Originally Posted by
sillygolem
FYI: If you wanted to convert your bike, you'd need the following -
A wheel with even dishing with a hub threaded for a freewheel and an axle long enough to fit your frame.
A freewheel
A chain tensioner (the rear derailleur will work as long as you can keep it shifted in one spot)
A single speed crankset (middle ring would probably line up if you -really- wanted to keep the same crankset)
A new bottom bracket to fit said crankset.
A new chain
So yeah, you can probably pick up a low-end single speed cheaper.
Not necessarily.
You can get a singlespeed cassette conversion for around $40. They pretty much all come with spacers so the rear wheel doesn't need to be redished or have freewheel threading. Most kits come with a chain tensioner too. The crankset should be fine if he just takes off a chainring and gets shorter chainring bolts. You probably would want a new chain though since most of the ss kits are probably 1/8".
Example of said kit:
http://www.performancebike.com/bikes..._1031512_-1___
I'm not familiar with which of these kits are good or will fit your cassette though.