All about bike Gears and How it Works

Gears are one of those lovely inventions that allow us to cycle faster, ride up hills more easily, and get a lot more enjoyment.

Gears convert the momentum from your pedaling into a certain output in all of the wheels. 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 lets you move forward more efficiently.

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

Bicycle external drivetrains explained

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

Gears are changed on the cassette (a set of sprockets 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 attached to the cranks.

The gears at the front provide large jumps, which effectively change the range of your gears so that they are more suited to high speed, flat terrain, or low-speed climbing. The cassette allows 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 chain set) and up to 11 sprockets (12 exist too in the form of SRAM Eagle and Campagnolo Record, and even 13 with Rotor) on the back wheel. That gives you a huge range of gears to choose from.

What is hub gear on a bike?

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 to 5,000km, internal hub gears are great for the low 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 lets you breathe a 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.

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

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

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 development in recent times is the Pinion gearbox. However, in general, gearboxes remain a niche in the bike world.

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 lets you thread the belt into the rear triangle.

What is an electronic drivetrain on a bike?

The majority of gears on bikes today are actuated by metal cables called Bowden cables.

However electronic drivetrains 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, currently, the expense.

The most common systems are from Shimano, in the form of its Di2 shifting, and SRAM, which offers wireless eTap shifting. Even Rohloff now offers electronic shifting for its 14-speed hub gear.

What is a single-speed/fixed/fixie bike?

Single-speed bikes use a single cog with the freewheel and allow 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 low cost. Although there’s no doubt that single speeds have also become a bit of a fashion statement in many cases.

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?

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

Shifters for the front and the rear will be separate, located on the left and right side 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

Nowadays, the trigger shifter is the most widespread design. It has two levers under the bars, 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 shifter and brake lever into one unit.

How to use a grip shifter

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 bars, and you change gears up or down by twisting the shifter – similar to the throttle on a motorbike.

How to use a thumb shifter

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

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

In the past, shifters did not have this defined click. 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

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.

How do the gears on my bike work?

Gear inches

Your gears convert your input at the cranks into output at the back wheel. Your cadence (how quickly you are pedaling) is converted into different speeds at your back wheel depending on whether you are in 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 is a range of online calculators that calculate this based on your wheel size, tire 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

Gear range is often specified as a percentage that describes the overall range offered by the system. That means that a 300 percent range would offer a 3:1 ratio. Pedaling 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 chainset multiplied by the ratio of the largest and smallest sprocket on the cassette.

A triple 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 two chainrings. These will come either on a standard or compact crankset, generally with 53-39t 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 riders for riding both at speed and climbing steep inclines.

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

Mountain bike chainsets 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 percent range, while a Pinion P1.12 gearbox has a massive 600 percent range.

What gear should I be in?

Gears are all about being efficient.

Imagine trying to pedal up a steep hill in 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 pedaling 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.

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 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, allowing 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?

The key to shifting gears is anticipation. Look ahead and try to predict how your speed will change and how likely you 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 easier gear so that 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 that you are pedaling 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, then 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. They’re often quite sensitive to shifting under load, so it helps to ‘unload’ your cranks slightly when shifting.

Still, if you have any doubts, please let us know in the comment box, and we will get back to you with a proper answer to your query.
MEANWHILE, RIDE HARD & RIDE SAFE!!