Roller races

[Dirtroadie]

I ran into an interesting dilemma yesterday.
My hometown hosts has annual winter festivities involving many types
of events, social, athletic, indoor, outdoor, frivolous, serious etc.
see:
http://snowdown.org/

The bicycle related part of this is the roller races, an event with a long standing history
http://snowdown.org/wednesday.htm#roller

Prior to this year two riders would go head-to-head, the official measuring device being a dedicated
front wheel with a cyclometer mounted to an arm clamped in place with the front wheel quick release,
the same wheels being used for all riders. While this was accurate, it didn't allow a rider to use
his/her own front wheel which generally also meant giving up one's own computer readout unless the
bike had a rear wheel speed sensor. It also didn't provide any direct way for the spectators to
directly compare the progress of the competing riders.

So this year a new system was developed to solve the aforementioned problems but also attempting to
keep the roller system essentially intact (no extra variables , i.e. drag) so that distances and/or
records could be compared from one year to the next.

The new system placed magnets directly on the rollers themselves matched to sensors for Sigma
cyclometers (properly calibrated for the roller size). Preliminary tests showed the system to be
perfectly calibrated to the origanal system. Then the cyclometers were positioned together so that a
video camera could capture an image of all three simultaneously (3 riders at once this time around)
and project it onto a wall. Pretty slick.

Or so it seemed. Come race day it turned out that the calibration seemed way off. And, in fact,
EVERBODY was riding almost exactly the same distance. Every race seems to have the riders within .01
miles of each other from start to finish. (call it a "no rider left behind" policy) And apparently
what was happening was that the rollers (4.5 inch) at race pace were turning about the same RPM as a
normal front wheel would be doing at 240 mph! (Top end race pace is 40-ish mph, our new unofficial
record is 10.3 miles in 15 minutes) In fact anything above about 25 mph was wasted effort as far as
the "official" devices were concerned.

So either the reed switch in the pickup is beyond its capabilities or the electronics trying to
"read" and calculate from the pulses of the switch are not fast enough to keep up.

So I'm seeking proposals of a good way of setting up an accurate system taking into account (1)
spectator friendliness (2) consistency with prior roller setups and (3) no need to modify the bikes
at all. And keep in mind this is a low-key not-for profit, no prize money, fun type event, so
expensive and exotic computerized mechanisms are not likely to to be used. And we are talking
rollers, not trainers.

While we're at it, since this is a little different from actually riding along on the road, how
would you set up a bike (let's ignore the training for now) to optimize the results (go fastest) on
rollers? The first things that come to mind for me are (1) Disk wheels would be nice if possible
(aerodynamics) although nobody used them, (2) the heavier the wheel the better for the flywheel
effect, and (3) tires with low rolling resistance and/or using the highest tire pressure that the
tires can tolerate, (4) squeaky clean and well-lubed drive train.

DR

 

[Rosco]

"DirtRoadie" <[email protected]> wrote in message
news:[email protected]...
> I ran into an interesting dilemma yesterday. My hometown hosts has annual winter festivities
> involving many types of events, social, athletic, indoor, outdoor, frivolous, serious etc. see:
> http://snowdown.org/
>
> The bicycle related part of this is the roller races, an event with a long standing history
> http://snowdown.org/wednesday.htm#roller
>
> Prior to this year two riders would go head-to-head, the official measuring device being a
> dedicated front wheel with a cyclometer mounted to an arm clamped in place with the front wheel
> quick release, the same wheels being used for all riders. While this was accurate, it didn't allow
> a rider to use his/her own front wheel which generally also meant giving up one's own computer
> readout unless the bike had a rear wheel speed sensor. It also didn't provide any direct way for
> the spectators to directly compare the progress of the competing riders.
>

How about keeping your old system but add video cameras pointed at the cyclometer readout with video
monitors so the riders and spectators can both see what is going on.

