Commuting to work or school by bicycle is a great way to get daily exercise and lower your impact on the environment. And what better way to do it than on a fixed gear or single speed bike? They are perfect for city riding and are much simpler and easier to maintain than their multi-speed counterparts.

But with only one choice of gear ratio for the whole ride, how do you know which is right for you? To help you make an informed decision, we’ll look at some of the most popular setups and why people choose them for their daily commute.

There are numerous factors to consider in finding your optimal gear ratio, from local geography to wheel diameter. We’ll get into some of those, but the gist of it is this:

Common gear ratios for commuting are a 44 or 46 teeth chainring combined with a 16 teeth sprocket (denoted 44:16 or 46:16). For slow pace or hilly commutes, 44:16 or 46:18 may be ideal. But lower is not always better. Flat, open road commutes may be easier to cover with a higher ratio like 46:16.

It’s important to experiment for yourself with different components to see what gear ratio works best for you. But if you really don’t know where to start, then as a first order approximation, the 2-by-2 matrix below should give you a rough idea of what kinds of ratios to consider.

  Hilly Flat
Relaxed 44:18 (2.4) 46:16 (2.9)
Intense 46:18 (2.6) 48:15 (3.2)

Additionally, if your commute involves stopping at red lights every minute or two, then it may be wise to add a couple teeth to your sprocket or knock down your chain ring by one or two teeth.

While it may be tempting to install an ‘easier’ (lower) gear to make your commute easier, it’s not quite that simple. If your commute is on mostly flat terrain with few serious hill climbs, then paradoxically a so-called ‘harder’ (or higher) gear might make that distance easier to cover.

As you can see, this is quite a nuanced topic. There is no one gearing setup that works for everyone everywhere.

Before going into the details, we have to talk about what exactly a gear ratio is, and how we conventionally talk about them.

What does gear ratio mean?

Put simply, your gear ratio is just a number that tells you how ‘easy’ or ‘hard’ your gearing setup is.

The higher the gear ratio, the harder you must push the pedals to maintain the same speed. Lower ratios are more ‘spinney,’ meaning a higher cadence for the same speed.

Technically, gear ratio is a dimensionless measure of the mechanical advantage of the drivetrain. It’s a way to express how many rotations the rear wheel will make for each full turn of the cranks.

The way a gear ratio is calculated is by taking the fraction of two whole numbers: the number of teeth on the chainring divided by the number of teeth on the sprocket.

They’re typically represented using colon notation; for example, 46:16 is the gear ratio of a bike equipped with a 46 teeth chainring and 16 teeth sprocket.

Decimal representation

Sometimes you’ll see a gear ratio written as a decimal, like 46:16 = 2.875:1. But 2.875 what? I told you it’s a dimensionless quantity, so what exactly is it supposed to convey?

What this means is that, with this 46:16 gear ratio, the rear wheel makes almost three (2.875) full turns with each revolution of the cranks.

There are more sophisticated ways to measure the mechanical advantage of a bicycle, most notably gear inches which takes into account the diameter of the rear wheel (including the tire’s width). But since almost all adult bicycles these days have the same 700c rim diameter, and tire width is a somewhat negligible addition, we can ignore that factor and talk about gear ratios in terms of teeth count alone.

Geography

By far the most pertinent factor is landscape. Is your local area quite mountainous or relatively flat? What does your route to work or school look like?

As I mentioned earlier, a lower gear at the same speed will not necessarily result in an easier ride. Higher gear ratios provide a more moderate, efficient cadence on the open flat roads where you’re maintaining a greater speed. This means you will be covering a greater distance for the same effort!

So for flat commutes with few interruptions (like sharp turns and traffic lights), a higher ratio is advisable. Something like a balanced 46:16 or even faster 48:16, depending on exactly how flat your route is.

Where I live in Sheffield it’s really hilly so I swapped out my 16 teeth sprocket for an 18. This 11% decrease in gear ratio makes the climbs noticeably more bearable.

Combined with my 46 teeth chainring, I’ve been able to get to campus and around town comfortably and even head to the more mountainous Peak District for longer rides over the past year or so. That’s not to say climbing mountains is easy! But the easier gearing makes it feasible.

To make the hill climbs even more surmountable, consider a smaller chainring such as 45 or 44 teeth, and/or an easier 19 or 20 teeth sprocket.

Desired pace

Average speed varies among cycle commuters. Ask yourself what kind of pace you want to maintain on your ride to school or work.

For a nice relaxed pace, a lower gear ratio is more suitable. For example, if you’re comfortable riding 46:16 over flat ground, then drop that to a 44:16 or 46:18 for hilly rides.

Traffic lights

Inner city commuters may need to consider road traffic congestion and the number of stop lights en route.

These external factors might seem trivial as far as gearing, but remember that lower gears make for greater acceleration for the same effort. With, say, 44:16 or 46:18 you can spring off from the lights and beat the cars to the next junction, no sweat.

Closing remarks

Whatever gear ratio you decide upon, what matters is you and your relationship with your bike. There is no one-size-fits-all configuration. If conventional wisdom tells you to use a ratio that simply doesn’t work for you, the good news is you can tweak it so that it does.

If the hills are too much of a grind then try a larger sprocket or smaller chainring. On the contrary, if the descents and flats are too spinney then try a smaller sprocket or larger chainring.

Sprockets tend to be less expensive so I recommend starting there. Also, don’t forget to tension your chain properly after installing one. Visit your local bike shop if you have any trouble.

And as you invest is new components, keep your cog collection in good condition and stored away somewhere safe. Whether you move city, gain strength as a rider or just fancy a change, you never know when you might want to use those old parts again.