# Bicycle Mechanics - Gear Ratios, how do they work?

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View Full Version : Gear Ratios, how do they work?

MATTO
11-14-04, 04:23 PM
Hi im interested in geting a knew cassest umm I saw that theres like 11/13 11/15 and stuff like that

would i get a knew chain with that 2 so they wear together

but can u explain to mean what the numbers mean.

chris_krueger
11-14-04, 05:20 PM
I believe the numbers are the number of teeth on the chain ring

phantomcow2
11-14-04, 05:53 PM
I can hardly understand your english, try making your message clear and use the right word. its new not knew. Where are you seeing these numbers?

MATTO
11-14-04, 06:55 PM
sorry i have a habit of adding K to letters,

but it says when I would go to buy a Cassette(sp)
it is availibale int he following ratios
11/13................etc

twahl
11-14-04, 07:43 PM
Usually cassettes are listed by the smallest and largest cogs in the set. The smallest will be your fastest gear for a given RPM on a certain chain ring, and the largest will give you the most pulling power. Basically 1 revolution of the pedals goes further on the smallest gear, and gives the most power on the largest gear. Road bikes have closer ratio cassettes, and mountain bikes have more difference in the gears. For instance a road cassette might be anywhere from 11-21 to 12-27, and a mountian cassette might be anywhere from 11-32 to 11-34. Getting a new chain isn't a bad idea just because they do need to be replaced periodically anyway.

531Aussie
11-14-04, 07:43 PM
The numbers refer to the numbers of teeth on the rear cogs.

If you buy a 9 speed "11 to 21" cassette, the 9 cogs will
most have the following numbers of teeth on them: 11,12,13,14,15,16,17,19,21.

The smaller the number of teeth on the back cogs, the bigger/harder the gear,
and the smaller the number of teeth on the front chainring (near the pedals), the
easier the gear.

Some people think that an 11 tooth cog provides such a big gear that is
unnecessary, so they usually get a "12 to 23" cassette or even a 12 to 25, or even
higher.

In my opninion, it's preferable to buy a new chain at the same time

Biketo120
11-14-04, 08:19 PM
For detailed info, here is a link to a site to download a software package that will calculate gear ratios:

sydney
11-14-04, 08:21 PM
In my opninion, it's preferable to buy a new chain at the same timeThat's a potential waste of ALOT of money ,and that isn't an opinion.

531Aussie
11-14-04, 08:26 PM
That's a potential waste of ALOT of money ,and that isn't an opinion.

"ALOT" of money???!!! That's just hooey

Let's do a poll

Hitchy
11-14-04, 10:29 PM
"ALOT" of money???!!! That's just hooey

Let's do a poll

theres no 'hooey' here is there.......???...thought it was just BS!....:D

hitchy

Vittorio
11-15-04, 06:56 AM
No, new chain is not waste of "A LOT" money. Chain is wear item, as tyres or brake rubbers. Wear out, replace, repeat.

Answer to original question: Roadracing have small number cassettes, as 11/25, for best horsepower (manpower?) at high RPMs. Horsepower makes speed.

Hybrid & VTT have bigger numbers, as 13/32, for more torque. Torque makes ability to climb. All cassettes have ratios for to provide both, but compromise in favour of purpose for bicycle.

Best is to replace cassette with same numbers, thus u will not have any troubles with shifts. If now u have 11/25, purchase same. Too high last number, and rr derailleur pulley can crash to cassette.

Install new chain before is too late can prevent destruction on cassette. I report 2 000, 2 200km
before chain wear out, some tell me is normal, others no. Chi sa?

For chains, more expensive = less weight. If u can accept a few more g, u can purchase for less money.

Example, in Italia, Shimano XTR 9sp = 21€, and HG93 = 18€. I purchase Shimano HG53 (9sp) at 11€, five at one time. Extra weight of chain for me is not importante, for I have 10, 15 kg on rack, lights, tools, etc.

Just my opinions, good luck!

MATTO
11-15-04, 04:27 PM
well im okay im 500m from the 2000mile mark on my bike. where I live i have moderate hills and flats what would be a good set up?

oh and I would get a chan so the cassette and the chain could wear evenly :D

Alphie
11-15-04, 06:47 PM
I see that you have a Trek 1200. If it has a triple it has a 52/42/30 chainring and a 12/25 cassette. That is almost the same as on my Lemond, and that gearing is just fine for this area. My commuting route is mostly flat, but there are some hilly areas of Atlanta that make having the 30 ring nice.

MATTO
11-15-04, 06:56 PM
nice man, umm so would more torque= less straightaway speed but more speed up hill or?

John E
11-15-04, 07:15 PM
nice man, umm so would more torque= less straightaway speed but more speed up hill or?

Changing gears lets you trade torque against road speed. You use the larger rear cogs and/or smaller front chainrings to creep up hills without damaging your knees, and you use the high gears (small cogs / large chainrings) to go fast with the wind or downhill. Since I am one of those who feels strongly that 11- or 12-tooth cogs are useless with any chainring larger than 48T, most of my rear cogsets run 13 to 26 teeth.

MATTO
11-15-04, 08:35 PM
so what categorys would be mid rang?
ie chainring and cassette, i kinda want both but i guss its a trade off, i kinda dont wanna be working hard on flats..

blue_neon
11-15-04, 10:36 PM
I can hardly understand your english, try making your message clear and use the right word. its new not knew.

God, does it really matter that much?

MATTO
11-16-04, 03:15 PM
well thanks to yall who helped me out