Limitations of Bike Touring on a Brompton
I love my Brompton, it has taken me on many adventures since I bought it just two years ago. In particular I rode it across the Trans Pennine Trail last year and the Wild Atlantic Way from Kinsale to Galway this year. In all I've probably ridden about 1000 miles bicycle touring with it and, although many have travelled much further on their Brompton, it has been enough to give me a good idea of the pros and cons of using a Brompton for such trips. Within the ALC we have many who own Bromptons and perhaps some of you are contemplating buying one for touring. Bromptons have some fantastic advantages, not least the ability to fold them up neatly and carry them onto a train without a thought, or a cycle space reservation! However, I will focus on what I see as disadvantages, in no particular order.
Gearing - the Brompton is too highly geared.
When I bought my Brompton I had a 44 tooth chain ring fitted instead of the standard 50 tooth, thus reducing the gearing by 12%. In gear inches this gives a range of 29 to 88 inches. If I went for a 39 tooth chain ring I would get down to about 25 inches, but also with a reduction in top gear. However, carrying me, about 95kg, plus about 22kg of camping gear I think 20 inches is really what you need on hills. As it is I spend a lot of time walking, pushing the bike and camping gear up hills!
Brakes - Brompton rim brakes
It's worth reminding ourselves that a Brompton was designed for multi-mode commuting in London, not riding up and down the Connor Pass in Ireland with luggage! As a commuter the rim brakes are perfectly fine, as a tourer carrying a rider and luggage they are insufficient and you really need to take care. Long descents are liable to overheat your wheel rims, which are also being gradually worn away by the brake pads.
Parts availability - Bromptons use a lot of proprietary parts
If you take a Brompton touring, especially to more remote places such as western Ireland, you need to take some special parts! This is because Bromptons use a lot of parts which are just not available in a local bike shop. In my case I got caught out in Dingle, Ireland, when my gear changer failed, see next point. Remiss of me I know, but I just didn't think to take a complete Brompton brake lever/gear changer assembly with me!
Gear changers - post 2017 bikes likely to fail.
Post 2017 Brompton six speed bikes (necessary for touring) have two "gear changers", the one on the left is for the derailleur (low or high) and the one on the right is for the three speed Sturmey Archer internal gear hub change. Both changers are special Brompton products, that use a lot of plastic parts. After some time, especially when exposed to sun, heat and water they stop working! Mine failed in Dingle, a long way from a Brompton dealer in Dublin and, after multiple attempts to rebuild, I had to admit failure and return to England. I have now changed both left and right changers for standard Sunrace/Sturmey Archer devices, easily fixed and readily available.
Wheels/Tyres - Too narrow
Many people can hardly believe that a bike with 16 inch wheels can be used for serious touring, one guy in Ireland even wanted to sit down with me and explain the maths behind the necessity of using larger wheels! I haven't found the small wheel size to be a problem, and they also contribute hugely to the small folding size. However, it is only possible to fit narrow tyres, there just isn't space for "fatter" tyres. On soft ground or gravel surfaces this tends to give you a sinking feeling! I particularly remember a long stretch (miles) of pea gravel on the Trans Pennine which really dragged me down.
In conclusion every bike is a compromise and people make buying decisions based on their own needs. For touring, especially in the UK/Ireland, a folding bike is VERY convenient on buses and trains. Bromptons have been successfully used for huge tours (look up "Brompton Traveler" on YouTube), but I am now seriously considering buying another folder, more of which later...