A little experiment

Richard Bates said:

Just had a mad idea whilst I was in the shower:

This year (May and June) I am doing a six week, very
indirect trip from John O'Groats to Land's End.

I thought it would be fun to measure the difference in
distance travelled by the front and rear wheels of my
bicycle.

I'm a knowledgaeable in scientific experiment construction
up to about A-Level standard. Apart from what is listed
below, can you think of any other important facts to make
it a valid setup?

1) Identical computers
2) Not wireless models (to avoid crosstalk)
3) Measure wheel circumferences independantly with bike
containing luggage with tyres pumped to my normal
pressure.

How much difference in circumference would be caused by
everytime you got up off the saddle?

John B

Richard Bates said:

Just had a mad idea whilst I was in the shower:

This year (May and June) I am doing a six week, very
indirect trip from John O'Groats to Land's End.

I thought it would be fun to measure the difference in
distance travelled by the front and rear wheels of my
bicycle.

I'm a knowledgaeable in scientific experiment construction
up to about A-Level standard. Apart from what is listed
below, can you think of any other important facts to make
it a valid setup?

1) Identical computers
2) Not wireless models (to avoid crosstalk)
3) Measure wheel circumferences independantly with bike
containing luggage with tyres pumped to my normal
pressure.

4. Switch them off automatic start stop. Most computers
have a lower speed limit below which, in automatic
mode, they assume the bike is stationary. There may be
differences in when they cross that threshold
(different magnet positions on the wheels) which could
lead to errors.

Tony

Richard Bates said:

Just had a mad idea whilst I was in the shower:

This year (May and June) I am doing a six week, very
indirect trip from John O'Groats to Land's End.

I thought it would be fun to measure the difference in
distance travelled by the front and rear wheels of my
bicycle.

I'm a knowledgaeable in scientific experiment
construction up to about A-Level standard. Apart from
what is listed below, can you think of any other
important facts to make it a valid setup?

I doubt you can make the measurements that way with
sufficient accuracy to be worthwhile (esp wheel radius).
Just ride through a puddle and continue on a dry road for a
short distance, then get a piece of string and measure the
two tracks. This'll give you the ratio between the two
wheels, assuming your wobbliness is consistent. Then you
don't need to do the trip at all!

James

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

Quoted message said:

Just had a mad idea whilst I was in the shower:

This year (May and June) I am doing a six week, very
indirect trip from John O'Groats to Land's End.

I thought it would be fun to measure the difference in
distance travelled by the front and rear wheels of my
bicycle.

I'm a knowledgaeable in scientific experiment construction
up to about A-Level standard. Apart from what is listed
below, can you think of any other important facts to make
it a valid setup?

1) Identical computers
2) Not wireless models (to avoid crosstalk)
3) Measure wheel circumferences independantly with bike
containing luggage with tyres pumped to my normal
pressure.

If both ends of your bike arrive together, both wheels will
have travelled the same distance!

Rich

On Mon, 29 Mar 2004 13:15:18 GMT, in
<[email hidden]>, "Richard

Goodman said:

If both ends of your bike arrive together, both wheels will
have travelled the same distance!

I assume your are jesting? Net distance-same. Gross
distance=front>rear (I hypothesise this to be the case
anyhow!)

--
[email hidden] Personal Site: www.artybee.net (same
[censored], different layout) Sutton Brass :
www.suttonbrass.org.uk

On Mon, 29 Mar 2004 14:29:21 +0100, Richard Bates <[email hidden]>

Quoted message said:

On Mon, 29 Mar 2004 13:15:18 GMT, in
<[email hidden]>,

Richard Goodman said:

If both ends of your bike arrive together, both wheels
will have travelled the same distance!

I assume your are jesting?

I don't see he is. If the wheels travelled at different
speeds your bike would be very wierd looking after an E2E.

Quoted message said:

Net distance-same. Gross distance=front>rear (I
hypothesise this to be the case anyhow!)

What is the gross distance? How are you defining it? Maybe
you are thinking about how many times each wheel rotates?

Colin
--

"Colin Blackburn" <[email hidden]> wrote
in message

Quoted message said:

I don't see he is. If the wheels travelled at different
speeds your bike would be very wierd looking after an E2E.

No, the front wheel will travel further but I don't think
that there's a hope in hell that you could set up a
milometer on a bike this accurately and I assume if you used
a GPS front and back, that they would read the same.

David Brown :o) said:

"Colin Blackburn" <[email hidden]> wrote
in message

Quoted message said:

I don't see he is. If the wheels travelled at
different speeds your bike would be very wierd looking
after an E2E.

