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-   -   miles per hour to RPM (https://www.bikeforums.net/indoor-stationary-cycling-forum/1220118-miles-per-hour-rpm.html)

sendero 12-24-20 01:05 PM

miles per hour to RPM
 
Dear all, Just bought an indoor bike and I would like to calculate rpm as the monitor only shows KPH or MPH
can you please help me?
best

base2 12-24-20 01:23 PM

Wahoo cadence sensor.

There are various versions of bluetooth, bluetooth LE, bluetooth smart, bluetooth FE-C, (and probably more,) & ANT likely has the same varieties. I think the various competing "standards" work to varying degrees well or against eachother depending on manufacturer relationships with or against other manufacturers.

What you need to know is WAHOO stuff works equally well with any bluetooth or ANT standard. So, this little guy here will have you set.

I find bluetooth to be a sketchier/weaker/more problematic connection than ANT, but it works well enough, often enough it's not really a problem. Nevertheless if my device supports ANT, so much the better & I'll make an effort to pair in ANT protocol when available.

billridesbikes 12-24-20 01:36 PM

Here is a super cheap and easy way. Get a watch with a second hand and stick it on the handlebars. Count the number of times your right knee come up in 15s, multiple by four. A count 20 is a good rpm (aka cadence) for a beginner. After a while you’ll develop a feel for what cadence you’re doing.

sendero 12-24-20 03:34 PM

thanks a lot, my friends!!

mr_pedro 12-24-20 03:52 PM


Originally Posted by sendero (Post 21847146)
thanks a lot, my friends!!

You could also use the seconds hand to ride at 60 rpm, so one full revolution of one of the pedals every second. And note the speed. You can now multiply that speed with eg 70/60 to get the speed at 70 rpm. Do this for a range of cadences and you can make a small list to keep by the hand.

cb400bill 12-24-20 04:12 PM

Thread moved from Introductions to Indoor Cycling.

bmcer 12-27-20 03:55 PM

All you need to know is your gear ratio, your wheel circumference in feet, and the number of minutes in an hour and the number of feet in a mile.

RPM = (MPH X 5280)/(Gear Ratio X wheel circumference in feet X 60)


For example:

50 x 12 = Gear ratio = 4.17

Wheel circumference in feet = ~6.89 for a 770c x 25 wheel

MPH = 29

(5280 X 29)/(4.17 X 6.89 X 60) = 153120 / (4.17 X 6.89 X 60) = 88 rpm


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