 

[B. Schneider]

"DirtRoadie" <[email protected]> wrote in message
news:[email protected]...
> The new system placed magnets directly on the rollers themselves matched to sensors for Sigma
> cyclometers (properly calibrated for the roller size). Preliminary tests showed the system to be
> perfectly calibrated to the origanal system. Then the cyclometers were positioned together so that
> a video camera could capture an image of all three simultaneously (3 riders at once this time
> around) and project it onto a wall. Pretty slick.
>
> Or so it seemed. Come race day it turned out that the calibration seemed way off. And, in fact,
> EVERBODY was riding almost exactly the same distance. Every race seems to have the riders within
> .01 miles of each other from start to finish. (call it a "no rider left behind" policy) And
> apparently what was happening was that the rollers (4.5 inch) at race pace were turning about the
> same RPM as a normal front wheel would be doing at 240 mph! (Top end race pace is 40-ish mph, our
> new unofficial record is 10.3 miles in 15 minutes) In fact anything above about 25 mph was wasted
> effort as far as the "official" devices were concerned.
>
> So either the reed switch in the pickup is beyond its capabilities or the electronics trying to
> "read" and calculate from the pulses of the switch are not fast enough to keep up.
>
> So I'm seeking proposals of a good way of setting up an accurate system taking into account (1)
> spectator friendliness (2) consistency with prior roller setups and (3) no need to modify the
> bikes at all. And keep in mind this is a low-key not-for profit, no prize money, fun type event,
> so expensive and exotic computerized mechanisms are not likely to to be used. And we are talking
> rollers, not trainers.
>

First of all, what a cool idea for an event !

I would suggest you use a belt that drives a bigger disk. If you size the disk properly,
(circumference at least 2x bigger than the roller drums), the disk should spin slow enough for your
computers not to exceed the maximum samples per second. The disk should add little drag, and in any
case the drag would be the same for all riders.

Bengt-Olaf.

 

[Dave Lehnen]

DirtRoadie wrote:
> I ran into an interesting dilemma yesterday. My hometown hosts has annual winter festivities
> involving many types of events, social, athletic, indoor, outdoor, frivolous, serious etc. see:
> http://snowdown.org/
>
> The bicycle related part of this is the roller races, an event with a long standing history
> http://snowdown.org/wednesday.htm#roller
>
> Prior to this year two riders would go head-to-head, the official measuring device being a
> dedicated front wheel with a cyclometer mounted to an arm clamped in place with the front wheel
> quick release, the same wheels being used for all riders. While this was accurate, it didn't allow
> a rider to use his/her own front wheel which generally also meant giving up one's own computer
> readout unless the bike had a rear wheel speed sensor. It also didn't provide any direct way for
> the spectators to directly compare the progress of the competing riders.
>
> So this year a new system was developed to solve the aforementioned problems but also attempting
> to keep the roller system essentially intact (no extra variables , i.e. drag) so that distances
> and/or records could be compared from one year to the next.
>
> The new system placed magnets directly on the rollers themselves matched to sensors for Sigma
> cyclometers (properly calibrated for the roller size). Preliminary tests showed the system to be
> perfectly calibrated to the origanal system. Then the cyclometers were positioned together so that
> a video camera could capture an image of all three simultaneously (3 riders at once this time
> around) and project it onto a wall. Pretty slick.
>
> Or so it seemed. Come race day it turned out that the calibration seemed way off. And, in fact,
> EVERBODY was riding almost exactly the same distance. Every race seems to have the riders within
> .01 miles of each other from start to finish. (call it a "no rider left behind" policy) And
> apparently what was happening was that the rollers (4.5 inch) at race pace were turning about the
> same RPM as a normal front wheel would be doing at 240 mph! (Top end race pace is 40-ish mph, our
> new unofficial record is 10.3 miles in 15 minutes) In fact anything above about 25 mph was wasted
> effort as far as the "official" devices were concerned.
>
> So either the reed switch in the pickup is beyond its capabilities or the electronics trying to
> "read" and calculate from the pulses of the switch are not fast enough to keep up.
>
> So I'm seeking proposals of a good way of setting up an accurate system taking into account (1)
> spectator friendliness (2) consistency with prior roller setups and (3) no need to modify the
> bikes at all. And keep in mind this is a low-key not-for profit, no prize money, fun type event,
> so expensive and exotic computerized mechanisms are not likely to to be used. And we are talking
> rollers, not trainers.
>
> While we're at it, since this is a little different from actually riding along on the road, how
> would you set up a bike (let's ignore the training for now) to optimize the results (go fastest)
> on rollers? The first things that come to mind for me are (1) Disk wheels would be nice if
> possible (aerodynamics) although nobody used them, (2) the heavier the wheel the better for the
> flywheel effect, and (3) tires with low rolling resistance and/or using the highest tire pressure
> that the tires can tolerate, (4) squeaky clean and well-lubed drive train.
>
> DR