No, the front wheel will travel further

In that case can someone please explain to me how the whhels
can be separated by the same distance when they get to the
other end?

Quoted message said:

but I don't think that there's a hope in hell that you
could set up a milometer on a bike this accurately and I
assume if you used a GPS front and back, that they would
read the same.

Of course they bloody would (within the accuracies of GPS).

Sorry, I may be being extremely thick here or missing some
amazing joke but I'd still like someone to define what
they actually mean when they say the front wheel will
travel further.

Do you mean go through more rotations? Because if you do
then that isn't travelling further but rotating more.

Colin
--

Colin Blackburn said:

Sorry, I may be being extremely thick here or missing some
amazing joke but I'd still like someone to define what
they actually mean when they say the front wheel will
travel further.

Do you mean go through more rotations? Because if you do
then that isn't travelling further but rotating more.

Okay, I think I understand what is meant now. I don't think
it is through being extremely think but I do think the OP
needs to define what they mean by gross distance travelled.

Colin
--

On 29/3/04 3:17 pm, in article [email hidden], "Colin

Blackburn said:

David Brown :o) said:

"Colin Blackburn" <[email hidden]> wrote in
message

Quoted message said:

I don't see he is. If the wheels travelled at
different speeds your bike would be very wierd looking
after an E2E.

No, the front wheel will travel further

In that case can someone please explain to me how the
whhels can be separated by the same distance when they get
to the other end?

Quoted message said:

but I don't think that there's a hope in hell that you
could set up a milometer on a bike this accurately and I
assume if you used a GPS front and back, that they would
read the same.

Of course they bloody would (within the accuracies
of GPS).

Sorry, I may be being extremely thick here or missing some
amazing joke but I'd still like someone to define what
they actually mean when they say the front wheel will
travel further.

Do you mean go through more rotations? Because if you do
then that isn't travelling further but rotating more.

That depends on whether the axis of the wheel is moving from
side to side relative to the path of the back wheel.

As an extreme example, take a bike. Place the front wheel at
90 degrees and walk it in a circle keeping the back wheel in
exactly the same spot. The front and rear wheels stay
separated by exactly the same scalar amount but the front
wheel travels further than the back wheel.

..d

Colin Blackburn said:

David Brown :o) said:

"Colin Blackburn" <[email hidden]> wrote in
message

Quoted message said:

I don't see he is. If the wheels travelled at
different speeds your bike would be very wierd looking
after an E2E.

No, the front wheel will travel further

In that case can someone please explain to me how the
whhels can be separated by the same distance when they get
to the other end?

Quoted message said:

but I don't think that there's a hope in hell that you
could set up a milometer on a bike this accurately and I
assume if you used a GPS front and back, that they would
read the same.

Of course they bloody would (within the accuracies
of GPS).

Sorry, I may be being extremely thick here or missing some
amazing joke but I'd still like someone to define what
they actually mean when they say the front wheel will
travel further.

Do you mean go through more rotations? Because if you do
then that isn't travelling further but rotating more.

Colin
--

You've never sat on a bike and weaved from side to side,
leaving a relatively straight rear-wheel rut, and a very
sinuous front-wheel rut, then. That is how the front wheel
can put in both more revolutions AND distance.

Every time you steer on a bike, the front wheel takes a
slightly different line to the rear wheel, over time,
this adds up - I think this is what the OP is proposing
to measure.

Velvet

David Martin said:

On 29/3/04 3:17 pm, in article
[email hidden], That depends on
whether the axis of the wheel is moving from side to side
relative to the path of the back wheel.

As an extreme example, take a bike. Place the front wheel
at 90 degrees and walk it in a circle keeping the back
wheel in exactly the same spot. The front and rear wheels
stay separated by exactly the same scalar amount but the
front wheel travels further than the back wheel.

Yes, thanks. I sussed this out after getting all confused.
I was, from the start looking at the scalar distance
translated in moving the bike from A to B. I now see that
the line described on the ground in a given journey, by
each wheel will be different for anything other than a
straight line.

Colin
--

Colin Blackburn said:

On Mon, 29 Mar 2004 14:08:47 +0000 (UTC), David Brown :o)
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

I assume if you used a GPS front and back, that they
would read the same.

Of course they bloody would (within the accuracies
of GPS).

Sorry for that. I assume any differences in the trip
distances for (hypothetically accurate, rim mounted) GPS
would be down to the sampling interval. In the real world I
can't see any differences other than the errors,
perticularly if the bike passed through forests!

Colin
--

Richard Bates said:

Just had a mad idea whilst I was in the shower:

This year (May and June) I am doing a six week, very
indirect trip from John O'Groats to Land's End.

