Cycle Gears Simplified

 Understanding the fundamentals of how gears work changes the way we use, shift & ride. But most often gears on a bike confuse many people, don’t worry if you're one of them, I'll try my best and help demystify the jargon & principals associated with bicycle drive-train.

Q. Why do we need gears?

For efficient riding its important to maintain a decent cadence, which is pretty easy on flats. What if you ride up the grades of Nandi hills or a steep flyover in your city? It's humanly impossible for most common Joe's to maintain that same efficiency and thus we have gears. Regardless of where you ride, gears help maintain a comfortable cadence. Now that you understand the basic function of a gear let's mover further.

Chainrings

The front gears are referred to as chainrings, most chainsets come in single, double, or triple-chainring(s). The obvious difference between these chainrings is the size/number of teeth on them. So the smaller the ring the easier to pedal and the bigger the chainring the harder to pedal but you go faster. Chainring along with the crank arm together is called a crankset/chainset.

 

The chainring(s) along with the chain, gear cluster/cassette & front/rear derailleur is called the drivetrain. Drivetrain with the crankarm helps the rear wheel move forward. You're riding experience highly dependents on this, often degreasing & lubrication can go a long way. 

Let's deep-dive: as mentioned earlier the chainrings differ in diameter hence varying the number of teeth it holds. These days commonly found chainset assemblies are Standard Double, Compact, & Triple. Let's throw in some clarity on each one of them.

• Standard Double Chainset: Earlier this was the standard on most road cycles, it was an assembly of 2 chainrings with 53T-39T, meaning the outer ring "big one" has 53"T" for teeth and the smaller ring with 39 teeth. They have mostly been used in races and by advanced riders.

• Compact Chainset: These mostly come in 50T-34T combination, they are increasingly becoming more popular among many riders as the reduction in size over the standard chainset makes a perfect blend of lower & higher gears ratios, basically giving you the best of both worlds, tackling steeps & decent speeds on flats & descends. 

• Triple Chainset: These come with 3 chainrings, giving you the widest gear ratios possible. They are in 50T/39T/30T combination. 30T gives you a really low gear ratio possible, letting you take off from standstill almost on any terrain/climb, often found on MTB's. 

Cassette 

A Cassette is an integral part of the cycle's drivetrain. It's basically a cluster of sprockets assembled close to each other in ascending/descending order, these days anything between 5 to 12 sprocket assembly is found in a cassette, most bicycles come with 8 to 11 sprockets. So what do they do? Just like we looked before with the chainrings they depending on the size of the sprocket as the number of teeth varies, cassette in combination with the chainrings gives us a whole bunch of useful gearing options for every condition.

So usually we see terms like 11-21T, 11-32T, 11-34T. Again just like our chainrings they are the number of teeth the lowest and highest sprocket have in a cassette.

For example: 

an 11-34t, 8-speed cassette will have sprockets in the sequence 11/13/15/18/21/24/28/34. The smallest sprocket (11T) being the hardest to pedal which gives us a higher ratio and biggest (34T) being the easiest to pedal. 

I know, I know! what you're going to say, yes cassette behave opposite to the chainrings.

Remember 

Chainrings: the biggest chainring = hardest to pedal/fastest

smallest = easiest to pedal/climb steeps.

Cassette: the biggest chainring =  easiest to pedal/climb steeps

smallest = hardest to pedal/fastest.

Q. How many gears you're cycle got?

Most often as newbies/amateur cyclists we'd like to boast on the number of gears you're bike got  7, 8, 9, 10, 11.....16........21......30........100!!! LOL 😂 

But what's really the truth? How do you calculate the number of gear you're bike got? 

The answer is simple, you count the number of sprockets in the cassette. In other words, the number of sprockets in the cassette is the number of gears your cycle got. 7 speed, 8 speed, 9 speed, 10 speed, 11 speed, and so on.

Then you may be wondering? if that's the case the salesperson at the bike shop sold me a 16 gear cycle, 21 gear cycle..etc ?! 

It's a sort of marketing thing "more the better". Now you may ask, "ok it's a gimmick, but how did they come to these numbers..16, 21, and so on"?

You basically multiply the number of rear sprockets with the number of chainrings. so an 8-speed cycle with 2 chainrings is 16, a 7-speed cycle with 3 chainrings is 21 gears. Also referred  (7-speed with 3 chainrings 7x3, 8-speed with 2 chainrings 8x2 and so on)

In reality on a multi-geared set-up, ‘overlapping’ gears are unavoidable. In other words, some gear combinations will result in the same ratio as others using a different sprocket and chainring. 

Gear Ratio

Ok, we've used this term "gear ratio" quite often now, so what exactly do I mean when I say gear ratio?

Removing all the noise around gear ratios, in simple layman terms, a gear ratio on a bike refers to how many times the back wheel will rotate for each full turn of the crank arms (pedals).

If we have a chainring with 30 teeth and a sprocket with 30 teeth, there is no difference between the two; one full revolution of the pedals will result in one full revolution of the wheel. As a ratio, this is 1 to 1 (1:1).

If we have a chainring with 30 teeth and a sprocket with 10 teeth, the chainring is 3 times bigger than the sprocket; one full revolution of the pedals will result in 3 full revolutions of the wheel. As a ratio, this is 3 to 1 (3:1).

If we have a chainring with 20 teeth and a sprocket with 30 teeth, the chainring is only 2/3 the size of the sprocket; one full revolution of the pedals will result in two-thirds of a revolution of the wheel. As a ratio, this is 2 to 3 (2:3).

To better understand, the below table is the ratio for a 53-39 chainset to an 11-25 cassette. So if you were on the 11th gear and the big chainring(53T) for every full pedal stroke your rear wheel will rotate 4.82 times. Understanding ratios help us with efficient gearing. 

Before I end this article one important point DO NOT CROSS CHAIN. When I mean cross-chain i.e riding the smallest cassette to the small chainring or big cassette to the big chainring. We will delve into the reasons in another post.

I hope this article gave you some degree of understanding with cycle gears, if you still have some questions do feel free to leave it in the comments, will try my best to help answer. 

Ride safe & ride more! 🚴🏻 🚴🏻‍♀️ 👍🏻
-
Nelson John
https://www.strava.com/athletes/nelsonjohn

https://www.strava.com/clubs/TheBangaloreCyclists

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