An Introduction to Bicycle Gearing by John Josephs, MS
Filed under: Workouts & Training Plans
One of the subjects that has to eventually be addressed with new cyclist is gearing. Clients new to cycling give me that blank stare when I ask them to count the teeth on their front chain ring and rear cogs. However, once they get past the initial shock and embrace the notion that this is an important topic, they have already taken great strides in improving their cycling abilities. As a coach, I feel it is important that new cyclist know the gears they have on their bike, comprehend the concept behind effective gearing, and are capable of explaining this topic intelligently.
If your bike is geared wrong for you, you will lack efficiency. Most cyclists are geared too high and waste important energy causing them to fatigue prematurely by using fast twitch, anaerobic instead of slow twitch, aerobic muscle fiber. In addition, they will deplete their glycogen stores at a faster rate then if they were gear correctly.
Technically, the combination of the front chain ring (usually 53-39) and the rear cog create a gear ratio (39 Front and 13 Back = 3:1 ratio). This ratio times the diameter of the wheel (27") equals 81 gear inches (3X27"=81"). This means that you bike will travel 81 inches for every pedal revolution. If you want to know more about this, just search the Internet and find a gear chart. Plot your front and back gears to find the gear inches on your bike.
How does this apply to you? First, I want you to be able to talk the talk about technical issues involving your bike. If you go to the bike shop, read an article, or talk to an experienced cyclist, I want you to be able to carry on an intelligent conversation without sounding "inexperience" about gearing.
How would you explain to another cyclist, what gears you have on your bike, other than saying it's a 9-speed, which really doesn't explain anything. If someone asked an experienced cyclist about their gearing, they would respond, "I have a 53-39 up front with a 12-21 in the rear." The range of gears in the back tell me that it's a narrow range good for riding primarily on flat terrain. If I was going to NE Georgia or North Carolina to ride in the mountains, I would certainly need to change my gearing. I wouldn't be able to get up the mountains because I couldn't turn the pedals very long before I fatigued and had to stop. I would probably add a 25 and/or a 27 tooth gear to the rear cog. I wouldn't just remove the 21 and add the 25, I would have to change some of the other gears so they were evenly spaced. This means that when you shift gears, you want to gently go up and down in intensity and effort and not have a large gap in gear changes. Sometimes, however, one gear is too easy and you shift to the next gear and it's too hard. This is what I call "missing a gear" and can be changed by rearranging the combination(s) of gears or the type of gearing system you have on your bike. So if you're riding or racing in different parts of the state or country, you better research the topography so you can plan your gear choices appropriately.
What do I mean by finding your racing gear? We have reached the point in training that we have to fine-tune your training and get you ready for racing. When you train, shift through your gears and find the one or two gears that you feel the fastest and strongest within the parameters I set for you. These parameters are keeping your cadence between 90 to 100 rpms and keeping your HR in your lactate threshold zone for 40 to 60 minutes on flat terrain.
I want you to be able to tell me your gearing (yes, you have to count the teeth in all the gears in your rear cog) and your race gear(s) the next time I ask you. What chain ring up front creates more power for you? What cog in the back creates more power for you? What is your easiest and hardest gear combination?
Understanding these concepts will increase the pleasure you receive from the sport and improve your effectiveness as a cyclist. Knowing the answers to these questions will make you a better climber and save your knees. It will take the guess work out of increasing your speed and enable you to become more economical on your bicycle. It will also give you an advantage against your competition. You will be able to go faster and further.
Elements of an Efficient Drivetrain
As you begin to examine bicycle gearing, it is important to grasp that no matter how many speeds your bike has, its most efficient gearing should include:
• A low-enough first gear for you to comfortably climb hills. • A high-enough top gear to meet your need for flat-out speed. • Even steps between ratios across the entire gear range. • A smooth shifting progression that limits double shifting.
So gear up and get going!
1. GéRZ (Say "GEARS") Bicycle Gear Tables http://home.il.net/~dwolfe/gerz