Cadence

[neptune]

In cycling, cadence is the speed that your pedals rotate expressed in revolutions per minute. While everyone has their own preferred cadence, sports cyclists aim for a cadence between 80 and 100 rpm on the flat. You can buy fancy gadgets to measure cadence. If you have a stop watch, or a timing function on your bike computer, you can count your pedal revolutions for one minute. Here is another way using just a speedo.

I want to determine my cadence at 10 MPH. At this speed, I will be on the middle chainwheel, 36 teeth. I will be in third or fourth gear, depending on the wind conditions. In third gear, I am on a 21 tooth rear sprocket.In fouth gear, it is an 18 tooth sprocket.

At 10 MPH, my rear wheel, which is of 29 inch diameter is turning at 126 RPM. I know this because 10 MPH is 880 feet per minute. So wheel rpm is 880 divided by my wheel circumference [ pi X wheel diameter in feet=
3.142 X 2.25 = about 7
So wheel RPM is 880 divided by 7 = 126

In third gear, ratio is21 divided by 36 = 0.58 so pedal turn at 126 X 0.58 = 73 RPM



In forth gear ratio is 18 divided by 36 = 0.5 so pedals turn at 126 X 0.5 =
63 RPM

So to conclude my cadence at 10 MPH is 73 RPM in third gear and 63 RPM in fourth.

Anyone care to check my calculations? I am to mathematics what Alex Salmond is to hang gliding...

 

[Alan Quay]

Circumference = 2πR, or πD.

 

[neptune]

Thanks mike. I used 2 x pi x diameter initially, and realised it should be Pi x D. I corrected the actual workings though, so I think the resulting circumference, and the cadence, is correct. Do you agree?

 

[flecc]

In third gear it's 67.3

In fourth gear the cadence is 57.7

These are using your 29" diameter wheel, 36 chainwheel and 18 and 21 rear sprockets in this calculator that I always use to save doing the calculations:

http://www.soulbikes.com/gears/

In both cases the calculator comes up with 10.4 mph as the nearest speed and I've adjusted the cadence down from that.
.

 

[Alan Quay]

Thanks mike. I used 2 x pi x diameter initially, and realised it should be Pi x D. I corrected the actual workings though, so I think the resulting circumference, and the cadence, is correct. Do you agree?

Yup, that looks better now. It also sounds about right from experience.

 

[neptune]

Thanks for that Mike and flecc. I am happy that I managed an answer that was in the right ball park. I am also happy that anyone who has a speedo and is interested can determine their cadence.

 

[Gringo]

How dose that work out with my internally geared Bosch motored cube 29er running 2.1" big Apples.
I tried working it out once but found it easier just to count for one minuet Along a straight bit of road.
I'm sitting at about 75 rpm (average) even after 30/40 miles it's still about the same

 

[Alan Quay]

How dose that work out with my internally geared Bosch motored cube 29er running 2.1" big Apples.
I tried working it out once but found it easier just to count for one minuet Along a straight bit of road.
I'm sitting at about 75 rpm (average) even after 30/40 miles it's still about the same

2.1's will turn your 29er into a 29-and-a-bit-er.

cadence@10mph=114/gear ratio

Gear ratio = teeth on pedal cog/teeth on wheel cog.

OR

Raise the rear wheel wheel, turn the crank 10 times, count revolutions of rear wheel, divide last by first.

How dose that work out with my internally geared Bosch motored cube 29er running 2.1" big Apples.
I tried working it out once but found it easier just to count for one minuet Along a straight bit of road.
I'm sitting at about 75 rpm (average) even after 30/40 miles it's still about the same

 

[JohnCade]

What I used to do to check on my cadence now and then was just count the number of times my right knee came up in a ten second period. Quite easy to get used to counting seconds accurately in your head if you don't have seconds on the bike computer. So I aimed to keep it at about fifteen times in ten seconds.

That was back in my road bike days, but nowadays I don't bother.

 

[flecc]

To get an accurate wheel diameter with the wheel in the bike, place a spirit level across the topmost point and measure to the floor at a point clear of the forks/frame etc. That will give all the precision needed. Then using a calculator like this one I linked to above will give you a whole range of information at varying speeds, not just cadence.
.

 

[neptune]

I have been out on a ride this morning, and have been putting my new found knowledge to the test. As near as I can tell, a cadence of 65 to 70 is what suits me best. 75 is my "peak revs" figure. These figures are a bit low, but then, I am old, and these figures are comfortable.
Here is another way to check cadence which has occurred to me, but which I have yet to try. Select the gear in which you want to know your 10 MPH cadence. Back your bike up to a wall, with one pedal at top dead center. Wheel the bike forward in a straight line, whilst turning the cranks. [ It is easier with a helper].Stop when that same pedal reaches top dead center.
Now measure the distance from the extreme back of your bike, to the wall. This needs to be in feet, and decimal fractions of a foot. [To convert inches into a decimal fraction of a foot, divide by twelve.]
Divide 880 by the answer. The result is your cadence at 10mph in the selected gear.

Added later. I tried this method, but with no helper, measurements were not precise.
Results; third gear 67.5 Fourth gear 56.7

 

[flecc]

That is very close though Neptune, and certainly more than good enough.

0.3% error in third gear and 1.7% error in fourth gear are negligible.
.

 

[Alan Quay]

It a bit of a shame that the displays don't show cadence - if the bike has a pedal sensor it would have been dead easy to implement with the latest gen. of LCD displays - perhaps the BMS battery LCD3 has this.

 

[RobF]

As near as I can tell, a cadence of 65 to 70 is what suits me best. 75 is my "peak revs" figure. These figures are a bit low, but then, I am old, and these figures are comfortable.

This is another example of assuming what is right for a pro roadie must be right for every cyclist.

There are no hard and fast rules, but two riders with a lot more experience than me reckon 60 to 70 is about right for leisure riding of a hybrid/upright bike.

Even in pro roadie circles, the fashion for three figure cadences is fairly recent.

It is credited to Lance Armstrong.

I'm not going to tell Chris Froome his 125rpm cadence is wrong, and I bet he wouldn't suggest it's suitable for a recreational cyclist on a hybrid.

 

[neptune]

@rob F. I think your comments are spot on. In recent weeks, I have taken part in a few "Skyrides", which are organised by our local cycling club. I ride a hybrid, but most of the other riders have high tech roadbikes. We tend to pootle along at around 11 or 12 MPH. I was quite surprised that most of the other riders use a cadence similar to my own.

Going back to methods of measurement, I now think that the last method is simplest. All you need is a tape measure, a piece of chalk, and perhaps a helper. It saves you getting oily fingers counting sprocket teeth. It also works on hub gears.

 

[NZgeek]

It also works on hub gears.

'Cept the Nuvinci's

I've recently been trying to find my favourite cadence for certain situations.

My cargo bike is having an 8Fun BBS mid-drive and a Nuvinci Autoshifting CVP, so I can program it to different cadences for hills or flats etc.

I'm either going to have to go "trial and error", or get something to measure cadence. Even my commuter cycle has a manually shifted Nuvinci, so I can't do any calulating - trying to measure it on a flat bit of road is near impossible around here too.

Rough timing/counting measurements seem to suggest 73 for me most of the time, and a little faster for climbing (maybe 80???).