OBRA: OBRA Chat: cadence question

cadence question

← Newer
OBRA Chat
Older →

Philip D Barila

2005-03-21

This is a multi-part message in MIME format.

------=_NextPart_000_0192_01C52E74.B80EAA20

Content-Type: text/plain;

charset="us-ascii"

Content-Transfer-Encoding: 7bit

Not to sound like a know-it-all or anything, but the site links already

forwarded to this question don't really explain the math in simple terms.

I'll try, but I've been told that sometimes, my idea of simple isn't

coincident with most people's idea of simple. If you're not into geek math,

you've probably already lost interest. :-) Anyway, here goes:

Start with what we know, and substitute some unit conversion constants, so

we can get down to a simple equation:

G = Gear Ratio = (Chainring teeth/cog teeth)

C = Cadence (Revs/Min = RPM)

D = Wheel Diameter (26.5 is a reasonable approximation for a 700C x 25)

V(MPH)

= C (RPM) * 60 (Min/Hour) * G * D (inches) * pi (see below) / 63360

(inches/mile)

= C * G * ( (26.5 * 60 * pi) / 63360)

= C * G / 12.7

This is your equation for figuring out how fast you are going at a specific

cadence in a specific gear.

You multiply the wheel diameter by pi to get the wheel circumference. If

you prefer, you can multiply G*D and call it Gear Inches(GI). If you do

that, you can't include the D in the constant part, so the constant part of

the equation becomes:

(60 * pi) / 63360 = 1/336

So if you already know GI, you have:

V = C * GI / 336

For our purposes, we'll assume the standard D and solve for cadence:

C = V * 12.7 / G = 42 * 12.7 / (53 / 12) = ~120

Nice spinning. :-)

Hope this helps.

Phil

_____

From: David Hart [mailto:kerch-@hotmail.com]

Sent: Monday, March 21, 2005 9:40 PM

To: bike chat

Subject: [OBRA Chat] cadence question

Here is my question and if the answer is easy, I will feel stupid.

If you are doing 42mph in a 53x12 gear, what is your cadence?

What is the formula to find the answer?

I was thinking I could put my bike on the trainer with no resistance and

spin to see what the cadence is, but I want to know the formula out of

curiosity.

------=_NextPart_000_0192_01C52E74.B80EAA20

Content-Type: text/html;

charset="us-ascii"

Content-Transfer-Encoding: 8bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<HTML><HEAD>

<META http-equiv=Content-Type content="text/html; charset=us-ascii">

<STYLE></STYLE>

<META content="MSHTML 6.00.2900.2604" name=GENERATOR></HEAD>

<BODY id=MailContainerBody

style="PADDING-LEFT: 10px; FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #000000; BORDER-TOP-STYLE: none; PADDING-TOP: 15px; FONT-STYLE: normal; FONT-FAMILY: Verdana; BORDER-RIGHT-STYLE: none; BORDER-LEFT-STYLE: none; TEXT-DECORATION: none; BORDER-BOTTOM-STYLE: none"

leftMargin=0 topMargin=0 name="Compose message area" CanvasTabStop="true"

acc_role="text">

<DIV dir=ltr align=left><SPAN class=667154706-22032005>Not to sound like a

know-it-all or anything, but the site links already forwarded to this question

don't really explain the math in simple terms. I'll try, but I've been

told that sometimes, my idea of simple isn't coincident with most people's idea

of simple. If you're not into geek math, you've probably already lost

interest. :-) Anyway, here goes:</SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT

color=#0000ff></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>Start

with what we know, and substitute some unit conversion constants, so we can get

down to a simple equation:</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>G

= Gear Ratio = (Chainring teeth/cog teeth)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>C =

Cadence (Revs/Min = RPM)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>D =

Wheel Diameter (26.5 is a reasonable approximation for a 700C x

25)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT

color=#0000ff></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT

color=#0000ff>V(MPH)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>=

</FONT></SPAN><SPAN class=667154706-22032005><FONT color=#0000ff>C (RPM) * 60

(Min/Hour) * G * D (inches) * pi (see below) / 63360

(inches/mile)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>= C *

G * ( (26.5 * 60 * pi) / 63360)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>= C *

