The bike itself is actually quite sturdy.
Thank you. This may be the case for a normal Brompton. However on this custom one, the rear hydraulic caliper and rotor are vulnerable, as is the Rohloff external gearbox. And because there is no central support, the front hydraulic disc brake caliper and the chainring/crank will get stressed if much pressure is applied there. How is the middle supported on a normal Brompton?