A bit of instrument information from the Velobanjogent...The earliest use of a tachometer on a racing motorcycle?

I posed a question on a Facebook group site I run...Motorcycle speedos,tachos and other instruments  .... the earliest use of a tachometer on a racing motorcycle...? 
 I illustrated it with a French Jaeger tacho on Roger Loyer's 1933 KTT Velocette during the IOM Junior TT, but Andrew Rachstraw found a 1922 photo from Brooklands with a 494cc Douglas using what looked like a Smiths governor instrument clipped to the handlebar... well I searched though my 1919-20 and 1924 Smiths catalogues featuring the governor speedo and tacho...the only type Smiths offered at that time as it was not until the late 1920's they acquired the rights to make the chronometric from Jaeger (Paris) by purchasing the newly formed UK, Jaeger E.D. ( and renaming it British Jaeger around 1930). And there was the tacho drive..as illustrated and the tacho, obviously with likely a special dial face made probably to around 6000rpm. Illustrated is a dial from my master catalogue of when I printed dials for a 5000rpm gnvr tacho, My artwork was done from an original dial I had.

Roger Loyer astride his 1933 KTT Velocette at the IOM TT races of that year... the Jaeger tachometer is visible mounted low down near the front of the petrol tank and it is driven by a bronze tacho drive from the bottom magneto chain sprocket...

T.Eve on his 494cc Douglas in 1922 at Brooklands, UK...the tachometer is a Smiths governor principle tacho, unsure of the ratio or dial scale...

The tacho drive from a 1919-20 Smiths catalogue.... 

The Smiths "domeback" type governor tachometer and clip mounting to a motorcycle handlebar...

Tachometers from the 1919-20 Smiths catalogue...the latter mounting is for a car and attaches to the car dashboard.

 Illustration of the internals of the Smiths governor instrument showing the rotor which operates in the same way as a steam governor...the weights swing out as the cable speed increases and the collar at the top of the rotor moves down, and via a rocker arrangement swings the pointer around the dial face.

Above is an original Smiths governor dial face from the 1920's ...and the scale is non linear, which is a characteristic of the Smiths governor instrument. It makes calibration difficult.

Smiths chronometric instrument drives.................

In an earlier Blog I discussed Smiths tachometer drive gearboxes.
This blog discusses the small 90 degree instrument drive gearboxes that were fitted to the Smiths chronometric speedometer and tachometer. As well the later BG2410 series drives that were a thumb screw attachment to Smiths speedometers to get a more suitable cable run in Rover 2000 and 3500 P6 cars and Jaguar XJ6 cars in the period mid 1960-end 1970.
Left click on any image to enlarge it....
The first pic is one that perplexes me....
You'll note it is a 250MPH speedometer in 80mm dia. format...wow! 
I obtained this with the stock of the ex Smiths Competition Shop, Oxgate Lane, London, that I bought in the 1980's from the last manager, the late Jack Owens.
I never questioned him over it's use regrettably....so now I figure it could be off a Le Mans endurance racer, note the black bezel rim to cut reflection rather than the usual chrome version. To this day we can't identify it....
H'mm....
Well new information to light from Rodger Howard of Howard Instruments in Melbourne, Victoria to whom I sold the speedo to.
He chased up it's history and it is from a 1966 Jaguar XJ13 Le Mans racer

You'll notice that it has the small angle drive, attached by a keyplate to the case.

The method of attachment is shown...you'll notice that the internal die-cast frame that holds the movement mechanism has no threaded section with mainshaft, rather this is all in the small drive.
So the other drive, mentioned above is a clamp on type Smiths drive..illustrated below.

Illustrated is an assembly of both keyplate and clamp-on drives in parts...

I mentioned above the three types...illustrated below, beside each other.

The BG2410 series has several attachment methods , illustrated as well as  in parts. We tooled up to make these years ago and still make and supply them.

KTT made Smiths 150mph Vincent Black Shadow speedo with BG2410 angle drive attached.