Measuring the roller speed directly is a good idea, as long as both rollers have matched diameters.
However, as you noted, not even the Sigma computers, which are rated for 180 mph (and the computers
of choice for an add-on computer for motorcycles) can't keep up at some point. The problem isn't
only reed switch bounce or slow activation, but the requirement of the computer to allow for a de-
bounce period, a dead time after switch closure when further openings and closures are ignored.

A few years back I used a Sigma 800 as an add-on speedometer/ odometer on my CBR900 bike. Rather
than use a wheel magnet and reed switch, I thought it would be slicker to use the same signal the
bike's electronic speedometer used. This turned out to be a pulse train of higher frequency than
once per wheel revolution. Anyway, in the process of checking out the Sigma, I found it would handle
pulse trains corresponding to mid-200 mph values before malfunctioning, so reed-switch bounce wasn't
the only limitation. Using an integrated circuit counter to divide the bike's high speed pulse train
down to a lower value made the whole thing work.

Back to your roller problem, mount a magnet on the side of a roller, preferably one of the rear ones
to avoid belt-slip issues. Use a hall-effect IC to avoid any bounce and frequency limitations of a
reed switch, and then either a divide-by-8 or divide-by-16 counter IC to get the speed into the
proper range. An open-collector output will work directly with Sigmas or other computers looking for
a simple reed switch closure, as long as you put the computer's plus lead on the collector.

Total cost of parts should be very low, but you'd need someone with a little basic electronic
knowledge to make it work. If you're interested in pursuing this, but need more information, email
me direct and I can draw and send you a schematic within a few days.

Dave Lehnen

 

[Werehatrack]

On 29 Jan 2004 14:35:44 -0800, [email protected] (DirtRoadie) may
have said:

>So either the reed switch in the pickup is beyond its capabilities

This is almost certainly the problem. I doubt that a reed switch can cycle at any significant
fraction of that speed.

>or the electronics trying to "read" and calculate from the pulses of the switch are not fast enough
>to keep up.

Very doubtful from a purely technical standpoint in my opinion, but does the cyclometer in use have
the ability to compensate for such a tiny wheel diameter? It may have been expecting a range of
wheel sizes that reflects market reality.

>So I'm seeking proposals of a good way of setting up an accurate system taking into account (1)
>spectator friendliness (2) consistency with prior roller setups and (3) no need to modify the
>bikes at all.

Possible solution #1: First, verify whether the cyclometer can read the higher-rate signal if one is
present. Thiss will require a the assistance of a tech with access to a variable frequency square
wave generator, which is almost certainly among the things in the science labs of any local college
or university, and possibly a lot of other places as well. (If not, go to Possible Solution #2) If
it can, then employ a Hall-effect switch instead of a reed switch. Hall switches are among the
devices used to control electronic ignition systems, and they are *very* fast. ( They are not wired
exactly the same way, though, so the assistance of an electronics tech will likely be needed.)

