How To Determine Wheel Size For A Bike Computer BikeBlogger
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- čas přidán 29. 05. 2015
- The easiest way of how to determine the wheel size for a bike computer is to roll the bike on the ground.
First, pump up the tires.
Second, place a tape measure on the ground.
Third, line the front wheel up with the tape measure with the valve stem as a reference point.
Fourth, roll the bike forward next to the tape measure one complete turn of the wheel.
Fifth, the place where the wheel stops is the measurement you need to input into the bike computer. The unit conversion from inches to millimeters is (inches x 25.4 = millimeters).
Sigma is a bike computer manufacturer and they are really good at providing helpful installation videos, for instance, here are links for the Sigma BC 8.12 ATS.
Installation • SIGMA SPORT // BC 8.12...
Settings • SIGMA SPORT // BC 8.12...
Functions • SIGMA SPORT // BC 8.12...
Manual www.sigmasport.com/us_media/pr...
I prefer wired bike computers, but to each his/her own.
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5 year old video but still saving the day!
Thanks for the video!
Most accurate way to measure wheel; pump to correct pressure, then get a pen and make a make across the tire then ride forward straight away with ink still wet, then you will have two makes on the floor, then measure, 100% accurate every time.
I've owned 3 Sigma computers, 2 of which I still have after 15 years of buying them, I've never had to zip tie the docking stations, nor have I ever had to tape the computer to the docking station, and never once had a computer go flying off. One of the Sigma computers the rubber band thing broke when I went to remove the computer docking station from the bike to put it on another bike, and that one I did zip tie back onto the handlebar. I've ridden my bikes down chip and seal roads, gravel roads, roads that were in extreme disrepair with cracks and pot holes, over railroad tracks, etc and never had a computer come off. I've had and still have Cateye and VDO computers and none of those ever came off unexpectedly either.
You should try and sit on the bike when rolling it forward. The weight will change the size of the tire slightly. I usually do it 3 times and use the average. But since I hardly ever ride a straight line (dodging potholes and such) I guess it doesn't have to be perfect.
I was going nuts how to figure the wheel size.. you did it so easy.. thanks and Happy Easter !!!!
Thank you for this video! I needed to do this after a new battery change. I forget everytime how to do this because the time it takes to drain 1 battery is like 2-3 yrs lol
Clear and concise... Thanks FYI: Some tape measures have Millimeter numbers on the other side of the ruler that can be used therefore eliminating the calculating portion of this exercise...
Thanks, I lost the information and this is a simple tutorial to follow and makes sense. Gr8 work
thank you for all this information,great video!!!! got it to work.
Very well explained Thanks a lot, Gr8 help Cheers
what a useful information you shared ! i've been searching for this, and now i got this.. haha,, thx a lot
Very cool! Thank you,
exactly the same size wheel👍👍
I have an old BC800 that had a dead battery, and I wanted to reuse it on my mountain bike converted to a stationary bike. I put a new battery in, but couldn't get it to accept any programing. Then you said hold the Reset button down 3 seconds. It worked, my wheel size was correct, and I was able to change from KPH to MPH. THANK YOU!!!!!!
simple stuff when someone who knows how shows you how,, Thanks! (my kid lost the instructions)
Thanks! After watching this vid, it seems pretty do-able.
Thanks alot. Very easy!
Thank you man, you are a lifesaver
Where up and down on the fork and spoke do you mount the sensor and magnet? How do you determine the accuracy of the reading?
mine easy computer just dial in 700c with the size of the tyre job done
Well defined... short and sweet
Thanks a lot! This is so damn helpful!
Love from INDIA ❤️ thanks
Hello there, I just picked up a SIGMA SPORT 500 for a GIANT REVEL mountain bike. I will be using it 95% of the time on the streets. The problem I need help with is where do I set the transmitter and magnet on the suspension fork and spoke ? Can you help me ? My tire is a 26 x 2,10 and after measuring three times the rotation is 81 inches.
Also... the more revolutions you can do the lower your overall error will be
I like to do 3.. I use on of my kids to help me
Thank you.
thanks man!
Very nice video
I have the Sigma 1009. The tire size is 26 X 2.125. What would be the approx setting? I saw a chart that equals 1325. But your method give me 2074.
measure the wheel from end to end going through the center to find the diameter "D". and use the formular πD on a calculator to get it much more accurate.
That's what I was thinking
Great informative video bike blogger! I would presume if the tire lost some air, that would effect the accuracy of the speed and distance somewhat wouldn't it?
SolarReturn Most tires do not lose that much pressure each day to make a big difference. It is sort of like the difference observed when putting more weight on the wheel. For best accuracy you just don't want to set it based on an under-inflated tire.
I've been debating on what wheel size I should get for my committee bike. Should I get the 700 or the 26 inch I want to use my bike for school and work so far I have chosen the surly long haul trucker frame but I just don't know what wheel size should I get. I am 6 feet tall
Paulo Ramirez Hello Paul Ramirez. There are many more tire choices with the 700c, so I would stick with that since it has become the standard. 26 inch will give you more wide tire options though. I have a 26er mountain bike. It can corner faster and accelerate faster than 29er's (700c) but cannot roll over things as easily.
PROBLEM.. hopefully you can help? I purchased the Pedrone for my Cannodale Bad Boy 1... This bike has a thick round front (lefty) fork that is making it difficult to mount the speed sensor.. SUGGESTIONS? Thank you
The band that mounts the sensor is basically a rubber o-ring. You might be able to find a larger o-ring at your local hardware store, otherwise maybe some thick rubber band?
ty I will try..
