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I am (I hope) close to getting my Inter speedo but there's a delay sorting out the hub gear.
But I found somewhere... Chronometrics are allegedly 1600 revs per mile unless they have a 4 digit number such as '1476' or '1500' or '1620' or something similar. Perhaps someone can confirm?
Doing some calculations. Norton motorcycles could use identical hubs and speedo drive gears on models with 21" wheels as they could with 20" wheels provided the standard 19" wheel models had a '1600' speedo, and the 21" models had a '1476' version. Is that what they did, or did they use different hub gears instead? My Inter hub came without speedo gear.
Neither of the speedos on my Dommie and 16H has a number on the dial. I wonder if anyone with an Inter having a 21" wheel might confirm if it has a number somewhere close to '1450" on the dial?
Hello David, the "1600"…
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Thanks Sam. I looked at my…
Thanks Sam. I looked at my 16H today. It has the internal gears. The backplate dimensions are identical to the Inter backplate. So if I fitted its gears into the Inter hub, they would fit.
By my calculations, if I assume the 16H has 1600 tpm, it would over read by 5%, which is what I imagine they intended. So I think the 16H does have 1600tpm. It has no marks. And if I could fit the same gears (43 on hub, and 14 on speedo gear drive) , I need just under 1500 tpm. But the speedo must be reversed since the Inter brake plate is on the right.
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Hello David, the "1600" number you're referring to is called the TPM number, Turns per mile.
most of the early pre war speedos are usually 1600, but just because it doesn't have a TPM number on the face doesn't mean it's definitely 1600. im selling a pre war pin drive speedo with cable and drive, not sure if the inters had the drive fitted into the hub? Either way this one has a gear that's fitted to the wheel.