The triathlon training blog of Phil Barnes

Low tech cadence (rpm) counting

I learned to appreciate cadence (the number of R.P.M.s or pedal strokes per minute) a couple of years ago.

I used to just grind huge gears without any consideration whatsoever. I thought cadence sensors were just gimmicky toys… until I happened to get one on a cheap bike computer.

Then, I started paying attention to it, and noticed that speed sometimes went up when I used an easier gear at a higher rpm… *light bulb over head effect* …and then, I read some stuff, heard some stuff, learned some stuff from others – long story short, cadence is important.

:::Fast forward to now.

My brand new state-of-the art Tacx Flow ergotrainer, includes a cadence sensor. However, it’s still not working. I’m on my second display unit – and it too has the same problem as the first. The trainer still works, as a manual trainer would, and I did a spin last night; using my bike’s gears to adjust resistance.

My goal last night was to maintain high cadence; help get my legs back into cycling strength. I did pretty well, averaging high 90’s to low 100’s.

But Phil, I thought you said your cadence sensor wasn’t working?

Correct. There is a trick that I learned a while ago. It’s brutally simple. Perhaps everyone in the world knows this. But, it seemed revolutionary to me at the time, so I share it with the Internet today: all you need is a watch and a command of the “4 times table”.

Step 1: Start cycling

Step 2: When you’re ready to get a cadence reading, observe your watch

Step 3: When the seconds are at a convenient location; e.g. :00, :15, :30, :45 start counting the number of times your left leg hits the bottom of the pedal stroke*

Step 4: Continue counting for 15 seconds

Step 5: Multiply that the number you counted to by 4 – voila your cadence in RPM.

*I find, for some reason, that it’s easier to count my left leg. I think this might be because, I’m right handed. Perhaps lefties will find it easier to count their right leg?

If it’s too difficult to look at your watch, consider setting a countdown timer, that will beep for you. I’ve done this before. Setting a timer for a minute, and counting for the entire minute works too.

Bonus: Cadence Conversion Chart (for 15 second intervals)

CountCadence
1456
1560
1664
1768
1872
1976
2080
2184
2288
2392
2496
25100
26104
27108