converting km/hr to rpm's ????

[iFred]

I just got one of those Schwinn bike speedometer/odometer things and wanted to do a check on how fast my RPM's was on my 11 inch rotor disk. By can't seem to convert the KM/hr to RPM's Any ideas??

Thanks in advance!!

[John II]

Hello: What bike wheel diamenter is the Speedometer / odometer set for ? This would have everything to do with the formular you are looking for.

John II

[baggo]

Hi,

Checkout http://www.fieldlines.com/story/2004/6/1/102512/0682.

John

[Ungrounded Lightning Rod]

I just got one of those Schwinn bike speedometer/odometer things and wanted to do a check on how fast my RPM's was on my 11 inch rotor disk. By can't seem to convert the KM/hr to RPM's Any ideas??

V = reading (velocity in KM/Hr)

D = wheel diameter in meters.

W = RPM.

Pi * D = wheel circumference in meters = meters / revolution

V*1000 = meters/hour

V*1000/60 = meters/minute

V*1000/(60*pi*D) = meters/minute * 1/(meters/revolution)

                 = meters/minute*revolutions/meter

                 = revolutions/minute

So compute 1000/(60*Pi*D) and multiply the reading by that to get RPM.

Can someone check my math?

[baggo]

That seems spot on by my reckoning,

John

[elvin1949]

you will have to add one step

the smallest wheel dia. it will read is 20'in

so will have to figure the difference as a ratio and do one more step [i have one of those on my bike ]

later

elvin

[wayne]

Hi

I saw them in Canadian Tire and had the wireless on sale. So had to get one. Found out the wireless was not much good, any R.F noise it would go crazy. Also saw many of the packages were preopened up, now I know why!! Took it back and got the wire model. This one looks alot better. Haven't had any time to test yet but hope this weekend.

Wayne