G / 12.7</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>This

is your equation for figuring out how fast you are going at a specific cadence

in a specific gear.</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005>You multiply the wheel diameter</SPAN> by pi to

get the <SPAN class=667154706-22032005>wheel circumference</SPAN>.<SPAN

class=667154706-22032005> If you prefer, you can multiply G*D and call it

Gear Inches(GI). If you do that, you can't include the D in the

constant part, so the constant part of the equation

becomes:</SPAN></FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT><FONT color=#0000ff><SPAN

class=667154706-22032005>(60 * pi) / 63360 = 1/336</SPAN></FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005>So if you already know GI, you

have:</SPAN></FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT><FONT color=#0000ff><SPAN

class=667154706-22032005>V = C * GI / 336</SPAN></FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT><FONT color=#0000ff><SPAN

class=667154706-22032005></SPAN></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff><SPAN

class=667154706-22032005>For our purposes, we'll assume the standard D and

s</SPAN>olve for cadence:</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>C = V

* <SPAN class=667154706-22032005>12.7</SPAN> / G = <SPAN

class=667154706-22032005>42</SPAN> * <SPAN

class=667154706-22032005>12.7</SPAN> / <SPAN class=667154706-22032005>(53 /

12)</SPAN> = ~<SPAN class=667154706-22032005>120</SPAN></FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>Nice

spinning. :-)</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT

color=#0000ff></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>Hope

this helps.</FONT></SPAN></DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT

color=#0000ff></FONT></SPAN> </DIV>

<DIV dir=ltr align=left><SPAN class=667154706-22032005><FONT color=#0000ff>Phil

</FONT></DIV></SPAN>

<DIV dir=ltr align=left> </DIV>

<BLOCKQUOTE dir=ltr

style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">

<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>

<HR tabIndex=-1>

<FONT face=Tahoma><B>From:</B> David Hart [mailto:kerch-@hotmail.com]

<BR><B>Sent:</B> Monday, March 21, 2005 9:40 PM<BR><B>To:</B> bike

chat<BR><B>Subject:</B> [OBRA Chat] cadence question<BR></FONT><BR></DIV>

<DIV></DIV>

<DIV>Here is my question and if the answer is easy, I will feel stupid.</DIV>

<DIV> </DIV>

<DIV>If you are doing 42mph in a 53x12 gear, what is your cadence?</DIV>

<DIV> </DIV>

<DIV>What is the formula to find the answer?</DIV>

<DIV> </DIV>

<DIV>I was thinking I could put my bike on the trainer with no resistance and

spin to see what the cadence is, but I want to know the formula out of

curiosity.</DIV></BLOCKQUOTE></BODY></HTML>

------=_NextPart_000_0192_01C52E74.B80EAA20--

Dan H

2005-03-21

This is a multi-part message in MIME format.

------=_NextPart_000_01D3_01C52E66.CC984400

Content-Type: text/plain;

charset="iso-8859-1"

Content-Transfer-Encoding: 8bit

http://www.jbarrm.com/cycal/cycal.html

----- Original Message -----

From: David Hart

To: bike chat

Sent: Monday, March 21, 2005 8:39 PM

Subject: [OBRA Chat] cadence question

Here is my question and if the answer is easy, I will feel stupid.

If you are doing 42mph in a 53x12 gear, what is your cadence?

What is the formula to find the answer?

I was thinking I could put my bike on the trainer with no resistance and spin to see what the cadence is, but I want to know the formula out of curiosity.

David Hart

North River Racing

Vancouver, Washington

To respond to the whole group send to ob-@topica.com.

To respond to the list manager send to cmur-@obra.org

------=_NextPart_000_01D3_01C52E66.CC984400

Content-Type: text/html;

charset="iso-8859-1"

Content-Transfer-Encoding: 8bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<HTML><HEAD>

<META http-equiv=Content-Type content=text/html;charset=iso-8859-1>

<STYLE></STYLE>

<META content="MSHTML 6.00.2800.1170" name=GENERATOR></HEAD>

<BODY id=MailContainerBody

style="PADDING-LEFT: 10px; FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #000000; BORDER-TOP-STYLE: none; PADDING-TOP: 15px; FONT-STYLE: normal; FONT-FAMILY: Verdana; BORDER-RIGHT-STYLE: none; BORDER-LEFT-STYLE: none; TEXT-DECORATION: none; BORDER-BOTTOM-STYLE: none"

bgColor=#ffffff leftMargin=0 topMargin=0 name="Compose message area"

