The complete guide to bike gears | Bicycle transmissions explained

A beginner's guide to gears and how to use them

Shimano GRX-800 rear derailleur and cassette

All too often you will see people spinning their pedals manically or laboriously grinding their way along, barely able to move the bike. Life would be a little bit easier for these folks if they were using their gears properly.

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This is the ultimate guide to what bicycle gears are and how to use the gears on your bike.

What are gears on a bike?

The Ultegra R8000 rear derailleur allows me to run an 11-30 cassette.
Gears are your friend.
Oscar Huckle / Our Media

Gears are one of those lovely inventions that enable us to ride faster, climb hills more easily and get a lot more enjoyment out of our riding.

They convert the effort you put in at the pedals to a certain output at your wheel. There’s only so much force your muscles can produce and usually an optimum cadence (how fast you spin your pedals) at which you’ll be most efficient.

Changing your gears based on the terrain and conditions to stay broadly in that band enables you to move forward more efficiently.

There are a few different systems that bikes use to change gears, though by far the most common are derailleur gears.

Derailleur gears explained

An external drivetrain with a front and rear derailleur
An external drivetrain with a front and rear derailleur.
Oli Woodman / Immediate Media

The majority of bikes on the market today sport derailleur gears, which have been refined into simple, lightweight and efficient systems.

Gears are changed on the cassette (a set of sprockets installed on the rear wheel) by the rear derailleur. This shifts the chain up or down the cassette. As the derailleur moves to change gear, it forces the chain against ramps or steps, moving it onto a bigger or smaller sprocket.

The bike may also have a front derailleur, which shifts the chain between chainrings, which are part of the crankset.

The gears at the front provide large jumps, which effectively change the range of your gears, so they are more suited to high-speed, flat-terrain or low-speed climbing. The cassette enables you to select your gear more precisely within that range as you modulate your effort.

You will usually find between one and three chainrings (single, double or triple crankset) and up to 12 sprockets (although 13 exists with Campagnolo Ekar and Rotor 1×13). That gives you a huge range of gears to choose from.

What is an internal gear hub on a bike?

A Shimano Alfine 11-speed hub with Gates Carbon Drive belt
A Shimano Alfine 11-speed hub with Gates Carbon Drive belt.
Jonny Ashelford

Internal gear hubs (also known as hub gears) are a popular option for commuters and those who want a robust and relatively maintenance-free drivetrain.

With service intervals ranging between 3,000 and 5,000km, internal gear hubs are great for the less maintenance-inclined.

There’s also no doubt that derailleurs are relatively exposed and susceptible to damage. Having everything nicely packaged away inside your rear wheel helps you breathe that little bit easier, especially during winter, when keeping gears protected from the elements doesn’t hurt.

There are lots of hub gear options available, but the most common are from Shimano, SRAM, Sturmey-Archer and well-known manufacturer Rohloff.

With systems ranging from three to 14 gears, there’s a wide range of options for whatever terrain you find yourself on.

However, the main drawback is weight. You’re riding around with a small gearbox inside your hub and that in turn contains a lot of metal parts that add substantial heft.

Fixing a puncture can also be harder with a hub gear.

Do bikes have a gearbox? What is a gearbox bike?

Pinion gearboxes have found a niche mainly on mountain bikes
Pinion gearboxes have found a niche mainly on mountain bikes.
Mick kirkman / Immediate Media

Part of the problem of a hub gear is that it adds weight at one end of the bike, which can lead to unbalanced handling.

Instead, a gearbox is integrated directly into the frame, with the weight positioned centrally on the bike. The cranks drive the gears directly and the output is converted in the gearbox and then transmitted to the back wheel via a chain.

One of the most exciting developments in recent times is the Pinion E-Drive Motor Gearbox unit. However, in general, gearboxes remain a niche in the bike world.

A Gates Carbon Drive belt requires less maintenance than a traditional chain
A Gates Carbon Drive belt requires less maintenance than a traditional chain.

Both gearboxes and hub gears can also be used with belt drives. This requires even less maintenance than a chain because there are no links to lube, meaning they are also much cleaner than an oily chain.

However, only certain frames are compatible with a belt drive. Because the belt is a continuous loop, the frame requires removable dropouts or a chainstay splitter that enables you to thread the belt into the rear triangle.

What is an electronic groupset on a bike?

Shimano Ultegra R8100 Di2 groupset – front derailleur
Electronic groupsets allow for more consistent shifting.
Russell Burton / Our Media

The majority of gears on bikes today are actuated by metal cables – Bowden cables to use their proper name.

However, electronic groupsets have been on the market for some time now, and are only likely to become more widespread as time goes on.

Instead of cables, the gear is shifted by an electronically controlled motor. The primary benefit is consistency. While cables can develop slop and stretch over time, an electronic drivetrain will maintain accurate shifting in all conditions.

Of course, the drawbacks are that batteries need to be charged (though not on a particularly regular basis) and the expense, although prices are slowly creeping down.

