Why do some bicycles have so many gears?

Question

A lot of bikes have 21 gears - does anybody use all of them?
How many gears do professional racing cyclists have? How many gears do professional mountain bikers have?

You only need five gears, maybe 10 maximum, to get up hills, Sid. I remember people coping quite well with the limited number of ratios provided by the Sturmey Archer 3 speed as well.

MR, you are an arrogant muppet. Shut up you fool!

Answer 1

Actually, you can't use all the gears in a bike. That means you shouldn't cross chain (use the leftmost gear at the front ant the rightmost gear on the rear, or viceversa). So a 27 spd mountain bike will likely have only 13 or 14 usable gear combinations.

Having this range will make the bike adapt better for the type of riding you're doing at any single time. If you're on a long climb you could use a low gear, but if you want to clear a short steep climb, probably a mid-range gear would let you stand up and hammer. Or if you're on paved roads you would want a larger gear.

About mountain bikes, most bikes comes with the crankset with 3 gears and on the rear with 7, 8 or 9 speeds. Mostly, the largest gear at the front is seldomly used. Some bikes go with only 2 or a single gear up front, depending again, of the type of bike (freeride bikes usually replace the largest front gear for a bashguard, and downhill bikes usually have only a single gear upfront with a chain guide). Most mid to high level bikes come with 9 speeds at the rear.

Road bikes are sort of different, or the gear ratio are. Usually, I think they come with two gears at the front and 9 or 10 spd at the rear.

Answer 2

As noted by others, you can't use all the apparent possible combinations, but I'm here to tell you I have used all of the gears on both my mountain bike and my road bike, and wished for a few more on occasion.

Road Bike: Try the Ironman Wisconsin bike course, or better yet, the Horribly Hilly Hundred, or even the Sugarloaf area in Central Florida.

Mountain Bike: Palos in Illinois, or Blue Mound and Devil's Lake in Wisconsin.

Answer 3

Consider an V-8 engine - it idles at about 500 RPM and can rev up to say 5000 RPM. Furthermore, a V-8 engine has lots of torque (power) throughout most of its entire operating range. With such a wide range of operation, it can take on nearly all terrains and different road speeds with a three or four speed transmission.

On the other hand, most cyclists are comfortable pedaling between about 50-100 RPM. This is a very narrow range of operation. Thus, having a very wide range of gears on a bike allows a cyclist to operate in his or her most comfortable pedaling range.

Most professional level road bikes have 18 or 20 gears while, most professional level mountain bikes have 27 gears.

As others have stated not all gear combinations are usable, though. For example, "cross gearing" is bad on your chain. Cross gearing refers to using your outside front chainring on your inside rear cog (or vise versa.) This gear combination causes the chain to twist and puts extra wear on it. The amount of chain your rear derailluer can take up also affects which gears you can use. If your rear derailleur won't take up the slack when using a small front chain ring (like a granny gear) and a small rear cog, you can't use the gear without risking the chain popping off.

Hope this helps.

Answer 4

Some wise good answers, little I can add.

So "many" gears are there to allow the cyclist to find the most comfortable or suitable one according to the terrain, speed, cadence and effort he is facing or willing to face.

It adds "flexibility" to the rider according to: effort, speed, cadence and terrain.


Many professional cyclist can choose and adapt the gears in their bikes according to the demands of the day the are facing ( hilly ride, long flat ride, etc.) Most of use, will have to settle with what we have in our bicycle, so a "generous" amount of possibilities is welcome from a buyer and seller point of view. Specially if the combination of front rings and rear gears is adequate as not to duplicate any (or many) of the posible ratio combinations.

Hope this helps.

Answer 5

Lets see....

Using a Rohloff 9 speed hub with a 10 speed cassette and a triple in the front will allow 270 gears. That might be JUST enough for the serious cross country tourer.

Yes, one can cope with 10 gears- heck, I raced 10 speeds- but the technology now has proven that additional gears and use of those gears appropriately will reduce fatigue and increase performance, but not necessarily speed.

MR... wha... didn't take your 'nice' pill today? ;)

Answer 6

Well Neil thanks for letting us all know how many gears are needed - I'm sure the pros will take your advice. Many people here and certainly pros cycle more in a week than you do in a year(s) most likely.

You comments indicate you have little understanding about the subject and are simply attempting to antagonize people here.

BTW the number of gears you need to go up hill? 1 - the right one at the right time. (read what I just wrote and see if you can extrapolate the reason for the "excessive" number of gears that bothers you so much).

EDIT: I just added 1 gear to my bike now I have a 19 speed... I'm getting 3 more for Christmas too, since I've been a good boy.

EDIT: Stan you got one strange set up on your ride! Post a picture.

EDIT: I think I have gear envy, I'm getting 5 more gears this weekend - hope have 37 by new years day...

EDIT: Ok listen, I just found out Santa isn't real... I'm stress out man... please no more thumbs down... just couldn't handle another one...

Answer 7

Bikes have that many gears to cater to different tastes. One of my road bikes has 30 speeds. Still, they really don't have that many gears because on triple cranksets, many of the gears overlap each other. Anyway, as I mentioned before, it's to cater to different taste. You may have a high cadence when you ride and the next person may like a lower. Having this many gears makes it easier for a manufacturer to sell a comfortable bike to the masses without having to make some bikes of the same model double, triple, or compact crank. Also, models come at a pricepoint and manufacturers have to be able to sell that particular model at that pricepoint without deviating from it.

Answer 8

My road bike has 30 gears. Some of them are duplicates, but it is handy to have them available without having to switch chain rings. Avoiding cross-chaining also reduces the number of useable gears as well.

Why so many? Half of the reason is that that they are useful. The other half is competitive specmanship from the manufacturers. More is better.

HTH

Answer 9

Top road racers use 2x10 = 20 gears. Top mountain bike racers use 2x9 = 18 gears. No, they don't use all of them, but if you've ever been on a serious bike ride, you'd know that one chainring in the front is not enough.

Answer 10

because the world has so many hills.

although it should be pointed out that some bikes (bmx, fixied gear, etc) only have one gear.

pro road bikers probably have 20-speeds, although two of those combos (cross-chaining) aren't used since they'll put extra wear on the cogs/chain, so they really have 18 usable speeds.