If you regularly fly with a folding bike, you will know all about baggage handlers, the meticulously trained gorillas employed by airlines to heave your precious possessions from tarmac to hold and vice versa.

With a full-size bike, air-carriage may be expensive and time- consuming, but you can at least be confident that something so evidently fragile won’t get lobbed around too much. For folding bikes like the Brompton – that look much like other bit of luggage, but are both heavier and more fragile – it’s a different story.

Brompton has produced a bike cover for many years, but it’s more about disguise than protection, and there’s a coherent argument for leaving the cover off, in the hope that the handling-gorillas will show a little compassion.

The only real alternative is a conventional hard case – we usually suggest marching into a luggage shop with your Brompton and choosing a size that will comfortably take the bike, plus a few pairs of knickers and classic lightweight trousers tucked in where space permits.This will protect the bike against most eventualities, but makes life mighty difficult at point B. In short, what do you do with the case when you arrive? One option is to throw the whole lot in a taxi, but cycling straight out of the airport is one of the joys of folding bikedom, and you’ll need a better solution if you’re touring. Bike Friday gets around the problem with its patented TravelTrailer – basically a hard case that sprouts wheels and becomes a trailer. But the wheels add extra drag, weight, expense and complication.

The boffins at Brompton think they have come up with a compromise in the form of a padded soft bag, tough enough to give some protection during and after the flight, but light and compact enough to carry away on the bike.This, to avoid confusion with soft bags and hard bags, has been christened the ‘B’ bag. So in this crazy world, you might just find yourself explaining to a ‘one’ booking clerk in Bombay that you need space for a ‘B’ bag in coach C of the 8.20 ‘one’ service to Diss. No room for confusion there, then.

A Brief Description

The ‘B’ is made of a ruggedly woven nylon cordura fabric, padded to a depth of 5mm on the sides, with a solid base of laminated alloy and plastic.The result is very strong, but flexible enough to roll away into a manageable package. At the rear of the bag are two rugged little castors, supported on ball bearings, to give mobility on smooth surfaces. In ‘wheeled suitcase’ mode, you lift the bag with a little strap at the front and it whizzes along beautifully. For tougher customers, there’s also a broad shoulder strap, and a pair of conventional handles.

Weight is 2.3kg – a lot less than a hard case, of course, but rather more than a conventional soft bag. Dimensions when loaded are approximately (the bag is sculpted to some extent around the bike) 24cm wide, 64cm long and 58cm to 67cm tall. Any Brompton will fit, even those without a folding pedal (though we’d strongly recommend getting one) and/or with the longer SP6 seat post.The packed bag is little larger than the bike, but there’s enough space for carefully packed clothes, and even documents in the near (but not quite) A4-size zipped internal pocket. Another clear-fronted pocket just happens to take a copy of your favourite folding bicycle magazine, which may be pure coincidence, but thanks anyway lads.

With quick-releases on the straps, and floor to floor zips, the bag opens right out, so there’s little or no lifting required to load the bike. Ride off, and you’re dealing with a bag measuring 15cm x 25cm x 65cm – relatively cumbersome, but manageable enough, either on your back, strapped to the rack, or even poking out of the ‘Touring’ pannier bag.

In Practice

No doubt, the bag will be used in innumerable different ways.We would suggest carrying the ‘B’ on your back, and packing clothes into several plastic bags stuffed into a touring pannier for the trip to the airport. At the check-in, the bike and clothes go in the ‘B’ as hold luggage, and the Touring pannier plus essentials stays with you as hand luggage, with the packing and unpacking operation reversed at the other end.

Without the bike, the ‘B’ has an 80 litre capacity, although you wouldn’t want to carry too much weight in it. One question we had to answer was whether you can ride a Brompton carrying a second bike in the ‘B’ bag? Well, you can, but it’s not an operation for the faint-hearted, and you wouldn’t want to carry 12kg too far…The other classic use will be for yachting folk – yes, the straps are long enough, and the bike small enough, to dangle down through a 60cm x 60cm hatch. Hopefully, there’s enough padding should you forget the bike’s there and chuck the anchor down after it…

We’ve seen all sorts of travel bags over the years, from the basic (our own lightweight covers), through the cumbersome, to the plain useless (see Trek F600, A to B 41).This new Brompton-specific bag answers most of the criticisms of previous designs, being light enough and small enough to transport, but tough enough to give the bike some real protection. If the handlers drop it three metres off the end of an elevator, the bike will suffer, but it should survive the everyday knocks and bangs of air travel.

Brompton ‘B’ Bag £95 . Weight 2.3kg . Unfolded Dimensions H67cm W24cm L64cm Folded dimensions H15cm W25cm L65cm . Manufacturer Brompton tel 020 8232 8484