The policy has since been re-revised (now you just can't use full-size bikes at peak hours), but during the time it was in effect I got myself acquainted with a category of bicycle with which I didn't have much prior experience at all, the Folding Bike.
Folding bikes come in a wide range of styles, sizes and price ranges, from weird little A-frame things with tiny wheels to full-size Mountain Bikes with collapsible frames. Generally speaking, bikes with little wheels fold smaller, but can offer a rougher ride and, because of the extra-long seatpost and stems, tend to feel a bit more flexy to big and tall riders (and I'm both big and tall).
I started out my foray into the world of folding bikes with a vintage Raleigh, which was pretty great to ride, but didn't fold all that small. Unfortunately, it suffered from one of the curses of vintage bikes, nonstandard parts. The bottom bracket (the axle around with the cranks and pedals revolve) failed and affordable replacements haven't been made for a long, long time.
From there I decided to look at new Folders, and ended up with a Melon Slice, which is in a lot of ways fairly typical of folding bikes.
|I had just returned a rental car. Just toss the bike in the trunk, drop off the car and pedal a few miles home.|
Many folding bikes have either 16" or 20" wheels, joined by a low-to-the-ground frame and sporting a high-rise handlebar stem and super-long seatpost to accomodate riders of different heights. The frame usually has some sort of hinge device in the middle, which lets you fold the bike so both wheels sit side-by-side. With the seatpost all the way down and the stem folded over, the bike is about the size of a largish suitcase.
The collapsible design does affect strength, and riders over 200 lbs have to be careful not to abuse these bikes (most of them have listed maximum weight limits between 225 and 240 lbs, although plenty of riders that exceed the weight limit ride Folders without incident), and riders of any weight probably want to avoid serious off-road riding.
On the other hand, within their limits Folding Bikes have a lot going for them. First of all, a lot of public transport options have restrictions on full-size bicycles, either all the time or during peak hours. A small-wheeled folding bike can usually ride on a train, bus or in a cab just about any time. You can also bring a Folding Bike in a lot of buildings where a full-size bike might not be allowed (you may need to have it in a bag of some sort, but most manufacturers offer a carrying case, and many bikes will easily fit in an oversized duffel bag).
Furthermore, the super-adjustability of a small-wheeled Folder means that they will accomodate a wide range of rider sizes. For example, I'm 6'3" and have a kid who's currently 5' tall. We can both ride the same folding bike, with just a seat adjustment. This makes a Folding bike a great bike to loan to an out-of-town friend who you'd like to take out for a ride, and because it can be folded up and put in the back of a closet or garage without taking up too much extra room. They're also great for people who have cramped living space, yet have to bring their bikes indoors with them.
|More than a foot in height difference, but we can ride the same bike... one of us looks more at home on it though.|
One will occasionally run into a place that won't let you bring your bike indoors, and locking up a folding bike can be a bit tricky. Because they often have a single long beam for a frame, rather than a traditional diamond, finding places through which to pass a U-lock can be tricky. Additionally, the easy-adjustment of the seatpost also makes it easy to steal, so you may have to experiment with various ways to lock your seat to the bike (or bring it with you, if you don't mind having a three-foot long piece of aluminium to carry along).
The other disadvantage of a Folding Bike is price. Because of their complexity, Folders cost more than similarly equipped non-collapsible bikes . There are budget options, though, such as Citizen Bikes, which, although I don't have any personal experience with them seem to offer a few decent no-frills options (even their "larger" bikes with the 20" rather than 16" tires are recommended for riders under 6 feet tall, though, so if you're like me you'll probably have to look elsewhere). Many major manufacturers such as Schwinn and Giant also offer a folder as part of their line, which may be available at the same price as an entry-level comfort bike, or slightly above. If your budget can extend to about $400, there are a large range of options, such as the Melon like I have, as well as bikes by Dahon and other companies.
Finally, there is one huge problem with Folding Bikes compared to full-sized bicycles, especially if you're a big guy with a beard like I am. No matter what you do or how you dress, you're gonna look like this.