|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Accurate calibration of cycle computers/cyclometers
Accurate calibration of cycle computer
I measure the distance convered by several revolutions of the wheel that I am calibrating. Make a scratch mark on the surface with the valve stem at the bottom of the wheel. Make several revolutions of the wheel and make another scratch mark with the stem at the bottom again. I usually use 10 wheel revolutions. Measure this distance and record it. If the distance was measured in feet, you usually have to convert it to centimeters to use it in setting your wheel circumferance. First, find your wheel circumferance by dividing the distance by the number of wheel revolutions. Then multiply this answer 30.48 -- this will be the number you use to set the wheel size. Some cyclocomputers require different inputs for KPH or MPH. - If you need to use a conversion factor to change from KPM to MPH, simply divide the kilometer wheel size number by 1.61 - this should give you speed and distance in miles instead of kilometers. The tables included with bicycle electronic speedometers work pretty well, but I like to calibrate them accurately, so I inflate my tires to working pressure and sit on the bike while doing the wheel measurements so that they will be more typical of actual operation. |
Ads |
#2
|
|||
|
|||
"Dex" wrote in message news:1122470159.70c6ed5bb0271305fb5d1b10abb65485@t eranews... Accurate calibration of cycle computer I measure the distance convered by several revolutions of the wheel that I am calibrating. Make a scratch mark on the surface with the valve stem at the bottom of the wheel. Make several revolutions of the wheel and make another scratch mark with the stem at the bottom again. I usually use 10 wheel revolutions. Measure this distance and record it. If the distance was measured in feet, you usually have to convert it to centimeters to use it in setting your wheel circumferance. First, find your wheel circumferance by dividing the distance by the number of wheel revolutions. Then multiply this answer 30.48 -- this will be the number you use to set the wheel size. Some cyclocomputers require different inputs for KPH or MPH. - If you need to use a conversion factor to change from KPM to MPH, simply divide the kilometer wheel size number by 1.61 - this should give you speed and distance in miles instead of kilometers. The tables included with bicycle electronic speedometers work pretty well, but I like to calibrate them accurately, so I inflate my tires to working pressure and sit on the bike while doing the wheel measurements so that they will be more typical of actual operation. Do some cyclometers have more than one digit of accuracy? My Cateye only has a single digit to the right of the decimal. I think there is going to be a 1% tolerance at best. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#3
|
|||
|
|||
bent_pilot wrote:
Do some cyclometers have more than one digit of accuracy? My Cateye only has a single digit to the right of the decimal. I think there is going to be a 1% tolerance at best. Cateye Astrale can be done to the nearest mm, as can the Trek Incite 11 which I have on my MTB after the Astrale which used to live there went to sleep with the fishes. At the bottom of the canal. The Mity, however, can only be set to the nearest cm. Don't know about any others, as it's been ages since I've used anything else. -- Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/ A complimentary biro(tm) is /not/ to be sniffed at. |
#4
|
|||
|
|||
"Dave Larrington" wrote in message ... bent_pilot wrote: snippage Cateye Astrale can be done to the nearest mm, as can the Trek Incite 11 which I have on my MTB after the Astrale which used to live there went to sleep with the fishes. At the bottom of the canal. -- Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/ A complimentary biro(tm) is /not/ to be sniffed at. I certainly hope you applied for the proper licenses for adding to the detritis at the bottom of the canal. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#5
|
|||
|
|||
Dex wrote:
Accurate calibration of cycle computer I measure the distance convered by several revolutions of the wheel that I am calibrating. Make a scratch mark on the surface with the valve stem at the bottom of the wheel. Make several revolutions of the wheel and make another scratch mark with the stem at the bottom again. I usually use 10 wheel revolutions. Measure this distance and record it. If the distance was measured in feet, you usually have to convert it to centimeters to use it in setting your wheel circumferance. First, find your wheel circumferance by dividing the distance by the number of wheel revolutions. Then multiply this answer 30.48 -- this will be the number you use to set the wheel Where does this number come from? The conversion I use is: millimeters = Inches * 2.54 A 20 inch wheel should be in the range of 1400 - 1500 if your cyclometer takes 4 digits. If it only uses 3 digits it would be 140 - 150, and I'd toss it to get a cyclometer that is some accuracy, not just a guess at speed and distance. mike |
#6
|
|||
|
|||
