I know this is a dumb question but I can't tell how many speeds I have on my bike. I have 3 positions on the left handle bar and 7 on the right handle bar. Can anyone help me?
2006-11-26 13:07:29 · 6 answers · asked by Cares 1 in Sports ➔ Cycling
Technically your bike has 21 gears--the number of rings on the front times the number of rings on your cassette in the back. However, you don't really have 21 usable different gears. This is because:
1) Depending on how many teeth are on your chainrings (front rings, you have 3) and your cassette (7 rings on back), you may have some gears that repeat. It is all about the ratio between the front ring and the back ring the chain is on. For example, let's say your middle front ring has 38 teeth and one of the rings on your cassette in the back has 19 teeth, you have a ratio of 2 to 1 when your chain is on these two rings. If your smallest ring in the front is 28 teeth and your smallest ring in the back is 14, you again have a ratio of 2 to 1, so these gears are actually the same.
2) There are also certain gears you should not use. You should avoid cross-chaining--being in smallest ring in front (closest to the bike, on the inside) and the smallest ring in back (farthest away from the bike) or largest in front (farthest away from bike) and largest in back (closest to the bike). Either of these gears, or close to them, puts a lot of stress on your chain because it torques it sideways. This will cause additional wear on the chain and shorten the life of it. Most bikes will allow you to do this because the chain is put at a length to allow for it, but it will also likely cause your chain to rub somewhere and also possibly make your bike not stay in gear very well.
However, these days, rather than multiplying the number of front and back rings to get speeds, bikes are now often referred to by the number of rings on the chain ring and cassette separately. You ride a 3 by 7 (3x7). A double road bike with a 10 speed cassette (typical of today's high end road bike) is a 2x10. A more touring oriented road bike often has a triple chainring and is likely to be a 3x9 or 3x10. A fairly typical mountain bike is a 3x9, but there are a lot of 2x9 or 3x8s out there too.
2006-11-26 14:01:45 · answer #1 · answered by triscuit121 2 · 1⤊ 0⤋
Aha! Is this a trick question? The answers above me are generally correct (you can shift 3 x 7 times which is 21 gears), but there is a caveat...
If you want to know the number of DIFFERENT gears you have on your bike, you need to calculate each combination to determine the amount of distance you travel with each pedal stroke. Your bike probably has at least 1 overlap so ultimately it has less than 21 gears.
2006-11-27 02:36:01 · answer #2 · answered by bikeworks 7 · 0⤊ 0⤋
Multiply the amount of gears on the back axle times the amount at the pedal. A ten-speed has 5 gears on the back and 2 on the pedal. A twenty-one has 7 in the back and 3 on the pedal.
2006-11-26 13:15:07 · answer #3 · answered by cornbreaded23 4 · 0⤊ 0⤋
the three positions on the left shifter means you have 3 chain rings, or front gears. the 7 positions on the right means you have 7 gears in the rear. multiply the two numbers and you have 21 speeds total.
2006-11-27 01:22:30 · answer #4 · answered by Anonymous · 0⤊ 0⤋
This usually means you have a 21 speed bicycle -- there should be 7 gear plates on your rear wheel, and 3 gear plates in the other location.
2006-11-26 13:16:26 · answer #5 · answered by sglmom 7 · 0⤊ 0⤋
by multiplying
you have a 21 speed bike
:)
2006-11-27 12:38:26 · answer #6 · answered by Anonymous · 0⤊ 0⤋