gears...what does this mean?

[elk]

FREEWHEEL SRAM Powerglide 950 9-speed 11-32
CRANKSET FSA Vero Forged 52/42/30
165mm (47) 170mm (50-53) 175mm (55 - 62)

I'm trying to figure out this whole gear ratio thing....and I'm somewhat numerically dislexic......

Can someone explain what my gears are doing? I was reading about 36 being great for hills.... so I looked at my specs and just got dizzy...

just wanting to know...

[jesvetmed]

'm trying to figure out this whole gear ratio thing....and I'm somewhat numerically dislexic......

ME TOO! I look forward to someone who can enlighten us!

[ilima]

Okay.

CRANKSET FSA Vero Forged 52/42/30
This is the crankset and chainrings on the crankset. FSA (Full Speed Ahead) is a brand and Vero is the model. Forged means it's steel and heavy. It's a triple crankset with chainring sizes of 52, 42, and 30. The smaller the chainring used on the front, the easier it is to pedal and the higher your cadence will be for a set speed. 52/42/30 and 53/39/30 are common road triple combinations.

165mm (47) 170mm (50-53) 175mm (55 - 62)
This refers to the crank lengths for the different sizes of bikes in parentheses. Tall folks generally need longer cranks, shorter folks use shorter cranks.

FREEWHEEL SRAM Powerglide 950 9-speed 11-32
This refers to the cassette that's used on the back. In contrast to the chainrings, the more teeth the easier it is to pedal and the higher your cadence will be for a set speed. This is because the more teeth the fewer the revolutions of the back wheel per revolution of the cranks. This particular cassette happens to be a mountain bike cassette made by the company SRAM. Road cassettes typically only go to 27 max (SRAM to 28), while mountain cassettes go to 32 or 34.

To get easier pedaling (and to have more gears for us slowpokes up hills), you want smaller rings on the front and bigger rings on the back.

Sheldon Brown has a gear calculator that's fun to play with.
http://www.sheldonbrown.com/gears/

[elk]

Okay.

CRANKSET FSA Vero Forged 52/42/30
This is the crankset and chainrings on the crankset. FSA (Full Speed Ahead) is a brand and Vero is the model. Forged means it's steel and heavy. It's a triple crankset with chainring sizes of 52, 42, and 30. The smaller the chainring used on the front, the easier it is to pedal and the higher your cadence will be for a set speed. 52/42/30 and 53/39/30 are common road triple combinations.

165mm (47) 170mm (50-53) 175mm (55 - 62)
This refers to the crank lengths for the different sizes of bikes in parentheses. Tall folks generally need longer cranks, shorter folks use shorter cranks.

FREEWHEEL SRAM Powerglide 950 9-speed 11-32
This refers to the cassette that's used on the back. In contrast to the chainrings, the more teeth the easier it is to pedal and the higher your cadence will be for a set speed. This is because the more teeth the fewer the revolutions of the back wheel per revolution of the cranks. This particular cassette happens to be a mountain bike cassette made by the company SRAM. Road cassettes typically only go to 27 max (SRAM to 28), while mountain cassettes go to 32 or 34.

To get easier pedaling (and to have more gears for us slowpokes up hills), you want smaller rings on the front and bigger rings on the back.

Sheldon Brown has a gear calculator that's fun to play with.
http://www.sheldonbrown.com/gears/

OK..so 11-32 indicates that the number of teeth on each of the 9 rings is different and the smallest # is 11 and the largest 32? 11 teeth are on the smallest ring.

SO...my spinningest gear is 30/32?
and when I stay mostly on the middle ring up front...it's 42/ and 11 through 32?

and where does the RATIO part come in?

BY the way...this is the Jamis Aurora touring bike.

(thanks for all the info...!!!)

[aicabsolut]

Use Sheldon Brown's calculator http://www.sheldonbrown.com/gears/.

Explanation (from the website):

Gear Inches

The simplest system in common use is the "gear inch" system. This dates back to before the invention of the chain-drive bicycle. It originally was the diameter of the drive wheel of a high-wheel bicycle. When chain-drive "safety" bikes came in, the same system was used, multiplying the drive wheel diameter by the sprocket ratio. It is very easy to calculate: the diameter of the drive wheel, times the size of the front sprocket divided by the size of the rear sprocket. This gives a convenient two- or three-digit number. The examples listed above are all around 74-75 inches. The lowest gear on most mountain bikes is around 22-26 inches. The highest gear on road racing bikes is usually around 108-110 inches. Unfortunately, the handwriting is on the wall for all inch-based measurement systems.

Gain Ratio

I would like to propose a new system, which does take crank length into account. This system is independent of units, being expressed as a pure ratio.

This ratio would be calculated as follows: divide the wheel radius by the crank length; this will yield a single radius ratio applicable to all of the gears of a given bike. The individual gear ratios are calculated as with gear inches, using this radius ratio instead of the wheel size.

