MAX speed on a Coker

Unicycles and Equipment
1

Lately I’ve been paying particular attention to my max speed on my Coker. I
set the timer on my wristwatch to one minute and then count the revolutions.
This seems to be a reasonably accurate way of measuring a one minute
averaged top speed.

I’ve been somewhat discouraged. I had previously believed (based on little
more that a “gut” feeling) that I had approached 20mph occasionally. As it
turns out for me my top one minute cadence is about 140. On a Coker that
translates to just under 15mph. Can anyone who has paid attention to these
things suggest if it is likely that during the course of one minute of near
maximum pedalling that my cadence would vary significantly? I don’t feel
like it does. But I cannot say for sure.

I recently swapped cranks on the Coker to ~124mm cranks. These allow me to
use a smoother, more circular pedal stroke. Unfortunately they haven’t
yielded the speed increases that I had hoped for. I believe that this is
due, in part, to a reduction in my ability to control the Coker. With time
I expect (hope?) to routinely achieve cadences above 150 (16mph).

I think that part of my previous overestimation of my speed is based on
reports of max speed here in the newsgroup. I also believe that many
reports of >15mph are incorrect. I believe that this inaccuracy is a
result of a rider using a cycle computer’s max speed function.

I do belive that 20+mph is possible, just not as common as I had initially
believed. It seemed that every Coker owner was reporting 20+mph. I myself
fell prey to this misinformation and posted “guestimated” speeds. Or maybe
I’m just the “slow guy”. I guess I’ll find out at UNICON (if I can figure
out how to get my Coker there).

-mg

2

Re: MAX speed on a Coker

You have brought up quite a few good points here.

Reducing your crank length doesn’t automatically increase your top speed.
In fact it decreases it in my experience. It does increase your average due
to the smoothness. I agree I think it is the balance/control factor which
is affecting this. I speed up after I have got my self settled on the
unicycle, normally between 5 to 10 miles.

On rides I regularly reach a max of 18.9, that seams to be my figure. I
very rarely get above that. It is using the max figure which does
occasionally show something like 24mph, this is I would have said almost
certainly due to dismounting and letting the wheel spin or idling. I know
that I can ride at 18mph, because I can read my clock while I ride.

When we were on the MN ride gilby showed me a burst of speed going down a
hill, I was on 110 cranks and he was on stock 152. I am reasonably certain
I was doing about 18 (I did not check it while riding that time, but what
the max showed at the time) but Gilby pulled away from me at quite a speed
which would imply that he was over 20mph.

I will have my Coker at UNICON so we can do some tests, it will be
interesting.

Roger

The UK’s Unicycle Source

----- Original Message -----
From: “Michael Grant” <michael_j_grant@msn.com>
Newsgroups: rec.sport.unicycling
To: <rsu@unicycling.org>
Sent: Friday, June 21, 2002 2:13 AM
Subject: MAX speed on a Coker

> Lately I’ve been paying particular attention to my max speed on my Coker.
I
> set the timer on my wristwatch to one minute and then count the
revolutions.
> This seems to be a reasonably accurate way of measuring a one minute
> averaged top speed.
>
> I’ve been somewhat discouraged. I had previously believed (based on
little
> more that a “gut” feeling) that I had approached 20mph occasionally. As
it
> turns out for me my top one minute cadence is about 140. On a Coker that
> translates to just under 15mph. Can anyone who has paid attention to
these
> things suggest if it is likely that during the course of one minute of
near
> maximum pedalling that my cadence would vary significantly? I don’t feel
> like it does. But I cannot say for sure.
>
> I recently swapped cranks on the Coker to ~124mm cranks. These allow me
to
> use a smoother, more circular pedal stroke. Unfortunately they haven’t
> yielded the speed increases that I had hoped for. I believe that this is
> due, in part, to a reduction in my ability to control the Coker. With
time
> I expect (hope?) to routinely achieve cadences above 150 (16mph).
>
> I think that part of my previous overestimation of my speed is based on
> reports of max speed here in the newsgroup. I also believe that many
> reports of >15mph are incorrect. I believe that this inaccuracy is a
> result of a rider using a cycle computer’s max speed function.
>
> I do belive that 20+mph is possible, just not as common as I had initially
> believed. It seemed that every Coker owner was reporting 20+mph. I
myself
> fell prey to this misinformation and posted “guestimated” speeds. Or
maybe
> I’m just the “slow guy”. I guess I’ll find out at UNICON (if I can figure
> out how to get my Coker there).
>
> -mg
>
>
>

> rec.sport.unicycling mailing list -
www.unicycling.org/mailman/listinfo/rsu
>
>

3

Have someone (whose driving skills you absolutely trust) clock you in a car.

