Will it fit?


The JR will fit most bicycles with rim brakes. The diameter of the axle cannot be greater than 10mm (fits 3/8”). The diameter of the hub flanges, where the spokes attach, should not be greater than 52mm (2”).  The clearance from the forks to the spokes should be more than 12mm (1/2”).  These are very common dimensions. In general, simple, inexpensive bicycles seem to allow its installation better than expensive ones.  Features such as carbon-fiber forks, or beefy shocks on the front tend to be more problematic, but not always. A couple customers experienced multiple failures within a mile or so after installing the counter “properly” on a brand-new bike, and unfortunately they had to buy different axles/rims in order to be able to use it.


There is now a right-hand version that fits bikes with disc brakes, but the larger hubs can be an issue. See the “Special Sale” page for details.


5 digit or 6?


Both counters produce the same resolution of approximately 9 to 10 centimeters per “count”. On 700c x 35 tires, this is almost exactly 11,000 counts per kilometer after including the 1.001 SCPF. Smaller tire will have greater counts/km. The 5-digit will “roll over” at approximately 10km, and the 6-digit at about 100km. Both units can be used to measure any length of course. Rollovers are easily handled by adding a “one” in front of the data like an auto speedometer. A 5-digit requires fewer numbers need to be recorded “in the field”, and may lessen transcription errors.


Top speed:


The manufacturer of the counter specifies the unit should not exceed 5,000 counts per minute, which equates to 27kph, or 17 mph on 700c x 35 tires, and slower on 26” tires. Many people have exceeded this briefly during routine riding without incident, however the limit exists, and failures have occurred. In one case, the user admitted to routinely exceeded 35 mph on a long downhill.


Lubrication / maintenance:


If there is any resistance to turning, first examine the setup. If there is resistance or excessive noise during operation, something is binding. Try a little oil - it's possible that this will seek out the binding and smooth out the operation. 



Properly installed it does make a little noise, but sometimes prior to failure it sounds louder. It’s likely the unit was bent laying the bike down, or otherwise catching the counter on something loading or riding the bike. Possibly it’s getting worn out. In normal operation there should be little noise, and no “grinding” sound. Oil is often the cure for noise.

Be careful:

Personally I’ve bent up a few of my counters, and it isn’t the end of the world. It can however end the day’s measuring. Once I crammed my bike into the back of the car, and bent the chassis. Another time, I ran off the trail I was riding, and a twig got into the chassis / gear and fouled things up. Last, my kickstand gave out, with the bike/ curb in the wrong spot as it fell. I fixed this one with a little twist of the chassis.

If you recognize the sound it makes is “different”, check to make sure the unit spins freely and the gears aren’t binding. If the gears mesh too tightly, you may have bent the chassis slightly. I’ve bent a couple straight, usually a slight tug on the counter is all it takes to get the gears to mesh properly again.

Can it be reset?

The counter does not have a reset button. Over the years Jones Counters have never had them. The counter is part of the measurement process, and the process includes review by a state certifier. Having people reset their count in the middle of a measurement, unless fully explained, can lead to confusion. Thus no great demand for a resettable counter has yet arisen.

The drive tang broke

Unfortunately there are a couple things that can cause the tang to bend. Under normal operation, there’s plenty of strength to drive the counter, but the tang is the weakest part off the assembly.

One common cause is the gears are meshing too far, and it binds. This can happen if the counter is bent on something in transit or in an accident. If you catch this one in time you can save the unit, just bend it back so the gears mesh properly.

Another cause is when the gear is sandwiched between the cup (on the inner portion), and the chassis (holding the counter). Think of this like the disc brakes on a car pinching the rotor. This can happen if the assembly isn’t being held “nicely” between the axle and the hub, i.e. the hub / fork doesn’t fit right. Or, the hub got loose and the tire wiggled a bit when riding.

The last thing that will cause the tang to fail is wear. I’ve only had a couple returned where the big gear is so “sloppy” the gears no longer engage properly and I’ve replaced them for free. Once installed and free from damage, the assembly should go for thousands of miles. One of the units first produced is still in operation with 5 years and least 4,000 miles on it.

Replacing the chassis will cost $23 plus postage. Usually the counter itself and the black gear are undamaged. You can either send the counter to me with a payment, or send the money via Paypal and I’ll mail you with a “replacement chassis kit”, with instructions, nuts / bolts etc. Contact me and we can work out the details. See the “Other Items” page.

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