I thought it would be fun to measure the difference in
distance travelled by the front and rear wheels of my
bicycle.

Good one!

Quoted message said:

I'm a knowledgaeable in scientific experiment construction
up to about A-Level standard. Apart from what is listed
below, can you think of any other important facts to make
it a valid setup?

1) Identical computers
2) Not wireless models (to avoid crosstalk)
3) Measure wheel circumferences independantly with bike
containing luggage with tyres pumped to my normal
pressure.

Don't let the wheels spin or disconnect computers when
carrying the bike (eg. up and down stairs) or when testing
for buckled wheels, etc.

Don't do any wheelies or endos :-)

Switch(es) on the sensor cables could be handy for easily
disconnecting computers when not riding.

~PB

On Mon, 29 Mar 2004 12:47:11 +0100, in
<[email hidden]>, Richard Bates
<[email hidden]> wrote:

[excuse the top post but in this case it makes things
simpler]

As a follow up to my own post (below) in order to shed some
light on what I mean, let me explain.

When I cycle, although my front and rear wheel start and end
the same distance apart, I believe that the front wheel
actually travels via a more indirect route than the rear
i.e. it wobbles sideways more. This can be seen, as another
poster maintains, by riding through a puddle and
subsequently watching the trail made by the front and rear
wheels. The rear wheel, being the trailing wheel, appears to
resemble a straighter line than the front.

I thought it would be amusing to measure the distance
travelled by each wheel independently.

Quoted message said:

Just had a mad idea whilst I was in the shower:

This year (May and June) I am doing a six week, very
indirect trip from John O'Groats to Land's End.

I thought it would be fun to measure the difference
in distance travelled by the front and rear wheels of
my bicycle.

I'm a knowledgaeable in scientific experiment construction
up to about A-Level standard. Apart from what is listed
below, can you think of any other important facts to make
it a valid setup?

1) Identical computers
2) Not wireless models (to avoid crosstalk)
3) Measure wheel circumferences independantly with bike
containing luggage with tyres pumped to my normal
pressure.

--
[email hidden] Personal Site: www.artybee.net (same
[censored], different layout) Sutton Brass :
www.suttonbrass.org.uk

Richard Bates said:

I guess this depends upon how the distance is measured. I
am not interested in the speed of each wheel. If the
computer calculates distance indirectly from speed and
time then the autostart function will interfere. (i.e. revs-->speed--

Quoted message said:

distance)

If however the computer calculates distance directly from
wheel revolutions (and subsequently calculates speed from
distance and time) then I think the auto start function
will not matter.

Anybody know whether computers primarly measure distance
or speed?

I would assume they measure distance, and then calculate
the speed.

On Mon, 29 Mar 2004 13:41:10 +0100, in
<[email hidden]>, "Tony Raven"

Quoted message said:

4. Switch them off automatic start stop. Most computers
have a lower speed limit below which, in automatic
mode, they assume the bike is stationary. There may be
differences in when they cross that threshold
(different magnet positions on the wheels) which could
lead to errors.

I guess this depends upon how the distance is measured. I am
not interested in the speed of each wheel. If the computer
calculates distance indirectly from speed and time then the
autostart function will interfere. (i.e. revs-->speed--

Quoted message said:

distance)

If however the computer calculates distance directly from
wheel revolutions (and subsequently calculates speed from
distance and time) then I think the auto start function will
not matter.

Anybody know whether computers primarly measure
distance or speed?

--
[email hidden] Personal Site: www.artybee.net (same
[censored], different layout) Sutton Brass :
www.suttonbrass.org.uk

On Mon, 29 Mar 2004 16:40:09 +0100, in
<[email hidden]>, Richard Bates

Quoted message said:

I guess this depends upon how the distance is measured. I
am not interested in the speed of each wheel. If the
computer calculates distance indirectly from speed and time
then the autostart function will interfere. (i.e. revs-->speed--

Quoted message said:

distance)

OOps bad wording again (indirectly is the word at fault).
What I mean is "if the computer caluclates distance as a
function of speed and time"

Quoted message said:

If however the computer calculates distance directly from
wheel revolutions (and subsequently calculates speed from
distance and time) then I think the auto start function
will not matter.

Anybody know whether computers primarly measure distance
or speed?

--
[email hidden] Personal Site: www.artybee.net (same
[censored], different layout) Sutton Brass :
www.suttonbrass.org.uk

I think they measure the time between each pulse and use the
wheel diameter to calculate everything else.

--

Dave Larrington - legslarry.beerdrinkers.co.uklegslarry.beerdrinkers.co.ukOpen ↗
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