4

Re: MAX speed on a Coker

> Have someone (whose driving skills you absolutely trust) clock you in a
> car.

I don’t trust that an automobiles speedometer would be very accurate at
these (relatively) slow speeds. I can just see it now: “You were
travelling at somewhere between 12 and 18 mph.” Not exactly the accuracy
that I’d like.

I trust that Roger’s (and others) method of mounting a cycle computer where
it can be seen while riding probably provides the most accurate measurement.
Perhaps if I could see my computer while riding I’d be pleasantly surprised
to find that I have “bursts” of speed above my one minute average.

Roger, do you have more than one magnet mounted to the wheel?

-mg

5

Michael -

I pay pretty close attention to my max/average speeds on my Coker. I have my computer mounted such that I can see it safely while riding. Please see:

http://www.public.iastate.edu/~gbarnes/
Click on “Coker Handle”

These new handles are available from Unicycle.com now, and should be on their website shortly.

I use a Trek Radar computer on my coker. I set my wheel size to 2776 on the computer, so no need for 2 magnets. One of the features on the Radar is its “Workout Window”. This is a seperate set of data that records only when you want it to (you start and stop it manually). This will record your dist, ave, max, time, etc from when you start it until you stop it. Your overall data (dist, ave, max, etc) is still recorded in the background. This an easy way to determine average speed for a given time period.

6

Re: Re: MAX speed on a Coker

I’ve done this. You’re right. My wife clocked me at a TOP speed of 4 mph over a distance where my AVERAGE speed was 10 mph. Hmmmm…

7

RE: MAX speed on a Coker

> Lately I’ve been paying particular attention to my max speed
> on my Coker. I
> set the timer on my wristwatch to one minute and then count
> the revolutions.
> This seems to be a reasonably accurate way of measuring a one minute
> averaged top speed.

Several other people have provided good information here. I was just going
to add that in my own experience, I know I can do much faster “burst” speeds
than what I can hold for a whole minute. In racing, a minute is a long
time. So an honest max. speed number should be more likely achieved through
sprinting.

But then there’s the “dishonest” max. speed you might get from a cycle
computer, which you get from unusual movements of the wheel (mounting,
idling), or through breaks in the data stream being delivered from your
wheel. You have to weed those out to know that your max. speed is for real.

> Can anyone who has paid attention to these
> things suggest if it is likely that during the course of one
> minute of near maximum pedalling that my cadence would vary
> significantly?

You should be able to feel it unless it’s fairly minor. So you probably have
a very solid cadence. With practice, you should be able to make bursts of
acceleration like Roger described Gilby doing. You can always use a hill to
help, then go back to level ground if you’re a purist.

> I recently swapped cranks on the Coker to ~124mm cranks.
> These allow me to use a smoother, more circular pedal stroke.
> Unfortunately they haven’t yielded the speed increases that
> I had hoped for. I believe that this is due, in part, to a
> reduction in my ability to control the Coker.

Roger seemed to share this belief. Crank length is going to be a matter of
personal preference, but for everybody there comes a point at which they
stop getting any return on using shorter cranks. I prefer longer cranks on
my 45" wheel (6.5"), but I was okay with the 125mm cranks on the Coker I
rode in the marathon race at NUC last summer. I wonder, between the two of
those, which one I could make go faster?

> I do belive that 20+mph is possible, just not as common as I
> had initially believed. It seemed that every Coker owner
> was reporting 20+mph.

