wheel rollout test?
Mark Cleary
calibrate. My 700 x 23 front wheel was 2089.2 mm, a little different
than the stardard 700 X 23 which the Trek computer uses 2096. Not alot
of difference but wonder if anyone would do a rollout test that have
wheels that are 700 X 23 and let me know the results they get. It does
make for a more accurate computer per as Mike said.
--
Deacon Mark Cleary
Epiphany Roman Catholic Church
landotter
Don't forget to sit on the bike when doing a roll out.
Lou Holtman
> I decide to measure the wheel for my computer using the rollout and
> calibrate. My 700 x 23 front wheel was 2089.2 mm, a little different
> than the stardard 700 X 23 which the Trek computer uses 2096. Not alot
> of difference but wonder if anyone would do a rollout test that have
> wheels that are 700 X 23 and let me know the results they get. It does
> make for a more accurate computer per as Mike said.
For a 23 mm tire I measured in the past several times close to 2096 mm.
Set it to that figure and you are within 0.5% accurate. You measured
2089.2 mm. How did you measured the 0.2 mm? Well never mind. The
difference with the 2096 mm is within 0.5%.
Lou
Dennis Ferguson
> I decide to measure the wheel for my computer using the rollout and
> calibrate. My 700 x 23 front wheel was 2089.2 mm, a little different
> than the stardard 700 X 23 which the Trek computer uses 2096. Not alot
> of difference but wonder if anyone would do a rollout test that have
> wheels that are 700 X 23 and let me know the results they get. It does
> make for a more accurate computer per as Mike said.
The number varies with tire brand and model as well as the nominal
size. The 700x25c Michelin tires I usually ride measure 2104 mm, the
last 700x25c Continental tires I had measured 2096 mm. What you
measure with the roll-out is bound to be better than whatever default
Trek uses since Trek has no idea what kind of tires you have.
Dennis Ferguson
Mark Cleary
much finer. But I used math 25.4 times 82.25 inches.
Leo Lichtman
"Mark Cleary" (clip) But I used math 25.4 times 82.25 inches.
^^^^^^^^^^^^^^^^^^^^
If you carry more significant figures in a calculation than you had in the
original data, you create a false impression of the accuracy. 82.25, having
four significant figures, should be given as 208.9. Actually, since 25.4
has only three sig figs, the product should be rounded to 209. However, an
independent check shows the next figure to be a zero, so you can consider
four figure accuracy to be okay.
Mike Jacoubowsky
news:df967f50-3e15-417c...@x37g2000yqj.googlegroups.com...
Not that big a deal, since it's the front tire that's measured, which gets
only 35% or so of rider weight on it. You can just push down on the
handlebars as you move it forward and you'll get a very good reading.
--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA
Radey Shouman
25.4 mm/inch is exact, being the current definition of the inch.
Chalo
>
> Actually, since 25.4
> has only three sig figs, the product should be rounded to 209.
25.4mm/in is an absolute conversion factor. Substitute 25.4000 if it
makes you feel better.
Chalo
Mike Jacoubowsky
news:hbauhg$ade$1...@news.eternal-september.org...
If you *really* want an accurate number, roll out the wheel *two*
revolutions, measure that, and divide by two. Obviously make sure you do it
in a straight line. But if you've got a tiled floor, just start at a tile
intersection, looking straight down and making sure the center of the hub,
the valve and the intersection in the floor all line up, and then just roll
down the line until you see the same again. If you've got a second person
handy, instead of fiddling with the tape measure, have them mark the floor
with a pencil, or just simply place the pencil on the floor at the relevant
place. One revolution should be plenty accurate if you're reasonably
careful.
Keep in mind that the reason for doing the rollout is because various 700x23
tires will have varying rollouts. 700x23, in the absence of standards for
how tires are actually measured, doesn't have a lot of meaning. In other
words, there are 700x23 tires on the market that are actually smaller than
another manufacturer's 700x25. Thus anything preset in a computer is just an
approximate. Generally pretty darned close, but rarely perfect.