Possible solution #2: Use a second wheel of a more suitable diameter riding on the rollers, of a
known and constant size (perhaps due to having a hard rubber rim?) as the "measuring wheel"

More elegant version #2, to use if #1 won't work because of frequency input limits on the
cyclometer: Still use a Hall sensor, but run the signal through a digital logic gate that it only
relays every nth pulse; the roller is 4.5 inches in diameter, so relaying every 6th pulse would put
you into the same range as a 27" wheel. This isn't a difficult device to make, but once again,
you'll need an electronics tech or hobbyist to assist.

>And keep in mind this is a low-key not-for profit, no prize money, fun type event, so expensive and
>exotic computerized mechanisms are not likely to to be used. And we are talking rollers, not
>trainers.

Yup, but if you've got an electronics techie in the group or town, I'll bet you can get this
built for under $50 in parts plus a pizza and a six-pack. Given a long enough lead time, I know
I could build it, but I'm not exactly close by, and I'd need to have access to the setup to test
it directly.

You might try contacting some of the cyclometer manufacturers to see if they have an off-the-shelf
unit that would do the job. I suspect that there probably is one available.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

 

[Rick Onanian]

On Fri, 30 Jan 2004 17:53:03 GMT, Dave Lehnen
<[email protected]> wrote:
>Rather than use a wheel magnet and reed switch, I thought it would be slicker to use the same
>signal the bike's electronic speedometer used. This turned out to be a pulse train of higher
>frequency than once per wheel revolution. Using an integrated circuit counter to divide the bike's
>high speed pulse train down to a lower value made the whole thing work.

Couldn't you just have adjusted the wheel size in the computer?
--
Rick Onanian

 

[Alex Rodriguez]

The club I belong to use to have a roller race series in the winter. The first time I saw them doing
it, they have what looked to be an ancient pair of follers and this giant free standing clock like
device. There were two pointers on the clock, one for each racer. The pointers would Then spin
around the clock until the race was over. The nice part was that the racers could see where they
were in relationship to the end of the race and the other racer with a quick glance at the clock.
The problem with this set up was the that the rollers were really big and heavy. In later years they
had a different set up. It used kreitler rollers that had a disk, with black and white lines, taped
to one of the rear rollers. There was a sensor on the rollers frame and got a readout of speed. The
sensor was then wired to a computers serial port. The software, sorry I don't know the name, then
took care of the rest. It allowed more than two riders and it displayed more data. This setup would
was easier to carry.
---------------
Alex

 

[Dave Lehnen]

Rick Onanian wrote:

> On Fri, 30 Jan 2004 17:53:03 GMT, Dave Lehnen <[email protected]> wrote:
>
>> Rather than use a wheel magnet and reed switch, I thought it would be slicker to use the same
>> signal the bike's electronic speedometer used. This turned out to be a pulse train of higher
>> frequency than once per wheel revolution. Using an integrated circuit counter to divide the
>> bike's high speed pulse train down to a lower value made the whole thing work.
>
>
> Couldn't you just have adjusted the wheel size in the computer? -- Rick Onanian

No, the pulse train was too fast for the computer to handle, even at low speeds, and IIRC there was
also a minimum wheel size on the Sigma. At smaller wheel sizes you also lose setting resolution,
since the smallest increment of circumference is a bigger fraction of the set circumference.

Dave Lehnen

 

[Gary Young]

[email protected] (DirtRoadie) wrote in message news:<[email protected]>...
> I ran into an interesting dilemma yesterday. My hometown hosts has annual winter festivities
> involving many types of events, social, athletic, indoor, outdoor, frivolous, serious etc. see:
> http://snowdown.org/
>
> The bicycle related part of this is the roller races, an event with a long standing history
> http://snowdown.org/wednesday.htm#roller
>
<snip>
> So I'm seeking proposals of a good way of setting up an accurate system taking into account (1)
> spectator friendliness (2) consistency with prior roller setups and (3) no need to modify the
> bikes at all. And keep in mind this is a low-key not-for profit, no prize money, fun type event,
> so expensive and exotic computerized mechanisms are not likely to to be used. And we are talking
> rollers, not trainers.