I don’t think most Coker riders are going 20 mph, though they may be hitting
it in bursts. The cadence required for that speed would be pretty high, and
wind resistance is a big factor at that point (unlike at the slower speeds
of 24" racing)

Stay on top,
John Foss, the Uni-Cyclone
jfoss@unicycling.com
www.unicycling.com <http://www.unicycling.com>

Not a Coker owner (yet)

8

Re: MAX speed on a Coker

michael_j_grant@msn.com writes:
>Lately I’ve been paying particular attention to my max speed on my Coker.
> I
>set the timer on my wristwatch to one minute and then count the
>revolutions.
>This seems to be a reasonably accurate way of measuring a one minute
>averaged top speed.
Well, this is hardly going to jibe with your computer’s readout of max
speed if you do anything that could give you a short burst – like riding
fast down a hill or suddenly speeding up a bit in order to preserve
balance. A minute is a long time. Another way is to time yourself for a
set # of revs. Be careful not to count ‘1’ until you’ve actually rotated
once around (that is, don’t say one as soon as you’ve hit the stopwatch).
If you set a goal of 40 revs in 15 seconds, then you will have an easier
time of reaching your goal than if you try for 160 in 60 – it’s just not
easy to maintain top speed for a minute (unless it’s a really long hill).
>
>I’ve been somewhat discouraged. I had previously believed (based on
>little
>more that a “gut” feeling) that I had approached 20mph occasionally. As
>it
>turns out for me my top one minute cadence is about 140. On a Coker that
>translates to just under 15mph. Can anyone who has paid attention to
>these
>things suggest if it is likely that during the course of one minute of
>near
>maximum pedalling that my cadence would vary significantly? I don’t feel
>like it does. But I cannot say for sure.
If you have an even surface, your cadence certainly can be constant for a
minute. You won’t usually get much spiking – maybe within 7% of an
average speed. So if you hit 16mph as measured by cadence, you’re likely
going 15-17mph (as measured by a precise computer). The important thing is
not max speed, tho, is it – it’s max average speed. What I sometimes do
is sorta like wind sprints: I occasionally count revs to see if I can hit
a certain goal. I actually never tried this on a Coker, but on uni.5 I hit
165 cadence for a minute. On a Coker, I can probably hold 200 for a minute
on a hill – I’ll try today. There is a nice stretch of Prospect Park road
where I routinely hit a max of 20mph and maintain that range of speed
(about 19-20.5) for at least 30 seconds. 20mph would be 232 cadence.
>
>
>I recently swapped cranks on the Coker to ~124mm cranks. These allow me
>to
>use a smoother, more circular pedal stroke. Unfortunately they haven’t
>yielded the speed increases that I had hoped for. I believe that this is
>due, in part, to a reduction in my ability to control the Coker. With
>time
>I expect (hope?) to routinely achieve cadences above 150 (16mph).
Yeah, I found that going to 110s really helped with average speed. As
Roger noted, it doesn’t really help with max speed.
>
>I think that part of my previous overestimation of my speed is based on
>reports of max speed here in the newsgroup. I also believe that many
>reports of >15mph are incorrect. I believe that this inaccuracy is a
>result of a rider using a cycle computer’s max speed function.
>
>I do belive that 20+mph is possible, just not as common as I had initially
>believed. It seemed that every Coker owner was reporting 20+mph. I
>myself
>fell prey to this misinformation and posted “guestimated” speeds. Or
>maybe
>I’m just the “slow guy”. I guess I’ll find out at UNICON (if I can figure
>out how to get my Coker there).
Or neither. It is just that there are quite a few Coker riders now, and
among us, some can routinely hit 18mph or average 14mph. So you may be an
average rider and it could be that there are quite a few fast riders. I
also know that there are quite a few slow riders. As I have noted before,
I was surprised that no one else could maintain 12 mph for more than a few
minutes at last year’s Unithon, tho in part this may have been bc ppl were
preserving their strength for the 18.5-mile ride. The Unithon rides again
tom’w, and I intend to ride it in about 90-100 mins. We’ll see.

