Single Speed Endurance Racing

While it pretty much guarantees street cred and respect, endurance racing on a single speed probably isn't has hard as most people think. In the right conditions, it may even be easier than riding with gears.

Basic physics says riding up a hill is the same amount of work, regardless of gear ratio, or speed for that matter. Biomechanics, however, says it isn't quite that simple. Everyone has an optimum cadence, but cadence efficiency is roughly bell-curve shaped and changes with speed/intensity (from personal experience). When trying to ride as fast as possible, say in an XC race, cadence becomes extremely important. Picking the right gear ratio is critical to winning. Similarly, in ultra-endurance racing, picking a gear that you can maintain hour after hour, day after day is essential to having a good time. But, there's a grey area in between. If you aren't on the limit, and you're ok with going a bit slower on the flats or a bit harder up the hills, a gear ratio that's kind of close to ideal is fine. Even though my ideal cadence is probably 80 - 85rpm, anything from 50 - 100rpm is fine in small doses. Efficiency drops off quickly outside of that range, however.

For example, I recently raced 100km of gravel on the single speed, riding a 32x16 gear ratio because I was too lazy to swap chainrings. I've run this ratio on flat single track, but generally, the lowest I would run on gravel is 38x18. Too my surprise I got 4th overall. With that gear, I could go uphill faster and/or easier and still spin up to 17/18mph on the flats. For a while now, I've wanted to build a gravel bike, but that course was rough enough that I was glad to be on a mountain bike. I probably could've finished a bit faster with a higher gear, but it wasn't really a concern.

Another factor to consider is that the direct chain-line of a single speed is more efficient than a chain winding through a derailleur. So, given the same cadence and speed, a single speed is actually easier. The difference may be small, but it adds up over several hours.

In conclusion, pick an appropriate gear for the course hills and race intensity, combine this with increased chain-line efficiency and the facts that there's far less to go wrong with a single speed and they're virtually unaffected by mud, and you get the ideal weapon of choice for endurance racing.

Edit: I'd also like to add that single speeds force you to be more dynamic on the bike - seated spinning on the flats, standing on the climbs (sometimes even walking), "resting" on the descents. It's good to move around and stretch; cranking out a constant cadence in a seated position for hours on end will surely lead to a painful finish.