sportsguru

hi can anyone tell me if it is posable (and how 2) make a cadence monitor out of a spedometer , i have a few old cyclecomputers that i could put to use!

ie where to mount and how to programme the cyclecomputre
thankyou in advance

twobikes

If you simply want to know your cadence, there is a formula you can use. When you are pedalling at the cadence you want to know, note the gear you are using. How many sprockets from the outside on the back and which chainring on the front? Note your speed. After your ride multiply the constant 336 by your speed in miles per hour and divide by your gear in inches.

As for converting a spedometer to measure cadence, it would seem an unlikely possibility. I am guessing, though. You might be farther ahead to start fresh with a reed switch for a sensor and an IC counter chip you can configure for events per minute. You would need to make your own case and mount. It could be fun, but would be involved.

Many say they used a cadence measuring spedometer for a while and later learned how to judge their cadence from experience. After a time they no longer used the cadence readout on their spedometer.

ericgu

The answer is "yes".

There's no reason you can't mount a speedometer sensor on a crank, and it will give you a reading. The problem that you will have is that if you are riding at 100RPM, your computer might say something like 7mph, and you would have to figure out the conversion factor.

You might be able to play around with the tire size setting and switch between MPH and KPH to get a number that's easier to convert.

BILL SCHMIDT

Get or borrow a musician's metronome, set the cadience you want and pedal along at that cadience
while your speedometer is hooked up to your crank. Note the speed. Change the cadience on the
metronome and repeat the process several times until you generate a conversion chart between the registered speed and the cadience. You can then either post the chart on the bike or alter the dial readout.

socalslowguy

Sounds like a fun math problem so I broke out the calculator. If you set your computer to a tire circumfernce of 2682mm cadence will show as mph where each .1 mph = 1rpm. So 10.0 mph on the computer = cadence of 100 rpm. 7.5mph = cadence of 75 rpm etc.

You'll want to mount a magnet on one of the crank arms. A simple flat magnet held by wrapping electrical tape around the crankarm would work. The sensor can go on the chainstay.

UrbanChicago

I suspect what you really want is for the computer to show you cadence as if it were speed. As in the computer reads 100 mph or 100 KM/h when your cadence is 100 rpm.

If your computer will accept your wheel circumference as 88ft (14ft radius) or 1666.67cm (265.4cm radius) if using KM/h, that will get you your desired results. But will the computer be able to display numbers that large?

bh357

https://www.63xc.com/martink/cadence.htm

sportsguru

i am very interested in finding out the calulations that you used to get the quoted figure ?

i have now got 3 difering numbes to input and i am trying to workout which one is best/correct

sportsguru

does the length of the crank make a differance to the input number??