led in bed randomly searching for new things to do and change on my mini and found that you can fit push bike speedos.. how true is this and if so are the accurate and hard to fit? any ideas on this? thanks.
Digital Speedo
Started by
jcollingwood
, Aug 17 2011 11:21 AM
9 replies to this topic
#2
jcollingwood
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Stage One Kit Fitted
Posted 17 August 2011 - 11:48 AM
**are they accurate and hard to fit?
#3
dklawson
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Posted 17 August 2011 - 12:03 PM
You can use the search features here to learn about fitting both bicycle and motorcycle speedometers. There have been several threads.
I have a Sigma BC1600L (bicycle) computer on my Mini. It supplements (in MPH) my metric (KPH) Smiths speedometer. They are easy to fit.
Accuracy depends on what you put into it. You can calculate the pulses the bike speedo will receive per mile and program that scale factor. That will get you close. After that you can tweak that initial value up or down as needed to exactly match GPS measurements. As I said, it all depends on how accurate you want it to be. Regardless, the gauge will be consistent and steady.
FYI, I chose the Sigma BC1600L because it has a EEPROM chip that holds the memory settings even when the battery goes dead. This means you don't loose your odometer readings or the scale factor. That's a real plus.
Some people fit various Trailtec bike speedos. You will also find numerous threads for people fitting the Acewell motorcycle gauge. They each have their own attraction.
I have a Sigma BC1600L (bicycle) computer on my Mini. It supplements (in MPH) my metric (KPH) Smiths speedometer. They are easy to fit.
Accuracy depends on what you put into it. You can calculate the pulses the bike speedo will receive per mile and program that scale factor. That will get you close. After that you can tweak that initial value up or down as needed to exactly match GPS measurements. As I said, it all depends on how accurate you want it to be. Regardless, the gauge will be consistent and steady.
FYI, I chose the Sigma BC1600L because it has a EEPROM chip that holds the memory settings even when the battery goes dead. This means you don't loose your odometer readings or the scale factor. That's a real plus.
Some people fit various Trailtec bike speedos. You will also find numerous threads for people fitting the Acewell motorcycle gauge. They each have their own attraction.
#4
jcollingwood
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Stage One Kit Fitted
Posted 17 August 2011 - 12:30 PM
i have been reading threads on people fitting push bike speedos to the pot joint... this seems fairly straight forward but i dont understand the calibration.
for example fitting it to a push bike with a wheel size (x) if the magnet and sensor are fitted at any two different points of the wheel there is going to be a different number of rotations per min.. hence it will display a different speed reading?? correct if im wrong.. but that tells me you have to calibrate it somehow?
for example fitting it to a push bike with a wheel size (x) if the magnet and sensor are fitted at any two different points of the wheel there is going to be a different number of rotations per min.. hence it will display a different speed reading?? correct if im wrong.. but that tells me you have to calibrate it somehow?
#5
dklawson
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Posted 17 August 2011 - 01:05 PM
Something happened to my browser while typing a reply and I lost everything.
The succinct answer to your question is:
Yes, you do calibrate the bike computer by determining a pulse per mile scale factor based on the circumference of your car's tire size. You program that pulse per mile value into the bike computer so it is calibrated for your car.
GPS and/or measured mile measurements can then be used to fine tune that scale factor up or down to achieve the accuracy you want.
The succinct answer to your question is:
Yes, you do calibrate the bike computer by determining a pulse per mile scale factor based on the circumference of your car's tire size. You program that pulse per mile value into the bike computer so it is calibrated for your car.
GPS and/or measured mile measurements can then be used to fine tune that scale factor up or down to achieve the accuracy you want.
#6
jcollingwood
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Posted 17 August 2011 - 01:07 PM
ok i understand, but what i now dont understand is how you would determin the number of pulses per mile.
#7
Ethel
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Posted 17 August 2011 - 01:19 PM
There will be instructions with speedo, most allow you to input the wheel circumference.
Trailtech & Acewell are 2 popular makes that produce moderately priced instruments suitable for cars. You could do it cheaper with a pushbike speedo, but it wont be designed to hook up to your battery & is unlikely to have a back light - or fuel gauge!
Trailtech & Acewell are 2 popular makes that produce moderately priced instruments suitable for cars. You could do it cheaper with a pushbike speedo, but it wont be designed to hook up to your battery & is unlikely to have a back light - or fuel gauge!
#8
dklawson
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Posted 17 August 2011 - 02:59 PM
Ethel is correct. The Sigma I have does not have a backlight or fuel gauge. However, I am only using it to supplement my stock speedo so that is not important to me. However, I have added an LED light to shine on the display of my Sigma so I can read it at night.
As for calculating the pulses per mile... don't take this wrong but it is fairly simple math.
Tire circumference can be measured or taken from tire size tables.
1 mile = 5280 feet or 63,360 inches
1 mile divided by the tire circumference (using the same units... feet, inches, etc) = the number of tire revolutions per mile = the number of pulses per mile when one magnet is mounted to a driveshaft or rim.
The reset comes down to how to enter that value into the bike computer. As Ethel said, it will be explained in the bike computer instructions.
As for calculating the pulses per mile... don't take this wrong but it is fairly simple math.
Tire circumference can be measured or taken from tire size tables.
1 mile = 5280 feet or 63,360 inches
1 mile divided by the tire circumference (using the same units... feet, inches, etc) = the number of tire revolutions per mile = the number of pulses per mile when one magnet is mounted to a driveshaft or rim.
The reset comes down to how to enter that value into the bike computer. As Ethel said, it will be explained in the bike computer instructions.
#9
jcollingwood
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Posted 17 August 2011 - 03:03 PM
thanks. i understand it all now and am just looking and asking around for what bike computer to get. does it matter if it is wireless or not?
#10
dklawson
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Posted 17 August 2011 - 03:12 PM
Do not get wireless. Wireless bicycle computers are designed for short, line-of-site communication between the sender and the computer. They were not designed for cars and won't work well on them.
Sigma, Trailtech and Acewell are the most common choices and I listed them in what will probably prove to be an increasing levels of sophistication and cost. I am happy with my Sigma and consider it a good introductory model. If you want more features later you can move up to the other brands and invest a bit more.
Sigma, Trailtech and Acewell are the most common choices and I listed them in what will probably prove to be an increasing levels of sophistication and cost. I am happy with my Sigma and consider it a good introductory model. If you want more features later you can move up to the other brands and invest a bit more.
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