David Perry of BikeWorks in NYC (and the author of Bike Cult) may be able to help you out:

http://www.bikecult.com/works/rollers.html

 

[A Muzi]

Alex Rodriguez wrote:

> The club I belong to use to have a roller race series in the winter. The first time I saw them
> doing it, they have what looked to be an ancient pair of follers and this giant free standing
> clock like device. There were two pointers on the clock, one for each racer. The pointers would
> Then spin around the clock until the race was over. The nice part was that the racers could see
> where they were in relationship to the end of the race and the other racer with a quick glance at
> the clock. The problem with this set up was the that the rollers were really big and heavy. In
> later years they had a different set up. It used kreitler rollers that had a disk, with black and
> white lines, taped to one of the rear rollers. There was a sensor on the rollers frame and got a
> readout of speed. The sensor was then wired to a computers serial port. The software, sorry I
> don't know the name, then took care of the rest. It allowed more than two riders and it displayed
> more data. This setup would was easier to carry.
> ---------------
> Alex
>
>
I used to own a PC-plugin setup which I sold to someone here on RBT a few years ago. We like the
clock better, even though the electronic unit could race four riders at once.

Our big Cinelli clock clips on to any two same-size rollers driven by the belts. You do not need big
rollers , although those were popular at one time.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

 

[Dirtroadie]

Werehatrack <[email protected]> wrote in message news:<[email protected]>...

> Possible solution #1: First, verify whether the cyclometer can read the higher-rate signal if one
> is present. This will require a the assistance of a tech with access to a variable frequency
> square wave generator, which is almost certainly among the things in the science labs of any local
> college or university, and possibly a lot of other places as well. (If not, go to Possible
> Solution #2)

Note that as a less technical way of checking the cyclometer's capability to process higher
frequency signals (in the 3000-4000 Hz/rpm range), several standard sensors could be spliced
together in parallel, so that the each sensor is working within known capabilities but the circuit
itself would be operating at the higher rate.

> If it can [read the higher rate signal], then employ a Hall-effect switch instead of a reed
> switch. Hall switches are among the devices used to control electronic ignition systems, and they
> are *very* fast. ( They are not wired exactly the same way, though, so the assistance of an
> electronics tech will likely be needed.)

Thanks. I like it. Time to do some investigating to see whether such a sensor can be simply spliced
in to replace the original reed switch. (and actually, I am merely assuming that the original sensor
is a reed switch, I know it is in Cateye cyclometers because you can hear the mechanical sound of
its operation) But here's a place I can start: http://www.allegromicro.com/hall/

> Possible solution #2: Use a second wheel of a more suitable diameter riding on the rollers, of a
> known and constant size (perhaps due to having a hard rubber rim?) as the "measuring wheel"

While it would certainly work, this is not as appealing. There is a distinct problem of how to
postion such a secondary wheel so that it does not interfere with the operation of the rollers. For
one thing the system also has to be somewhat immune from damage if a rider falls off (it happens
regularly). And adding an additional belt would also change the system.

> More elegant version #2, to use if #1 won't work because of frequency input limits on the
> cyclometer: Still use a Hall sensor, but run the signal through a digital logic gate that it only
> relays every nth pulse; the roller is 4.5 inches in diameter, so relaying every 6th pulse would
> put you into the same range as a 27" wheel. This isn't a difficult device to make, but once again,
> you'll need an electronics tech or hobbyist to assist.

I like this too, especially since it allows the simplicity of version
#1 even though it does require a more complicated circuit to be
created. I'm not a techie, but is this type of "digital logic gate" an off-the-shelf type of
component or would it require some custom fabrication?

> >And keep in mind this is a low-key not-for profit, no prize money, fun type event, so expensive
> >and exotic computerized mechanisms are not likely to to be used. And we are talking rollers, not
> >trainers.
>
> Yup, but if you've got an electronics techie in the group or town, I'll bet you can get this built
> for under $50 in parts plus a pizza and a six-pack. Given a long enough lead time, I know I could
> build it, ....

