Speed = Cadence

N

Nvreloader

Well-Known Member
Region
USA
I am attempting to add mph & cadence into my log book.

I am using this calculator = https://www.gear-calculator.com/,
I set all the info block to match my gearing and speed per OEM Display and my accurate Gramin GPS 60cxs, all the info blocks can be change via the gear/wheel display at the top right corner.
I then move the cadence block until the speed matches the display and GPS readings,
then get the cadence info. (Click on wheel center for minute changes)

I know the display is off, (can't change it, tire set for 26",) as compared to the GPS readings.

44T Ring and 34T back gear = 100# bike and 200#'s for me,
26.5" Fat Tire @ 15 psi F and 20 psi B = 2350mm tire circumference (measured) = 29.5" tire Dia,

No power, display is on to read the info only,
Speed = Display vs GPS - cadence readings for both/Manual Pedal only
Mph = 6.4 Display vs 7.0 GPS = 52 rpm -62 rpm cad

44T ring and 34T gear
Power on, Eco -1 step,
Speed = Display vs GPS - cadence readings for both/Pedal Only
Mph = 7.1 Display vs 7.4 GPS = 63 rpm -66 rpm cad

44T ring and 34T gear
Power on, Eco -1 step,
Speed = Display vs GPS - cadence readings for both/Throttle Only
Mph = 15.0 Display vs 15.5 GPS = 133 rpm -139 rpm cad

All the above reading were taken 2 times = up and back, for the same distance/wind factor.

Would these be accurate readings/SWAG?

Your thoughts and suggestions..........
Tia,
 
Thanks Matt
The only problem is that calculator doesn't work with fat tires and I can't change to tire circumference either to fit these tire sizes.
 
Nvreloader said:
I am attempting to add mph & cadence into my log book.

I am using this calculator = https://www.gear-calculator.com/,
I set all the info block to match my gearing and speed per OEM Display and my accurate Gramin GPS 60cxs, all the info blocks can be change via the gear/wheel display at the top right corner.
I then move the cadence block until the speed matches the display and GPS readings,
then get the cadence info. (Click on wheel center for minute changes)

I know the display is off, (can't change it, tire set for 26",) as compared to the GPS readings.

44T Ring and 34T back gear = 100# bike and 200#'s for me,
26.5" Fat Tire @ 15 psi F and 20 psi B = 2350mm tire circumference (measured) = 29.5" tire Dia,

No power, display is on to read the info only,
Speed = Display vs GPS - cadence readings for both/Manual Pedal only
Mph = 6.4 Display vs 7.0 GPS = 52 rpm -62 rpm cad

44T ring and 34T gear
Power on, Eco -1 step,
Speed = Display vs GPS - cadence readings for both/Pedal Only
Mph = 7.1 Display vs 7.4 GPS = 63 rpm -66 rpm cad

44T ring and 34T gear
Power on, Eco -1 step,
Speed = Display vs GPS - cadence readings for both/Throttle Only
Mph = 15.0 Display vs 15.5 GPS = 133 rpm -139 rpm cad

All the above reading were taken 2 times = up and back, for the same distance/wind factor.

Would these be accurate readings/SWAG?

Your thoughts and suggestions..........
Tia,
Click to expand...
Sorry, I don't follow. Once you have the correct tire circumference, what are you trying to accomplish here?
 
Nvreloader said:
I know the display is off, (can't change it, tire set for 26",) as compared to the GPS readings.
...
26.5" Fat Tire @ 15 psi F and 20 psi B = 2350mm tire circumference (measured) = 29.5" tire Dia,
Click to expand...
Surely you can choose a different "stock" size on the display. I'd play around to see if a larger stock size ends up with closer approximation of your tire's actual circumference.
 
Jeremy
I not sure of your post..........???

I do not know what my cadence is, at whatever speed, I am moving.

I am checking what the approximate cadence is,
via the GPS speed obtained, from the gears ratio used = 44R/34G teeth.

The calculator I listed does NOT have the correct tire size for my bike,
26 x 4.5" @ 2350mm circumference (measured).
therefore I have to use the circumference of my measured tires, ONLY
(to set up the calculator) along with the chain ring and the cassette gears info etc.

I set the calculator Display to the speed (mph) setting, (bottom row of boxes),
then change the speed readings (above the triangles posted for the gear tooth) speed) via the cadence settings until everything matches, ie gear ratios vs speed = cadence.

Set the calculator to these values/settings,
Use the gear design TOP right corner, click on it,
change the cadence to 50 > 150, click OK,
Change the tire circumference to 2350mm, (rear tire measurement),
Set the ring gear @ 44T and the cassette gear @ 34Teeth,
Set the display reading to speed, box/bottom row.

What does the 34T gear speed read = 5.67mph @ 50 (rpm) cadence..
(look right above the black triangle, for the speed),
move the cadence wheel slightly to the right,
the 34T gear (mph reading) will change,
click on the outside of the the circle (right side) and the speed will increase,
click on the left inside edge of the circle and the speed will decrease,
adjust till you reach 6.4 mph, (my speed) according to my GPS readings,
the cadence is approximately 57rpm's.
If you change the speed to 7.0 = via the cadence rpm's = 62 cadence.