CanvasTabStop="true" acc_role="text">

<DIV><FONT face=Arial><A

href="http://www.jbarrm.com/cycal/cycal.html">http://www.jbarrm.com/cycal/cycal.html</A></FONT></DIV>

<BLOCKQUOTE dir=ltr

style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">

<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>

<DIV

style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>

<A title=ke-@hotmail.com href="mailto:kerch-@hotmail.com">David

Hart</A> </DIV>

<DIV style="FONT: 10pt arial"><B>To:</B> <A title-@topica.com

href="mailto:ob-@topica.com">bike chat</A> </DIV>

<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, March 21, 2005 8:39

PM</DIV>

<DIV style="FONT: 10pt arial"><B>Subject:</B> [OBRA Chat] cadence

question</DIV>

<DIV><BR></DIV>

<DIV>Here is my question and if the answer is easy, I will feel stupid.</DIV>

<DIV> </DIV>

<DIV>If you are doing 42mph in a 53x12 gear, what is your cadence?</DIV>

<DIV> </DIV>

<DIV>What is the formula to find the answer?</DIV>

<DIV> </DIV>

<DIV>I was thinking I could put my bike on the trainer with no resistance and

spin to see what the cadence is, but I want to know the formula out of

curiosity.</DIV>

<DIV> </DIV>

<DIV> </DIV>

<DIV> </DIV>

<DIV>David Hart <BR>North River Racing <BR>Vancouver, Washington</DIV><PRE>To respond to the whole group send to ob-@topica.com.

To respond to the list manager send to cmur-@obra.org

To unsubscribe send to obra-uns-@topica.com</PRE></BLOCKQUOTE></BODY></HTML>

------=_NextPart_000_01D3_01C52E66.CC984400--

Clark Ritchie

2005-03-21

Your cadence would be about 120.

http://www.analyticcycling.com/GearCadenceSpeed_Page.html

__________________________________

Do you Yahoo!?

Yahoo! Small Business - Try our new resources site!

http://smallbusiness.yahoo.com/resources/

David Hart

2005-03-21

This is a multi-part message in MIME format.

------=_NextPart_000_0027_01C52E56.1E5A80C0

Content-Type: text/plain;

charset="iso-8859-1"

Content-Transfer-Encoding: 8bit

Here is my question and if the answer is easy, I will feel stupid.

If you are doing 42mph in a 53x12 gear, what is your cadence?

What is the formula to find the answer?

I was thinking I could put my bike on the trainer with no resistance and spin to see what the cadence is, but I want to know the formula out of curiosity.

David Hart

North River Racing

Vancouver, Washington

------=_NextPart_000_0027_01C52E56.1E5A80C0

Content-Type: text/html;

charset="iso-8859-1"

Content-Transfer-Encoding: 8bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<HTML><HEAD>

<META http-equiv=Content-Type content=text/html;charset=iso-8859-1>

<STYLE></STYLE>

<META content="MSHTML 6.00.2900.2604" name=GENERATOR></HEAD>

<BODY id=MailContainerBody

style="PADDING-LEFT: 10px; FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #000000; BORDER-TOP-STYLE: none; PADDING-TOP: 15px; FONT-STYLE: normal; FONT-FAMILY: Verdana; BORDER-RIGHT-STYLE: none; BORDER-LEFT-STYLE: none; TEXT-DECORATION: none; BORDER-BOTTOM-STYLE: none"

leftMargin=0 topMargin=0 acc_role="text" CanvasTabStop="true"

name="Compose message area">

<DIV>Here is my question and if the answer is easy, I will feel stupid.</DIV>

<DIV> </DIV>

<DIV>If you are doing 42mph in a 53x12 gear, what is your cadence?</DIV>

<DIV> </DIV>

<DIV>What is the formula to find the answer?</DIV>

<DIV> </DIV>

<DIV>I was thinking I could put my bike on the trainer with no resistance and

spin to see what the cadence is, but I want to know the formula out of

curiosity.</DIV>

<DIV> </DIV>

<DIV> </DIV>

<DIV> </DIV>

<DIV>David Hart <BR>North River Racing <BR>Vancouver,

Washington</DIV></BODY></HTML>

------=_NextPart_000_0027_01C52E56.1E5A80C0--

← Newer
OBRA Chat
Older →