I can give you just about a year ;-)

> You might try contacting some of the cyclometer manufacturers to see if they have an off-the-shelf
> unit that would do the job. I suspect that there probably is one available.

That kinda' takes the fun out of it, but is probably worth looking into. No point in reinventing the
wheel (sensor).

DR

 

[Tom Sherman]

Werehatrack wrote:

> ... Very doubtful from a purely technical standpoint in my opinion, but does the cyclometer in use
> have the ability to compensate for such a tiny wheel diameter? It may have been expecting a range
> of wheel sizes that reflects market reality....

Many cyclometers will not work with an ISO 305-mm wheel - the manufacturers are either unaware that
there are serious bicycles with wheels this small, or do not feel the market is large enough to be
worth while pursuing.

Tom Sherman - Quad Cities

 

[David Kerber]

In article <[email protected]>, [email protected] says...
> Werehatrack <[email protected]> wrote in message
> news:<[email protected]>...
>
> > Possible solution #1: First, verify whether the cyclometer can read the higher-rate signal if
> > one is present. This will require a the assistance of a tech with access to a variable frequency
> > square wave generator, which is almost certainly among the things in the science labs of any
> > local college or university, and possibly a lot of other places as well. (If not, go to Possible
> > Solution #2)
>
> Note that as a less technical way of checking the cyclometer's capability to process higher
> frequency signals (in the 3000-4000 Hz/rpm range), several standard sensors could be spliced
> together in parallel, so that the each sensor is working within known capabilities but the circuit
> itself would be operating at the higher rate.
>
> > If it can [read the higher rate signal], then employ a Hall-effect switch instead of a reed
> > switch. Hall switches are among the devices used to control electronic ignition systems, and
> > they are *very* fast. ( They are not wired exactly the same way, though, so the assistance of an
> > electronics tech will likely be needed.)
>
> Thanks. I like it. Time to do some investigating to see whether such a sensor can be simply
> spliced in to replace the original reed switch. (and actually, I am merely assuming that the
> original sensor is a reed switch, I know it is in Cateye cyclometers because you can hear the
> mechanical sound of its operation) But here's a place I can start:
> http://www.allegromicro.com/hall/
>
>
> > Possible solution #2: Use a second wheel of a more suitable diameter riding on the rollers, of a
> > known and constant size (perhaps due to having a hard rubber rim?) as the "measuring wheel"
>
> While it would certainly work, this is not as appealing. There is a distinct problem of how to
> postion such a secondary wheel so that it does not interfere with the operation of the rollers.
> For one thing the system also has to be somewhat immune from damage if a rider falls off (it
> happens regularly). And adding an additional belt would also change the system.
>
> > More elegant version #2, to use if #1 won't work because of frequency input limits on the
> > cyclometer: Still use a Hall sensor, but run the signal through a digital logic gate that it
> > only relays every nth pulse; the roller is 4.5 inches in diameter, so relaying every 6th pulse
> > would put you into the same range as a 27" wheel. This isn't a difficult device to make, but
> > once again, you'll need an electronics tech or hobbyist to assist.
>
> I like this too, especially since it allows the simplicity of version
> #1 even though it does require a more complicated circuit to be
> created. I'm not a techie, but is this type of "digital logic gate" an off-the-shelf type of
> component or would it require some custom fabrication?

It's a simple divider circuit, which you could get or build in one of those "100-in-1" electronics
kits for kids, or Radio Shack would have the stuff. If you know an Electrical Engineer, he could
whip one up out of discrete logic gates as well. There are probably electronics hobby newsgroups
which might give you more info on where you could find kits for this stuff.

