We build our bikes to last, and if cared for will give many years of useful service. It is hard to quantify exactly how long that will be as the work each Brompton is put to by its owner will vary so much, but choices in our design and manufacturing techniques have been made to maximise this useful life.
The single-tube design and folding mechanisms put our frame under different stresses to that of a conventional ‘double-diamond’ design, and this is a key consideration in our use of chromoly steel as a mainframe material. While not as lightweight as aluminium, steel is compliant and can absorb more of these stresses. It isn’t immune to material fatigue of course, but failure tends to be gradual rather than sudden. If your bike is older or subject to higher mileage (i.e. 100+ miles per week), particularly a short wheelbase models that are now typically over 15 years old, it is advisable to periodically examine the frame and hinges for signs of fatigue and other symptoms of wear and tear. Be aware of any unusual creaks or noises coming from the bike while pedalling, as this could be a warning that a fatigue crack is developing.
The Brompton frame parts (front frame, main frame, rear frame, forks and handlebar support assembly) are covered by a 5 year warranty against manufacturing or material defects (please note that normal wear and tear is not covered). Compared to the frame warranty widely offered on conventional bikes - often referred to as “limited lifetime” - this may seem quite short. However, the nature of our frame design, with its regularly folded and unfolded frame sections, and with the majority of Bromptons used in day-in, day-out commuting, our bike can be subject to the stresses more comparable with bikes with full-suspension frame parts, for which a 5 year warranty is the norm. Nevertheless, if your Brompton is over 5 years-old and develops a fatigue failure, please report this to your local Brompton dealer so that the circumstances of the failure can be discussed with the factory.