Rollout setting for computer - 20 x 1 1/8

25.4 mm/inch "Glen Goldstein" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

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

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

Quoted message said:

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

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

Denny Voorhees said:

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

Quoted message said:

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

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

Quoted message said:

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

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 said:

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

Quoted message said:

IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of

1561

Quoted message said:

mm on a 10 mile tt it hits right on the money

Quoted message said:

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

"Glen Goldstein" skrev...

Quoted message said:

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! ;-)

onlineconversion.comonlineconversion.comOpen ↗

M.

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

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

Quoted message said:

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

Quoted message said:

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,

Quoted message said:

Quoted message said:

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

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

Quoted message said:

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

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

Quoted message said:

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

Quoted message said:

IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of

1561

Quoted message said:

mm on a 10 mile tt it hits right on the money

😕 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

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

Quoted message said:

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

Quoted message said:

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

Quoted message said:

IRC roadlite (451) on the front of a Rotator Pursuit has a roll out of

1561

Quoted message said:

mm on a 10 mile tt it hits right on the money

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

Quoted message said:

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