SRAM Rival eTap AXS rear derailleur and FFWD RYOT 33 wheel against a stone background
There’s not a wire in sight with SRAM’s AXS ecosystem.
Oscar Huckle / Our Media

Shimano, Campagnolo and SRAM all offer electronic groupsets. Both SRAM’s AXS ecosystem and Campagnolo Super Record Wireless forego wires between the derailleurs.

Shimano’s Di2 ecosystem is semi-wireless – it’s wireless between the shifter and derailleurs but there is a wire connecting the front and rear derailleurs to the battery.

What is a singlespeed/fixed/fixie bike?

Surly Steamroller Gravel Bike-2
Fixies cannot freewheel.
Jack Luke / Immediate Media

Of course, you always have the option of just one gear, and that’s how bikes started out.

Singlespeed bikes use a single cog that can freewheel and allows the rear wheel to rotate without the pedals moving.

Fixies are even more rudimentary, with the rear cog ‘fixed’ in place, meaning if the bike is moving, the drivetrain moves, so you always have to pedal.

The main benefit is simplicity, with low maintenance requirements and cost. However, there’s no doubt singlespeeds have also become quite fashionable.

The key is to choose a gear ratio that is easy enough to get up the steepest hill you’re likely to encounter while being hard enough to avoid spinning out when things get faster.

How do I use the gears on my bike?

Nukeproof Digger RS V3 gravel bike
It’s all well and good having gears but how do you use them?
Russell Burton / Our Media

There’s no use having all these gears if you can’t change them. There are a number of different designs of shifter on the market, which may be operated in slightly different ways, but they’re all fairly intuitive once you get to know them.

Shifters for the front and rear will be separate, located on the left and right of your bars respectively.

How to use flat-bar/mountain bike shifters

Flat bars are common on hybrid/commuting bikes, as well as mountain bikes. There are a few different shifter designs available.

How to use a trigger shifter

Trigger shifters on a Specialized Sirrus commuter bike
Trigger shifters on a Specialized Sirrus commuter bike.
Oli Woodman / Immediate Media

Nowadays, the trigger shifter is the most widespread design. It has two levers under the bar, which can be actuated with your thumbs or fingers: one to shift up and one to shift down.

Depending on the design, you may be able to change multiple gears at once or not. Shimano also has some designs that integrate the shifter and brake lever into one unit.

How to use a grip shifter

A grip shift shifter for a Pinion gearbox
A grip shifter for a Pinion gearbox
Jack Luke / Immediate Media

With a trigger shifter, you can usually only change one gear at a time, but with a grip shift, it’s possible to move through multiple gears very quickly.

The shifter integrates with the grip on your bar, and you change gears up or down by twisting the shifter – similar to the throttle on a motorbike.

How to use a thumb shifter

An old-school thumb shifter
An old-school thumb shifter.
Daniel Oines / Flickr Creative Commons

Though a little more old-school, thumb shifters still pop up from time to time.

A lever on top of your bars can be moved clockwise or anti-clockwise to move through your gears.

Modern gears are indexed, meaning a click on the gear shifter corresponds directly to a gear change.

In the past, shifters did not have this defined click and instead, the shifter was held in place by friction and moved continuously until the gear changed. In some rare cases, you may still encounter such thumb shifters.

How to use road bike shifters

Weve put together a separate guide on how to use road shifters.
We’ve put together a separate guide on how to use road shifters.
Matthew Loveridge / Immediate Media

You’ll find drop bars on more dedicated road bikes aimed at speed rather than all-out comfort. Again, there are a few different designs available.

We have a separate guide on how to use road bike shifters.

How do the gears on my bike work?

Gear inches

Your gears convert your input at the cranks into an output at the back wheel. Your cadence (how quickly you are pedalling) is converted into different speeds at your back wheel depending on whether you are in a high or low gear.

Your gear development – how far your bike moves with each pedal stroke – is typically described in gear inches, i.e. how many inches your bike will roll forward with each full rotation of your cranks.

There are a range of online calculators that work this out based on your wheel size, tyre size and chainring/sprocket sizes.

Gear inches can give you a good idea of how hard or easy the gears are, with ranges around 20 inches being easy, 70 inches being medium and above 100 inches getting quite hard.

Gear range

Wilier Zero SLR road bike cassette
An 11-28 cassette would have an 11-tooth smallest cog and a 28-tooth largest.
Aoife Glass / Immediate Media co

Gear range is often specified as a percentage that describes the overall range offered by the system. That means a 300 per cent range would offer a 3:1 ratio. Pedalling in the highest gear would move you three times as far forward per pedal stroke as in the lowest gear.

For external drivetrains, the gear range can be calculated by taking the ratio of the largest and smallest chainring teeth at the crankset multiplied by the ratio of the largest and smallest sprocket on the cassette.

The cassette specs will typically be identified by the smallest and largest sprocket. Thus an 11-28t cassette would denote a cassette with a smallest 11-tooth and largest 28-tooth sprocket.

Cranks come in a number of forms for road bikes, including standard, compact, super-compact and triple.

I'm a sucker for old-school polished cranks
A triple crankset has three chainrings.
Jack Luke / Immediate Media

A triple crankset has three chainrings. While this was once the most widely used type of crankset, now it is found mainly on touring bikes or for hilly terrain, where you require a very wide range of gears.

