A Bromptons’s fold seems mysterious until you learn it well, and rather counter-intuitive, though it soon becomes second-nature. Here’s Basil, to start (pretend his bright blue water bottle isn’t there — I forgot to remove it, at first):
To fold, I press a release beneath the rear section of Basil’s top bar, then grasp the center bar (it’s yellow on Basil) at the seat end, and flip the rear wheel under the bar. (You want to make sure the Folding pedal is Forward, with the pedals close to parallel to the ground). Keep those Fs together.!)
Flipping the rear wheel requires lifting Basil, and then swinging the rear wheel forward. After a bit of practice, this becomes one fast, fluid, motion.
This flips the rear wheel upside down. See Basil’s rear rack? It’s now resting on the ground — and supporting Basil. The rear rack is Basil’s “kickstand”; this is how you set a Brompton upright as quickly as using a traditional kickstand — except that it’s a lot more stable, and keeps the bike upright on more surfaces.
There’s a clamp with a twist handle near the front of Basil’s yellow bar. (It’s visible in the image above, below, and to the left of, the blue water bottle). The next step is to open the clamp, grasp the handlebar stem, and move the front wheel next to the folded rear wheel.
This is really the only tricky part; you want to keep the front wheel as parallel as possible to the body of the bike, in order to avoid stretching cables. Just go slowly at first, until you “get” it; then it, too, becomes second-nature.
This step is also known as “trolley mode” or “shopping cart mode”. If I add a basked to Basil’s mounting block, this is the fold I use when shopping. I pop the basket on the black block that is just above his yellow bar (and just below the green handlebar stem), lower the seat, and then push Basil around the store using the handlebars. In this configuration Basil takes up less room than most strollers.
If folding Basil completely, the next step is to completely drop his handlebars. If you’re a hot-dogger, you just undo the clamp on the handlebar stem, and give the handlebars a shove. They will fall satisfying rapidly, and clip themselves into position next to the front wheel. It’s also possible to do this less emphatically, with the same success.
The final step is to lower the seat. Lowering the seat locks the frame so that Basil won’t unfold when lifted. If you want to effectively “brake” your folded Brompton, lower the seat so that the rubber stopper in the seat tube touches the ground. If keeping your folded bicycle from rolling isn’t an issue, the seat need only be lowered most, not all , of the way, down.
There’s a nifty, built-in, grip under the Brompton stock seat. Basil can be lifted and carried using his seat, or simply by holding him by the main bar (it’s the yellow on Basil).
That’s all there is to it. Whilst waiting for Basil to arrive, I obsessively watched Brompton’s own instructional video; it was very helpful, both as a distraction and as an instructional guide.