Dummies Guide To Bicycle Gears

BICYCLE GEARS

Getting to know your bike gears should be simple… you push the lever one way to make it easier to pedal, and then the other way to go faster… choosing the right gears for your bike however can be much trickier!

Most of us just end up riding the gears that came with our bikes, but if you don’t think about swapping out for different scenarios, you might end up making things much more difficult than they need to be.

The gear ratios you want to use for a cycling holiday in Morocco may not be the same as the gears you want for a ride in the Alps or for a time trial, or commute. This guide to bike gears takes the mystery out, and will have you joining in the café chat on gear ratios in no time at all – that’s if you want to of course 😉

 

Front Gears (Chainrings/Crankset)

The front gears are referred to as by workshop mechanics as chainrings, or as a crankset, or by the the rest of us… ‘the front rings’. The complete assembly of crank arms and the front gears together is properly known as the ‘crankset’, or sometimes ‘chainset’. Most cranksets have either two (called a double or 2x), or three (called a triple or 3x) chainrings. Single (or 1x) chainrings are gaining popularity, particularly among mountain bikers and cyclocross riders, but are still a fairly niche. Ordinarily the chainrings are identified by their position (“inner”, “outer”, or, in the case of a triple “middle”), or by their size “big ring”, “little ring”. On a triple they’re usually called “outer/big”, “middle” and the smallest one has a special name – “granny gear” or just “granny”. On the crankset, the smallest chainring is closest to the frame. The smaller the front chainring, the easier the pedalling. As we move the chain out from the smaller (inner) onto the larger (outer) ring(s), the pedalling gets harder but you go faster.

 

Rear Gears (Cassette)

The gears on the rear wheel are called ‘cogs’ and when you put them together in ascending size and attach them onto your back wheel, they are referred to as a ‘cassette’. Most bikes built in the last few years have between 8 and 11 cogs in the cassette. The largest cogs are closest to the wheel and the gears are numbered from the inside out. The larger the cog the ‘lower’ the gear and the easier it will be to pedal, but the slower you will go.

How Many Gears?

When we talk about how many “speeds” a bike has, there can be some confusion. The marketing department likes to multiply the number of cogs by the number of chainrings because big numbers are impressive. But the fact is there’s actually a lot of overlap, so a 9×2 doesn’t really have 18 gears.  People who actually ride bikes only refer to the number of cogs in the cassette, so an 8 speed, a 9 speed etc… They may also mention whether they have a single, double, triple crankset, or they may simply say “9×2” or “2×9”.

 

Derailleurs

‘Derailleur’ is a bit of a tongue twister – other than that  they’re pretty easy to understand. The chain gets moved from one cog to another or one chainring to another by means of a derailleur. The front derailleur is a fairly simple device that simply pushes the chain from one chainring to be picked up or ‘caught’ by the next.

The rear derailleur (AKA rear mech) is a little more complex as it has two jobs. Like the front derailleur, it guides the chain from one cog to the next, but it is also responsible for maintaining chain tension and taking up the slack when we move from bigger gears to smaller ones. Therefore, the rear derailleur has two little gears (actually called ‘pulleys’) in it, and the chain makes an ‘S’ turn through them. The upper pulley (closest to the cassette) is referred to as the ‘jockey pulley’ and the lower pulley is called the ‘idler pulley’. The pulleys are held in position by the ‘cage’.

With both the front and the rear derailleur, when the shift cable is pulled, it will move the chain to a larger gear.  When the cable is released, it will move the chain to a smaller gear. Just remember that larger gears at the rear mean easier pedalling but more torque, and larger gears at the front mean harder pedalling but more speed. Going from “easier” gears to “harder” gears is called “upshifting”, and the reverse is called “downshifting”.

TIP: You’ll find it’s much more difficult to shift your front gears while the chain is pulled really tight (under load), so you should lighten your stroke very slightly when switching chainrings.

 

Teeth & Bike Gear Ratios – The Numbers Crunched. (not the gears)..

11 cogs on the rear cassette and two on the front chainring essentially gives you 22 different options (though some of these may cross over so not strictly true).

The key element that will determine how hard you work is the difference in the number of teeth (the wee pointy bits that hook through the gaps in your chain) between the front chainring at the front and your selected rear cog.

Example: The chainring (front) on a bike is 50/34T. That means the outer ring has 50 teeth and the inner ring has 34 teeth. The rear cassette is 11 speed 11-32. This means there are 11 cogs ranging from 11 teeth up to 32 teeth (the exact cogs are 11/12/13/14/16/18/20/22/25/28/32). The combination of your selected chainring and cog determine the gear ratio.  The gear ratio, combined with the circumference of your wheel and tyre determines how far you will travel with each revolution of the cranks – see the table below for distances based on a standard 700c wheelset.

Cassette Gear Ratio Table

1112131416182022252832
504.554.173.853.573.132.782.502.272.001.791.56
343.092.832.622.432.131.891.701.551.361.211.06
Cassette gear ratio table for 11/32 cassette using compact chainset 50/34

 

The Big Gear

Let’s say you’re in the hardest gear on front and back which means you would be riding on the 50 tooth ring on the front, and the 11 tooth ring on the back. To get your gear ratio you divide the number of teeth on the front by the number on the back:

50 ÷ 11 = 4.55

This is expressed as 4.55 : 1 meaning that for every 1 turn you make of the pedals at the front, you will turn the back wheel 4.55 times. This is the gear you would use on the flat. It is going to take quite a lot of effort to get it moving, but when you do it will be quickly.

 

The Small Gear

This would be the opposite end, the small ring on the front and the biggest on the back. The reason for this is that they are the closest together, meaning you get a really low ratio. On our bike this is 34 teeth at the front and 32 at the back – so really close.

