Downhill biking Gear

April 23, 2021
Downhill Bike

Bicycles have multiple gears so that it's easier to go up hills, and so you can go faster on level ground. Read this article and in five minutes you'll know how to use your gears.

First, let's get our terms straight so we're on the same page

You can think of gears as the same thing as speeds - a bike with 18 gears is an 18-speed bike. Bikes generally have 1, 3, 18, 21, 24, or 27 speeds. (10- and 15-speeds are obsolete and you don't see them on new bikes any more.)

Lower numbers are the low gears, and higher numbers are the high gears. First gear is a low gear. Twenty-first gear is a high gear. That's pretty easy, right?

Shifting means going from one gear to another. You shift gears by sliding the shifter on the handlebars. On most bikes this shifts the chain onto a different sized ring. On three-speed bikes the gears are inside the hub of the wheel so you don't see them.

Downshifting means going to a lower gear, and upshifting means going to a higher gear. You can also say shift down and shift up.

How do I tell what numbers my gears are?

If your bike has three speeds then telling the gears apart is easy, because there's only one shifter and it's labeled 1-2-3. You can skip the rest of this section and go on to the next one.

But if your bike has 10 or more speeds then it's just a little bit trickier, because you have two shifters. Let's say you have an 18-speed bike. Your left shifter will be labeled 1-2-3, and your right shifter will be labeled 1-2-3-4-5-6. This means that for each number on the left, you get six different speeds on the right, for a total of 18. Here's how it works:

Left shifter #1

Left Shifter #2

Left Shifter #3

1 Right-Hand Shifter
(Rear Ring Set)

Right-Hand Shifter
(Rear Ring Set)

Shifting moves the chain onto a different ring. Moving the lever changes where the chain is.

The Rear Ring
1-2-3-4-6-7-8-9
Lower | Higher
Your bike might have only 6, 7, or 8 rings.

The left shifter changes the ring next to the pedals. The smallest ring is 1, the middle ring is 2, 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. This is opposite of the front set: On the rear wheel the biggest ring is 1, and the smallest ring is 6.

You don't have to worry about the ring sizes if you don't want to, you can just look at the numbers on the shifter. You can downshift with either shifter, moving it from a higher number to a smaller number. You get a bigger change when you shift with the left-hand shifter than when you shift with the right-hand shifter.

Now that you know what the terms mean, let's see how to use our gears

Here's pretty much all you need to know about shifting gears:

If you're going uphill and it's too difficult, shift down.
If your legs are spinning the pedals way too fast (it's too "easy") then shift up.

That's it, in a nutshell. Of course there are nuances but that's 90% of what you need to know.

Here it is with more detail:

Let's say you're on a three-speed bike, in second speed. You start to go up a hill, and suddenly your legs can't spin the pedals as fast. You're barely turning the pedals, pushing hard on them, and you're going so slowly you think you might fall over. The solution? Downshift to first gear.

How does that solve the problem? First gear moves you a shorter distance for each spin of the pedals, which makes it easier to pedal.

Now let's say you've reached the top of the hill, and you start going downhill slightly. Soon you find there's no resistance in the pedals - you can spin them as fast as you want and you're not really getting anywhere. Solution? Upshift back to 2, and if it's still too easy, then upshift to 3.

This works because the higher gears move you farther for each spin of the pedals, making you do more "work", and making it less "easy".

Which shifter to use?

So you've learned the basics: Uphill = shift down, Downhill = shift up. But you have an 18-speed bike and you're wondering which shifter to use, the left one or the right one?

It's easy: If you need a big change, use your left shifter. If you need a small change, use the right one. As you ride you'll get a feel for whether you need a big change or a small change.

Don't bend the chain too much

Try to keep the chain in a sort-of straight line between the front and rear sets, rather than going at an extreme angle from left to right. For example, in the very lowest gear the chain will be all the way on the left on both sets. In the very highest gear the chain will be all the way on the right. That's fine. What you don't want to do is to use the left-most ring in the front and the right-most ring in the back, making the chain go diagonally. That stretches the chain and wears it out. Likewise, don't use the right-most ring in the front and the left-most ring in the back.

Let's say you're in the easiest gear (left-hand on both rings) and you need to upshift, so you move the chain on the rear set to the middle. That's not enough for you and you want to upshift some more. At this point, don't keep shifting the rear set, since that would make the chain diagonal between the front and rear sets. Instead, shift the front set from the left to the middle (1 to 2). That keeps your chain nice and straight.

Let's have another look at our gearing chart. The green boxes are the combinations you'll use, and the gray ones are the combos you'll avoid.

1 Right-Hand Shifter
(Rear Ring Set)

Right-Hand Shifter
(Rear Ring Set)

So yes, you won't use every gear available to you. You're not supposed to. Which brings us to...

How many gears do I need? Are more gears better?

The ever-increasing number of gears on bikes is mostly marketing hype. For the most part, all the extra gears are useless. My childhood bike had just 10 gears. Then bikes went to 15 gears. Then 18. Then 21. Now we're at 27. Do you really need that many gears? No. What you really need is a good range of gears. You need gears that are low enough for going up tough hills, and gears that are high enough that you can keep pedaling when going down gentle inclines. If your gear range is good, the number of gears is irrelevant.

You can't know the gear range of a bike by the number of gears it has. It's true that a bike with more gears often has a wider range than one with fewer gears, but not always, and even if it does, you don't necessarily need the widest gear-range possible. You just need enough of a range. (Think of it like this: There's no use in buying a car that goes 250 mph, because you're not allowed to drive that fast. More isn't necessarily better.) The only way to tell what the gear range of a bike 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.

In fact, if your area is relatively flat, you might not need gears at all. Or you might be able to get by with as little as three. As I write this, I'm in Osaka, Japan, where most bikes, including mine, have just three gears. The low gear isn't as low as I'd like for getting up hills, but it's good enough. If I were staying here longer, I'd get a bike shop to make the lower gear lower.

Yes, you can do that. 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.

I hope this helps, and have fun with your gearing!