Rollout setting for computer - 20 x 1 1/8



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G

Glen Goldstein

Guest
Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to do
this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape measure! ;-)

Anybody have the correct figure for this?

many thanks,

Glen
 
A

Alma Williams

Guest
25.4 mm/inch "Glen Goldstein" <[email protected]> wrote in message
news:BAFADFBC.8825%[email protected]...
> Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
> do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
> measure! ;-)
>
> Anybody have the correct figure for this?
>
> many thanks,
>
> Glen
 
D

Denny Voorhees

Guest
If I Recall correctly it should be around 1575, start there and tweek. Denny in Sayre, Pa "Bent but
not broken" www.recumbentstuff.com "Glen Goldstein" <[email protected]> wrote in message
news:BAFADFBC.8825%[email protected]...
> Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
> do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
> measure! ;-)
>
> Anybody have the correct figure for this?
>
> many thanks,
>
> Glen
 
B

Bentbiker

Guest
that's what I thought too recently Denny, but for 1.25 it's 1472 so his probably around 1440 or so.

Denny Voorhees wrote:
> If I Recall correctly it should be around 1575, start there and tweek. Denny in Sayre, Pa "Bent
> but not broken" www.recumbentstuff.com "Glen Goldstein" <[email protected]> wrote in
> message news:BAFADFBC.8825%[email protected]...
>
>>Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
>>setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
>>do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
>>measure! ;-)
>>
>>Anybody have the correct figure for this?
>>
>>many thanks,
>>
>>Glen
>>
>
 
L

Lewis Campbell

Guest
Hi, Glen, in order to get the 'correct' figure, one needs to know how much you weigh, what model of
rim you are using and the PSI that your tire is inflated to.

You managed to find this newsgroup, so I KNOW that you are smart enough to use the 'roll out'
method, because even I can do that.
:)

Just roll the wheel thru one revolution and divide the number of inches by .03937 and BINGO.

Lewis.

.................... Glen Goldstein <[email protected]> wrote in message
news:<BAFADFBC.8825%[email protected]>...
> Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
> do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
> measure! ;-)
>
> Anybody have the correct figure for this?
>
> many thanks,
>
> Glen
 
S

S. Delaire \"Ro

Guest
IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of 1561 mm on a 10 mile tt it
hits right on the money

Glen Goldstein wrote:

> Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
> do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
> measure! ;-)
>
> Anybody have the correct figure for this?
>
> many thanks,
>
> Glen

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R

Robert Siegel

Guest
Funny, I "think" that's what I got for a Stelvio 451. I have to look.

--
Gator Bob Siegel EasyRacers Ti Rush "S. Delaire "Rotatorrecumbent"" <[email protected]> wrote in
message news:[email protected]...
> IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of
1561
> mm on a 10 mile tt it hits right on the money
 
G

Geob

Guest
> I KNOW that you are smart enough to use the 'roll out' method

I found on my 20" tire, that I measured 150cm, that it went to 152 when I actually *sat* on it
(inflated properly) while doing the roll-out.

GeoB
 
M

Mikael Seierup

Guest
"Glen Goldstein" skrev...
> Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
> do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
> measure! ;-)

http://www.onlineconversion.com/

M.
 
G

Geob

Guest
My number of 1520mm (loaded) is for a 406 Schwalbe Marathon. I'm right about 200 lbs.
 
O

Okiemoose

Guest
"...start there and tweek..." says Denny. Good advice, I think.

When I did the rollout method with my Stratus, the result was far from the setting recommended for
the tire in the computer's instruction booklet. I tried both settings and found neither setting
seemingly accurate enough.

What I did, however, was to drive a relatively flat piece of road in two cars (for a double check),
zeroing the trip odometers before starting, for an even 10 miles (it just so happened to be a good
start and end point, but other multiple-mile runs would work, too -- the longer the run, the more
accurate you can set your bike computer).

Then I rode that same stretch of road with my 'bent, zeroing my bike computer's odometer at the
starting point. I made note of the bike computer's miles readout at the end point. Then, with a
simple comparative equation, I found the most accurate setting for my bike computer.

For example, assume at a bike computer setting of 1500, the bike's odometer reads 7.5 miles for an
automobile odometer-measured 8 mile run. Working the comparative equation 7.5/1500 = 8.0/X ----->
7.5X = 12000 -----> X = 1600, which is the accurate setting for this bike's computer.