34 ÷ 32 = 1.06

1.06 : 1 means you are only just moving the back wheel through more than one revolution for every turn of the crankset. This would be the gear you use on the very toughest of climbs allowing you to spin the wheels quickly to get your cadence high.

 

Different Gearing Setups

The Front Ones – Crankset: You may sometimes hear cranksets referred to as ‘compact’ or ‘standard’.  A compact crankset typically has a 50 tooth (50T) big ring and a 34 tooth (34T) little-ring. Standard cranksets are typically 53T/39T.  In most cases, you can change your chainrings to have different tooth counts, but as a general rule you don’t want to have more than a 16-tooth difference between the big ring and little ring or you may have shifting issues. As for triples, they tend to run even smaller gears and more closely spaced 26T/36T/46T and 52T/42T/32T are common triple crankset configurations.  With 10 and 11 speed drivetrains becoming the norm, we’re seeing triples fall out of fashion and even single ring cranksets are becoming popular because of the wide range of ratios an 11-speed cassette can span.

The Back Ones – Cassette: As mentioned earlier, today’s bikes typically come with 8 to 11 cogs in a cassette.  When choosing cassettes, you can choose a cassette that has a narrow range of ratios but closely spaced between each cog, or you could choose a cassette that offers a wide range of ratios but at the cost of bigger jumps between cogs.  Choosing a bike that has more speeds reduces the tradeoff some, and gives you more versatility. If you do most of your riding in a place that is generally flat, it’s probably best to opt for a narrow-range cassette with small ratio jumps as that allows you to really fine-tune your cadence and effort level.  If you live in an area that has more varied terrain, a wider-ranged cassette may be the better choice to help you get up those hills. Wider-ranged cassettes with higher cog counts typically have the ratios more closely spaced on the smaller cogs, and then have the bigger jumps in the bigger “climbing” cogs to give you a little of the best of both worlds.

 

What Does It All Mean?

The key learning from all this information is to make a conscious choice when you purchase a bike as to the gear range that you want.

If you are climbing, then the natural choice is going to be a compact crankset (50/34), or in extreme cases a triple, but think about the rear cassette. An 11-28 is pretty standard, but if you like keeping a high cadence on the hills, an 11-32 might suit you better. This means you still have a nice fast high gear, but the lowest gear is significantly easier to pedal. If you are a keen time trial rider then you may want to opt for a standard crankset (53/39), as it will give you a higher top gear. This paired with something like an 11-23 rear cassette would be great for flat course as it would give you very small changes between the gears meaning you could keep the cadence exactly where you wanted it.

The key is to know the kind of riding you are planning to do with the bike you purchase and choose the gearing accordingly. Below is a chart to help you understand typical ratios available. Remember the higher the ratio, the harder/quicker the gear is going to be.

 

Bicycle Gear Ratio Table

ChainsetSTANDARDCOMPACTSEMI-COMPACTTRIPLE
533950345236503930
105.303.905.003.405.203.605.003.903.00
114.823.554.553.094.733.274.553.552.73
124.423.254.172.834.333.004.173.252.50
134.083.003.852.624.002.773.853.002.31
143.792.793.572.433.712.573.572.792.14
153.532.603.332.273.472.403.332.602.00
163.312.443.132.133.252.253.132.441.88
173.122.292.942.003.062.122.942.291.76
182.942.172.781.892.892.002.782.171.67
192.792.052.631.792.741.892.632.051.58
202.651.952.501.702.601.802.501.951.50
212.521.862.381.622.481.712.381.861.43
222.411.772.271.552.361.642.271.771.36
232.301.702.171.482.261.572.171.701.30
242.211.632.081.422.171.502.081.631.25
252.121.562.001.362.081.442.001.561.20
262.041.501.921.312.001.381.921.501.15
271.961.441.851.261.931.331.851.441.11
281.891.391.791.211.861.291.791.391.07
291.831.341.721.171.791.241.721.341.03
301.771.301.671.131.731.201.671.301.00
311.711.261.611.101.681.161.611.260.97
321.661.221.561.061.631.131.561.220.94
331.611.181.521.031.581.091.521.180.91
341.561.151.471.001.531.061.471.150.88
351.511.111.430.971.491.031.431.110.86
361.471.081.390.941.441.001.391.080.83

 

Use Those Gears!

So now you’ve had a quick intro to how your gears work together, here are three final tips to take with you on your next ride.

  1. Avoid ‘cross-chaining’:  Cross-chaining is when you have a little/little or big/big combination.  This puts stress on the drivetrain and can cause premature wear of the components.  It’s OK if you occasionally find yourself cross-chained – say for a short, steep climb – but it is something you’ll generally want to avoid.  The rule of thumb to follow is that when on the big ring, only use the smaller two-thirds of the cassette. When on the inner (or middle) ring, only use the inner two-thirds.  When in ‘granny gear’ limit yourself to the largest two or three cogs.
  2. Anticipate your shifts: Keep an eye on the road ahead and shift before you have to. You’ll maintain a smoother power output, and you’ll be shifting at a time when there’s less stress on the drivetrain – so your shifts will be smoother too. As you approach a red light or stop sign you should also downshift a couple of gears, in anticipation of getting rolling again as smoothly as possible.
  3. Keep pedalling!:  It is much more efficient to keep a constant, steady power rather than ‘burst and coast’ riding.  It sure feels like you’re getting better exercise when you make that big effort, but you’re putting all the load on your muscular system, which isn’t really good at sustained effort. Spinning light and fast ends up putting out the same amount of power, but shifts the load to your cardiovascular system, which is good at endurance activity.

 

We hope this guide is useful to you and helps with the future setup and enjoyment of your bike and cycling adventures wherever you are in the world, if it’s in the mountains or on your commute… enjoy 😀

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