David Stone

Co-founder, Unatics of NY
1st Sunday / 3rd Saturday
@ Central Park Bandshell
1:30 start time after 11/1/01

Cadence chart:
Revs/minute Speed (approx) in mph
116 10
128 11
139 12
151 13
162 14
174 15
185 16
197 17
209 18
220 19
232 20
… …
290 25
302 26
toe clips death

Basically, just recall the rule that 1/10 of a mile = c. 116 revs. Then
add 11 or 12 (11.6, really) between each speed. If you want to go 14mph,
you can just calculate your initial 116 + (4x11.6) = approx. 162 cadence.

9

OK, have a cop with a radar gun clock you. :wink: Oops! Same thing. Never mind. Hope you’re good at counting! How many fingers am I holding up? :smiley:

10

The math used in this thread to compare cadence/speed for the Coker tire is incorrect. At 10mph the cadence is 94(approx).
I have tried to count while riding but I don’t care for that method.
I prefer to let my cycle computer do that for me. All I care about tho is avg speed for the entire day. I don’t try to “max” out much since I broke my collar bone.
-Mark

11

Michael did it correctly with his 140 rpm => 15 mph.

SPEED(mph) x 9.34 = CADENCE(rpm)

for a 36" diameter Coker tire.

My max speed on a Coker is very, very, very low. I think it is, anyway. I don’t wear a watch and I don’t have a speedometer and I don’t pass alot of bicycles. The ones I pass are usually chained to parking meters or trees.

12

I reread my post and then David’s. David said that 116 revs = 1/10th of a mile. But I’m saying that 10 mph = 94 revs per minute(cadence). It would be nice if there were 1/10th mile markers everywhere to count speed. Where I live, there are not, so I used to count revs while looking at a watch. Another good method is to ride with a bicyclist who can tell you your speed.
Michael’s “140 cadence =just under 15mph” would be correct.
-Mark

13

Re: MAX speed on a Coker

> If you have an even surface, your cadence certainly can be constant for a
> minute. You won’t usually get much spiking – maybe within 7% of an
> average speed. So if you hit 16mph as measured by cadence, you’re likely
> going 15-17mph (as measured by a precise computer). The important thing is
> not max speed, though, is it – it’s max average speed. What I sometimes
do
> is sort of like wind sprints: I occasionally count revs to see if I can
hit
> a certain goal. I actually never tried this on a Coker, but on uni.5 I hit
> 165 cadence for a minute. On a Coker, I can probably hold 200 for a minute
> on a hill – I’ll try today. There is a nice stretch of Prospect Park road
> where I routinely hit a max of 20mph and maintain that range of speed
> (about 19-20.5) for at least 30 seconds. 20mph would be 232 cadence.

Naw… 20 mph times 1760 yards/mile times 1 hour/60 minutes divide by 1 yard
wheel diameter divide by pi equals 187 revolutions, not 232.

> Cadence chart:
> Revs/minute Speed (approx) in mph
> 116 10
> 128 11
> 139 12
> 151 13
> 162 14
> 174 15
> 185 16
> 197 17
> 209 18
> 220 19
> 232 20
> … …
> 290 25
> 302 26
> toe clips death
>
> Basically, just recall the rule that 1/10 of a mile = c. 116 revs. Then
> add 11 or 12 (11.6, really) between each speed. If you want to go 14mph,
> you can just calculate your initial 116 + (4x11.6) = approx. 162 cadence.

A tenth of a mile is 176 yards, 176/pi = 56 revs. So ten miles is about
5600 revs. Divide by 60 and you get 93 revs/minute = 10 mph, and to go a
mile an hour faster add 9.3 revs/minute.

14

Re: MAX speed on a Coker

> Never mind. Hope you’re good at counting! How many fingers am I
> holding up? :smiley:

Uhh, one? Hey! Put that finger away. No need to get rude. :wink:

-mg

15

Re: MAX speed on a Coker

I got a little lost in your math (although it seems correct). Here is how I
arrived at the numbers I have:

wheel_diameter * PI * cadence * minutes_in_hour / inches_in_foot /
feet_in_mile

So on a coker riding with a cadence of 187 the formula would be:

36 * 3.14159265 * 187 * 60 / 12 / 5280 = 20.02765

I’ve put up a simple vbscripted web page that you can plug in the diameter
and cadence and it will tell you the speed. It’s at
http://mgrant.unicyclist.com/cadence.html

Don’t complain that it’s buggy. It doesn’t do any input validation so it
will bomb out if you put bad input. I also think that this will only work
for windows users.