This is, of course, dependent upon the accuracy of your car's odometer (for instance, are your car's
tires the original size that were fitted when new? Are they significantly worn? etc.). This method
obviously works best using a new or near-new car as the odometer standard. Also, if your bike
computer gives you a readout in hundredths of miles instead of merely tenths, you can arrive at a
much more accurate bike computer setting using this method.

Hope this helps!

"Denny Voorhees" <[email protected]> wrote in message
news:[email protected]...
> If I Recall correctly it should be around 1575, start there and tweek. Denny in Sayre, Pa "Bent
> but not broken" www.recumbentstuff.com "Glen Goldstein" <[email protected]> wrote in
> message news:BAFADFBC.8825%[email protected]...
> > Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> > setting (IN MILLIMETERS!) for the front
wheel,
> > which is a 20x 1/18. Yeah, I know the best way to do this is to do a rollout and measure it, but
> > I seem to have misplaced my millimeter tape measure! ;-)
> >
> > Anybody have the correct figure for this?
> >
> > many thanks,
> >
> > Glen
>
 
J

Jeff Wills

Guest
bentbiker <[email protected]> wrote in message news:<[email protected]>...
> that's what I thought too recently Denny, but for 1.25 it's 1472 so his probably around
> 1440 or so.
>

Wrong. A 20 x 1.25" (ISO 406) tire is much smaller than the 20 x 1
1/8" (ISO 451) tire. A 1575 setting is close to correct- but rollout is still the best method.

Jeff
 
J

Joeg

Guest
With me (195-200ish) on my GRR, and a Stelvio 451, the figure is 1584 and change. When I ride with a
cyclometer and GPS simultaneously, they both read the same mph.

"Robert Siegel" <[email protected]> wrote in message
news:[email protected]...
> Funny, I "think" that's what I got for a Stelvio 451. I have to look.
>
> --
> Gator Bob Siegel EasyRacers Ti Rush "S. Delaire "Rotatorrecumbent"" <[email protected]> wrote in
> message news:[email protected]...
> > IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of
> 1561
> > mm on a 10 mile tt it hits right on the money
 

g19glock1

New Member
May 24, 2003
84
0
0
:confused: Making sure that I understand the roll out for accurate cyclo comp measurement. I have the Cateye Mity 8. My front tire is a primo comet 20 x 1.50. When I used my wifes fabric measuring tape I started from the center of the presta valve and rotated the wheel back to the center of the presta valve. I got 155 cm's. (Locked in a Park Bike Stand)

I then put the presta valve directly under the wheel with the bike on the floor, marked the starting point, and followed the expansion cut in the concrete floor in my pole barn for 3 complete revolutions of the wheel until the presta valve was again directly below the wheel. My weight was on the bike durring this process. My rollout measurement was 456 plus a few mm's so I divided that by three and came up with 152. Hense, my question. Which measurement should I use, or should I split the difference? The cyclo instructions say that for my size tire to use the 152.

Next question, how much difference is 3 cm's going to make in an average mph?

What do you think?

thanks for the feedback.

kim
 
R

Robert Siegel

Guest
Close enuf. My SO's GRR and my Rush read out distance within .01 of each other after more than 10
miles together so I guess they are set up OK. She has a 406 on her GRR and I have a 451o n my Ti
Rush. She weighs about 125 and I weigh 180.

--
Gator Bob Siegel EasyRacers Ti Rush "JoeG" <[email protected]> wrote in message
news:[email protected]...
> With me (195-200ish) on my GRR, and a Stelvio 451, the figure is 1584 and change. When I ride with
> a cyclometer and GPS simultaneously, they both read the same mph.
>
> "Robert Siegel" <[email protected]> wrote in message
> news:[email protected]...
> > Funny, I "think" that's what I got for a Stelvio 451. I have to look.
> >
> > --
> > Gator Bob Siegel EasyRacers Ti Rush "S. Delaire "Rotatorrecumbent"" <[email protected]> wrote
> > in message news:[email protected].com...
> > > IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of
> > 1561
> > > mm on a 10 mile tt it hits right on the money
> >
>
 
J

Jim

Guest
Glen Goldstein <[email protected]> wrote in message
news:<BAFADFBC.8825%[email protected]>...
> Trying to set up my new cycle computer with my Tour Easy, and looking everywhere for the correct
> setting (IN MILLIMETERS!) for the front wheel, which is a 20x 1/18. Yeah, I know the best way to
> do this is to do a rollout and measure it, but I seem to have misplaced my millimeter tape
> measure! ;-)
>
> Anybody have the correct figure for this?
>
> many thanks,
>
> Glen

I have the same wheel 451 and a bell computer I set it at 1600 and had no problems. jim/geowizard86
 
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