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I read that road bikes on average have around 22 gears and mountain bikes up to 30-40.

But my hybrid only has gears numbered 1-3 on the left hand and gears numbered 1-8 on the right, so my bike's a 8 gear biked.

the 8 gears stacked together are a bit under 4cm horizontal.so 22 gears would be around 10cm. so for a mountain bike the gears could go up to 20cm.

Wouldn't that look really ridiculous?

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  • There are no 40 gear bicycles. 3x11 = 33 is largest, but unlikely, combination now available. There are rumors of 12-speed cassettes.
    – mkpaa
    Commented Jan 19, 2016 at 18:15
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    33 is not the largest. Sheldon brown constructed a 63 speed bicycle: sheldonbrown.com/org/otb.html.
    – Batman
    Commented Jan 19, 2016 at 18:50
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    You could, if you were so inclined, use a Pinion with a Rohloff to get 16x14=224 gears without any problems at all. Other than financial, anyway.
    – Móż
    Commented Jan 19, 2016 at 20:19
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    You multiply front and back. Your bike has 3 x 8 = 24 gears. A 22-gear bike has 2 x 11 gears.
    – PeteH
    Commented Jan 19, 2016 at 20:32
  • "Speeds" is not technically correct, but it is the common marketing jargon. When I was a child, there were "3-speed", "5-speed", and "10-speed" bicycles. Once that terminology got established, it would be really tough to dislodge it.
    – Monty Harder
    Commented Jan 19, 2016 at 21:59

2 Answers 2

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I think the terms used here are a bit confused. Rather than saying that a road bike has 22 "gears", you should be saying that it has 22 "speeds" (or more correctly, as pointed out in the comments, "gear ratios" is the technically correct most accurate term (when people say 'gear', they are using it as short for 'gear ratios')).

Even that can be a bit confusing, but to figure out the number of "speeds" a bike has, you would multiply the the number of gears in the front (in the case of your bike, 3) by the number of gears in the back, (in the case of your bike, 8). Meaning that your bike is actually a 24 "speed" bike.

A typical road bike manufactured today might have 2 gears in the front, & 10 or 11 in the back - so a 20 or 22 speed bike.

For a mountain bike, 30 - 40 speeds is a bit of an exaggeration. Most mountain bikes will have 2 or 3 gears in the front & up to 10 or 11 in the back. The largest cassettes (gear set in the back) manufactured have 11 gears. So the max number of speeds (again, gear combinations) a bike can have would be 33 (3 in the front x 11 in the back), although this may be an uncommon combination.

Here is a photo of a 30 speed drive train.

enter image description here

Here is a photo of a 24 speed drive train.

enter image description here

Here is a photo of a 22 speed drive train.

enter image description here

Whether or not all of these gear combinations are actually practical to use is another question though.

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  • 2
    And here is what a 63 speed bike looks like.
    – Batman
    Commented Jan 19, 2016 at 18:07
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    "gears" is the traditional short form of "gear ratios", and it is entirely accurate, but the rest of your answer is pretty good. "Speeds" is inaccurate to the point of being wrong - you can travel at the same speed in almost any gear ratio, what changes is how much torque is required.
    – Móż
    Commented Jan 19, 2016 at 20:22
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    Saying "speeds" is not right either, since it's not at all unusual to have two different combinations that produce the same gear ratio, or so close at to be inconsequential.
    – Daniel R Hicks
    Commented Jan 19, 2016 at 20:37
  • I have seen 4 chainrings being mentioned at a lot of places (usually with the remark "not needed, there are already enough") and seen it once on a tandem. It may not be common or available from mainstream manufacturers, but it certainly isn't totally unavailable if you really wanted to. Similar I guess would be for more than 11 at the back, though both certainly not available OTS.
    – PlasmaHH
    Commented Jan 19, 2016 at 20:43
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    @DanielRHicks not "correct", but probably accurate, at least in the vernacular. I've always heard them called "N-speed" bikes, which is naturally ridiculous, but then so are "ATM Machines" and it doesn't stop people using that term either ;)
    – Wayne Werner
    Commented Jan 19, 2016 at 21:12
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Short answer: you multiply the number of front chainrings by the number of cogs at the back.

That bike with two chainrings and 11 cogs on the cassette has 2x11 gears = 22, rather than just 11. Bike Gears Explained has lots more detail and this diagram:

bike gears explained diagram

You can see that for each of the three chainrings every cog on the back can be used. In this case that means 3 chainrings times 7 cogs = 21 gears.

Gears in this case is short for "gear ratios", meaning the ratio between the pedal speed and the wheel speed that you get from that gear. It's terminology used in industry and anywhere that gearboxes are used. The bicycle labels like "10 speed" and "21 speed" are an advertising term that's become common usage and is, like much advertising, inaccurate and causes confusion. Speed is the product of the gear you're in and the speed you're pedalling at, not just the gear alone.

The different colours are showing the gears that work well (green) compared to those that don't and should be avoided (red). This is called cross chaining (google) if you want to read more (wikiworks).

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