Erm, actually, no. It's only the size of the rear sprocket that matters. No calculation required. Think about it.

Sorry Guys not a clue, but they tune the Ducati's for the Monster Mob Team.

Is that, or wasn't that slingshot racing?

Jim Stock etc?

no,its FW developments,frank wrathall,ie Dynojet uk !!!,jims nothin to do with them at all.he sells race bikes !!!

....Errrr and sets up the Monstermob bikes for Birdy

Felix, Go on then, I'll bite. If your using the pulses on the front sprocket as the speed input, why don't you need to do the math? The speed the front sprocket rotates compared to road speed, is goverened by tyre circumference and final drive ratio. Eg. a tooth of the back means more road speed for same front sprocket rotations.

Rgds, Rob

One revolution of the rear wheel equals the number of teeth on the rear sprocket, which is also that many links of chain travel. What your measuring is chain links, even when the sensor is positioned on the front sprocket. I know it seems counterintuitive but that's how it works.

Ah, different approach. You mount the sensor on the front sprocket, but tell the dash, logger, whatever, that it's a 41 tooth and is equivalant to x meters of travel. Got ya.

Rgds, Rob

Regardless of all that, spoke to Translogic today and they reckon it won't work with their dash. Not sure why, but looks like I'll be putting a couple of ferrous bolts back into the rear disc.

Hard to believe, that.