-35L or 35-55L). Too big and it flaps in the wind. Too small and it won't stretch over your bag properly

The BTR waterproof backpack cover ticks all of these. It's fully waterproof with a three-point strap system designed specifically for cycling, and the hi-vis yellow with reflective strips makes you visible from a distance. At under £15, it's a fraction of the cost of replacing a water-damaged laptop.

The belt-and-braces approach: cover plus dry bags

If you carry expensive electronics or important documents, don't rely on any single layer of protection. The smartest commuters use a waterproof backpack cover on the outside and dry bags or waterproof pouches on the inside.

A lightweight dry bag (the kind sold for kayaking) costs a few pounds and keeps your laptop completely isolated from moisture. Even if water somehow gets past the cover, through the gap where the bag meets your back for instance, your electronics stay dry. This is the approach experienced cycle commuters swear by on forums and Reddit threads: two layers of protection, zero worry.

For clothes, a simple plastic bag works. Roll your work shirt, drop it in a carrier bag, and stuff it in the main compartment. Not glamorous, but effective.

What about waterproof backpacks?

You could buy a dedicated waterproof rucksack instead. Brands like Ortlieb make roll-top bags with welded seams that are genuinely watertight. They work brilliantly, but they cost £80-£150 and you're locked into using that specific bag for every commute.

A rucksack rain cover lets you use whatever bag suits your day. Got a slim laptop bag for office days? Cover it. Bigger bag for gym kit on Fridays? Same cover stretches to fit. That flexibility is worth a lot more than most people realise until they've committed to a single-purpose waterproof bag.

Quick tips for dry commutes

• Fit the cover before you leave: if it looks even slightly grey outside, put the cover on before you set off. You won't want to stop and fumble with it mid-ride when the rain starts
• Keep the cover in your bag permanently: they pack down to the size of a fist. There's no reason not to carry one year-round
• Check the seams every few months: UV exposure and folding can degrade seam tape over time. A quick inspection takes thirty seconds
• Dry the cover after use: shake off the excess water and hang it up at the office. Stuffing a wet cover back into your bag creates a damp environment that can transfer moisture to your belongings
• Pair with mudguards: a cover protects from above, but road spray hits from below. Mudguards on your bike stop the worst of the spray reaching your bag and your back

Don't forget your phone

Your backpack isn't the only thing that needs protecting on a wet commute. If you use your phone for navigation, a silicone phone mount keeps it accessible on the handlebars. For heavy rain days, stashing your phone inside your bag (in a waterproof pouch) is the safest bet. We've written a full guide on keeping your phone dry while cycling if you want the detail.

The cost of getting it wrong

A soaked laptop repair can run into hundreds of pounds. Even without electronics damage, arriving at work with damp clothes and a soggy lunch isn't a great start to the day. One forum poster described finding a teaspoon of water trapped between their MacBook screen and keyboard after a single wet commute. That's all it takes.

A waterproof rucksack cover costs less than a round of coffees. It weighs almost nothing. It fits in seconds. There's really no reason to leave it to chance.

If you're still building up your wet-weather commuting kit, our complete guide to cycling in the rain covers everything from jackets to lights. And if you want to compare different backpack cover options, the best waterproof backpack covers buying guide is a good starting point.

Frequently asked questions

My rucksack came with its own built-in rain cover. Is that enough for cycling?

Built-in covers are designed for hiking or walking, not cycling speeds. They usually have a single elastic hem and no strap system, so they flap or lift off on a fast descent or in a headwind. They're also rarely hi vis, which matters more when you're sharing road space with drivers than it does on a trail. Keep yours for walking days and buy a cycling cover with a three point strap system for the bike.

Can I just spray my rucksack with waterproofing spray and skip the cover?

Waterproofing sprays help the outer fabric bead water off, but they don't seal the bigger leaks that actually soak your stuff. Zips, seam stitching and the back panel pressed against your jacket are where water finds its way in, and no spray fixes any of those. Nikwax or Grangers treatments are worth applying anyway, but pair them with a proper cover for the commute. Spray alone is fine for a ten minute walk, not for a rainy ride to work.

What do I do if rain starts mid-ride and I didn't fit the cover before setting off?

Pull over somewhere safe, ideally under a shop canopy, bus shelter or tree line, and fit the cover straight away. It takes about ten seconds once you've done it a couple of times. If you're on a cycle lane with nowhere to stop, pick the next side street or junction rather than trying to fit it while riding. In future, check the forecast the night before and fit the cover at the start of any ride where rain is on the cards.

How do I dry out a soaked rucksack if I didn't have a cover fitted?

Empty it fully and open every compartment and pocket, since padding and liner foam hold onto moisture for hours. Stuff the main compartment with newspaper or paper towels to pull water out from the inside, and swap the paper once it soaks through. Hang the bag upside down somewhere warm with airflow, ideally an office radiator or drying room. Most rucksacks are back to normal by morning if you act straight away rather than leaving it crumpled on the floor.