The original article, “A Breakdown of Bike Gears,” by Jo Allen, written for Cycling Camp San Diego appeared in active.com. Josephine Allen is a level 2 USA cycling coach and an experienced endurance cyclist.
Put simply: The right gears will make your cycling experience a lot more enjoyable and can make you faster and help you cycle for longer without tiring.
Unless you’re only ever going to cycle on flat roads then considering the best gears to maintain your pedaling speed (cadence) and effort level over a variety of terrain is one of the most important decisions you can make when setting up your bike.
(i.e. your front chain rings and pedal cranks)
- Triple (3 chain rings): Large chain ring usually has 52 teeth, medium 39 teeth, and small 30 teeth.
- Standard (2 chain rings): Large chain ring usually has 53 teeth and small 39 teeth.
- Compact (2 chain rings): Large chain ring usually has 50 teeth and small 34 teeth (sometimes 36).
Rear Cassette Options
(i.e. your rear wheel cogs)
Usually 10 or 11 speed (occasionally 9), which denotes the number of cogs on the cassette, and therefore the number of gear options you have. Common brands you may come across are Shimano, Campagnolo and SRAM, which offer a variety of options to suit all budgets.
Help! I Don’t Know What I Need
First step: Understanding gear ratio.
Gear ratio, in its most simple calculation, is a function of the number of teeth on the front chain rings, compared to the rear cogs. Dividing the front number of teeth by the rear numbers arrives at a number. The higher the number, the harder effort per turn of the wheels. The smaller the number, the lower effort per turn.
Think of it in extremes: If you turn the front chain ring once with a pedal stroke and that movement turns the rear cog four times then you’ll travel four times the circumference of your wheel in return for that effort.
If a single pedal stroke only turns the rear wheel two times, that would be a gear ratio of two.
Next step: How does different gearing set up affect gear ratio?
So, your highest and lower gear ratio will be determined by the crank set you have and the size of the smallest and largest cogs on your cassette. Go and count the teeth now, write it down and come back to finish reading this.
Now take the number of teeth on your large chain ring and divide it by the number of teeth on your smallest cassette cog. This gives you your highest gear ratio and therefore how fast and how much power you can put in on the flat or downhill.
Then take the small chain ring and divide the number of teeth by those on the largest cog on your cassette. This is the lowest gear ratio you can achieve with your gearing set up and will determine how easy you can make a climb feel.
This calculation often helps people decide between a triple and a compact. E.g. a triple with a 30-tooth chain ring and an 11-25 cassette will give you about the same lowest gear ratio as a compact with a 34 chain ring and an 12-28 cassette.
These days you can get cassettes in a wide variety of sizes and match your lowest gear ratio to your personal ability and riding terrain.
Finally: Using your gears for maximum efficiency and speed.
Continually pushing a gear that is too high for you will result in fast fatigue and possible injury. Instead you should try and maintain a nice steady rhythm and cadence, changing up and down the gears as the terrain undulates.
Also, you’ll notice that the gear ratios you achieve at the two extremes of large chain ring with large cassette cog and small chain ring with small cassette cog can also be easily achieved with an alternative chain ring/cog combination towards the middle of the cassette. “Cross chaining” as it is known is not great for the bike or chain and is unnecessary.
Here’s an example of different gear ratios for a couple of different set ups:
You’ll notice that you achieve exactly the same gear ratio using the 53–15 as you do using the 39-11, except that using 39-11 will cause the chain to be stretched at an extreme angle and therefore wear it faster (and you’ll get that annoying clicking sound!).
So What Should I Put On My Bike?
To a certain extent it is a matter of trial and error. There is no standard recommendation for e.g. a century ride with 8,000 feet of climbing. It really does depend on the rider.
But, I can tell you…I’ve never heard anyone saying “I wish I had less gears!” More often than not I hear people struggling up a hill in their lowest gear ratio and wishing that they had another couple of slightly larger cogs on the back cassette.
As a guide, if you can’t maintain a steady cadence of 80 on a long hill of about 6-7 percent then you should consider a bigger cassette at the back. Trust me, this could make you faster and you may just discover your inner grimpeur.*
* grimpeur – noun, m (plural grimpeurs; feminine grimpeuse, plural grimpeuses): 1.(climbing) climber (someone who climbs) 2. (cycling) climber (expert in mountainous races) 3. social climber
- Read the original article, “A Breakdown of Bike Gears,” by Jo Allen, written for Cycling Camp San Diego and posted on active.com.
- For more, see, “Be a Gear Guru on Your Bike,” by Jonathan Cane, originally for Windy City Sports.
- Read about the Shimano Ultegra 6800 with 11-speed cassette.
- For more on climbing, see our recent article, Tips for Better Hill Climbing.