Bicycle Gears

Bicycle Gears

Shimano Dura-Ace CS-7900 10-speed CassetteBicycle Gears – It can be thought of as speeds – a bike with 18 bicycle gears is an 18-speed bike.  Bikes generally have 1, 3, 18, 21, 24, or 27 speeds.  The lower numbers are the low gears, and the higher numbers are high bicycle gears.

Shifting bicycle gears means going from one gear to another by sliding or adjusting the set of shift levers typically located on the handlebars.  The shift lever actuates the derailleur to move the chain from sprocket to sprocket on a gear set.  “Down shifting” means going to the lower bicycle gears and “up shifting” means going to the higher bicycle gears.  You may also hear the terms “shift down” and “shift up.”  You may be wondering which shift lever to use -the left one or the right one?  If you need a big change – use your left shift lever.  If you need a small change, use the right one.  For our example, let us consider the bicycle gears on an 18 speed bike.

The left shifter changes the front bicycle gears set attached to the crank assembly, where the pedals are on a bicycle. This gear set usually has three fixed sprockets ranging from small to large, which turn only when a bicycle is pedaled.  The smallest ring is 1 and the biggest ring is 3.  When you downshift with your left shifter, you’re moving to a smaller ring.

The right shifter changes the ring on the rear wheel.  The rear gear set is on the right side of the rear wheel and consists of a cluster of several sprockets, from small to large, mounted on the axle.  This gear set contains a ratchet assembly which allows the wheel to spin while the gears remain still.  When pedaling, the ratchet engages and the gears lock in place to allow the chain to drive the rear wheel.  There are two types of rear gear sets available.  The freewheel type threads directly onto the hub of the wheel.  The cassette type locks in place onto a hub body, which is threaded to the hub.  This makes the cassette type easy to remove and change.  On the rear wheel, the gearing is setup is opposite, where the biggest ring is 1 and the smallest ring is 6.  The lower the bicycle gears, the shorter the distance for each spin of the pedals, which makes it easier to pedal.  The higher bicycle gears will move you farther for each spin of the pedals, making you do more “work” and making it less “easy” to pedal.

Here’s the basics that you need to know about shifting bicycle gears: if you’re going uphill and it’s too difficult, then shift down; and if your legs are spinning the pedals too fast (it’s too “easy”), then shift up.  As you ride, you’ll get a feel for whether you need a big change or a small change.  Most importantly, you need to try to keep the chain in a sort of straight line between the front and rear set of bicycle gears because an extreme angle from left to right stretches the chain more and wears it out faster.  For example, if you’re in the easiest gear (left hand on both rings) and you need to up shift, you would move the chain on the rear set to the middle.  If that’s still not enough and you want to up shift some more, don’t keep shifting the rear set of bicycle gears, since that would make the chain diagonal between the front and rear sets of bicycle gears.  Instead, shift the front set from the left to the middle (1 to 2) which keeps your chain nice and straight.

How many bicycle gears do I need?  Are more gears better?  The ever-increasing number of bicycle gears on bikes nowadays is mostly marketing hype.  You need bicycle gears that are low enough for going up tough hills, and bicycle gears that are high enough that you can keep pedaling when going down gentle inclines.  If the range of the bicycle gears is good, than their number is irrelevant.  The only way to tell what the range of the bicycle gears is like is to take it on a test ride, going up the hardest hill you’ll be going up in the future, and going as fast as you care to down a gentle incline.  If your area is relatively flat, you might not need gears at all.  If you’ve already got a bike and you’re not happy with the gear range, you don’t have to get a whole new bike.  A bike shop can change either the front or rear rings (usually the front) to give you a higher range for bicycle gears.

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