At the 2015 UCI Mountain Bike World Cup Downhill final in Leogang, Austria, competitors and spectators alike were staggered when Aaron Gwin took first place despite suffering the apparent misfortune of a snapped chain in the first few seconds. The closest precedent was Neko Mulally's chainless run which secured him fourth place in the 2014 World Cup Downhill final, so Gwin not only achieved World Cup glory that day, but also made competitive mountain biking history.
The general consensus was that Gwin would have won by an even greater margin if his chain had remained intact. Any ideas that the loss of his chain might have actually enhanced his performance were not given much of an airing. The guys at Dirt Magazine spotted a missed opportunity here, so Steve Jones and the team have produced this fascinating video looking at the implications and possible benefits of riding without a chain.
To get as close to recreating Gwin's improbable ride as possible, they've taken a Specialized Demo bike which is very similar to the one he uses, and tested it on various specially chosen downhill tracks at the Forest of Dean in Gloucestershire. Two runs are timed for each track, one with a chain, and another without. The overall verdict is that, while riding without a chain gives the bike a lighter, freer feel and heightens ease of body movement, the loss of power is enough to make the idea of competing without a chain unrealistic.
So would it be advisable for the average mountain biker to attempt to tackle those tricky downhill paths chain-free? Well, by all means give it a go. Just don't forget to put the chain back on afterwards for your ride home!