Frank Krygowski
>
>
> For a 23 mm tire I measured in the past several times close to 2096 mm.
> Set it to that figure and you are within 0.5% accurate. You measured
> 2089.2 mm. How did you measured the 0.2 mm? Well never mind. The
> difference with the 2096 mm is within 0.5%.
>
> Lou
And ordinary variations in how you ride a route will cause greater
differences than 0.5%.
I always calibrate my cyclometer at the same time I calibrate my
wife's. But on the same ride, hers usually seems to measure a little
less, which bothers her a bit. Maybe it's because I wander around a
bit more on the road, or maybe it's because I carry more weight in my
handlebar bag compared to when I calibrate.
When we did our coast-to-coast ride, I finally had to do some trial-
and-error calibration of hers so it would match mine, just to keep her
happy. Love trumps science, I guess.
- Frank Krygowski
Mark J.
...In other words, there are 700x23 tires on the market that are
> actually smaller than another manufacturer's 700x25.
Or even the other way around, as I expect you meant.
BTW, I'm having lots of fun with Paselas - the 700x25's are about half a
mm wider than my Michelin 700x23's, but the wider Paselas (on a
different rim, admittedly) seem to measure true. Some 700x28's are
coming soon (and I'll have a complete set! Whee!)
Mark J.
carl...@comcast.net
Dear Frank,
Interesting--I see an order of magnitude less variation than +/- 0.5%
in thousands of rides.
Mileages for my last 5 daily rides since a cold snap, no tire pumping.
15.118 +0.038% from average (15.1180/15.1122 = 1.0003837
15.112
15.105 -0.046% from average (15.1050/15.1122 = 0.9995235
15.110
15.116
15.1122 average
I zero my WalMart cyclocomputer with my spoke magnet just past the
sensor at the second expansion crack in my driveway and stop at my
garage door.
A difference of 0.001 miles is approximately a single wheelspin,
meaning that whether the magnet manages to pass the sensor just as I
stop accounts for about 15% of my +/- variation.
Right after pumping my front tire, I can see mileage as low as 15.090.
At 15.130 I admit that I have a slow leak in my 700x25 front tire.
For 0.5%, I'd have to see 15.112 leap up to 15.188 or so, a huge
change (0.076), far beyond the 15.130 (0.018) that signals a slow leak
or not pumping the tire for a few weeks.
Cheers,
Carl Fogel
thirty-six
> I decide to measure the wheel for my computer using the rollout and
> calibrate. My 700 x 23 front wheel was 2089.2 mm, a little different
> than the stardard 700 X 23 which the Trek computer uses 2096. Not alot
> of difference but wonder if anyone would do a rollout test that have
> wheels that are 700 X 23 and let me know the results they get. It does
> make for a more accurate computer per as Mike said.
My old cateye cycle computer uses a resolution of 10mm and I'm
perfectly happy with this. 209 or 210 sounds familiar(its entered in
cm) and a whole centimetre either way is an 'error' of less than
0.5% This is way more accurate than my car speedometer, which has
an error near to 10% over-read at most usable speeds. If there is
some reason you need accurate mileage checking then use a pacestick
and counter. For on the bike, better accuracy, use a rear wheel
sensor. This should improve accuracy more than millimetre resolution
on the front wheel, particularly if you have unstable steering.
Tim McNamara
Mark Cleary <mcle...@comcast.net> wrote:
> I decide to measure the wheel for my computer using the rollout and
> calibrate. My 700 x 23 front wheel was 2089.2 mm, a little different
> than the stardard 700 X 23 which the Trek computer uses 2096. Not
> alot of difference but wonder if anyone would do a rollout test that
> have wheels that are 700 X 23 and let me know the results they get.
> It does make for a more accurate computer per as Mike said.
That number will change slightly from one bike to the next. For one
thing, 700 x 23 is not an absolute measurement. Some brands run
smaller, some larger. The same tire will measure larger or smaller on
different rims. Differences in inflation pressure and rider weight will
change that number.
