Bikes are such a great mode of transportation and adventure because they move us around faster and easier than we can run or walk. This boost in speed comes from the gears on our bike, which help transfer the power of your legs to the movement of your wheels.
The basics or gearing.
- The chainring(s) are the gears in the front. The ones that your crank and pedals are attached to.
- Cogs make up your cassette in the back. The ones mated to your rear wheel.
Chainrings on road bikes come in standard and compact groups. A standard chainring combination is the pairing of one chainring with 53 teeth and one chainring with 39 teeth (this is typically abbreviated to 53/39). Compact chainring combinations are a pairing of one chainring with 50 teeth and one with 34 or 36 teeth, so 50/34 or 50/36.
Modern cassettes are most commonly built with 10 or 11 cogs that have a range of 11 to 25 teeth.
Now, let's look at how the chainrings and cogs work together.
When your chain is on the smallest (innermost) chainring and on the largest (innermost) cog, you will be in your easiest gear. Some people refer to this as the "Granny Gear" and it is the one that helps you climb up tough hills! Conversely, when your chain is on the largest (outermost) chainring and on the smallest (outermost) cog of your cassette, you're in the hardest gear. This is typically the position you'll be in when you are descending and want to go as fast as you can. What this gear does is allow you to cover the most ground possible with one rotation of your pedals. The remaining chainring and cog combinations give you the option to appropriately adjust your pedaling effort to the demands of the terrain - from easiest to hardest.
What type of gearing should your bike have?
This question is best answered by the topography of your area. Do you live in an area with a lot of changes in elevation or are you riding in a flat part of the country? If you live in an area similar to our home in Harrisonburg, VA, then we'd say that you will want compact gearing on your bike because you'll appreciate the easier gears while climbing steep roads. However, if you live in Florida, a standard group would work great for you and allow you to really cover some ground.
We've only scratched the surface on bike gearing, but this should help you make sense of all the 50/34s, 53/39s, etc. you see online, plus you should have a better sense of what gear you want to be in and why for climbing or descending.
Create a great self-propelled adventure!
-The crew at Bluestone Bike & Run