Wheel size for cycle computers

Paul Rose said:

1. 559 (or 26 inches) x 3.1416 = 1756mm
2. Table suggests (for a 26 x 2.00) = 2074mm
3. Measured distance after turning the wheel one complete turn = 218
cm / 2180mm

Number 3 will always be the correct figure.

Pete.

Paul Rose said:

I wonder if I could seek advice regarding selecting the correct wheel size
for inputting into a cycle computer.

Tyre size = 26 x 2.00
Wheel size 559 x 22mm (roughly 26 x 2)

Instructions advise as follows:

Either:

1. Multiply the wheel diameter (in millimetres) by 3.1416

That is pi*d which is the circumference of a circle.
They mean the actual diameter not the wheel size.

Quoted message said:

2. Use the table supplied with the instructions (approx. values it says)
3. Push the bike along until a wheel has completed a full turn and then
measure the distance covered, in millimetres.

The empirical method of finding pi*d the circumference of a circle.

Quoted message said:

After doing all three I get the following three completely different
answers:

1. 559 (or 26 inches) x 3.1416 = 1756mm
2. Table suggests (for a 26 x 2.00) = 2074mm
3. Measured distance after turning the wheel one complete turn = 218 cm /
2180mm

Go with number three you have got that right and it what they should
tell you to use in the first place, the distance travelled per
revolution of the wheel.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

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

Quoted message said:

Paul Rose said:

I wonder if I could seek advice regarding selecting the correct wheel

size

Quoted message said:

Quoted message said:

for inputting into a cycle computer.

Tyre size = 26 x 2.00
Wheel size 559 x 22mm (roughly 26 x 2)

Instructions advise as follows:

Either:

1. Multiply the wheel diameter (in millimetres) by 3.1416

That is pi*d which is the circumference of a circle.
They mean the actual diameter not the wheel size.

Quoted message said:

2. Use the table supplied with the instructions (approx. values it says)
3. Push the bike along until a wheel has completed a full turn and then
measure the distance covered, in millimetres.

The empirical method of finding pi*d the circumference of a circle.

Quoted message said:

After doing all three I get the following three completely different
answers:

1. 559 (or 26 inches) x 3.1416 = 1756mm
2. Table suggests (for a 26 x 2.00) = 2074mm
3. Measured distance after turning the wheel one complete turn = 218 cm /
2180mm

Go with number three you have got that right and it what they should
tell you to use in the first place, the distance travelled per
revolution of the wheel.

Hi Pete and Phil

Thanks for your feedback and advice. Much appreciated.

Now that I know number 3 is the way to go, I have just carried out the
measurement again, a little more accurately hopefully, and the measurement
was 209 cm / 2090 mm. (as opposed to 218 cm - don't know how I got 218 the
first time!).

That's what I'll be inputting in to the cycle computer. Thanks again,

--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk

May help.

http://www.sheldonbrown.com/cyclecomputers/

Paul Rose said:

Hi All

I wonder if I could seek advice regarding selecting the correct wheel size
for inputting into a cycle computer.

Tyre size = 26 x 2.00
Wheel size 559 x 22mm (roughly 26 x 2)

Instructions advise as follows:

Either:

1. Multiply the wheel diameter (in millimetres) by 3.1416
2. Use the table supplied with the instructions (approx. values it says)
3. Push the bike along until a wheel has completed a full turn and then
measure the distance covered, in millimetres.

After doing all three I get the following three completely different
answers:

1. 559 (or 26 inches) x 3.1416 = 1756mm
2. Table suggests (for a 26 x 2.00) = 2074mm
3. Measured distance after turning the wheel one complete turn = 218 cm /
2180mm

My maths isn't good at the best of times so I would appreciate your
input...please ;o)

Use no.2. No.1 is the bead seat diameter, which is actually in the rim!
No.3 is only accurate if the bike is loaded while doing the rollout test.

Simon Brooke said:

For best results, start with the valve at bottom dead centre
and make a chalkmark on the ground against the valve position; roll the
wheels several complete rotations (more is better, but limited by the
availability of suitable measuring tape etc) until the valve is once at
bottom dead centre; again make a chalkmark on the ground against the
valve position, measure the distance between the two chalkmarks, and
divide by the number of rotations.

You've also got to load the bike (e.g. by leaning your chest and most of
your weight on the saddle). There is a significant reduction in rolling
diameter. From the figure given, I reckon the manufacturer's
recommendation has allowed for this.

"Zog The Undeniable" <[email hidden]> wrote in message
news:422b47a2.0@entanet...

Quoted message said:

Paul Rose said:

Hi All

I wonder if I could seek advice regarding selecting the correct wheel

size

Quoted message said:

Quoted message said:

for inputting into a cycle computer.

Tyre size = 26 x 2.00
Wheel size 559 x 22mm (roughly 26 x 2)

Instructions advise as follows:

Either:

1. Multiply the wheel diameter (in millimetres) by 3.1416
2. Use the table supplied with the instructions (approx. values it says)
3. Push the bike along until a wheel has completed a full turn and then
measure the distance covered, in millimetres.

After doing all three I get the following three completely different
answers:

1. 559 (or 26 inches) x 3.1416 = 1756mm
2. Table suggests (for a 26 x 2.00) = 2074mm
3. Measured distance after turning the wheel one complete turn = 218 cm

/

Quoted message said:

Quoted message said:

2180mm

My maths isn't good at the best of times so I would appreciate your
input...please ;o)

Use no.2. No.1 is the bead seat diameter, which is actually in the rim!
No.3 is only accurate if the bike is loaded while doing the rollout

test.