-mg

“Scott Kurland” <skurland@juggler.net> wrote in message
news:uh7djmsr68kv2e@corp.supernews.com…
> > If you have an even surface, your cadence certainly can be constant for
a
> > minute. You won’t usually get much spiking – maybe within 7% of an
> > average speed. So if you hit 16mph as measured by cadence, you’re likely
> > going 15-17mph (as measured by a precise computer). The important thing
is
> > not max speed, though, is it – it’s max average speed. What I sometimes
> do
> > is sort of like wind sprints: I occasionally count revs to see if I can
> hit
> > a certain goal. I actually never tried this on a Coker, but on uni.5 I
hit
> > 165 cadence for a minute. On a Coker, I can probably hold 200 for a
minute
> > on a hill – I’ll try today. There is a nice stretch of Prospect Park
road
> > where I routinely hit a max of 20mph and maintain that range of speed
> > (about 19-20.5) for at least 30 seconds. 20mph would be 232 cadence.
>
> Naw… 20 mph times 1760 yards/mile times 1 hour/60 minutes divide by 1
yard
> wheel diameter divide by pi equals 187 revolutions, not 232.
>
> > Cadence chart:
> > Revs/minute Speed (approx) in mph
> > 116 10
> > 128 11
> > 139 12
> > 151 13
> > 162 14
> > 174 15
> > 185 16
> > 197 17
> > 209 18
> > 220 19
> > 232 20
> > … …
> > 290 25
> > 302 26
> > toe clips death
> >
> > Basically, just recall the rule that 1/10 of a mile = c. 116 revs. Then
> > add 11 or 12 (11.6, really) between each speed. If you want to go 14mph,
> > you can just calculate your initial 116 + (4x11.6) = approx. 162
cadence.
>
> A tenth of a mile is 176 yards, 176/pi = 56 revs. So ten miles is about
> 5600 revs. Divide by 60 and you get 93 revs/minute = 10 mph, and to go a
> mile an hour faster add 9.3 revs/minute.
>
>

16

Re: MAX speed on a Coker

This works great.

Lowell

> I got a little lost in your math (although it seems correct). Here is how I
> arrived at the numbers I have:
>
> wheel_diameter * PI * cadence * minutes_in_hour / inches_in_foot /
> feet_in_mile
>
> So on a coker riding with a cadence of 187 the formula would be:
>
> 36 * 3.14159265 * 187 * 60 / 12 / 5280 = 20.02765
>
> I’ve put up a simple vbscripted web page that you can plug in the diameter
> and cadence and it will tell you the speed. It’s at
> http://mgrant.unicyclist.com/cadence.html
>
> Don’t complain that it’s buggy. It doesn’t do any input validation so it
> will bomb out if you put bad input. I also think that this will only work
> for windows users.
>
> -mg
>
>
> “Scott Kurland” <skurland@juggler.net> wrote in message
> news:uh7djmsr68kv2e@corp.supernews.com…[color=darkred]
> > > If you have an even surface, your cadence certainly can be constant for
> a
> > > minute. You won’t usually get much spiking – maybe within 7% of an
> > > average speed. So if you hit 16mph as measured by cadence, you’re likely
> > > going 15-17mph (as measured by a precise computer). The important thing
> is
> > > not max speed, though, is it – it’s max average speed. What I sometimes
> > do
> > > is sort of like wind sprints: I occasionally count revs to see if I can
> > hit
> > > a certain goal. I actually never tried this on a Coker, but on uni.5 I
> hit
> > > 165 cadence for a minute. On a Coker, I can probably hold 200 for a
> minute
> > > on a hill – I’ll try today. There is a nice stretch of Prospect Park
> road
> > > where I routinely hit a max of 20mph and maintain that range of speed
> > > (about 19-20.5) for at least 30 seconds. 20mph would be 232 cadence.
> >
> > Naw… 20 mph times 1760 yards/mile times 1 hour/60 minutes divide by 1
> yard
> > wheel diameter divide by pi equals 187 revolutions, not 232.
> >
> > > Cadence chart:
> > > Revs/minute Speed (approx) in mph
> > > 116 10
> > > 128 11
> > > 139 12
> > > 151 13
> > > 162 14
> > > 174 15
> > > 185 16
> > > 197 17
> > > 209 18
> > > 220 19
> > > 232 20
> > > … …
> > > 290 25
> > > 302 26
> > > toe clips death
> > >
> > > Basically, just recall the rule that 1/10 of a mile = c. 116 revs. Then
> > > add 11 or 12 (11.6, really) between each speed. If you want to go 14mph,
> > > you can just calculate your initial 116 + (4x11.6) = approx. 162
> cadence.
> >
> > A tenth of a mile is 176 yards, 176/pi = 56 revs. So ten miles is about
> > 5600 revs. Divide by 60 and you get 93 revs/minute = 10 mph, and to go a
> > mile an hour faster add 9.3 revs/minute.
> >
> >
>
>
> ___________________________________________________________________________
> rec.sport.unicycling mailing list - www.unicycling.org/mailman/listinfo/rsu[/color]

