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I am new to road course measurement and have been reading the forum for the past few days. Having been a serious cyclist for 45+ years I have been particularly interested in the discussion of measurement with electronic cycle computers. Essentially all of the discussion has been about using a cycle computer as a revolution counter. What specs and/or qualities would a cycle computer need to have to be used directly, as designed, to accurately measure road courses in mi or km and not have to deal with counts per mi or km and all the calculations that go along with it?

Bob Wemer
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Here is the spec I wrote in 1997 on Measurement News Forum, which was an email forerunner of he present forum:

1. Shall count between 10 and 36 (the no of spokes) counts per rev of front wheel
2. Shall count at all speeds from 0 mph to 40 mph (could be relaxed to 20 mph if there was a excessive speed error indicator)
3. Shall count up when riding forwards and down when going backwards.
4. Shall correctly deal with jitter arising from small movements of a stationary bike with the pick up stopped at the trigger position.
5. Shall have a large easily read display, probably on the handlebars.
6. The display shall be capable of being read at night.
7. The display shall be able to show counts without rolling over in at least 10 km of riding.
8. It shall be possible to automatically calculate the working constant after the pre-mreasurement calibration, by using the counts recorded in the counter and entering the cal course length. The SCPF to be automatically used in the calculation, unless in a special mode is entered for course validation. This mode should automatically revert to the SCPF mode for the next calibration to ensure the default is with the SCPF. The working constant should be displayed for noting and stored.
9. The display shall be capable of displaying the counts divided by the working constant, so giving a read out to either 10 cm or 1 cm when in a metric mode, and to 0.0001 or 0.00001 miles when in the imperial mode (optionally a read out in miles and yards may be considered). The display shall show up to 99 km or miles without rolling over.
10. The display shall be capable of being easily switched to show the distance/count from a reset at the start of the measurement and also the distance/count from the last intermediate measurement.
11. Shall internally record the counts/distance for each split. The memory shall have a capacity of recording at least 100 splits and/or resets. The memory shall be non-volatile in the event of a low battery.
12. With each record the following parameters shall be measured and recorded: Date (dd/mon/yyyy format perhaps!), Time 24hr clock, Temperature sensed by a shaded sensor measuring air temperature near the front wheel with a resolution of better than 0.3C, Average velocity for last split.
13. Shall be capable of stepping through all the recorded data and displaying it.
14. Shall have a fault indicator light to indicate, low battery, lost counts, (lost counts shall be checked for by testing the regularity of the time beteen counts in relation to the possible maximum acceleration or decelration of the bike) and any other problems requiring the measurement to be aborted. (This is the counter equivalent of warning of a punctured tyre.)
15. The mean time before failure shall be greater than 100 measurement days over 20 years (a measurer's measuring life time)
16. Batteries shall last for at least one measuring day of 12 hours. Battery cost shall not be a signifcant increase in measurement costs.
17. Shall be capable of interfacing with a PC to down load all recorded counts, distances and other data.( Probably straight into an Excel or 123 Spreadsheet.) Spreadsheet software to be available for printing the measurement report.
18. Cost Target: not to exceed 200$ in quantities of 100+.
19. Shall be waterproof, and capable of operating from - 10 C to + 40 C.

Looking at this again 14 years later all I would add is recording of GPS way points at beginning and end of each ride.
As for the specs used with an electronic counter, we had many long discussion on this topic. In the end we concluded the following policy(see below). The main reason was several people found there could be problems with the device and thought it best to no longer approve its use by someone who has never used it.

The Policy establish in 2010 by the RRTC
The Electronic Counter is approved for measuring courses for certification only by those that have used this device previously, with the following exceptions:

a It is not be used for measurement of AIMS/IAAF courses.
b.It is not be used for measurement for any big-city marathons, Olympic Trials, Olympic Marathons or National Championship Races.
c.It may not be used for Validation measurements.
Thanks for the info on electronic counters and their shortcomings in calibrated course measuring.

I had already purchased a Schwinn cycle computer from Walmart for $11 before finding this forum because it read to thousandths of a mile - the only one I could find on the Internet that did. I may experiment with using it as a counter as was discussed in some forum posts. It can be programmed to 5999 so using 5000 and two magnets might work.

In the early 1990's before cadence was readily available on cyclecomputers I figured out how to mount and program a basic cyclecomputer to read out cadence (pedal rpms).

Thanks again.
Last edited by bobwemer

If you decide to use a cyclometer to assist (Jones is the counter to be relied-upon for actual measurement), be aware that most cyclometers won't count in reverse. Thus, when you overshoot a split location and have to roll backwards so your Jones registers the correct count for that split, your cyclometer won't be accurate after the roll-back. More calculations will ensue if you want to continue to use it to indicate you are getting close to your split locations.
I had already purchased a Schwinn cycle computer from Walmart for $11 before finding this forum because it read to thousandths of a mile - the only one I could find on the Internet that did. I may experiment with using it as a counter as was discussed in some forum posts. It can be programmed to 5999 so using 5000 and two magnets might work.

I have discovered that since the Schwinn cyclecomputer reads to thousandths of a mile or km, it only needs to be programmed to 1000 mm per wheel revolution, for one magnet, in the km mode to read out one count per wheel revolution. Disregard the decimal point when reading total revolutions. It will count to 99,999 revolutions before rolling over - which if my calculations are correct would be around 134 miles for a 26.5" diameter bicycle wheel.

WalMart had two Schwinn cyclecomputers - this wired one and a wireless one. This wired version has "Schwinn 12 Function Bike Computer" on the label. It doesn't say that it is wired but one can see the wire through the plastic packaging.

I'm thinking that I will probably use it in the normal mode to monitor when I am nearing a split. It will read to 0.001 of a mi (or km) which would be 5.28 feet (or 1 meter in km mode). For $11 one could justify a 2nd one - using one for mile splits and the other for km splits.
Last edited by bobwemer
Bob - yes, you could do thousandths of a mile, but you could also calibrate your cyclometer as you do the Jones. If you mark your front wheel in quarters, marking "0", ".25", ".5", and ".75", (I am lucky an have 20 spokes, so each spoke is .05 of a revolution, making simple work of determining hundredths of a revolution of my tire) you would then ride your (for instance) 1000-foot calibration course. I get about 147.83 wheel revolutions on my course. That then gets converted to revolutions per mile. Knowing that each mile is 781.61 (or so) revolutions, you can see when you are approaching your mile split.

I have a sheet for my electronic counter, and a sheet for my Jones counts. I get close with my electronic (easy to read, on the handlebar), then roll the one or two clicks for the Jones for precision.

Good Luck, and Happy Measuring.

I could go with either method in predicting upcoming split locations. I've already calculated out 0.05 revolution spacings for my wheel if I should go that route. (The bike I'm using has 32 spokes.)

I've been playing around with your Excel spreadsheets. They will be nice to use. I appreciate the work you've put into them. My experience with building a spreadsheet is that the fun part is getting it do what you want it do for your own use. The more difficult part is making it self explanatory so that someone else can use it.

Thanks for your suggestions and your spreadsheets.

Last edited by bobwemer

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