Gear Inches

go check out Sheldon's site, or www.fixedgearfever.com

Mike "Guy Goldich" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Does anyone have the formula for calculating gear-inches?

Years ago, Bicycling mag would publish a gear-inches chart for each bike they reviewed--a grid
with front & rear gearing along the top and side

with

Quoted message said:

the gear-inches in the center.

I'd like to make a gear-inches chart for my new bike but don't have the formula. My tires are
700c x 23.

In article said:

Ryan Cousineau said:

Quoted message said:

members.cox.netChopper.JPGOpen ↗

Quoted message said:

They're basically a style trend started by exaggerating riser bars. At

So, they're a big joke? That's what they look like.

Well, all cruisers, bicycle or motorcycle are "big jokes". They're styling exercises. That doesn't
stop a lot of people from enjoying riding both, because sometimes aesthetics (even weird aesthetics,
but de gustibus &c.) trumps function. If it didn't, nobody would buy a Hetchins, The whole chrome
styling thing would never have happened to 1950s cars, and there wouldn't be any bellybutton
piercings.

Now really, do you want to live in a world without bellybutton piercings? Or earrings? What do you
have against earrings, anyways?

Hey! look over there,
--
Ryan Cousineau, [email hidden] sfu.ca~rcousineOpen ↗ President, Fabrizio Mazzoleni Fan Club

"Guy Goldich" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Does anyone have the formula for calculating gear-inches?

Years ago, Bicycling mag would publish a gear-inches chart

for each bike

Quoted message said:

they reviewed--a grid with front & rear gearing along the

top and side with

Quoted message said:

the gear-inches in the center.

I'd like to make a gear-inches chart for my new bike but

don't have the

Quoted message said:

formula. My tires are 700c x 23.

There's lots of calculators on the web. Try my graphical gear calculator...

bellsouthpwp.netGearing.htmOpen ↗

"Guy Goldich" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Does anyone have the formula for calculating gear-inches?

Years ago, Bicycling mag would publish a gear-inches chart for each bike they reviewed--a grid
with front & rear gearing along the top and side

with

Quoted message said:

the gear-inches in the center.

I'd like to make a gear-inches chart for my new bike but don't have the formula. My tires are
700c x 23.

That arcane number, which remains a useful number only because we are all conversant with it, is the
equivalent highwheeler size to your geared bike.

Get that by dividing the rear number of teeth into the front and multiplying by the nominal wheel
size, e.g., 52/14*27=100. Put another way, pushing a
52/14 is the equivalent of riding a 100 inch highwheeler bike.

That sort of calculation is very easily done in a spreadsheet. In fact it uses such rudimantary
spreadsheet skills that I use it as a beginner's example for learning spreadsheet techniques.

Put the front chainwheel teeth in a row, let's say c5 is "50", d5 is "40" and e5 i s"30". Then run
your rear sizes down a column, such that b6 is "12", b7 is "13", b8 is "14" etc etc.. Enter the
wheel nominal size in the corner at b5.

Enter this in cell c6: +c$5/$b6*$b$5 copy that to the remaining cells in your array and hit the
F9 (recalculate) key. It is more readable if you select the array and format display to one or
zero decimals

If you have time to kill and an interest, most modern spreadsheets can automatically graph your gear
range in color!

When I was young this sort of chart (made up by sliderule and typewritten) could be seen taped to
handlebar stems on Sunday morning rides because, as Sheldon mentioned recently , the gaps in a five
speed are huge and daunting - often worth a double shift to avoid them!

And no, there are no 14-1/2 teeth cogs yet!

In the non-English speaking countries another system is more common, "development" or how many
meters the bike travels per crank revolution. Campagnolo used to provide nice business-card-sized
gear charts of that. My commuting 60" gear travels about 4.8 meters for example
--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Quoted message said:

Guy Goldich said:

Does anyone have the formula for calculating gear-inches?

"Harris" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Gear Inches = (chainring teeth / cassette teeth) x Tire diameter

To determine your tire diameter, measure the roll out for one revolution, and divide by pi.

Or check out Sheldon's gear calculator at:

sheldonbrown.comindex.htmlOpen ↗

Precise wheel diameter derived from a rollout? While that works, using the nominal size, 26" or 27",
is close enough and is the usual factor used in standardized printed gear charts.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Guy Goldich said:

Does anyone have the formula for calculating gear-inches?

Chainring teeth/sprocket teeth)*wheel diameter.

--

David L. Johnson

__o | "Business!" cried the Ghost. "Mankind was my business. The _`\(,_ | common welfare was my
business; charity, mercy, forbearance, (_)/ (_) | and benevolence, were, all, my business. The
dealings of my trade were but a drop of water in the comprehensive ocean of my business!"
--Dickens, "A Christmas Carol"

A Muzi said:

Quoted message said:

Guy Goldich said:

Does anyone have the formula for calculating gear-inches?

"Harris" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Gear Inches = (chainring teeth / cassette teeth) x Tire diameter

To determine your tire diameter, measure the roll out for one revolution, and divide by pi.

Precise wheel diameter derived from a rollout?

Yes? ... or yes.

Quoted message said:

While that works, using the nominal size, 26" or 27", is close enough and is the usual factor used
in standardized printed gear charts.

Lot's of people have computers and don't need/want one-size charts anymore.

"A Muzi" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Quoted message said:

Guy Goldich said:

Does anyone have the formula for calculating gear-inches?

"Harris" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Gear Inches = (chainring teeth / cassette teeth) x Tire diameter

To determine your tire diameter, measure the roll out for one

revolution,

Quoted message said:

Quoted message said:

and divide by pi.

Or check out Sheldon's gear calculator at:

sheldonbrown.comindex.htmlOpen ↗

Precise wheel diameter derived from a rollout? While that works, using the nominal size, 26" or
27", is close enough and

is

Quoted message said:

the usual factor used in standardized printed gear charts.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Using rollout is the only way to get a precise measurement for gear inches. Close enough won't work
as you will likely be off by 2" or so. I found this out when trying to get qualifying times for
track nationals. I figured the speed I needed to maintain in the gear size I was using (almost all
charts are based on a 27" wheel). All of my gears were 2" off which can mean a few 10'ths of a
second over 400 meters... T