You live in a small space / live with someone who resents the amount of space bicycles take up / need all the space you have for your exotic orchid collection.
A folded Brompton makes a 24" x 24" x 8" package, taking up approximately 1.5 sq ft of floorspace, and fits neatly in a closet, under a desk, or in the corner of entryway or garage.
(It also fits nicely on a rimmed rubber boot tray, which is handy to have during wet weather, and will definitely minimize any spousal resentment).
Your office building does not allow bicycles.
I'd say they're not very progressive. Haven't they heard about peak oil and the havoc internal combustion engines are wreaking on the environment? Apparently not. But, guess what? They don't have to know that tidy little black package you're wheeling in and out every day is a bicycle. Or they can pretend not to know.
The Brompton Cover Bag is a sneaky lightweight device that protects you from being accused of bringing a bicycle into the building, as well as protecting others from coming into contact with potential dirt from your Brompton.
You hate bike share.
Right? Those Divvy bikes have roughly all the grace of a cow. A Brompton can do the same thing -- close the gap between the train stop and your office, hop short distances while doing errands, give you a lift when you're running late -- only with style and finesse.
You'd rather not ride a bike when it's raining. Or when you're really tired. Or on those occasions when you've had a few cocktails with people after work.
A Brompton lets you seamlessly combine cycling with other forms of urban transit. If you set out on a bike, but don't feel like continuing for any reason at all, fold it up, hail a cab or hop on the bus. Or maybe just pop into a coffee shop for a quick cup of Joe, and discover that you don't mind riding further after all (you can still change your mind later). Conversely, if you've been interminably waiting at a bus stop, you may decide to just say no, whip open your Brompton (while other commuters gasp with envy and amazement), and get wherever you're going on your own power.
You can't stand the thought of being separated from your bike. Ever.
Bring it with you. That way your bike will probably never be stolen. Bring it home, to work, into the grocery store, restaurant, or to Wyoming.
You're sick and tired of Chicago.
See note about Wyoming, above. If you can swing it, bring your Brompton on a plane, and get away for a month. If not, put in the trunk of your car and get out of town for a day.
You don't want to get your hands dirty. Or your pants. Or other people's pants.
It's a little talked about fact that a Brompton folds with all of its naughty bits neatly tucked away inside. This vastly minimizes the chances of you or anyone else coming in contact with chain grease.
You are not mechanically inclined.
You don't need to be. Unlike some other folding bikes which require you to (a) have time and patience, and (b) be a contortionist or (c) have the use of three hands, the Brompton fold is quick, easy, and secure. All it takes is about 8 seconds (this is not an exaggeration), and three simple steps, and the bike is securely folded without the need for any additional straps or magnets. Unfolding is even quicker and more impressive (and even if you're really not mechanically inclined, it can make you appear that way).
You work on an aircraft. Or you own one. Or a boat, or RV (in which case I definitely don't want to hear you complain about how expensive Bromptons are).
Bromptons are great for anyone who regularly travels using some other means, and wants reliable transportation at their destination. Money jokes aside, one of our customers is a professional truck driver. He keeps his Brompton in the living space behind the cab, and when his truck is being loaded or unloaded (which can take hours, usually in the middle of nowhere), he uses it to get to the nearest town.
You like well-made things. Or cute small things.
The people at Brompton take quality seriously, that is why each bike is built by hand by highly qualified team at their London factory. (And it's also why the last sentence was dead serious. It was lifted straight off the Brompton page, and they don't mess around). It is true, however, that Bromptons are exquisitely made little engineering marvels, with surprising little touches that cause delight every time they're used. And, yes, they are cute and small.