Cadence mathmaticians.

"David Brown :o)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I've been looking for a cordless computer with cadence counter but even
non-cordless ones cost a fortune. Then it occured to me, Doh! I ride a
singlespeed so it can easily be worked out from my speed.
So could one of you please take a peak at my calculations to check I

haven't

Quoted message said:

made any silly mistakes.

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.
1 mile = 63360"
1 mile = 389 revolutions

So far so good,

Quoted message said:

Therefore Cadence = 6.5 @ 1mph.

But.. but.. on a 32/16 each turn of the big ring causes two turns of the
small (and therefore of the whole wheel)? So to do 389 revs of the rear
wheel you have to turn the cranks 195 times? So if you turn it 195 times
in one hour, that's 3.25 rpm.. isn't it?

Rich

"Richard Goodman" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.
1 mile = 63360"
1 mile = 389 revolutions

So far so good,

Quoted message said:

Therefore Cadence = 6.5 @ 1mph.

But.. but.. on a 32/16 each turn of the big ring causes two turns of the
small (and therefore of the whole wheel)? So to do 389 revs of the rear
wheel you have to turn the cranks 195 times? So if you turn it 195 times
in one hour, that's 3.25 rpm.. isn't it?

Note the 52" x pi, not 26" x pi

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

Quoted message said:

"David Brown :o)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I've been looking for a cordless computer with cadence counter but even
non-cordless ones cost a fortune. Then it occured to me, Doh! I ride a
singlespeed so it can easily be worked out from my speed.
So could one of you please take a peak at my calculations to check I

haven't

Quoted message said:

made any silly mistakes.

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.
1 mile = 63360"
1 mile = 389 revolutions

So far so good,

Quoted message said:

Therefore Cadence = 6.5 @ 1mph.

But.. but.. on a 32/16 each turn of the big ring causes two turns of the
small (and therefore of the whole wheel)? So to do 389 revs of the rear
wheel you have to turn the cranks 195 times? So if you turn it 195 times
in one hour, that's 3.25 rpm.. isn't it?

He's doubled the (nominal) wheel size. The calculations are more-or-less
correct, but, of course, by approximating and rounding in several places
there is going to be an error built in. Not particularly significant,
though.

---
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Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.688 / Virus Database: 449 - Release Date: 18/05/2004

52"x pi = 163" of travel per crank revolution
1 mile = 63360"
1 mile = 389 crank revolutions

Therefore Cadence = 6.5 @ 1mph.

"David Brown :o)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.

No. 26" is the diameter, unless you really have a 4'4" high wheel.
Circumference is 2 pi r or pi d.

Quoted message said:

1 mile = 63360"

Yes.

Quoted message said:

1 mile = 389 revolutions

No, 776 revolutions, due to above error. Hence 12.9rpm/mph.

That's a really, really low gear. Are you sure you ride 32/16? I'd
struggle to maintain 10mph on your bike.

--
Mark.

Following on from David Brown :o)'s message. . .

Quoted message said:

I've been looking for a cordless computer with cadence counter but even
non-cordless ones cost a fortune. Then it occured to me, Doh! I ride a
singlespeed so it can easily be worked out from my speed.
So could one of you please take a peak at my calculations to check I haven't
made any silly mistakes.

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.
1 mile = 63360"
1 mile = 389 revolutions

Therefore Cadence = 6.5 @ 1mph.

Thank you

A much simpler method
(1) Cycle 1/4 mile counting crank revs
(2) times 4 = revs per mile
(3) divide by 60 = conversion factor mph to revs per min

Even simpler method.
Cycle at 10 mph for 1/2 minute counting the revs
Times 3 for 15mph cadence etc

IMHO bothering with cadence on a single speed is pointless. The reason
for measuring it is to help tune the gear ratios and can be a handy
input to something you can control. In your case there's nothing you
can alter so why bother?

--
PETER FOX Not the same since the submarine business went under
[email hidden]
www.eminent.demon.co.uk/wcc.htm Witham Cycling Campaign
www.eminent.demon.co.uk/rides East Anglian Pub cycle rides

"David Brown :o)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"Richard Goodman" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.
1 mile = 63360"
1 mile = 389 revolutions

So far so good,

Quoted message said:

Therefore Cadence = 6.5 @ 1mph.

But.. but.. on a 32/16 each turn of the big ring causes two turns of the
small (and therefore of the whole wheel)? So to do 389 revs of the rear
wheel you have to turn the cranks 195 times? So if you turn it 195

times

Quoted message said:

Quoted message said:

in one hour, that's 3.25 rpm.. isn't it?

