Bit Of Trivia

Been going through my substantial stash of old cycle parts lately; mostly Harley with a dab of Triumph and Indian. Ran across a NOS speedometer hand lock I acquired decades ago. That part is roughly 68 years old.
Back in the day (1950 in the case of my Harley cop bike) mounted and hand held radars were MIA. This led to the question of how to provide evidence of speeding by motorists.

This is how it worked. A panel was removed from the left side of speedo. The hand lock was mounted there. One wire went to power from the switch. The other lead went through the handlebars to a push button which would ground the lock when depressed.
The lock worked like a starter solenoid. It would extend and press the rubber cap against the drum with the speedo needle and lock the needle in place when the button was pushed briefly. The solenoid would not retract as the spring loaded bracket would hold the solenoid in the extended position. With engine off the officer could show the motorist the speedo reading and issue a ticket or warning. The solenoid would retract when a small button on the left side of the dash was depressed which in turn moved the spring loaded bracket and allowed the solenoid plunger to return to the closed position. Needle drops to 0. Worked fine until radar came on the scene.


I guess the cop would have to speed to catch up to the vehicle to pull it over. he could hit the button at his top speed and say it was the vehicle.


Now that’s got to be worth some money in the right circles.

I’d guess if you contested the ticket, he’d have to leave the speedo locked until court and then drive it in to show the judge. Man the world changed with transistors.

I don’t trust the law with radar guns. About 20 years ago we had an Okie state trooper here who stopped my wife (she got a warning), both of my sons, two of their friends, and my daughter along with no doubt others I do not even know.
The common denominator? The trooper’s radar showed all of them were traveling at 73 in a 55. One of them; maybe. The others no way. I was with one of my sons when he got stopped and the cruise was set at 65.
“Well, your speedometer must be off…” he says. Three checks showed it near dead on at 65.
Not wishing that upon him but maybe karma had something to do with him becoming deceased at 42 years old and in perfect health. Apparently not perfect enough.

Yet the trooper turned on a highway to avoid a local crop duster who was using a 2 lane to land his biplane and tank up on chemicals rather than fly 4 miles back to the airport. Trooper said he did not see a lemon yellow plane from 150 yards away with the engine running and several vehicles held up as they could not get around the aircraft.
Crop duster even landed behind a school bus one afternoon and gave the kids on the bus a stir. One panic stop by the bus and that could have been a 4 bladed meat grinder going into it.
“Uh…that’s a matter for the FAA”. Yes and no.

On another note, here’s the siren I have to go with it. Similar to the hand crank air raid sirens. I even have the red PD lamps and a Canadian police radio setup for it along with the rear crash guard/radio mount.


A vintage Triumph was the subject of a restore on “Counting Cars” last night on tv a re-run episode I presume). If you have no use for that gadget maybe the shop owner Danny would buy it from you, could bring a pretty penny I’ll bet.

the biggest technical challenge of this particular restore, the owner wanted it equipped with a sidecar. The problem was the cycle was originally sold in the UK , left side of the road driving, so the cycle was set up for a side-car on the left. I guess to make the passenger a little more safe. But this owner wanted to use it in the USA, and wanted the side car on the right.

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I could see a cop getting a bit aggressive with the hand lock thumb. Motorist doing 28 MPH in a posted 30 with the cop in trail a block back.
Blip the throttle with the right hand while stabbing the button with the left and voila; 5 to 10 over. This would have been even worse back in the day because then they had the onerous Justice of The Peace systems in place.

Yeah, this stuff is worth some serious money but I hang onto it for some reason. The pic below shows one of the 2 sets of 1949 and 1950 only rear fender trim I have called Sergeant Stripes. Also have 4 strays. All 6 in the set are different.
Camera angle makes them look way different but they are near impossible to differentiate so someone at the factory when they were manufactured used a tiny brush to mark them in HD colors on the inside. Two are marked orange, 2 black, and 2 in white. As little difference as there is in them, one out of sequence sticks out like a sore thumb.
Going rate on originals is 100 bucks each.
Thirty odd years ago a guy gave me a right side gas tank for a 1939 Harley. It was lying out in his back yard full of concrete and with a chain attached. It had seen much use as a boat anchor. I cut the chain off and 15 years later sold it for 500 bucks as is and still full of concrete. The buyer resurrected that tank as it is a one year only item.