I find that the number provided in the instruction manual for all cyclo
computers are inaccurate and are usually just based on simplistic math.
The numbers are almost always overestimates.
RobertH
> For a 23 mm tire I measured in the past several times close to 2096 mm.
> Set it to that figure and you are within 0.5% accurate. You measured
> 2089.2 mm. How did you measured the 0.2 mm? Well never mind. The
> difference with the 2096 mm is within 0.5%.
However, it's still going to be off about a half-mile for every
hundred miles, not that accurate for anyone trying to use their
odometer for gauging performance or attempting to follow mileage cues
on tour. A lot more accurate than the odometer in my car though since
I changed the tires.
Lou Holtman
> On Oct 16, 6:03 pm, Lou Holtman <lhollaatditmaar...@planet.nl> wrote:
>>
>> For a 23 mm tire I measured in the past several times close to 2096 mm.
>> Set it to that figure and you are within 0.5% accurate. You measured
>> 2089.2 mm. How did you measured the 0.2 mm? Well never mind. The
>> difference with the 2096 mm is within 0.5%.
>>
>> Lou
>
> And ordinary variations in how you ride a route will cause greater
> differences than 0.5%.
I doubt that and it is also not what I experience. Someone pointed that
out to me once and I asked him what difference it would make if he
wandered across the street, lets say 5 m wide, every 200 m. We agreed
that that is a lot. It is much smaller than 0.5%.
>
> I always calibrate my cyclometer at the same time I calibrate my
> wife's. But on the same ride, hers usually seems to measure a little
> less, which bothers her a bit. Maybe it's because I wander around a
> bit more on the road, or maybe it's because I carry more weight in my
> handlebar bag compared to when I calibrate.
I don't know. Is it the same computer, yours and your wifes? Are the
sensors both on the front wheel (front and back travel a different
distance in a curve).
>
> When we did our coast-to-coast ride, I finally had to do some trial-
> and-error calibration of hers so it would match mine, just to keep her
> happy. Love trumps science, I guess.
Yep. How much was the difference over that distance and why does it
bother her? ;-)
Lou
Lou Holtman
It is not only the width but also the height.
Lou
Lou Holtman
Please, give me a break. You have cue cards saying: 'turn left after 100
miles'? That must be a boring ride, or do you live in Australia ;-)
Lou
Nate Nagel
but do you have all the permutations of the various sizes? To have a
complete set, you'd have each size in regular, belted, and folding :)
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
Andre Jute
> RobertH schreef:
[snip]
> > However, it's still going to be off about a half-mile for every
> > hundred miles, not that accurate for anyone trying to use their
> > odometer for gauging performance or attempting to follow mileage cues
> > on tour. A lot more accurate than the odometer in my car though since
> > I changed the tires.
>
> Please, give me a break. You have cue cards saying: 'turn left after 100
> miles'? That must be a boring ride, or do you live in Australia ;-)
Hey, I resemble that remark. When I first went to Australia, I toured
right around the coastline. It was very interesting, in fact,
according to two Texan oilfield hands whose way I paid in return for
them handling the camping chores, the driving and suchlike boring
business, much more varied than Texas... Anyway, Australia is far more
interesting topographically than The Netherlands: you just gotta go a
thousand miles further to see the landscape change.
Andre Jute
The Big Country
Lou Holtman
I was just kidding. I was just wondering why a 0.5% accuracy is not
enough for cue card riding.
Lou
Mark J.
> Mark J. wrote:
>> Mike Jacoubowsky wrote:
>> ...In other words, there are 700x23 tires on the market that are
>>> actually smaller than another manufacturer's 700x25.
>>
>> Or even the other way around, as I expect you meant.
>>
>> BTW, I'm having lots of fun with Paselas - the 700x25's are about half
>> a mm wider than my Michelin 700x23's, but the wider Paselas (on a
>> different rim, admittedly) seem to measure true. Some 700x28's are
>> coming soon (and I'll have a complete set! Whee!)
