With SHIFTY CYCLES, I've worked very hard on designing a beautiful bike that's excellent for all types of rides and roads. One critical part of this is making sure our bikes have the right gearing to let you take on flats, slopes and big hills.
So why do we have only three speeds when your local bike shop is full of 18-speed, 21-speed, and 24-speed road bikes? Isn't more always better?
In this case, more isn't actually better. In fact, with bicycles, more speeds sometimes is decidedly less good. "Lots of speeds" is a great way to advertise and sell bikes — in the same way that "lots of megapixels" is a great way to sell cameras. But in both cases it's easy to end up making a bad choice if you don't know what's behind the sales speak.
Understanding bicycle gears really comes down to one question: what distance does your bike travel when you turn the pedals one full revolution?
That distance is what changes every time you shift gears. Lower gears result in a shorter distance traveled, while higher gears mean a larger distance. This is why pedaling feels different in each gear.
Let's say you're in a low gear. Your bike is traveling only a short distance when you turn the pedals, so it's probably pretty easy to pedal. Each time you turn the pedals, you aren't really doing that much work, so it doesn't take that much effort. But you're also not going to be traveling all that fast — that's the tradeoff.
On the other hand, in a high gear your bike will travel pretty far with each turn of the pedals. But you're doing quite a lot more work each time you pedal now, and you're going to feel it in terms of the effort it takes to mash down. Though if you can keep those pedals spinning, you'll speed handily along.
This whole concept is called the gear ratio. The gear ratio is different for every speed your bicycle has. Lower gear, lower gear ratio, less distance traveled, and less work to pedal. Higher gear, higher gear ratio, and more work.
How does all this factor into designing a bicycle, and why do I think three speeds is the perfect balance?
Well, to recap, the measurement that really matters is gear ratio. Each gear on a bike has a different gear ratio, which affects the effort it takes to turn the pedals. Lower gear ratios mean you're not traveling as fast, but they make pedaling easier so you can climb hills or just set a leisurely pace.
Higher gear ratios mean pedaling takes more effort, but let you really haul — especially if you're going downhill.
Notice that this is all independent of how many speeds your bicycle has. Even if your bike has twice as many speeds, if they all have similar gear ratios then you're really not gaining anything.
This is why advertising for 18-speed and 21-speed bicycle is deceptive. Those bikes might have a lot of different gears, but 30-50% will have very similar gear ratios. Sure, there might be 21 speeds, but they're not really distinct and you won't use most of them when you're riding around the city or commuting.
You're actually losing out with 18+ gears by having a more complicated system, with more parts that need maintenance, without giving you much benefit. But when you have just 3 gears, you can seal them inside a protective shell and get rid of the need for maintenance altogether.
SHIFTY CYCLES prototype with SA 3-speed hub
This is why we have the 3-speed philosophy — three different gears with the right gear ratios to take you where you want to go. A low gear for climbing hills, a middle gear for flats and slopes, and a high gear for downhill sprints.
Each SHIFTY CYCLES prototype today has three gears with three different gear ratios: 49.1 gear inches, 65.4 gear inches, and 87.2 gear inches. 
This gearing is really well-suited to cities and commutes and works great for hills. The middle gear is perfect for flats, and with the low gear an average rider can tackle fairly steep hills without stalling out.
Decades ago, 3-speed bikes like this were extremely popular, prized for their practicality, durability, and low cost. Over the years, though, the bicycle industry became more and more influenced by the needs of road racers, and (to a degree) mountain bicyclists. This led to some amazing innovations and wonderful road bikes and mountain bikes, but it's also been at the expense of everyday folks who want to use a bike to get from A to B.
You can see this when you walk into almost any bike shop in the USA or most of Europe. Racks upon racks of expensive race bikes and hardcore mountain bikes, but barely any practical, affordable day-to-day bicycles.
I started SHIFTY CYCLES to provide an alternative — a beautiful 3-speed bicycle that can get you where you're going in style and with no fuss.
: Due to a quirk of history, we measure ratios using gear inches, which are actually based on penny-farthings. In second gear, a SHIFTY CYCLES prototype has a gear ratio of 65.4 gear inches. That means it takes the same amount of effort to pedal as a classic penny-farthing with a wheel that's 65.4 inches across. So the next time you're riding your bike down the street, just imagine yourself sitting atop a 5½-foot tall beast.