Expert Answers
Shifting 101

Mike's Question:
As someone new to biking, I am having difficulty trying to figure out how many speeds are on a bike, and what order to switch them. If it's not a problem, I wouldn't mind your advice.

— Mike

Steve Jones's Answer:

	Steve Jones The author of four mountain-biking books, Steve Jones has logged thousands of miles of trails and backroads. Meet Steve Answer Archive Biking Forums

Dear Mike,

In order to start making sense of it all, locate the pedal sprockets, also called crank rings. That's the set (normally three) of circular teeth situated on the right of the frame, almost directly underneath you when you're sitting on the saddle. You'll note they are attached to the pedals. When the pedals turn a complete revolution, so do the crank rings.

You'll find it easier to see how the crank rings affect the ease (or difficulty) of turning the pedals by somehow holding (or having a friend hold) the back tire off the ground. Using the gear shifter on the left side of the handlebar (and remembering to keep the pedals turning whenever you operate the shifter), put the chain on the largest crank ring. Now change it so that the chain slips down onto the next smallest crank ring. You should notice an obvious decrease in pedaling resistance. Now shift the chain onto the smallest crank ring. Even less resistance, right?

The front set of rings can be viewed as"multiplier rings," with the largest ring acting as the factor of "3," the middle gear as the factor of "2," and the smallest as the factor of "1." These rings multiply the potential speed achieved with the gears found attached to the axle of the back wheel, also called the free wheel.

Rear Gears

With the back tire still off the ground, try this. Keep the crank ring in the Number 1 position and shift the chain onto the largest gear on the back. This is the gear arrangement offering the least resistance possible, or "first gear." You'll also see that with this arrangement, the chain travels parallel to the frame.

Now shift the chain onto the next smallest rear gear. You will notice an ever-so-slight increase in resistance. This is "second" gear. In other words, the #2 free wheel ring's potential power is being multiplied by the crank ring's #1 gear. The number of individual rear gears, normally seven or eight, determines the possible gear selections. So, if you have eight rear gears and you're in the largest crank ring, how many gears do you have available without changing to a different crank ring? If you answered eight, you've mastered the concept.

A Shifting No-No

Technically, you have eight choices per crank ring (in this scenario), but in practice you are limited to seven or even six. The reason comes from the fact that with each rear gear change, the chain travels farther away from parallel to the frame. A chain that travels parallel, or nearly so, is superior for maximum efficiency and less wear on both the chain and the gear teeth. Therefore, a gear position of largest chain ring and smallest rear ring (or vice versa) is considered poor practice.

But I won't quibble about that. Simply speaking, a bike with three chain rings and eight rear gears has a possible 24 gear choices. The tricky part comes from knowing when to make a change from the gear you're in. The simple rule-of-shift states, Find a gear that provides enough resistance to maintain a 90-pedal-revolutions-per-minute cadence. You find the right gearing by gaining riding experience. So what are you waiting for? Get out there and shift for yourself.