>>
>> Mark J.
>
> but do you have all the permutations of the various sizes? To have a
> complete set, you'd have each size in regular, belted, and folding :)
>
> nate
Non-belted folding appear to be unavailable, at least in 700c. The
choices appear to be unbelted wire bead and belted folding.
Mark J.
Nate Nagel
I believe that there's also a belted wire bead, at least there is in 27"
sizes.
Frank Krygowski
But as I recall, your ride is a very consistent solo trip on a bike
path, right? I think you don't have the opportunity for variation
that we have, because we normally ride together on suburban or country
roads, or on residential streets.
Sometimes I've been able to explain to her "But I turned around to
look at that hawk with my binoculars, remember?" But not often.
- Frank Krygowski
Frank Krygowski
> Frank Krygowski schreef:
>
> > I always calibrate my cyclometer at the same time I calibrate my
> > wife's. But on the same ride, hers usually seems to measure a little
> > less, which bothers her a bit. Maybe it's because I wander around a
> > bit more on the road, or maybe it's because I carry more weight in my
> > handlebar bag compared to when I calibrate.
>
> I don't know. Is it the same computer, yours and your wifes? Are the
> sensors both on the front wheel (front and back travel a different
> distance in a curve).
They're different brands, but I don't see why that would make a
difference. Both are triggered by the front wheel. We usually
(although not now) have the same tires fitted.
I suppose part of it _could_ be that I ride more than she does, so my
front tire would be a tiny bit smaller in diameter from wear, and I
usually calibrate with an empty handlebar bag, but sometimes have
extra weight in mine... but those seem like very tiny differences.
I could, I suppose, improve my calibration procedure. For my
rollouts, I use chalk marks on the ground. Change to a sharp pencil,
for better precision?
> > When we did our coast-to-coast ride, I finally had to do some trial-
> > and-error calibration of hers so it would match mine, just to keep her
> > happy. Love trumps science, I guess.
>
> Yep. How much was the difference over that distance and why does it
> bother her? ;-)
Sadly, we never got the _precise_ mileage for the trip. Best estimate
was 3982 miles. But my cyclometer battery died mid-trip and took a
day to replace, my wife's (old) cyclometer requires manually starting
(which she sometimes forgets to do), and my daughter's cyclometer
stopped working in the rain one day. Nobody's worked perfectly every
day.
Why does it bother her? Actually, she's joking, I think. But she
feels like when she exerts herself, she wants credit for every inch!
- Frank Krygowski
Lou Holtman
> On Oct 17, 4:31 am, Lou Holtman <lhollaatditmaar...@planet.nl> wrote:
>> Frank Krygowski schreef:
>>
>>> I always calibrate my cyclometer at the same time I calibrate my
>>> wife's. But on the same ride, hers usually seems to measure a little
>>> less, which bothers her a bit. Maybe it's because I wander around a
>>> bit more on the road, or maybe it's because I carry more weight in my
>>> handlebar bag compared to when I calibrate.
>> I don't know. Is it the same computer, yours and your wifes? Are the
>> sensors both on the front wheel (front and back travel a different
>> distance in a curve).
>
> They're different brands, but I don't see why that would make a
> difference. Both are triggered by the front wheel. We usually
> (although not now) have the same tires fitted.
Trust me it matters. A cyclometer is a actually a counter. It counts
internal clock pulses between two triggers from the wheel sensor. The
internal clock is not accurate. A good indicator is how accurate the
unit tells the time over a period. And there is firmware of course.
Lou
current...@veloemail.com
> I decide to measure the wheel for my computer using the rollout and
> calibrate. My 700 x 23 front wheel was 2089.2 mm, a little different
> than the stardard 700 X 23 which the Trek computer uses 2096. Not alot
> of difference but wonder if anyone would do a rollout test that have
> wheels that are 700 X 23 and let me know the results they get. It does
> make for a more accurate computer per as Mike said.
