Over the past few years the American magazines have been peppered with articles by knarly old buggers romancing the single-speed mountain bike. I was finally seduced last winter and opted to join the fray. My favourite tracks had lost a little of their thrill of late and I was keen to spice them up. My other motivation was to avoid trashing my shiny new XT drive chain over the winter. The idea seemed easy enough... pull the derailleurs off my existing bike and go ride. It proved a bit trickier in execution. Here's my story.
A few bits and pieces
- A 2:1 ratio is the universally recommended gearing. To match my (standard) 32 middle chain ring, I found a dead screw-together XTR cassette with a separate 16 tooth cog lurking in the nether regions of my tool box.
- My 99 XT shifter pods and brake levers hang out together in the same unit. A mate came to the party with some basic 'V' brake levers.
- Mountain bikes have vertical dropouts - single-speeds have horizontal ones to take up the chain slack. Not wanting to splash out on a new frame I needed a chain tensioner. Specialist devices are available but pricey. Fortunately another friend came to the rescue with a sloppy old LX derailleur.
- Wanting a clean, light bike I replaced the front suspension with an old pair of rigid forks.
- All the magazines recommended riser bars for extra leverage on the climbs and control on the descents. They are 100% correct - flat bars don't cut it for a single-speed. I couldn't scam any so had to shell out $35 for a set - my only expense.
- And the last requirement is a pair of strong legs and over-sized lungs.
Putting Frankenstein together
- The chain line must be as straight as possible. Space the rear cog along the length of the cassette until it lines up with the chain ring. For spacers I used the old cassette spider, a couple of cogs, some proper spacers and the lock nut.
- Bolt on the rear derailleur and adjust the high and low screws so it lines up with the rear cog.
- Now thread the chain. Set the chain length so the derailleur jockey wheels are almost parallel to the chain stay.
- Now the tricky bit. Undo the 'B' adjustment screw until the derailleur body is about 3mm away from the chain stay when pulled forward by the chain. Using a few trusty zip ties, tie the derailleur body as tight as possible to the chain stay. This will leave the jockey cage free to move independently of the rest of the derailleur keeping tension on the chain. This is the secret to the single-speed conversion - before nutting this out I broke my chain 3 times.
The Proof is in the Pudding
Riding a single-speed is the true born-again experience... mainly because you have to operate in a narrow speed band. Too fast and you run out of spin; too slow and you stall. Momentum is everything. This forced me to ride new (better) lines on tracks I've hammered for ten years. I'd blow through the corners and stomp up short, grunty climbs. My bike handling skills improved because I had to stay off the brakes, my pedalling technique improved from spinning on the flats and of course it was great for fitness and strength. Curiously, my average speed was only 3-4kph below my previous average for the same ride. I was seldom too far behind my riding buddies, and in some sections I would pull away as they delicately picked through some tricky bits that I had just bludgeoned through - or maybe they were just being kind to my ego. And as a bonus, with so few parts I hardly did any maintenance all winter. I saved all my good gear for the next season and was riding a bike that weighed only 9.5kg. Sensational! My gears are back on now and I am riding better than before and eager to tackle the race season. But am even keener for next winter to roll around so I can return my bike to its single-speed configuration. Now if I had a Voodoo Nzumbi frame and a Paul's single-speed rear wheel - all I'd need to do is ...
Owen Wing, June 2000