My previous post on single speed gearing covered all of the convoluted ground of figuring out the “gain ratio” to compare gearing between different types of bikes. But it can be simplified to just the “tooth ratio”, as long as you’re comparing bikes with reasonably similar wheel/tire sizes.
I mean, maybe you care more about the details if you’re racing the thing, but I’m talking about riding around town, right?
So the tooth ratio I’ve stuck with on my daily rider is 2.67. Some may call it laziness, but I prefer to think of it as, uh, Salsa’s excellent build design- I’ve stuck with the 48/18 gearing that came standard on my Cassaroll.
As it turns out, this ratio is quite similar to the popular single speed setup of a 42 tooth chainring and 16 tooth freewheel cog, which clocks in a tooth ratio of 2.63. In fact, that’s the setup on my rain bike, but because that beast (a Marin 29′er) has bigger wheels the gain ratio is very, very close to that of my Salsa.
However, there’s no need to stick with what comes standard – a new freewheel cog costs about $10-$15 and can be replaced in minutes.
Here’s a handy chart for comparing tooth ratio across different single speed gearing setups. I’ve highlighted the most common configurations: