31 June 2020 / www.theengineer.co.uk
sized bike,” said Lambert.
A number of different variants of the bike are available. The
cheapest of these is a ten speed sport folder (SF1A) which at
£1800 is considerably pricier than a Brompton and at 13kg a bit
heavier too. Other models push the price up further. A 20 speed
racing variant will set you back £2700 whilst an electric version
Unlike some folding bikes, the Crosshead is designed to
accommodate most generic components, making it relatively
easy to upgrade.
Designed, engineered and built in the firm’s small factory
in Deal, Kent the bike is constructed from about 20 aluminium
investment castings and two bespoke extrusions which are
welded in bespoke jigs before linishing by hand, heat treating
and aquablasting. The frames are then assembled and wax
finished before being fitted with the required componentry for
the particular product range.
Until now, Lambert has been producing the bike in small
batches of just ten, but having finessed the design through six
iterations he’s now keen to scale up production, potentially in
partnership with a larger manufacturer. “Crosshead is a great
folding bike with broad market potential, but our funding
model, manufacturing facilities and access to technology make
the project run a little slower than ideal,” he said. “It makes
business sense for us to consider different scale up scenarios,
to get our product to a wider audience as soon as practical.”
He added that he’s particularly keen to work with partners
to explore the potential of 3D printing, which he thinks could
be used to refine the bike still further. “Instead of combining
castings and extruded aluminum tubing with the skills of
welders, heat treatment and finishing processes, the printed
part with likely carbon-fibre reinforced composites, will
emerge fully formed and ready for sub-assembly use,” he said.
“This will make product development far more efficient and
crucially, will allow production to start earlier with minimal
Ultimately of course, the proof of any bike is in the riding.
And on The Engineer’s brief spin around South London’s
Brockwell park it felt well engineered, solid and nippy:
certainly much more like a larger road bike than this reporter’s
And whilst I’m not persuaded to turn my back on my old
folding friend for the daily commute, if I was in the market for a
folding bike that I could also do some longer weekend rides on
I’d certainly be tempted.
SUPPLIER PROFILE - IGUS
Lambert has worked closely with a
number of key suppliers during the
development of the bike, in particular
high-performance polymer components
The firm has supported the Crosshead
project during prototype and production
development and helped guide the team
on using the best plastic bushings and
bearings to achieve a positive hinged
fold without undue material creep or
deformation after an average ride or
unduly over time.
“Because of the folding part of the frame there’s quite a few bushes in the bike,” explained
Lambert. “The steering assembly has bushes, the front folding hinge has bushes and also the
rear swing arm. The challenge was to get the feel and strength so that when you’re riding the bike
it’s not wobbling around, but also that when you fold it it’s not too tight. That’s been a really big
The wear resistant iglidur J bearings supplied by igus were particularly key to solving this
challenge as they offer low oefficients of friction and are vibration dampening. What’s more, the
component is self-lubricating and therefore maintenance free and insensitive to influences such
as dirt and dust.