Understanding Bike Gears

When I first became involved in triathlon, I purchased a road bike. I hopped on and as I expected, I was able to ride it even though it had been several years since I had been on one. It took a few rides to figure out how to shift gears. The shifters were on the brake levers and the first few times I attempted to shift gears, I ended up pulling on the brakes. I was a newbie in every sense of the word. Once I figured out which side shifted my front ring and which side moved the chain on the rear cassette, I then had to figure out when and how to shift.

I basically learned by trial and error. During my first full triathlon season, I spent a lot of time in a high (hard) gear, just mashing the pedals because I was uncomfortable shifting and didn’t want to shift the wrong way and lose momentum  – or even worse, drop the chain. I remember having no clue as to what “gearing ratio” or “gear combination” meant. When someone would ask me about my “cog”, “sprocket” or “cassette”, I would use my salesman skills to pretend like I knew what they were talking about while steering the conversation in a different direction.

After being clueless for a long time, I finally decided to study up and learn about bike gearing. So if you are like I was and unsure about what it all means, I’ll try and make it easier to understand. Let’s start out with some common terms:

  • Chainring – the large gear in the front. Depending on what type of bike you have (road, tri, cross, mountain, etc.), youjust-sharing-anatomy-of-mountain-bike-parts-c-L-QZh9s7 may have one, two or three different size rings. The front derailleur is what moves the chain between the different rings.
  • Derailleur – the mechanism that moves the chain back and forth between the chainring or cassette through the cable that is attached to your shifter
  • Cassette – The set of smaller rings that is on the back wheel. It can have from a single ring up to 11 or 12 rings. It’s also called the Sprocket or Cluster. When looking at a cassette, it will be labeled with a dash between the number of teeth on the smallest cog (ring) and the largest cog. For instance, a 11-25 will have 11 teeth in the smallest cog and 25 teeth in the largest cog. This does not tell you how many cogs are in the cassette. If someone calls it a “10-speed” or “9-speed”, that refers to the number of cogs.  If you were to look at the number of teeth on each cog of a typical “11-25” 10-speed, it would look like this – 11/12/13/14/15/17/19/21/23/25.
  • Teeth – The teeth are those pointy things on the rings. The number of teeth on a ring (commonly 50-53 on the big front chainring and 35-40 on the small front chainring). When looking for a chainring, it will usually be labeled by the number of teeth. For instance, a 53/39 would have 53 teeth in the big ring and 39 in the small ring. A “compact” chainring will typically have rings of 50/34 teeth, while a “standard” will be 53/39.
  • Crank Set – composed of the chainring and crankarms (pedals are attached to the end of the crankarms).
  • Gear Combination – this refers to a specific gear selection that the chain is in at any given time. For instance, if someone is at 53×11, the chain is wrapped around the big 53 tooth ring in the front and the little 11 tooth cog in the back.
  • Gear Ratio – This is simply dividing the front and rear gears (chainring / cog). For instance, if the chain is wrapped around the big 53 tooth ring in the front and the little 11 tooth cog in the back, this would be 53 divided by 11 = a gear ratio of 4.818. It’s usually shown with a colon in the middle, like 53:11.
  • Bigger (Higher) Gear – this means that you are in your large ring up front and one of the smaller cogs in the back, making it “harder” to pedal. You “shift up” to get to a bigger gear.
  • cassette__derailleur_600wSmaller (Lower) Gear – this means that you are in the small ring up front and one of the larger cogs in the back, making it “easier” to pedal. You “shift down” to get to a smaller gear. You may also refer to this as “granny gear” when looking to poke fun of someone that always rides in this gear ratio.

So now that you know what all the lingo means, what do you do with this information? Depending on what type of course you are riding, you may want to look at different size chainrings and cassettes. If you are riding a really hilly course, you many need to have a chainring with fewer teeth on the small ring. So a 50/34 would be a better choice than a 53/39. For the cassette, the larger numbers equate to easier climbing (opposite of the front chainring). So a 11-28 would be better for climbing than a 12-25.

If you are a strong rider or prefer to power up hills, the lower gears are not as useful to you. You would rather have more gear on the flats that will allow you to go faster in your higher gears.

Since no one gear setup is ideal for every rider and every type of riding, many cyclists have different bikes, or different cassettes that they can use.

So hopefully this helps you understand your bike a little better and how to use gears to your advantage.

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