Keep on spinning
Watch an experienced cyclist during a ride over variable terrain (and that, in reality, is any route which is anything but pan-flat) and you will notice they are constantly changing gear. A quick flick or the lever here, a subtle shift there, and it's all to ensure they are using their gears as efficiently as possible.
Gear systems on bicycles range from single-speed (one gear), through various hub gear systems, to the most popular of all: the derailleur. Derailleurs are the usual gear setup on road bikes, but there are multiple options. At the rear the number of sprockets can range five to 11, depending on the age of the bike and similarly, at the front, double chainrings are normal but single and triple options are both available. There is no right or wrong, just choices.
When it comes to using road bike gears it's all too easy for a beginner to get confused about which gear to use and when. However, mastering the art of using the front and rear derailleur will make climbs easier and descents faster as you’re able to match the gear to your speed, just as you do when driving a car.
Learning how to use the gears correctly can also help to prolong the life of your bike’s drivetrain components. Common mistakes such a mistimed shifts and cross-chaining (which we'll come on to) can put unnecessary strain on not only the chain but also the derailleurs. Selecting the wrong gear can also put unnecessary strain on your body, namely your knees, as well your bike.
In this guide, we'll run through the basics in order to determine how many gears your bike has and how to use them, how to select the 'right' gear and common mistakes to avoid.
The basics - chainsets, cassettes and gear ratios
Two components directly impact the number of gears your bike has and the ratios available to you: the chainset and the cassette.
The chainset is located at the front of the drivetrain and either has one, two or three chainrings. The vast majority of road bikes have two chainrings in varying sizes and common combinations include the 'standard' double (with a 53-tooth outer ring and 39-tooth inner ring), as preferred by racing cyclists, the compact (with a 50-34t chainring combination), common on bikes aimed at recreational or sportive riders, and, as a more recent option and one growing in popularity, the semi-compact, which sits in between the two with 52-36t chainrings. Triple chainsets, meanwhile, have three chainrings and are designed to offer an even lower gear than a compact.
Meanwhile, the cassette is attached to the freehub on the rear wheel and on modern bikes will, depending on the component level and age of the bike, have either nine, ten or 11 sprockets. As technology has progressed, the number of sprockets on the cassette has grown, with 11-speed the current upper limit. The move towards a greater number of sprockets on a cassette can mean either smaller steps between gears for serious racers or wide-spread gear ratios for more casual riders, to offer a lower gear when climbing. Depending on the groupset and the manufacturer, cassettes can range from 11-23T to 11-32T, and switching your cassette is the easiest way to change the gear ratios on your bike, though the majority of bikes will now come with an 11-28t cassette to offer a wide range of gears. Anything bigger (and that means 11-32t) may also mean upgrading your rear derailleur to a long cage design to accommodate the extra size of the largest sprocket.
What do these numbers mean? In terms of the cassette, the higher the number of teeth, the lower the bottom gear available and the easier a bike will be to pedal up hill. The reverse is true at the front, where a lower number of teeth on a chainring equates to a lower gear. For example, a bike with a 50-34t compact chainset paired with an 11-32t cassette will have a significantly lower bottom gear than a bike with a 53-39t chainset and an 11-23t cassette, despite the fact that both bikes effectively have the same number of gears (22 if it is equipped with one of the latest 11-speed groupsets).
As for shifting technique, that depends on whether you use a Shimano, SRAM or Campagnolo groupset, as they all have their own intricacies when it comes to changing gear. We've run through the main difference between the big three manufacturers in our groupsets buyer's guide. What remains the same across the board is that the left shifter operates the front derailleur to move the chain between the front chainrings, and the right shifter moves the rear derailleur across the cassette sprockets.
All things considered, selecting a gear therefore means placing the chain on either the big ring and little ring on the chainset, and choosing an individual sprocket on the cassette. But how do you select the 'right' gear?
How to choose the right gear for the right road
Go on any club run and you’ll soon spot the new rider simply because they’ll be the one who is constantly pushing a big which is too big, and they'll look like they are churning the pedals.
