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715g approx. 20 litre capacity £39.99

BTR are a family run business: their cycling gear has grown out of the experience of family cycling in many and varied forms. In the case of the BTR Waterproof Bike Bag, this means a new take on some aspects of the design. Consequently, this old dog had to learn a couple of new tricks. With potential for bikepacking, commuting, and utility riding, there’s much to be said for its flexible, adaptable qualities.


Pros: waterproof, large capacity, adaptable, relatively inexpensive.


Cons: pack carefully, best on wider, longer racks, may obscure rear light.

BTR Waterproof rack bag bicycle cycle bike luggage bikepacking



100% waterproof Polyester is perfect for all-year round use, whether on backwoods bikepacking ventures or cycling home form work. The fabric is also very easy to clean, with little more than the wipe of a damp cloth.


The waterproof seal comes via the familiar roll top and plastic buckled straps: roll tightly and pull the straps tight.


There’s a single chamber inside, able to take a variety of items. However, although the base is reinforced it is not rigid. The twenty litre, approximate, capacity beats many of its rivals. On the other hand, stretching it out to its full size make things pretty bulky. 46cm is longer than many racks, whilst 22.5cm is wider than others (mind you, when packed the bag takes on a curved profile, so don’t worry too much): the height is 23cm.

The bag comes with robust three straps: two are integral to the bag, and a third optional rack strap if you expect the going to get rough. Unlike many rack bags, there’s no strap to loop around the seat post. There’s a detachable shoulder-strap, too, which turns it into a nice gym bag or such like.


At first the bag may appear symmetrical, but it isn’t. One end has a light loop and reflective detail. The loop is particularly important if you use a rack mounted light and the bag droops to obscure it. This was easily overcome; I strapped the Ravemen TR300 rear light to the loop.

Mounting 3.5/5


This isn’t as intuitive as it is with most rack bags I have used. Practice it, if you are going to be doing it in the dark; tricky, at first, rather than complex. Not all Velcro straps are easy to connect under a rack, either – so don’t view ‘the twist’ as too big an issue.

Fundamentally, the two longer straps are twisted round the rack tubing before being passed under the bag and twisted 

bag rack pack btr bicycle cycle bikepacking luggage
twist bike pcking btr bag mount rack bicycle cycle

around the opposite tube. Buckle it up and pull tight. The third strap works in a similar way, but is not linked to a strap and buckle for holding the rolled top in place. There are two buckles at each end to further fasten the roll-top and keep the weather out.


Getting the straps tight is important. As BTR say, the bag doesn’t move, let alone become dislodged – if you do. Packing and the items you are carrying have a part to play, too.


I’ve tried it on several racks. The Hase Pino’s 12cm wide rack, with tiered pannier rails, allowed a good deal off sag over the side. On the !4.5cm wide rack that graces the old Supergalaxy, was a better fit, likewise the beefy Tubus rack on the touring machine. Length of rack, or absence of slide protectors at the seat post end of the rack, plays a part, too, in how much the bag extends over the end of the rack. On the TorTec rack pictured here, the length of the bag was better supported. Mind you, with tight straps and a good twist, the bag did not move an inch – even if aesthetics may not have pleased fastidious friends.

rack bike train

Capacity/Packing 3.75/5


Soft construction and around 20 litres capacity promise lots of adaptability. This is an all-purpose bag. However, I have found it best when heavier items, such as a D-lock, are combined with bulkier, soft items, such as the family’s swimming gear. On their own, weighty bits of gear can sag. In itself, this is not necessarily a problem. However, speedier gravel riders may find movement within the bag a little disconcerting, at first.

rack bike bag btr

I was impressed that there was room enough for a solo off-road late summer camping trip for weekend, like the Zefal Adventure F10 – even without the latest, most lightweight gear – if coupled with a decent sized bar bag. Faster off-roaders may prefer full bikepacking gear and leave the rack at home.

bike packing bag tent sleeping mat burner bivi

Rigid, longer items, such as an E.Bike battery (check the length), folded tent poles, and such like, stiffen the shape and stop the end of the bag drooping over a rack mounted rear light. Smaller, loose items, such as a bit of grocery shopping, lock, spare lights, tools, have tended to move about inside the bag. No chance of escape, but not good for more delicate gear, such as your phone, bottles of beer lights, and such like.


Remember the twist: not intuitive, at first, especially if you are used to bags like the Zefal Traveller. In that sense, you may feel it is less convenient for commuting, perhaps, than for longer journeys where removal and attachment are less frequent. Moreover, my regular commuting stuff remains more organised in a rack pack with pockets and a rigid construction: on the other hand, I can’t pick up much shopping on the way home.


Waterproofing 5/5


Well, BTR say it is waterproof, and they aren’t making it up. Just ensure you roll the top and keep things tight. We are all pretty much familiar with roll-top cycling luggage. I’ve half a mind to bung it in the River Trent to see if it floats – I’d bet it would – but have resisted the urge.

Performance 3.75/5


Even in the context of mounting and packing foibles, it is hard to fault performance. The bag does not move around, even over the roughest ground. I’ve taken it along stony forest tracks at 17-20mph and bounced over setts, and there’s no hint of movement. On the other hand, loosely packed goods have shifted; destination reached, they’ve made their way to one side, however tightly I’ve pulled the straps.


Using the Ravemen TR300 rear light in the light loop proved pretty successful. With watch-strap pulled tightly in place, the light did not stand perfectly straight, but didn’t droop at an ungainly angle. The light was visible at all times.


Heading out with one-man tent, summer-weight sleeping bag, sleeping mat, gas, burner, and billies on board – and waterproof jacket, I was mightily impressed. Capacity surprised me; the bag was absolutely secure; gear shifted not an inch: tools, food etc was carried in a bar bag. Equally, when I was a touring novice of a threadbare budget, a dry bag and bungees performed a similar service – and still does when mounted upright on a Brompton rear rack. The BTR bag could be rigged like this, too

btr waterproof bag rack bikepacking cycling gravel commute luggage

Value 3.75/5


Comparison is not easy. Most rack packs are rigid or semi-rigid designs. BTR offer such models, in the twenty-thirty pounds bracket- water-resistant, as opposed to waterproof. Also water-resistant is the Zefal Z Traveller 60, offering similar capacity – in semi-rigid construction, but costing nearly ten pounds more. None offer the flexibility of the BTR Waterproof Rack Bag, even if they may be preferable in some other ways.


I’ve seen the £39.99 rrp considerably reduced. Mind you, a fully waterproof bag of this size for fractionally under forty pounds is relatively inexpensive.


A rack-less alternative would be something like the seat-post mounted Carradry SQR Bag. Significantly more expensive, it is equally waterproof and capacious: and you don’t have the weight of the rack on bikepacking and gravel ventures.




All adaptable all-rounders come with compromises. This could be a good addition to a heavy touring rig. It’s capacity as general luggage when away from the bike also suggest family or group trips to the leisure centre or the beach. On the other hand, whilst fine for the commute, my preference would be for a bag that allows more organisation and separation of items. Light-weight weekenders may well find it meets all their needs, too, although backwoods gravel adventurers may prefer seat-packs and frame bags. Such can be bought at £10 upward – but bring your own straps or bungees.


If you are after one bag to cover a host of needs, then the BTR Waterproof Rack Bag is well-worth a very close look.

Verdict: 3.75/5 Decent value, fully waterproof, adaptable bag, with minor drawbacks.


Steve Dyster




Ryton On Dunsmore

Coventry  CV8 3FH


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