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Yeah so arbitrary, guy was passing me and I got pulled over in a local speed trap. Got it reduced to failure to obey an official sign, but come on I am in the right hand lane, guy passing me in the left hand lane and I get pulled over and the ticket?


Early in my career I worked writing software for military Radar systems. We had a few engineers who came over from the commercial radar systems group that designs handheld systems for police. From what I learned while working there…if there are more then 1 car on the road it’s almost impossible for the cop to determine what car he’s picking up. It picks up the largest reflecting object. Is it the small Civic that’s 500’ away or the large tractor trailer that’s 500 yards away?

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An OHP official let it slip 8 years ago in the Tulsa area there were quotas; something they always denied.
Stated there were to be 4 tickets issued per 10 stops and 30 alcohol related arrests made per year. Promotions and pay is based on this. So that means if the trooper (through sheer lack of luck or whatever) is running below the norm he or she may start grasping at chances to make traffic stops.
Another rumor was that any trooper who strayed often found themselves stationed in Boise City, OK; the most western town in the OK Panhandle; a.k.a. No Man’s Land. Not a lot to do for many miles in any direction.,

The local cops stopped me once on a 30 degree day while I was jogging with an out of gas 500 pound motorcycle. They were going to write me up for speeding. When I started vehemently protesting I was told to shut up and get one ticket or keep talking and get a handful.
In the meantime I was still gasping for air and thinking heart attack…


you must run pretty fast. :rofl:


No it’s not. It’s the closest vehicle. The signal drops at the square of the distance each way, so the cube of the distance two way. Unless the two vehicles are just inches apart, it will always be the closest.

One exception is a moving radar where the cop is following another vehicle and you are coming the opposite way. In a moving radar, the cops speed is blanked out, so would any target going the same speed in the same direction.

Just for entertainment, you know the Wisconsin Patrol are very aggressive so I always watch my speed. Driving by the Dells a couple years ago on I 90, a trooper had pulled a driver over. As he stood there he pointed the radar gun at another car and aggressively waved him to the side. The car kept on going. In exasperation the trooper simply threw up his hands. What could he do? If it would have been me though, I would have taken the next exit and drove home on the side roads-at least until the river crossing into Minnesota.

No it isn’t. A large truck behind a small car can easily be a larger reflecting object. If there’s multiple vehicles it gets even tougher.

Had the same thing happen to me. I was driving a red Mustang GT. Guy in a Suburban passed me. Yet I got the ticket…because…red Mustang. Oh well. I argued, had to pay it anyway. Life goes on.


It would have to be very close and at long range and a very small car. Distance has the greatest variable on signal strength, size is second. Because distance is exponential, it easily overshadows size.

Speed is also a variable because the greater the speed, the greater the doppler shift. The doppler shift is the algebraic difference between the transmitted signal and the received signal. In the mixer, the greater the difference, the stronger the signal. But the difference is very small and would be difficult to determine if it had any bearing on which target is selected.

Some police radars can be set to select the highest speed instead of highest return. Those could actually select a return that isn’t even visible to the officer so I don’t think that is used anymore. I don’t think that option is even available in the newer radars. It might have been useful in that spot in the Oklahoma panhandle as it did have the longest range.

Reminds of a joke. An officer was posted in a place like that and was told he would stay there until he wrote a ticket. After a couple of days, a blond in a red Miata came screaming down the road at full throttle. He pulls her over and says to her “I’ve been waiting a long time for someone like you to come along.” She looked up at him and responded “I got here as fast as I could.”

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Just curious if anybody knows, is there a law which requires which side a motorcycle sidecar must be on?

I have not experienced that, though remember between Tomah and Black River falls is a highly patrolled zone. Never a problem going 10 over or so, but in the 70’s driving to Hayward my bud got an inattentive driving ticket while reaching for a soda out of the cooler as a trooper was passing.

Things have gotten a little better since they raised the interstate speed to 70 like everyone else (except South Dakota at 80). But like the Ohio trooper said “9 you are fine, 10 you are mine”.

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The point is…the radar doesn’t tell the operator WHICH it’s picking up. Only that one of the vehicles may be going over the speed limit. 1-2 vehicles it may not be a problem…but 10-20 vehicles close together - Problem

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[quote=“bing, post:18, topic:183318”] the Ohio trooper said “9 you are fine, 10 you are mine”.

The troopers — given this sort of attitude — should consider the source of their paycheck. If a driver is fined, the local business owners and their staffs are the folks who actually pay the fine for the most part.