Much more usual nowadays are bikes with two chainrings. These will come either on a standard or compact crankset, generally with 53/39t, 52/36t or 50/34t respectively. The standard is more suited to high speeds with the larger chainrings.

The compact provides a larger range and slightly easier gearing that is well suited for most cases for riding both at speed and climbing steep inclines.

On occasion, you may also find a super-compact crankset, which uses even lower ratios than the compact chainset, making the bike more suited to climbing.

SRAM NX Eagle gears on full suspension mountain bike
1x gearing is increasingly common on both mountain and gravel bikes.
Dan Milner/MBUK

Mountain bike cranksets tend to use even smaller chainrings to deal with steep and off-road terrain. It’s also now the norm to see most mountain bikes and many gravel bikes equipped with a single chainring up-front.

This is usually paired with a wide-range cassette at the rear. This arrangement is referred to as a 1x (one by) setup.

To figure out the number of gears you have, simply multiply the number of chainrings at the front by the number of cogs on your cassette at the back.

However, the number of gears can be a bit of a misnomer because similar gears may be duplicated depending on which chainring/sprocket combination you are using. Likewise, it may be inadvisable to use certain gear combinations because they can put the chain at an extreme angle.

For gear hubs and gearboxes, manufacturers will typically specify the range. For example, a 14-speed Rohloff hub has a 526 per cent range, while a Pinion P1.12 gearbox has a massive 600 per cent range.

What gear should I be in?

Oscar Huckle riding Marin Headlands 2 on a gravel road
You’ll want to aim for a cadence between 70 and 100rpm.
Russell Burton / Our Media

Gears are all about being efficient.

Imagine trying to pedal up a steep hill in a high gear. You would have to push incredibly hard on the pedals and grind your way up the hill.

Instead, in a lower gear your force input at the pedals is lower, but as a result you can spin faster.

Your energy input in each case is roughly the same. The work done is equal to the force times the distance – so if you halve the force input required, you’ll be pedalling twice as fast.

However, there’s a limit to how much force your legs can generate (and your knees can take), so there comes a point where it’s preferable to shift gears to reduce the required force input and increase your cadence.

The point about knee injuries really is a key one. It’s much nicer on your body to have to push relatively lightly (but more quickly) rather than having to grind your way along.

Conversely, there also comes a point where spinning any faster becomes inefficient and can even unbalance you. It makes sense to shift into a higher gear again in order to reduce your cadence.

You’ll quickly get a feel for what works for you, but the key is to strike a balance between having to push too hard or spinning far too quickly, enabling you to pedal smoothly. The ideal cadence will be very personal but is often considered to be in the 70 to 100rpm range.

When should I shift my gears?

Male cyclist in camouflage top riding a Bergamont Contrail Pro full suspension mountain bike
Anticipation is the key to effective use of your gears.
Dan Milner / BikeRadar

The key thing with shifting gears is anticipation. Look ahead and try to predict how your speed will change and how you are likely to need to change gears.

As you come to a tight corner, anticipate that you will need to slow down and shift into a lower gear so you can accelerate out of the corner more easily.

If you’re riding up a hill or into the wind, your perceived effort will increase, so it makes sense to shift to a lower gear to account for that.

Equally, if you need to stop at some traffic lights, shift into an easier gear so you can set off more easily when the lights turn green.

One big no-no is that you shouldn’t shift when you’re at a standstill with an external drivetrain. Always ensure you are pedalling to perform smooth shifts and shift gradually across the range of gears to find the right one.

Another thing to avoid is cross-chaining. If you have multiple chainrings, it’s best to avoid being in a small-small or large-large sprocket-chainring combination.

The extreme angles this puts the chain at can result in increased wear and high loads on the drivetrain.

Conversely, hub gears or gearboxes can usually be shifted when at a standstill. In fact, they’re often quite sensitive to shifting under load, so it helps to ‘unload’ your cranks slightly when shifting.

How to clean your drivetrain

Dirty bicycle chain.
Don’t let your chain get this dirty, it will just wear out your other drivetrain components.
Colin Levitch / Immediate Media

The key to keeping your gears running nicely is to ensure you keep them clean and well maintained. In fact, cleaning your bike in general helps you keep on top of maintenance and enables you to identify any potential issues before they become more serious.

As we’ve already covered, hub gears tend to be lower-maintenance, though you may still have to adjust cable tension because it stretches gradually over time.

General maintenance such as this works wonders in the long run because a well-adjusted and maintained bike is kinder on your components overall.

We’ve put together a guide on how to adjust the gears on your bike.

It’s also critical to clean your chain, by degreasing and lubing it regularly.

It's easy to check your chain for wear and there are lots of tools on the
It’s easy to check your chain for wear and there are lots of tools available.
David Rome / Immediate Media

Finally, we would recommend checking your chain for wear regularly with a dedicated chain checker. Replacing a chain is much cheaper than replacing other worn-out components on your bike.

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Equipped with this knowledge, get out there and start using your gears. You’ll be flying up the hills in no time at all.