> Deacon Mark Cleary
> Epiphany Roman Catholic Church
I used this method then comapred it to the mileposts from bend oregon
to ontario idaho about 250 miles there was a 2 percent differance.
Andrew Price
<tim...@bitstream.net> wrote:
>That number will change slightly from one bike to the next. For one
>thing, 700 x 23 is not an absolute measurement. Some brands run
>smaller, some larger. The same tire will measure larger or smaller on
>different rims. Differences in inflation pressure and rider weight will
>change that number.
They certainly do. I've found that the repeatability of the average
cycle computer is so good that increases in recorded distances between
two known fixed points on my usual training circuit are a pretty good
sign that the tyres need to be pumped up.
Mark J.
Yup, I forgot those. They are the ones I'm least interested in. -MJ
Frank Krygowski
I can see how the internal clock would matter for speed readings, but
not for distance readings. That's just a simple counter multiplying
by a constant.
Oh, and even regarding speed: the clock displays stay synchronized
very, very well, far better than the differences in odometer
readings.
- Frank Krygowski
Lou Holtman
> On Oct 17, 2:20 pm, Lou Holtman <lhollaatditmaar...@planet.nl> wrote:
>> Frank Krygowski schreef:
>>
>>> On Oct 17, 4:31 am, Lou Holtman <lhollaatditmaar...@planet.nl> wrote:
>>>> Frank Krygowski schreef:
>>>>> I always calibrate my cyclometer at the same time I calibrate my
>>>>> wife's. But on the same ride, hers usually seems to measure a little
>>>>> less, which bothers her a bit. Maybe it's because I wander around a
>>>>> bit more on the road, or maybe it's because I carry more weight in my
>>>>> handlebar bag compared to when I calibrate.
>>>> I don't know. Is it the same computer, yours and your wifes? Are the
>>>> sensors both on the front wheel (front and back travel a different
>>>> distance in a curve).
>>> They're different brands, but I don't see why that would make a
>>> difference. Both are triggered by the front wheel. We usually
>>> (although not now) have the same tires fitted.
>> Trust me it matters. A cyclometer is a actually a counter. It counts
>> internal clock pulses between two triggers from the wheel sensor. The
>> internal clock is not accurate. A good indicator is how accurate the
>> unit tells the time over a period. And there is firmware of course.
>
> I can see how the internal clock would matter for speed readings, but
> not for distance readings. That's just a simple counter multiplying
> by a constant.
>
Oops. you are right.
> Oh, and even regarding speed: the clock displays stay synchronized
> very, very well, far better than the differences in odometer
> readings.
OK
Lou
Andre Jute
Some people will whine when the accuracy is improved to 0.0005%.
Hairsplitting is their way of saying, "Me! Me! Look at me! I'm an
engineer!" -- AJ
RobertH
Point five percent is fairly accurate. Most folks' odometers are a lot
less accurate than that, I would guess. Over a fifty mile ride they
could easily be off by a few miles if they set their computer with the
number in the booklet. This adds an extra element of adventure for
anyone trying to follow any kind of mileage cues. I don't do that
myself but many people do. Imagine being out in the forest somewhere
trying to follow a long trail ride from a book. There are trails
spurring off here and there and you're not sure which one to take so
you go to the mileage cues for help. Of course even with a perfectly
accurate computer things are bound to happen to throw off the mileage
-- such as adding little detours as most of us do without even
thinking about it, or even turning around to go pick up your hat which
blew off. And the cues themselves are only as good as the rollout test
of the person who wrote the guidebook. Following mileage cues will
always be more art than science, or completely bogus, depending on how
you want to look at it.
Anyone training for time trials or triathlons and other sorts of
distance/clock cycling will want to have a carefully calibrated
computer.
I don't use a computer but I definitely don't see any point in looking
at an inaccurate one.
Tim McNamara
"Mark J." <MarkU...@comcast.net> wrote:
I use the former. They're fine, llght enough and cheap. I get 'em for
about $20 at the LBS. Sad to see that the tan wall versions are getting
hard to find, QBP apparently now only imports the blackwalls and I've
never been able to get used to that look.