Note the 52" x pi, not 26" x pi

Ah yes of course, circumference = 2 pi r and you did 2 pi d. So yes, you did
the gear doubling at first stage.

Rich

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

Quoted message said:

"David Brown :o)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.

No. 26" is the diameter, unless you really have a 4'4" high wheel.
Circumference is 2 pi r or pi d.

Yes, and he's taken the gearing into account. If his gear had been 52/13,
the numbers would have been 104" * pi = 326" of travel per rev. Gear inches
work this way.

Quoted message said:

Quoted message said:

1 mile = 63360"

Yes.

Quoted message said:

1 mile = 389 revolutions

No, 776 revolutions, due to above error. Hence 12.9rpm/mph.

That's a really, really low gear. Are you sure you ride 32/16? I'd
struggle to maintain 10mph on your bike.

And that should give you the clue that your sums are wrong - think for
yourself what a 32/16 gear on a 26" wheel is like.

cheers,
clive

"Peter Fox" <[email hidden]>

Quoted message said:

IMHO bothering with cadence on a single speed is pointless. The reason
for measuring it is to help tune the gear ratios and can be a handy
input to something you can control. In your case there's nothing you
can alter so why bother?

I'm working the other way 'round.....
95% off my riding is at a pretty constant speed as I ride riverbanks that
are bumpy but obviously flat. I can use my ideal cadence to work out gear
ratios as I get fitter.

David Brown :o) said:

I've been looking for a cordless computer with cadence counter but even
non-cordless ones cost a fortune. Then it occured to me, Doh! I ride a
singlespeed so it can easily be worked out from my speed.
So could one of you please take a peak at my calculations to check I haven't
made any silly mistakes.

I ride a 32/16 ratio on a 26" wheel (measures slightly under)

52"x pi = 163" of travel per rev.
1 mile = 63360"
1 mile = 389 revolutions

Therefore Cadence = 6.5 @ 1mph.

Thank you

There is an easier, if slightly more expensive method, which does not
require the user to tax his/her brain whilst enjoying the scenery. *

1. Buy a dirt cheap Cycle Computer.

2. Stick the magnet on the crank and mount the sensor accordingly.

3. Set the wheel size to 1.667 metres or 166.7 centimetres or even 1667
millimetres depending on type of computer.

4. A reading of 6.5 kilometres per hour will indicate a cadence of 65
revolutions per minute. (Just ignore the decimal point)

Terry Duckmanton

* Not a mathematician, can you tell?

"Terry D" <[email hidden]> wrote in message
news:jprrc.472$X64.267@newsfe3-gui...

Quoted message said:

There is an easier, if slightly more expensive method, which does not
require the user to tax his/her brain whilst enjoying the scenery. *

1. Buy a dirt cheap Cycle Computer.

2. Stick the magnet on the crank and mount the sensor accordingly.

3. Set the wheel size to 1.667 metres or 166.7 centimetres or even 1667
millimetres depending on type of computer.

4. A reading of 6.5 kilometres per hour will indicate a cadence of 65
revolutions per minute. (Just ignore the decimal point)

Aksherly that sounds like quite a good way of getting a cheap cadence
display, given that computers with this function built in tend to be a bit
expensive - and it would be one that is always 'on' while you can have speed
displayed on another computer. Good tip!

Rich

Richard Goodman said:

Aksherly that sounds like quite a good way of getting a cheap cadence
display,

An even cheaper and easier way is to use Sheldons online gear
calculator. Easy as point, click, print.

http://www.sheldonbrown.com/gears/index.html

You can use this to calculate and print a small chart showing cadences
at a variety of speeds. I have one sellotaped to the stem of my hack
showing cadence in different gears at 15mph and 20mph. Gives a good
estimate without bothering to buy a cadence capable computer.
--

"Bob"

'The people have spoken, the [censored]'

Email address is spam trapped.
To reply directly remove the beverage.

Isn't cadence was the speed of rotation of the cranks?

If so count your pedal revolutions over 15 seconds (from a cycle
computer) and multiply by four for rpm!

--
Wallace Shackleton,

Kinross,
Scotland.

Cycling in Kinross-shire www.cyclekinross.org.uk

Wallace Shackleton said:

If so count your pedal revolutions over 15 seconds (from a cycle
computer) and multiply by four for rpm!

Hi Wallace

I don't have a cycle computer and counting revs accurately is almost
impossible without one. My counting automatically gets in time with my
pedalling. The minus side to this is that i have no real way of
knowing my true cadence: the plus side is that my rpm can be anything
I wish!

However, if i were to take a guess, I would say that I pedal >75rpm
but <100rpm, which suits me, sir.

James