That may be a generalisation but new riders will often leave the chain on the big ring at the front and then tire themselves out by pedalling inefficiently, out of the saddle on the slightest of climbs, pushing a gear which is too tall. Look at more experienced riders and you’ll see them shifting regularly, using both the front and rear derailleurs, to maintain an ideal cadence (the speed at which they are turning the pedals) of 80-100rpm. That, after all, is the benefit of gears over a single-speed bike - it allows you to choose the appropriate gear for the road before you, enabling you to ride more efficiently (that essentially means riding quicker for less effort, which can only be a good thing).
If you're new to cycling, when it comes to getting the best from your gears the simplest thing is to start with the rear derailleur. Leave the chain on the smaller ring at the front for now and don’t worry about that for the time being. To begin a ride, you should have the chain somewhere in the middle of the cassette, in a gear that's easy for you to turn from a standing start and keep pedalling. Too low and your legs will be spinning inefficiently, too high and it will soon hurt. Once you’re rolling along shift up to a higher gear (smaller sprocket) while maintaining the same cadence, and your speed will increase as a result. You'll soon begin to find the balance between keeping your legs spinning and having enough pressure on the pedals - it's that word again, efficiency.
On an incline, it's simply a case of shifting back up the cassette to a lower gear (a larger sprocket). Keep doing this as necessary to maintain a reasonable cadence. Again, the aim is to keep the cranks spinning at between 80 and 100rpm, in order to keep your legs turning efficiently. This means shifting frequently to match your gear to the terrain, and maintain a smooth, consistent effort level. Of course, on the steepest roads you'll have no choice but to drop the cadence below 80rpm and get out of the saddle, but the aim is to use your gears to keep it as close to this number as possible.
Now that shifting across the cassette is sorted it’s time to think about how and when to change gears across the chainrings at the front of the bike. In basic terms, use the small ring for climbs and easy spinning on the flat and the big ring for fast riding on the flat and downhill. In reality, it's more intricate than that, but over time you will begin to learn what gear is best for the terrain.
Finally, let's consider some common mistakes to avoid when using the gears on your road bike.
Hint, tips and common mistakes
In theory you can use the entire range of gears on the cassette with either ring on the chainset, but best practice dictates otherwise.
In an ideal world you’ll use the larger sprockets of the cassette with the small chainring, when climbing for example, and then shift up to the big ring when working your way across the smaller sprockets at the back. The reasons for doing this are twofold: firstly, it avoids duplicating gear ratios and, more pertinently, it reduces lateral strain on the chain, which can cause premature wear. This is known as cross-chaining, as the chain is at an uncomfortable angle between the chainrings and cassette.
If you do try using a small/small or big/big chainring and sprocket combination you’ll be straining the chain and rear mech when you go big, and if you go small you’ll have to deal with the chain slapping on the stays and the possibility of it coming off the chainring and getting trapped behind the cranks. While those are the worst case scenarios you’ll also often have to deal with the noise of the chain rubbing on the front mech cage.
Even if you don’t cross-chain, you could still experience chain rub on the front mech, but there is a solution to this. Modern shifters allow you to trim the front mech. Basically, this means you can make small adjustments to the position of the mech, moving it just enough with a 'mini shift' to alleviate chain rub. If you’re running an electronic shift system, such as Shimano’s Di2, this won’t be a problem as the front mech automatically trims itself.
Something else to beware of is changing gear on a climb. Short steep rises in the road can sometimes be attacked without having to change gear, but if you see a big hill coming up, or a significant change in gradient, it’s best to be prepared and get into a low gear early. This means looking up the road and changing gear in advance. This applies on the flat, too. For instance, when coming to a stop, click down a couple of gears so you can move away easily again, rather than having to heave the bike back up to speed. You'll move away quicker and your legs will thank you for it.
If you do need to change gear when climbing, ease off on the pedals to the point where you are almost freewheeling before you change gear. Changing gear while standing up out of the saddle and mashing the pedals will at best result in a terrible crunching noise and worst it could be a mangled gear mech or snapped chain. Derailleur gears work by forcing the chain to move across sprockets, so easing off the torque you’re applying through the pedals before you shift helps to relieve the stresses involved.
A couple of other things to avoid are back pedalling, as it’s easy to lose the chain off the cassette or chainrings, and nor should you try and change gears while stationary.
Like most things in cycling, finding what works for you takes a little time and practice, and every rider will have their own personal preference when it comes to gear selection and cadence - but get it right and you'll soon be able to fully take advantage of the gears on your bike.