In the 1940’s and 50’s when cyclocross was a growing sport in Europe, riders used single freewheel bikes as derailleurs were still in their infancy. Without derailleurs or multiple cogs to get jammed up with mud a single drivetrain is efficient even in the worst conditions, and as the chain has little slack it is unlikely to come off even over the bumpiest terrain. Of course, the downside is, a single speed is limited on hillier terrain. That said, many cyclists still appreciate the simplicity of a good single free as there is little maintenance, the drive train last longer, they are quiet, and fun to ride. Most cyclocross and mountain bike races still have a single speed category.
With all this in mind we recently built an all-road single speed Mariposa with Paragon Machine Works sliding dropouts to accommodate different gear ratios, fenders and tire sizes. The frame was made with Kaisei and Columbus tubing and has a Ritchey WCS disc quick release carbon fork. A Silca Impero pump was painted to match. It is pictured with 43 mm Bruce Gordon Rock and Road tires. The customer provided the parts.
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I love my single-speed fixie, espedc in winter. I can commute over ice and snow and through the slush, through traffic and down the Waterfront Trail without skidding. It feels so much more secure than a freewheel bike. And it is easier to clean!