17

Re: MAX speed on a Coker

“Michael Grant” <michael_j_grant@msn.com> wrote in message
news:OIgRHrZGCHA.1860@cpimsnntpa03…
> >
> 36 * 3.14159265 * 187 * 60 / 12 / 5280 = 20.02765
>
> I’ve put up a simple vbscripted web page that you can plug in the diameter
> and cadence and it will tell you the speed. It’s at
> http://mgrant.unicyclist.com/cadence.html
>

Wouldn’t it be more accurate to use the actual radius of your particular
setup? Have someone measure the ground to axle center while you are mounted
on your ride. This would help with the many combinations of tires, tire
pressure, and rider weight. Then rebuild your nice web formula to use this
radius.

Doug

18

… and what’s that in kilometers/kilometres per hour for all of us who are in the metric world?

To convert from miles to kilometers/kilometres, multiply the number of miles by 1.609347.

So, that magical 20 mph becomes 32.18694 kph!

Over here, the legal speed limit for a 50cc motor scooter is 35 kph.

Cokers don’t have a 2-stroke engine, though.

19

Re: MAX speed on a Coker

> Wouldn’t it be more accurate to use the actual radius of your particular
> setup? Have someone measure the ground to axle center while you are
mounted
> on your ride. This would help with the many combinations of tires, tire
> pressure, and rider weight. Then rebuild your nice web formula to use
this
> radius.
>
> Doug
>

That’s a good question. Let’s assume that you have a gazz 24x3 fully
inflated and it’s (hypothetical) radius is 12.5". Now you deflate the tire
to 5psi. With the weight of the rider the radius may now be significantly
reduced. Let again use a hypothetical 12". So in the first case the
calculated circumference is 78.5" where in the second it is 75.4". I’m not
sure that there would be a difference of 3.1" just due to different tire
pressure. Plus, you still need to roll the tire all the way around so isn’t
the circumference the same regardless of how much of a contact patch there
is?

In any case I chose to use diameter instead of radius or circumference (or
any other number) because I wanted to be able to plug-in “standard” sizes
(i.e. 20", 24", 26" 36"). Having measured the rollout (111") of my Coker it
was pretty close to the rated (36*pi=113") size so I didn’t worry what I
considered to be a negligible innaccuracy. If you are greatly bothered by
this feel free to modify the vbscript. Or take your measured radius and
double it before you enter it into the diameter.

But, you are probably right. Actually using the rollout measurement would
yield more accurate results but would also be a big pain for most people.
Or you could just ride an accurate mile and count the pedal revolutions.
That would likely be even more accurate (and an even bigger pain).

-mg

20

Re: MAX speed on a Coker

On Sat, 22 Jun 2002 12:45:38 -0500, sendhair
<sendhair.6nuhy@timelimit.unicyclist.com> wrote:

>Cokers don’t have a 2-stroke engine, though.
They do, actually.
In addition, it is a two-cylinder engine!
Even, some Coker engines can switch off one cylinder… :slight_smile:

Klaas Bil