Back in 1982, Missing Persons asked the age-old question, “What are words for, when no one listens anymore?”
I won’t attempt to answer that mystery wrapped in an enigma, but I will attempt to clarify what gears are for. We’ll clarify the role of gears, and once you’re comfortable with the how then we will move on to the where and why.
What do gears do?
Simply put, gears allow us to vary our “stride length.” A low gear lets us take baby-steps, while a high gear has us striding about in Brobdingnag fashion. A typical road bike, equipped with a small chainring of thirty-four teeth and a large of fifty, paired with an eleven through twenty-eight tooth cog cassette, gives us a low gear that moves us forward a bit over eight-and-one-half (8.57) feet (2.61 meters) per pedal revolution while also sporting a high gear of 32.11 feet/9.79 meters.
If that makes you shake your head in bewilderment, then just realize that each pedal stroke in the bike’s highest gear is roughly four times more work than in the bike’s easiest. Pedaling the bike in lowest gear at a cadence of 100 revolutions per minute will drive you forward at a speed just shy of ten mph/sixteen kph, while pedaling at the same 100 rpm in a fifty/eleven gear combination (That’s the big, outer chainring up front and the smallest, outer cog in back) will have you flying down the tarmac at a speed just shy of thirty-seven mph/fifty-nine kph. (Buckle up, Colonel Sanders! We’re hitting Ludicrous Speed!)
Cool? Now let’s spell that out.
Do you remember the quadratic equation from high-school algebra class?
Neither do I!
But I do know how to add, subtract, multiply and divide, and today’s lesson only requires, as Jethro Bodine of The Beverly Hillbillies fame would say, “Goes into’s.”
To know how many times your wheel will travel with each pedal revolution simply take the number of teeth you front chain-rings have and divide by the number of teeth your rear wheel cogs/cassette have. The result is how many times around your wheel will spin.
Talk about a revolution! (How far we going with this?)
Bold and crossed through gears should not be used. Chain line matters. (We’ll return to this later.)
Simply put, the bigger the quotient, the more work we do with every pedal stroke. Our “biggest” hardest gear is always when the chain is farthest from the center-line of the bike, i.e., big chainring, small rear cog. Try not to get caught up in nomenclature of up shifting or down shifting. What we really want to know is how to do less work when the going gets tough, and how to do more work when you tough folks want to get going.
As a rule, using the big chainring will extend the service life of your drive train provided you keep your cadence high. A very low, acceptable cadence is seventy revolutions per minute and a cadence in the low hundreds is better. (More later.)
Harder gears/more work does not equal faster. High gears plus high cadence equals faster. If you are regularly riding in a gear that does not allow you to maintain an absolute minimum of 70 RPM then change to a lower gear that does allow this.
Sam Hill called. He wants his chart back.
So how do we change how far we travel with every pedal stroke? By following Golden Earring’s advice and shifting gears.
Your bicycle is likely equipped with two shift levers. If your bicycle has two shift levers, then you have a greater than 99.9% chance that the left shifter operates the front derailleur and the right shifter operates the rear. If your bicycle only has one shifter then it almost certainly works the rear derailleur and gears.
(If your bike’s shifters are not right equals rear and left equals front then it has a 99.9999999% chance of having been modified.)
If your bicycle only has a rear derailleur/right shifter, then the shift pattern is simple. Push it one way to do more work, i.e. travel farther with every pedal stroke, and operate the lever in the opposite direction to do less work and travel a shorter distance with each RPM. More work is needed when your feet are at too high of an RPM, less work is needed when you begin to struggle and cadence falls.
All shifting is to be done while pedaling the bicycle forward.
PEDALING the bicycle FORWARD!
Otherwise, damage can occur to your derailleur equipped shifting system.
Is the right shifter’s job clear? Push the right shifter one way to take smaller “steps” and push it the opposite way to take larger ones?
Let’s do the Time Warp and jump to the left!
The left shifter allows you to choose between two, or possibly three, front chainrings. The change (Delta) in the amount of work done when shifting between front chainrings is greater than the change/delta when shifting the back.
There is a 255 percent change in work from our twenty-eight-tooth rear cog to our eleven-tooth rear cog. We travel 255% farther in our 11-tooth smallest/hardest rear gear than we do in our 28 tooth largest/easiest rear gear. The difference in work between each rear cassette cog equals roughly ten percent. Each single rear shift in this example allows you to travel roughly ten percent more or ten percent less with every pedal stroke.
When we change from our 50 tooth, large/outer chainring (front gear) to our 34 tooth small/inner chainring we reduce our workload by roughly 33%, a much bigger, more abrupt change than the 10% delta from a rear shift.
When we have small or gradual terrain or wind direction changes we will shift the right shifter, if we turn a corner and are presented with Mordor’s Mount Doom then we’ll likely need to have a larger change and we’ll shift the left/front derailleur.