Hi, thanks for your input and advice. I might try No: 3 whilst sitting on
the bike and see how close it matches No: 2.

--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk

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

Quoted message said:

in message <[email hidden]>, Paul Rose

(') said:

Hi All

I wonder if I could seek advice regarding selecting the correct wheel
size for inputting into a cycle computer.

Tyre size = 26 x 2.00
Wheel size 559 x 22mm (roughly 26 x 2)

Instructions advise as follows:

Either:

1. Multiply the wheel diameter (in millimetres) by 3.1416
2. Use the table supplied with the instructions (approx. values it
says) 3. Push the bike along until a wheel has completed a full turn
and then measure the distance covered, in millimetres.

After doing all three I get the following three completely different
answers:

1. 559 (or 26 inches) x 3.1416 = 1756mm

Yes, but you're not allowing for the tyre.

Quoted message said:

2. Table suggests (for a 26 x 2.00) = 2074mm
3. Measured distance after turning the wheel one complete turn = 218
cm / 2180mm

My maths isn't good at the best of times so I would appreciate your
input...please ;o)

Use (3). For best results, start with the valve at bottom dead centre
and make a chalkmark on the ground against the valve position; roll the
wheels several complete rotations (more is better, but limited by the
availability of suitable measuring tape etc) until the valve is once at
bottom dead centre; again make a chalkmark on the ground against the
valve position, measure the distance between the two chalkmarks, and
divide by the number of rotations.

Thanks for the info. Will try measuring a number of rotations etc. and see
what sort of figures I get.
--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk

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

Quoted message said:

May help.

http://www.sheldonbrown.com/cyclecomputers/

Thanks for the link. Looks quite a useful site.

--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk

Paul Rose said:

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

Quoted message said:

May help.

http://www.sheldonbrown.com/cyclecomputers/

Quoted message said:

Thanks for the link. Looks quite a useful site.

Take plenty of food and drink with you when you go in there; you could
be gone for longer than you think.

--
Dave...

Every time I see an adult on a bicycle, I no longer despair for the
future of the human race. - H. G. Wells

Dave Kahn said:

Paul Rose said:

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

Quoted message said:

May help.

http://www.sheldonbrown.com/cyclecomputers/

Quoted message said:

Thanks for the link. Looks quite a useful site.

Take plenty of food and drink with you when you go in there; you

could

Quoted message said:

be gone for longer than you think.

That's a phrase to remember! *Chuckle*

Zog The Undeniable said:

Paul Rose said:

[snip question about wheel diameters from OP and some responses]

Use no.2. No.1 is the bead seat diameter, which is actually in the

rim!

Quoted message said:

No.3 is only accurate if the bike is loaded while doing the rollout

test.
No 2 is only accurate if the table of figures happens to correspond to
your tyre profile.

It makes most sense to decide what you would like to think your
cruising speed is and then adjust the computer until it matches your
expectations

best wishes
james

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

Quoted message said:

Zog The Undeniable said:

Paul Rose said:

[snip question about wheel diameters from OP and some responses]

Use no.2. No.1 is the bead seat diameter, which is actually in the

rim!

Quoted message said:

No.3 is only accurate if the bike is loaded while doing the rollout

test.
No 2 is only accurate if the table of figures happens to correspond to
your tyre profile.

It makes most sense to decide what you would like to think your
cruising speed is and then adjust the computer until it matches your
expectations

best wishes
james

LOL! Now that's a good idea :o)

--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk

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

Quoted message said:

Paul Rose said:

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

Quoted message said:

May help.

http://www.sheldonbrown.com/cyclecomputers/

Quoted message said:

Thanks for the link. Looks quite a useful site.

Take plenty of food and drink with you when you go in there; you could
be gone for longer than you think.

--
Dave...

Having had a quick look at the site I can well believe it!

--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk

Quoted message said:

It makes most sense to decide what you would like to think your
cruising speed is and then adjust the computer until it matches your
expectations.

I like that idea. Long rides at a decent speed: instant fitness.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

Paul Rose said:

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

Quoted message said:

Quoted message said:

Take plenty of food and drink with you when you go in there; you could
be gone for longer than you think.

Quoted message said:

Having had a quick look at the site I can well believe it!

When you suddenly find you're an authority on the history of Sturmey
Archer gears run for the exit.

--
Dave...

Every time I see an adult on a bicycle, I no longer despair for the
future of the human race. - H. G. Wells

Phil Cook said:

Quoted message said:

It makes most sense to decide what you would like to think your
cruising speed is and then adjust the computer until it matches your
expectations.

I like that idea. Long rides at a decent speed: instant fitness.

Double your speed, double your distance. Add a second magnet to the spokes.

--
Dave...

Every time I see an adult on a bicycle, I no longer despair for the
future of the human race. - H. G. Wells

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

Quoted message said:

Paul Rose said:

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

Quoted message said:

Quoted message said:

Take plenty of food and drink with you when you go in there; you could
be gone for longer than you think.

Quoted message said:

Having had a quick look at the site I can well believe it!

When you suddenly find you're an authority on the history of Sturmey
Archer gears run for the exit.

I'll bear that in mind ;o)

--
Regards, Paul (R)
My Lake District walking site:
www.lakelandwalker.co.uk