So I have a cadence of between 57 & 62 rpm's,
depending on what figures you use.
I trust my GPS speed reading's.

I DO NOT trust the OEM display as you can't change any of the values/settings.
ymmv
 
smorgasbord said:
Surely you can choose a different "stock" size on the display. I'd play around to see if a larger stock size ends up with closer approximation of your tire's actual circumference.
Click to expand...
Smorg
The largest 26" tire listed is 2160mm, I am at 2350mm for accurate measurements.
Every calculator I have found and used, does not jive with the measured measurements listed for 26x4.5" @ 2350mm for my tires etc.
Thanks,
Don
 
PedalUma said:
An easy way to do this is to measure using a piece of chalk. Mark the starting line on your driveway and sidewall then roll one rotation. Mark that spot. Tape measure. Divide by Pi to get the diameter. This way the thickness of a tire will not matter. The measurement is the number.
Click to expand...
Ped
I have done this 3 different times and 3 different ways,
come up with 2350mm every time.
The last time was propping up the tire, marking an ink across the tire, then stretched
a tight string on the exact center of the tire, to get the total overall circumference distance/length, changed the inches into mm and have the same 2350mm readings.
ymmv
 
Note the diameter in most displays is not the actual tire diameter, but the nominal wheel size
Nvreloader said:
The largest 26" tire listed is 2160mm, I am at 2350mm for accurate measurements.
Click to expand...
OK, so a 29" X 2.3 would give you 2326mm to 2330mm. That's off by only 1.1%

Some charts:
www.schwalbe.com

Bicycle Tire Dimensions | Schwalbe

All information about tire dimensions for bicycles and suitable rim sizes can be found at schwalbe.com. Discover now ►
www.schwalbe.com www.schwalbe.com
 
your working a lot for a easy thing. just use a timer and count your strokes if you dont want to buy a cadence sensor. why to to all this effort for a simple count or 15.00 easy fix?
 
Nvreloader said:
The last time was propping up the tire, marking an ink across the tire, then stretched
a tight string on the exact center of the tire, to get the total overall circumference
Click to expand...
Don't forget your riding circumfrance is shorter than unloaded circumfrance because of tire deflection.
 
Nvreloader said:
Jeremy
I not sure of your post..........???

I do not know what my cadence is, at whatever speed, I am moving.

I am checking what the approximate cadence is,
via the GPS speed obtained, from the gears ratio used = 44R/34G teeth.

The calculator I listed does NOT have the correct tire size for my bike,
26 x 4.5" @ 2350mm circumference (measured).
therefore I have to use the circumference of my measured tires, ONLY
(to set up the calculator) along with the chain ring and the cassette gears info etc.

I set the calculator Display to the speed (mph) setting, (bottom row of boxes),
then change the speed readings (above the triangles posted for the gear tooth) speed) via the cadence settings until everything matches, ie gear ratios vs speed = cadence.

Set the calculator to these values/settings,
Use the gear design TOP right corner, click on it,
change the cadence to 50 > 150, click OK,
Change the tire circumference to 2350mm, (rear tire measurement),
Set the ring gear @ 44T and the cassette gear @ 34Teeth,
Set the display reading to speed, box/bottom row.

What does the 34T gear speed read = 5.67mph @ 50 (rpm) cadence..
(look right above the black triangle, for the speed),
move the cadence wheel slightly to the right,
the 34T gear (mph reading) will change,
click on the outside of the the circle (right side) and the speed will increase,
click on the left inside edge of the circle and the speed will decrease,
adjust till you reach 6.4 mph, (my speed) according to my GPS readings,
the cadence is approximately 57rpm's.
If you change the speed to 7.0 = via the cadence rpm's = 62 cadence.

So I have a cadence of between 57 & 62 rpm's,
depending on what figures you use.
I trust my GPS speed reading's.

I DO NOT trust the OEM display as you can't change any of the values/settings.
ymmv
Click to expand...
Sounds like you're logging ground speed and want to convert your speeds in mph to cadences in rpm for a wheel circumference of 2350 mm = 2.35 m and a fixed gear ratio of R = 44/34 = 1.294.

Here's a one-step conversion specific to this case:

C = 8.82 * Vg

where C is cadence in rpm, and Vg is ground speed in mph. So when you're riding at Vg = 10 mph, your cadence C in this gear is 88.2 rpm.

If you'd like to experiment with the gear ratio R = (chainring teeth) / (cog teeth), the conversion becomes

C = 11.4 Vg / R

Derivation of conversion factors available on request.
 
Last edited:
www.coospo.com

BK467 Cycling Speed/Cadence Sensor

BK467 cadence or speed sensor wirelessly transmits your speed or cadence data to compatible bike computers or cycling Apps to help you monitor your cycling performance.
www.coospo.com www.coospo.com


For $20 (or less) you could just get this done.
 
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