General Cycling Discussion - How do you know how many RPMs you are turning?

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tabby
04-07-04, 02:22 PM
I have seen a few posts where rpms are talked about. How do you know how many times you are spinning? I am assuming you are talking about the pedals. Please clear this up for me. Thanks.


OregonBound
04-07-04, 02:36 PM
Well, you can purchase a cycle computer that has a cadence feature and then carefully mount the cadence sensor near the crank. Be sure you have calibrated it correctly. Check the read out.

On the other hand, you could count the number of times your turn the pedals for six seconds and multiply by 10.

Paul

threadend
04-07-04, 06:49 PM
Well, you can purchase a cycle computer that has a cadence feature and then carefully mount the cadence sensor near the crank. Be sure you have calibrated it correctly. Check the read out.

On the other hand, you could count the number of times your turn the pedals for six seconds and multiply by 10.

Paul

These ways both work fine. The computers with cadence are the easiest because you get continuous realtime information. Personally I like the Cateye Astrale w/ cadence. Yeah, initial installation is a bit more involved than a standard cyclecomputer, but not overwhelming for the average mechanically inclined. Not comfortable with the install, buy from the LBS and I'll bet install is free.

I'm not sure about other brands / makes, but the Astrale requires no calibration for the cadence feature, it's a 1:1 ratio.


DieselDan
04-07-04, 08:31 PM
You could count your cadence for 10 seconds and multiply by 6.

abc
04-07-04, 09:12 PM
Or you can count for 1 second and multiply by 60 :)

That's what I do - just make sure that I'm doing slightly more than 1 revolution per second giving me about 70-80 rpm. Only takes a second to calculate your current rpm.

slvoid
04-07-04, 09:56 PM
Or you can count for 1 second and multiply by 60 :)

That's what I do - just make sure that I'm doing slightly more than 1 revolution per second giving me about 70-80 rpm. Only takes a second to calculate your current rpm.

I think you'll have to obey your standard nyquist sampling theorem there :p

tabby
04-07-04, 10:29 PM
Cool. Thanks. I guess counting how many times you are spinning in 10 seconds would work really well. Why do I over-complicate things so much?

DnvrFox
04-08-04, 06:05 AM
Strangely, I use my cyclocomputer "seconds" feature and count for a whole minute. That way I don't have to use higher math and multiply by 10. Really! <g> :D

DieselDan
04-08-04, 09:58 AM
You could just ride your bike without worry.

tabby
04-08-04, 04:56 PM
I don't worry. I was just curious.

55/Rad
04-08-04, 05:01 PM
I do it by sound - I have a playing card clothes-pinned to my spokes. I then count the piston strokes.

And, I look at my Cateye Astrale 8 with the cadence feature.

55/Rad

Don Cook
04-09-04, 06:54 AM
I have seen a few posts where rpms are talked about. How do you know how many times you are spinning? I am assuming you are talking about the pedals. Please clear this up for me. Thanks.

I've posted this file before. It should answer your questions about determing cadence or crankshaft rpm.