--
Dave Kerber Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

 

[Stu]

Do these rollers use a flat belt or a round one(just like a big "O" ring)? If its flat "maybe" you
could glue a magnet to the outside of it. At a rough guess the belt would do about as many rpm as
the wheel. If its a round belt maybe you could crip a ring of steel around it and glue a magnet to
that. Does anyone know if round belts roll while they are turning?????? Easy enough to try,
depending on the cost of a new belt and how long it takes to replace. just an idea

Stu

 

[Frkrygow]

Is it possible to just buy three wireless cyclometers, and mount the magnets and sending units on
the competitors bikes? If it works, it would be much easier.

--
Frank Krygowski [To reply, omit what's between "at" and "cc"]

 

[Werehatrack]

On Sun, 1 Feb 2004 15:58:53 -0500, David Kerber
<ns_dkerber@ns_ids.net> may have said:

>It's a simple divider circuit, which you could get or build in one of those "100-in-1" electronics
>kits for kids, or Radio Shack would have the stuff. If you know an Electrical Engineer, he could
>whip one up out of discrete logic gates as well. There are probably electronics hobby newsgroups
>which might give you more info on where you could find kits for this stuff.

Exactly. I remember breadboarding one in Digital Logic class over a decade ago, and I've likely
still got the book here somewhere. With the right gates, it's a snap to build.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

 

[Ray Heindl]

Werehatrack <[email protected]> wrote:

> On 29 Jan 2004 14:35:44 -0800, [email protected] (DirtRoadie) may have said:
>
>>So either the reed switch in the pickup is beyond its capabilities
>
> This is almost certainly the problem. I doubt that a reed switch can cycle at any significant
> fraction of that speed.

My Flight Deck reads up to about 150 mph. That's still a long way from 240, though.

Somebody used to make a "cyclocomputer" for inline skates. A little Googling finds that it might
have been called a "Rollometer", but it may not be made any more. A skatecomputer should be able to
handle wheel sizes as small as rollers (skate wheels are under 100 mm), though it might not handle
the speed.

--
Ray Heindl (remove the Xs to reply to: [email protected])

 

[Mark Hickey]

Ray Heindl <[email protected]> wrote:

>My Flight Deck reads up to about 150 mph. That's still a long way from 240, though.

I'm almost scared to ask how you know it will go up to 150mph though...

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

 

[Per ElmsäTer]

Mark Hickey wrote:
> Ray Heindl <[email protected]> wrote:
>
>> My Flight Deck reads up to about 150 mph. That's still a long way from 240, though.
>
> I'm almost scared to ask how you know it will go up to 150mph though...
>
> Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

Simple. Put a magnet on every spoke! Actually I am almost doing this at the moment. My Cateye
Cordless II got reset a couple of weeks into the new year due to battery changes. I added another
magnet and will run double speed and distance until it shows 340.

--
Perre

You have to be smarter than a robot to reply.

 

[Dirtroadie]

"frkrygow" <"frkrygow"@omitcc.ysu.edu> wrote in message news:<[email protected]>...
> Is it possible to just buy three wireless cyclometers, and mount the magnets and sending units on
> the competitors bikes? If it works, it would be much easier.

While that sounds simple in theory, I don't think it would work out very well in practice due to the
need to move the equipment from one bike to another (meaning undesirable setup time between heats).
It might be a practical to adapt the original "dedicated wheel" to a wireless setup but then it
would still preclude riders from using their own cyclometers for monitoring their own pace.

And in simply going wireless, there's the issue of the likelihood of glitches in getting sensors
to work accurately. My experience is that once wheel sensors are properly set they work forever,
but the initial setup can require more trial and error than would be desirable for a reliable
temporary setup.

Then there is also the issue of calibration if each rider uses his/her own wheels. It can't
automatically be assumed that everyone's wheels are exactly the same size even though it is likely
that most are fairly close. Since the distances can be measured to .01 miles I don't think a ~1%
variation (ie typical 700x20 vs 700x23) is really acceptable since 1% error results in a tenth of a
mile difference over 10 miles (the upper end of the distance measured in 15 minutes).

So while incorporating wireless technology may have some benefits, it doesn't fully address the
existing problems and may create some others that don't presently exist.

DR