5000rpm in 5th on an 1100 cali -how fast?

[lazlokovacs]

I really don't know if my speedo is at all accurate... If I'm at 5k in 5th gear on a cali vintage with an 8/33 rear drive, does anyone know how fast I'm actually going? I know there's a way to work it out but I can't quite remember how to do it...

[ridingron]

Probably need to also know the circumference of the tire.

GPS?

Have someone track you with their bike/car?

Might be a little bit to pull off on a bike but ....  Time a few mile markers on the interstate and calculate speed.  example: 1 mile in a minute is 60mph

edit--The navigation phone app Waze has your current speed shown.

[Tkelly]

I think those signs that tell you your speed are pretty accurate,like when you are entering a construction zone or a town.

[elrealistico]

2004 EV--I think around 80-90MPH Indicated in 5th at 5K RPM. Checking with GPS--Beeline display--it usually is +3-5MPH on the speedo vice GPS. had iit up to 110 indicated. 105 on GPS over a bride a few days ago
Optimistic speedos have been a thing for many years. Maybe now with the mechanical units being slowly dropped from new machines, that will change, but I think it's as much a deliberate (or tolerated) thing by Mfrs to let the user think they are Speed Racer

[wirespokes]

If you've got an electronic tach, they're not always tracking exactly either. I believe they average the current, so it depends how hard the coils are working.

I don't know about your bike, but my 87 LeMans runs right around 70 at 4K. My touring beemers were pretty much the same.

It's a straight line graph so figuring it out is pretty easy. For example, if you know that you're doing 60 at 3500, plot those two points. Start the graph line at zero and run it through your data point and beyond.

So if 70 is 4K, 2K would be 35. 1K would be 17.5 mph.

I usually figure a loose guess of 20mph per thousand RPM. Probably more like 16 or 17, but for rough calculations I go with 20.

So then you know that 5K in top gear should be close to 90.

Hit one of those speed signs in fifth and see what you get and what RPM, then draw up the graph.

[Tom H]

If you have a cell phone and a bike mount. You could always get a GPS speedo app. Then you will know. Android, DigiHUD seems to work well for me. You can set it ( or is a default, can't remember) to remember MAX  speed and keep it in your pocket. Hit your RPM, pull over and see what the MAX is.

But IIRR that should be about 80-85mph on my EVT. IIRR 3500 is about 70mph.

FWIW: My loops are 70mph at 4000 give or take 2mph.

Tom

[Frenchfrog]

GPS or a correctly calibrated Sigma speedo are the way to go...factory ones always seem to over read as a safety measure.

[Swedemoto]

You can try these two links. May need to make some adjustments.
https://www.gearingcommander.com/
https://www.thisoldtractor.com/guzzitech.dk/gb_en_technical_gearing.htm

[chuck peterson]

Just right..

[PeteS]

I think 90 is about right with the 8:33. I think I calculated if my EV could pull 8K RPMS it would be going around 145. I was doing good to see 120, downhill with the wind.

Pete

[Alfetta]

for what it's worth, My V7(3) is optimistic by 5 MPH.
then again, every thing that i have owned from Italy, the speedo typically reads high.

[Wayne Orwig]

My 1994 Cali 1100, and my 2004 EV, are 80MPH at 4000 RPM. (after regearing it is now 71MPH @ 4000).

So, doing the math, 5000 would be 100MPH (+-).

That is off of a GPS, not the speedo.

[5154guzzi]

Here`s a gear chart I did Using Mike Wrights program for an EV drivetrain, but with a different wheel/tire combo. Will be testing with this same gearing on my land speed bike.  The important part is using the actual measured tire diameter, which can vary between same size, but different manufacturers. Not sure if any of the gearbox internals are different with the vintage box.

[rocker59]

I really don't know if my speedo is at all accurate... If I'm at 5k in 5th gear on a cali vintage with an 8/33 rear drive, does anyone know how fast I'm actually going? I know there's a way to work it out but I can't quite remember how to do it...

Here's an online calculator you can use:

https://www.omnicalculator.com/everyday-life/rpm#:~:text=Vehicle%20speed%20%3D%20Wheels%20RPM%20%C3%97,miles%20per%20hour%22)%3B%20and

[Gusable]

My 94 cali 1100 speedo reads dead nuts on the money but the odometer does not (iirc). I do have the 7/33 chunk in the back. 4K is 70mph exactly