The following text is taken from Sheldon Brown (http://www.sheldonbrown.com/singlespeed.html):
"Modern 24-27 speed bikes are marvels of technology, and allow a cyclist to select the gear ratio that will make the most efficient use of his/her energy. If what you're after is getting the maximum possible speed/distance for the minimum effort (and there's nothing wrong with that!) you need a multi-speed bike...but, efficiency isn't everything!
If you're riding for sheer pleasure, or for exercise, you don't necessarily place that high a premium on output results, as measured in speed, distance or vertical climb. Instead, you may care more about the actual experience of riding your bike. In this case, you may be a candidate for a singlespeed bike.
Riding a single-speed can help bring back the unfettered joy you experienced riding your bike as a child. You don't realize how much mental energy you devote to shifting until you relinquish your derailleurs, and discover that a whole corner of your brain that was formerly wondering when to shift is now free to enjoy your surroundings and sensations.
Paradoxically, a single-speed is, in another sense, more efficient than a multi-speed bike! While the single gear ratio will not be the "perfect" gear ratio for all conditions, in the conditions which fit the single gear, it is considerably more efficient mechanically than the drive train of a derailleur bike.
A single-speed bike dispenses with the weight of the derailleurs, shifters, cables, extra sprockets and longer chain. In addition, a single-speed gear train runs the chain in a perfectly straight line from sprocket to chain-wheel, and avoids the serpentine wind through the pulleys of a derailleur. You can really feel the difference! A single-speed is noticeably quicker and easier to pedal than a multi-speed bike in the same gain ratio.
Single-speed bikes are also considerably more sturdy and reliable than multi-speed bikes. There's no derailleur to bash if the bike falls over, catch on the underbrush or get over-shifted into the spokes. The rear wheel itself is a lot stronger than one made with off-center (dished) spoking to make room for a whole bunch of sprockets on one side."
The initial purpose of building this bike was to use excess parts lying around built around a cheap frame and sell it as a complete bike. The frame was a refurbished Merida 29er. The wheels came off the Vitus Dee 29er and most of the other parts as well, e.g. fork, crank, chain, stem, plastic pedals, brake levers. This is a single speed bike with a 14 teeth rear freewheel and 38 teeth crank.
The handlebar is by Ragley; a swept back old-school retro looking thing that most people would associate with vintage bikes. Unknown to those who scorn about its looks, this is about one of the most comfortable handlebar. The reason is because it conforms to the angle of the wrists due to the swept back and the little rise ensures a straight-up riding position. You could never feel any stress on the hands with this handlebar.
The fork is taken from the Vitus Dee 29er. It is not suspension corrected and so the bike looks a bit hunched. Being made of steel, it is also rather heavy.
As usual, the Ferrari leather seats provides the comfort that most saddles cannot match.
The 38 teeth crank is a simple piece of machinery. It does the job without any dramas.
The chain tensioner from OnOne was necessary to maintain the chain at the correct tension since the bike had vertical drop outs. The original 16 teeth freewheel was replaced by a 14 teeth freewheel and the result was obvious. The bike moves faster and climbing slopes is not a biggie unless it is really steep.
Avid BB5 mechanical disc brakes do their job well. They can be quite irritating to install and tune but once you get it right, they are wonderful.
The frame comes from Merida. The previous owner spayed it with a matt black paint scheme. To give some highlights to the blackish frame, I added a Crank Brothers sticker to make it look like it had lights in front. The plan to sell it off has somewhat been put off. This bike is a real blast to ride, no worries about shifters and derailleurs; you just put power to the pedal and off you go. Want to go faster, pedal faster or else, just enjoy the ride at your comfort level. The big 29er wheels really transmit your efforts into motion. The simplicity of this bike makes you want to ride it all day long.
Never settle. Always experiment. A Suntour M3030 fork was added to see if it made a difference to the ride. Of course, it did. I found myself jumping over kerbs and riding down short flight of steps when I would usually avoid them. I'm beginning to like this bike more and more. Noticed the height of the front end has increased significantly? While the increased height makes riding more comfortable, it actually slows down the ride. Aerodynamics play an important role in determining how fast you can go on a bike. However, speed comes with a price and that is comfort. Unlike the professional riders who are used to the crouched or hunched over position, casual riders will not appreciate it. Its best to know your preference or like me, have a few bikes for different occasions.
This bike was sold. Prior to the sale, a 3 x 9 transmission replaced the single speed configuration. The wheels were refurbished Merida 29er with Deore hub. The crank was replaced by a Truvativ 3-chainring crankset. I still get to see the bike since my friend was the one who bought it for his son.