An Example:

A road bike with 170 mm cranks: (The usual generic diameter value for road wheels is 680 mm, so the radius would be 340 mm.)

340 mm / 170 mm = 2.0. (The radius ratio)

2.0 X 53 / 19 = 5.58

This number is a pure ratio, the units cancel out. I call this a "gain ratio" (with thanks to Osman Isvan for suggesting this term.) What it means is that for every inch, or kilometer, or furlong the pedal travels in its orbit around the bottom bracket, the bicycle will travel 5.58 inches, or kilometers, or furlongs.


Now then there's Gear Ratios, which may be important in 2 situations. The first is for fixie riders. The ratio (ring/cog) determines how many skid patches may show up on a tire. The more skid patches, the longer the tire wear. The fewer, the shorter, because you'll wear out one part really quickly.

The second situation is for those with climbing bikes (I think it's more relevant on a road or touring bike, because the approach in selecting gearing on a mtn bike etc. is different) in balancing cadence with power output. The gear ratio essentially determines how many revolutions you're going to get of the wheel per revolution of the cranks. It takes a lot less resistance to turn the cranks with a gear that will move the wheel one revolution or less than it takes to turn a 39/17, for example. Your 30/32 is smaller (easier) than a 1 ratio (30/30), so you can compare. However, you get a lot more speed per revolution of the cranks on the "harder" gear, as we all know. So, you may want to consider gear ratios in figuring out how fast you'd need to turn the cranks at a given gear to go X mph. But then, you'd probably still want to use the rpm/mph calculator for different gear setups to figure out what you want. Then, you'd plug in something like this: I can get up this hill with maybe these gears, and I think I can turn the cranks at 60rpm or 80rpm or 100rpm. If so, how fast would I be going in each of these gears? Am I ok with that, or would I rather have to put out more or less power or use different rpms in another gear to go that speed? Or do I want to fight a bigger gear to try to get more speed?

I find it's easiest to stick with the Gear Inches chart. Smaller numbers = easier.

Kali, that's also why there are bigger jumps at the larger cogs. A small jump on the small cog end with be a bigger jump in gear inches than on the large cog end. So while the shift can be hard in terms of jumping sizes of cogs, it gets less and less easy per size of cog, if that makes sense. So if you're running out of gears on that end when you're in the small ring, then you want bigger jumps to be able to feel the difference. When you're trying to fine tune a comfortable cadence on the flat with the speed you want to go, then you want the tightest gearing possible on those smaller cogs to minimize the difference in feel between each gear.

[DebW]

FREEWHEEL SRAM Powerglide 950 9-speed 11-32

A brand new bike coming with a freewheel rather than a cassette? I don't think anyone has ever made a 9-speed freewheel, so it's probably a cassette.

[sundial]

Hey Deb, I have a Roubaix with a 11-27 cassette. Can I get one with more gearing (correct term?) for steep climbing?

[tulip]

The size of cassette cogs and chainrings are measured in the number of teeth. So 42x23 means you're chain is in the 42-tooth chainring up front and the 23-tooth cassette in the back.

Easier pedaling = smaller chainring (front) and larger cassette cog (back). Opposite for harder pedaling.

A long time ago, I sat down and counted teeth on chainrings and cogs, and it helped clarify things, since I'm more image-oriented than number-oriented.

[madscot13]

Hey Deb, I have a Roubaix with a 11-27 cassette. Can I get one with more gearing (correct term?) for steep climbing?

9 or a 10 speed?

I think 27 is as high as it goes for 10 speeds.

[Tuckervill]

I got all that part, but what confuses me is the word SPEED.

I rode 10-speeds in high school. I don't think it's the same thing anymore, right?

Karen

[xeney]

Well, it sort of is, except in the 70s they were talking about the total number of gear combinations, and now it refers just to the rear cassette.

Your 10-speed then had a total of ten total gear combinations available -- probably a double up front and a five-speed in the back. Now the 9 versus 10 speed designation refers only to the rear cassette: so if you have a triple chain ring up front and a 10-speed cassette in the rear, that means you have a total of 30 gear combinations available. If you have a double chain ring in the front and a 9-speed cassette in the rear, you have 18 gear combinations.

But 18-speed and 30-speed sound sort of ridiculous so the terminology has changed. I do see Craigslist ads advertising "27-speed women's bike," though.

[mudmucker]

SRAM has an 11-28 cassette for 10 speeds in their Force group. No 11-28 for 9 speeds. You'd have to go to a mountain cassette after that. Ilima describes the setup in the OP wonderfully.

[sundial]

9 or a 10 speed?

I think 27 is as high as it goes for 10 speeds.

SRAM OG-1070, 10-speed 11-28t

[SadieKate]

Actually, IRD makes a 10 spd cassette to 34 but you need a rear derailleur with the capacity for it.

[Grog]

Chain close to you as you pedal: easier pedaling (you're in the small chainring at the front and big cog at the back).

Chain away from you: harder pedaling (you're in the big chainring at the front and small cog at the back).