"Mike" wrote in message link.net... Dex wrote: Accurate calibration of cycle computer I measure the distance convered by several revolutions of the wheel that I am calibrating. Make a scratch mark on the surface with the valve stem at the bottom of the wheel. Make several revolutions of the wheel and make another scratch mark with the stem at the bottom again. I usually use 10 wheel revolutions. Measure this distance and record it. If the distance was measured in feet, you usually have to convert it to centimeters to use it in setting your wheel circumferance. First, find your wheel circumferance by dividing the distance by the number of wheel revolutions. Then multiply this answer 30.48 -- this will be the number you use to set the wheel Where does this number come from? The conversion I use is: millimeters = Inches * 2.54 A 20 inch wheel should be in the range of 1400 - 1500 if your cyclometer takes 4 digits. If it only uses 3 digits it would be 140 - 150, and I'd toss it to get a cyclometer that is some accuracy, not just a guess at speed and distance. mike A mm=1"/25.5 (.03937"/mm) so inches*25.4=mm. A centimeter is 10 mm, cm*2.54=inches. These conversions come from Machinery's Handbook. Where do your numbers come from, Mike? Either you made a typo, or your values are off by a factor of 10. Dex, what's with the 30.48??? ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#7
|
|||
|
|||
"bent_pilot" wrote in message ... "Mike" wrote in message link.net... Dex wrote: Accurate calibration of cycle computer I measure the distance convered by several revolutions of the wheel that I am calibrating. Make a scratch mark on the surface with the valve stem at the bottom of the wheel. Make several revolutions of the wheel and make another scratch mark with the stem at the bottom again. I usually use 10 wheel revolutions. Measure this distance and record it. If the distance was measured in feet, you usually have to convert it to centimeters to use it in setting your wheel circumferance. First, find your wheel circumferance by dividing the distance by the number of wheel revolutions. Then multiply this answer 30.48 -- this will be the number you use to set the wheel Where does this number come from? The conversion I use is: millimeters = Inches * 2.54 A 20 inch wheel should be in the range of 1400 - 1500 if your cyclometer takes 4 digits. If it only uses 3 digits it would be 140 - 150, and I'd toss it to get a cyclometer that is some accuracy, not just a guess at speed and distance. mike A mm=1"/25.5 (.03937"/mm) so inches*25.4=mm. A centimeter is 10 mm, cm*2.54=inches. These conversions come from Machinery's Handbook. Where do your numbers come from, Mike? Either you made a typo, or your values are off by a factor of 10. Dex, what's with the 30.48??? There are 30.48 cm in a foot (12 * 2.54). Jerry |
#8
|
|||
|
|||
This thread is timely for me because I just got in from doing a roll
out for my ScooterBike CLWB (16 x 1.75 front) to fit it for a new computer. I'll post the results here in case it helps someone else. I marked the start and rolled out 4 revolutions of the front tire (sitting on the bike). I repeated the roll out 3 times and it came out to 196 inches per roll out. So, one revolution comes out to: 196 / 4 = 49). 49 inches x 25.4 = 1244.6 mm. Let's call it 1245 even. |
#9
|
|||
|
|||
I use White-out on the concrete garage floor
"Dex" wrote in message news:1122470159.70c6ed5bb0271305fb5d1b10abb65485@t eranews... Accurate calibration of cycle computer I measure the distance convered by several revolutions of the wheel that I am calibrating. Make a scratch mark on the surface with the valve stem at the bottom of the wheel. Make several revolutions of the wheel and make another scratch mark with the stem at the bottom again. I usually use 10 wheel revolutions. Measure this distance and record it. If the distance was measured in feet, you usually have to convert it to centimeters to use it in setting your wheel circumferance. First, find your wheel circumferance by dividing the distance by the number of wheel revolutions. Then multiply this answer 30.48 -- this will be the number you use to set the wheel size. Some cyclocomputers require different inputs for KPH or MPH. - If you need to use a conversion factor to change from KPM to MPH, simply divide the kilometer wheel size number by 1.61 - this should give you speed and distance in miles instead of kilometers. The tables included with bicycle electronic speedometers work pretty well, but I like to calibrate them accurately, so I inflate my tires to working pressure and sit on the bike while doing the wheel measurements so that they will be more typical of actual operation. |
#10
|
|||
|
|||
bent_pilot wrote:
I certainly hope you applied for the proper licenses for adding to the detritis at the bottom of the canal. Yes, and sadly when British Waterways discovered that my bike does not currently have a permanent mooring, they charged me extra for a Continuous Cruising one :-) -- Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/ Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger Badger |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Unite Against Cycle Paths! | Steve McGinty | UK | 8 | August 15th 04 10:12 PM |
Helmets | Vivian | UK | 460 | April 28th 04 09:38 PM |
BRAKE on helmets | Just zis Guy, you know? | UK | 62 | April 27th 04 09:48 AM |
Who is going to Interbike? | Bruce Gilbert | Techniques | 2 | October 10th 03 09:26 PM |
Pick 'n Pay Cape Argus Cycle Tour - Cape Town, South Africa, 2004 | David Cowie | Racing | 0 | August 28th 03 10:29 PM |