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Understanding Your Bike Gears

  • By Scott Fliegelman
  • Published August 23, 2012
Photo: Nils Nilsen

I coach dozens of novice cyclists each season, and I’m constantly reminded how difficult it can be to ride well without a thorough understanding of your bike’s gears. The following tips will help you ride faster and lower your risk of an untimely mechanical meltdown.

Drivetrain anatomy
The drivetrain includes every part of your bike that helps move it forward—starting with the chainrings, crankset and pedals in front to the cassette and cogs in back. The chainrings are bolted to your crankset, and the pedals attach at the end of the crank arms. Most road/tri bikes have two or three rings with 30 to 53 teeth on them. The more teeth, the harder it is to pedal. Standard cranks usually come with 53 teeth on the big ring and 39 teeth on the small ring, while compact cranks offer a more climbing-friendly 50/34 pairing.

The cassette (aka cog set) is attached to your rear wheel hub. Cassettes usually have 8 to 11 cogs with between 11 and 28 teeth, but unlike the chainrings, the fewer teeth, the harder it is to pedal.

Cassette upgrades?
Forget weight, gearing is what’s most important. All the major component manufacturers offer cassettes with a wider range of cogs than comes standard on most bikes. Sram even makes a derailleur in its Apex line that can accommodate a super-easy 34-tooth cog. Count the number of teeth on your largest cog; if you have fewer than 25 and you struggle with maintaining a high cadence when climbing, you will surely benefit by upgrading to a cassette with 27 or more teeth on the largest cog (cassettes typically cost around $100). Conversely, if you ride in an area with few hills, consider a cassette with tighter spacing, like an 11–23, for smoother shifting performance. Also consider adding a cadence meter to your bike, as gear choices are often informed by cadence changes.

Pro tip: Before you buy a new cassette, take note of your favorite gear combination. Count the teeth on that “sweet spot” cog and then make sure that your new cassette includes one with that exact number of teeth. While it is tempting to go for the widest possible range, those cassettes skip over popular cog sizes like the 16-tooth in order to make the jump. If that’s your favorite cog and you don’t mind coasting when you top 35 mph, consider a 12–28 instead.

How to Shift
Now that you have the proper bike setup for your local terrain and riding style, here’s how to maximize its performance.

Front shifting (the chainrings) Spend most of your riding time in one chainring, while enjoying finer gearing adjustments courtesy of the cassette in the back. When the time comes to shift to the other ring due to an approaching hill, you may hear an annoying sound as the chain rubs against the front derailleur cage. This is a cue to make a macro shift with your left hand. First take a few hard pedal strokes, then back off a bit to take the load off your chain to make a clean shift.

Rear shifting (the cassette) You should rear shift (with your right hand) much more frequently than you front shift, especially on flatter courses. Aim for a gear that allows for a cadence of 85–95 RPMs. When the road tilts up and cadence begins to slow, shift with your right hand to an easier gear in the back, one with more teeth, closer to the hub. As speed begins to build and your cadence reaches 100 RPMs or more, shift with your right hand to a harder gear (one with fewer teeth, further from the hub) and allow your cadence to settle back into the 85–95 range. Aim to use the right hand micro shifting exclusively until you are almost out of cogs in the back or you start to hear that rubbing sound, then it is time to make a macro shift with your left hand.

Scott Fliegelman is the owner and head coach of FastForward Sports (Fastforwardsports.net) in Boulder, Colo.

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