Rear derailleurs shift far better under load than front derailleurs do. If you wait until you are struggling to keep the cranks turning before shifting the front derailleur you are setting yourself up for failure. Just because left and right shift levers are mirror images of one another don’t be misled into thinking the derailleurs work the same way: They don’t.
What’s my least favorite question?
What’s the best gear for riding in?
Answer: The one that allows you to do an appropriate amount of work at a crisp RPM that emphasizes a cardio workout and keeps knees from being overly stressed while extending the lifespan of your bike’s drive-train.
What’s that mean?
If your bicycle has two front chainrings then you should change back and forth between them whenever you have a large change in terrain, wind speed/direction or fatigue. A high cadence, or pedal RPM, stresses your knees and drive-train less than pushing a bigger gear at a lower cadence.
How high is high? On level ground a very low RPM would hover around 70 strokes per minute while a high cadence would be in the one-hundreds. Cadence tends to slow on climbs and rise with descents.
Pedal systems that enable a rider to clip into the pedals allow for higher cadence and better muscle use. (When we’re clipped in we can use our hamstrings in addition to our Quads and put power to the pedals for more of the pedal stroke.) They also allow for proper foot/knee/hip orientation and can help prevent repetitive use injuries.
Change your gears.
When starting a brief climb flick your rear/right shifter one gear easier. When your leg speed begins to slow do it again. Repeat as needed. Newer road bicycles are equipped with twenty-two gears, eighteen of which you should be using. (See Talk about a revolution! chart.)
Sinistra is Latin for left:
Anticipate front gear changes because that dag-gone left shifter is, well, sinistra! The right/rear derailleur hands the chain from cog to cog while the left/front one throws it. It is barbaric. Do not wait until you are in slow RPM, heaving on the pedals mode to shift your front derailleur. Anticipate and shift early.
If you have three front gears you will likely only use the tiny, innermost front chainring for climbing steep hills. Because of chain line issues, if your bike is equipped with three front chainrings, it is best to only use your bicycles smallest, inner front chainring in conjunction with the three or four, largest, easiest, inner rear cogs of your cassette for very steep climbs or times of overwhelming fatigue.
The middle chainring on a triple will likely see the most usage, and, unless the bicycle is ridden in very steep terrain, the inner, smallest chainring the least. Just remember to keep your cadence at an absolute minimum of 70 RPM except when climbing Mount Doom and you’ve run out of low gears and use your front chainrings accordingly.
I don’t need a full haircut just a little…
It takes about 40 mm or a bit over one and a half inches of space to fit eleven gears on your bikes rear hub. As you change gears on your cassette by flicking your right shifter from hard/small rear gears to large/easy ones, the chain moves from left to right up on the crank’s chainrings.
As the chain line sweeps from right to left or left to right your front derailleur may begin to rub the front derailleurs cage. Drop-bar style road bikes and many upper end hybrid or flat-bar bikes have “half clicks” in their shifters, allowing you to “trim” out the rub.
If your bicycle chain is down on the harder/smaller rear gears and the chain is rubbing the front derailleur then push the left shifter gently and minutely in the direction needed to go from a smaller to larger chainring. This trimming will eliminate chain on derailleur rub. Do the procedure in reveres, i.e. a gentle half-click toward a lower gear if the chain is rubbing the inside of your front derailleur in the bigger/easier rear cogs.
Derailleur hangers are low, vulnerable and susceptible to damage with even minor impacts. A minorly bent hanger can drastically affect rear shifting quality while a severely bent hanger can allow a bike’s chain to shift into the wheel’s spokes, causing catastrophic damage. Derailleur cables “stretch” with usage, which is one cause of slow shifting from smaller/harder rear cogs to larger/easier ones. Cable stretch is normal but a bicycle that is shifting slowly from larger/easier rear cogs to smaller/harder ones is likely suffering from either a bent hanger or a frayed cable, both of which are Red Flags! If your bike is shifting slowly from a larger/easier cog to a smaller/harder it needs professional help.
-ALWAYS pedal forward when shifting.
-Big chainrings in front equal more work, small chainrings in front equal less work.
-Small cogs in back equal more work, large cogs in back equal less work.
-Gears further out from the bikes center line are harder, gears closer in are easier.
-Some gears overlap (see Talk about a revolution! chart) and there are times when it makes more sense to achieve a gear using the big front ring versus the rear depending on what gear will likely be required next.
-Don’t stress about the “right” gear or the “next” gear. SHIFT! If your feet are flying, shift to a harder gear, and as your cadence begins to slow, shift to an easier gear. Strive for an absolute minimum RPM of seventy.
-Ride you bike, enjoy yourself and keep your head up!
-Slow shifting from large to small rear cogs may indicate a bent derailleur hanger. Seek assistance if your bike is shifting slowly to smaller/harder rear cogs.