If I was going on tour and was going to carry a spare, I'd buy a folder
to stick in my saddlebag.
carl...@comcast.net
Dear Frank,
About 6 miles bike path:
http://i36.tinypic.com/xogqxi.jpg
http://i36.tinypic.com/2mgjgy1.jpg
http://i35.tinypic.com/2vl2zuu.jpg
http://i37.tinypic.com/s6k6q8.jpg
http://i35.tinypic.com/2vagy39.jpg
http://i33.tinypic.com/2h2mjbl.jpg
http://i34.tinypic.com/5klqoz.jpg
About 2 miles rural road:
http://i34.tinypic.com/2s8k0ut.jpg
http://i35.tinypic.com/b6rksw.jpg
About 4 miles highway shoulder:
http://i36.tinypic.com/2v8onb6.jpg
http://i38.tinypic.com/20ksv7n.jpg
http://i34.tinypic.com/mkyhe1.jpg
http://i33.tinypic.com/33vzzit.jpg
http://i33.tinypic.com/9u5e9f.jpg
About 3 miles suburban and residential streets:
http://i37.tinypic.com/2a61jz9.jpg
http://i35.tinypic.com/sfklcx.jpg
http://i34.tinypic.com/bg8w75.jpg
http://i36.tinypic.com/2f03jpc.jpg
Obviously, we're talking about different things.
You're thinking of the mileage difference between two riders wandering
down the same road, taking slightly different lines and weaving
slightly differently as they pedal.
I'm thinking of the mileage difference same rider going over the same
road twice, with much smaller variations in line and pedal-weave.
Either way, the difference is trivial in terms of practical bicycle
navigation, 0.5% or 0.04%
On my daily 15-mile ride, the difference is just a few wheelspins.
On a 100-mile ride at a leisurely 15 mph with two people, it's only
half a mile, or two minutes out of seven hours.
Cheers,
Carl Fogel
Frank Krygowski
>
> Obviously, we're talking about different things.
>
> You're thinking of the mileage difference between two riders wandering
> down the same road, taking slightly different lines and weaving
> slightly differently as they pedal.
>
> I'm thinking of the mileage difference same rider going over the same
> road twice, with much smaller variations in line and pedal-weave.
>
> Either way, the difference is trivial in terms of practical bicycle
> navigation, 0.5% or 0.04%
I agree, it's not important at all. Unless it's helpful in keeping
one's wife happy!
- Frank Krygowski
carl...@comcast.net
Dear Frank,
If a husband riding alone checks his odometer . . .
http://www.zazzle.com/if_a_man_speaks_in_the_forest_and_theres_no_wo_tshirt-235397551093841785
Cheers,
Carl Fogel
AMuzi
Many Pana importers stock the full line but your average
"LBS" is pretty much below average now, I think, and unable
or unwilling. No shortage of natural skinside Panaracer, 27,
700, 559, 650...
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Tim McNamara
AMuzi <a...@yellowjersey.org> wrote:
Well, at least J&B imports the tan wall Paselas but they cost more than
QBP per my LBS. And of course my LBS is in Minneapolis and only a few
miles from the QBP warehouse, so he prefers to buy the majority of his
stock there. He is getting some tan walls in for me.
I use the 559 x 32 on one bike, the 700 x 25 on two more and the 700 x
28 on a third. I like the 559's and the 700 x 28s best in terms of ride
quality. Good tires. They don't last quite as long as the Contis I
used to use in terms of tread life, but on the other hand the sidewalls
don't fray.
thirty-six
> In article <hbfq1n$d5...@news.eternal-september.org>,> > > In article <hbcq4b$i3...@news.eternal-september.org>,
How about taking the conti treads and applying them to the panaracer
casing? Duh, Realised I have a roll of black rubber about 1/16" thick
and 7/8" wide, wonder where that came from. I think I have some tyre
tread in the making. Aren't slicks just brilliant? ; )