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The Veeder-Root counter used in all Jones counters has remained unchanged for decades. Below is a picture of a similar VR counter that has been disassembled. It consists of five numbered wheels mounted on a central shaft. On one side of each wheel are twenty teeth. On the other side is a single tooth.

Between the numbered wheels, mounted on a shaft which is parallel to the central shaft are four small intermediate tiny gears. They are set up so that when a wheel passes 9 digits, the small gear engages the single tooth on the next gear, and advances it one digit. This process continues along the counter gear train, until the counter reads 99999. At this point, all four of the small gears advance the wheels one count, and we get back to 00000.

The question of counter skipping has arisen. We are investigating this. We have one counter that has been returned. The first wheel rotates as it should but the following wheels do not. We intend to disassemble this counter, examine the first small gear, and photograph it.

I expect to see a damaged tooth, perhaps broken, perhaps worn. At this point it is uncertain what has happened. Because the counter is almost new I suspect breakage, but do not really know.

Veeder-Root places a 500 rpm operating limit on the counter, which translates into just over 15 mph or 25 km/hr of riding speed. Many have exceeded this, especially on long downhills, and not had a problem, but the stated manufacturer’s limit remains.

Because the first wheel is directly driven by the central shaft, it will not be affected by damaged tiny intermediate gears. This means that if a skip happens, it will happen somewhere between the first gear and the rest. Since one complete rotation of ten counts is about a meter, each skip would cause at least one meter of under-recording of distance.

It's possible that the plastic drive gear could be skipping, but I don't see how this would be undetected, as it's out there for all to see, and any malfunction would be obvious.

Stay tuned for further developments.
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A problem like this would almost certainly be detected. If it is not easily detected then it is almost certainly not a problem.

If the skipping occurs randomly then it is very unlikely you would get the same number of skips on 4 calibration rides. If there is a different number of skips on any of the rides it would give a large count difference (at least 10 counts) for one of the rides.

If the skipping occurs in a regular pattern, say one time every 20 revolutions, you'll get the same count number for every 300-meter calibration ride, and the skip will go undetected. However, you'll get the same count number for every 300 meters of the course as well, so the course measurement will still be accurate!

“I did a measurement over the weekend. I recorded my pre-cal counts with the Jones, and also my electronic. I only calculated my measuring constant with my electronic, as it has proven reliable over 3 years. I noted my starting Jones count, then my Finish Jones count. I then used my Jones pre-cal numbers to calculate my Jones constant. My pre-cals yielded counts of anywhere from 4625 to 4799 clicks per 1000-foot ride. Don't have the data in front of me, as I am at my day job. But, they all were very inconsistent. Proved to me there was an issue. (My electronic counter reflected my cyclometer measurements very closely. I re-calibrate my cyclometer every couple months, so it is almost as accurate as the Jones.)

So, I took the VR apart, and found the "ones" gear to have one smashed tooth. Prior to removing from my bike, I watched the counter as I increased speed. It was apparent there were skips in the "tens" digit. More apparent at higher speeds (over 5 mph).”

This is the first recorded time this problem has arisen on any variation of the Jones Counter, from original Jones to the present JR.

The cause of the tooth-smashing remains uncertain.
Last edited by peteriegel

Every time the right-hand digit wheel completes a revolution, the tiny intermediate gearing causes the next wheel to advance one digit. The right-hand wheel is moving; the next wheel is stopped. The tooth on the intermediate gear impacts the next wheel, which jolts it from a dead stop. The impact imparts a shock to the intermediate gear. This impact stresses the intermediate gear.

The impact is not severe if the contact speed is kept low. Veeder-Root recommends that rotational speed of the counter be kept below 500 rpm, or 15 mph (25 km./hr) as the JR counter is configured. If the speed is excessive, the shock of contact is increased.

If the counter is about to move the entire wheel set, as happens when the counter “rolls over” to 00000, the tooth contact stress is increased. Repeated overstress may damage the intermediate gear.

We have seen two examples to date of tooth breakage. This is not unique to the model JR counter. It has been present in all previous models as well. We believe that overspeed is the likely cause.

Tom gave me a six-digit counter on which the right-hand wheel rotated properly, but the following wheels did not rotate at all. This suggested that there was a problem with the intermediate gear.

Disassembly of the Veeder-Root counter revealed a broken tooth on the first intermediate gear. See below:

Out of curiosity I reassembled the VR counter, discarding the broken gear and substituting the gear which advanced the sixth wheel. It was a tedious job getting all the tiny bits properly aligned. I found that I now had a functional five-digit counter, with an inoperative sixth wheel.

I have no plans to use it in measuring, but thought it might be of interest.

Conclusion: Watch out for overspeed. It’s tempting to ride fast on downhills, and most of the time no harm will be done, as the problem is rare. But better safe than sorry.
Last edited by peteriegel
The picture shows just what happened to my gear. One tooth was disfigured, so it didn't rotate properly when its turn came to advance the next wheel.

I have not had this problem before, and I have kept my counter on for training rides which included high speeds (35 mph). This tells me that the VR is normally a very dependable counter, and I may have caught it once at a vulnerable location, causing the disfigurement. I will remove the VR when I am not measuring, as it is not worth the risk to have another gear go bad on me on a high-speed ride.

Thanks for the pics, as it shows just what my counter did. I didn't have good enough lighting to pick up the detail in my pics.
In about 30 years I've only had one counter go bad, and it's another example of what Pete has described: it broke between the 2nd and 3rd wheels. I never disassembled but maybe I'll look around to see if I still have it, then look inside.
I don't think I will start to take the counter off when I'm not measuring, it's not worth it I reckon-- but then (unlike Duane) I won't be hitting 35mph very often!

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