I have been thinking of purchasing the Sigma bc8.12 computer. What are your thoughts on it, I understand that you use Sigma. This video is very helpful for when I end up getting a computer.
Diego C.L I actually do not have any experience with the computer. I have used the Sigma BC 509 and the BC 1009 in the past. If it has the features you desire I say go for it!
I have a question. I use Strava on my iPhone and I mount it on my handlebar with a mount, but it only gives me a map of where I rode, average speed and distance. I would like to know the current speed, cadence and how many km my bike has. What are the differences between using an app vs an actual cycling computer? Is it worth it? I like the Bontrager brand because I buy everything from an authorized store near my house, do you recommend a Bontrager computer? I am a newbie at cycling, I only have like 800-1000 kilometers in my mountain bike. Greetings!
Jorge857 Good question, Jorge857. Unfortunately I do not have any experience using my phone for on demand cycle stats. I would think the accuracy is tied to your cell signal and the phone app. Regarding bike computers, they tend to take the average speed over short bursts of time and display that as current speed. This is evidenced by the fact when you spin the wheel with your hand there is a delay before the computer updates the screen. The algorithms are not exactly the same between bike computers and this is why different computers may display slightly different current speeds at the same time -- you could test this if you were crazy enough to install like 3 bike computers on one bike. LOL Bike computers vs. phone otherwise are not that different. Computers come in all different types, similarly there are a lot of phone apps available. I prefer a bike computer because I do not want to risk dropping my phone.
BikeBlogger I also prefer to have a separate bike computer and save phone battery. In case of emergency on a distant road you should have a functional cellphone with you.
Velogi - Pyöräilevä videoblogi BikeBlogger Well, the battery argument is actually relevant because when I use my phone the battery runs out fast because I use the GPS feature, however, I can take rides for more than 2 hours which is my maximum. The guy on the store said He wouldn´t recommend a cycling computer because it was enough with my phone, but I really want to know my cadence so I can train effectively. I guess I will have to watch some reviews, thank´s for your opinions guys.
+Jorge857 if you know your speed and what gear your in, you can find out what cadence was.
@cook7772: "if you know your speed and what gear your in." Know what gear you're in? That just makes it so much more complicated for several reasons including that you're likely to be changing gears. Your solution is more trouble than it's worth.
thanks now I can re use a bike computer of a bike that got trashed.
mine is 3.50x12 how do you work that in..
how much are for 27.5 and 29er sized wheels please? i have no measuring tool here. please help.
Is it 25.4 for a 26 inch wheel?
you should be sitting on the bike when doing it , a tire under pressure by the weight will be a shorter rolling distance
I used tape to to tape my measuring tape to the tire and then i just rolled the tire while keeping measuring tape at the middle of the tire. I think it's more accurate than the method you used. I did that too and it gave the same measure, but it would have been harder to say when to stop, if I didn't knew the right measure.
Or, just multiply the diameter of the wheel by Pi! Simples!
thank you 4 a great explanation
You're welcome millibs!
Hey to measure tire with just fork cause i dont have a tire
Why not measure the ground to the center of the wheel, times it by 2, then times by 3.14? That seems way easier.
3.1416
Even better, measure ground to center of wheel, then multiply that by TAU (6.28). It's easy to remember that formula, because TAU is the ratio of the RADIUS to the circumference. (It's the equivalent of one "Turn" of the wheel.) Note: Math geeks will notice that the numbers are the exactly the same. It's just that Tau is easiest to remember, and it's all you need for everything except area.
@ 0:25 it looks like the value is about 1 inch away from the end of the tape. This test should be done several times to insure that you are rolling in a straight line - if you get the same result say 3 times then you likely did it correctly. Also you should be sitting on the bike while taking this measurement since you will be on the bike when riding it outside.
.
@ 3:50 It really isn't a good idea to wrap electrical tape around the bike computer to the mount. You may wish to remove the computer now and again and don't want to deal with removing and then reapplying tape.
2.1 29" 90 inches x 25,4? But what is the 25,4 ? cm or inches ?
What is the circumference of a full size adult bike wheel
Good tutorial! Now I understand what that wheel size number means 👍👍👍👍👍💚💚💚💚
My bike tire came out to 82 inches.... when I times it by 25.4 it gives me 2082.8 should I round up to 2083?
I round to nearest whole number.
What is your wheel size? 27.5 or 29?
But you're not taking into account the weight of the rider. The rider's weight will flatten the tire a bit, which will change the tire's effective circumference when under a load. Might not make a difference for only a few miles, but after a 30 mile ride, you're distance could be off by as much as half a mile. Thus to get a true measurement, I'd think that the rider needs to be in the saddle during the measuring process.
sir... good pm sir where did you get the 25.4?hehe
You kinda sound like woody harelson
I have the same bike computer as you
Hi, what's the lenght of your Stem in mm?
+Ramy Bardi On this bike the stem length is 85mm with a 10 degree rise.
hey man great vid should i have to input the wheel size every time i turn it on again
Why 25.4 for mm, where do you get this calculation from?
One inch = 2.54cm, which is 25.4mm.
Ok, this was helpful as I have sooped up my Marin for a flight today and am offski :) many thanks. I am getting 2507, as mine register 81 inches, MTB.
Why not just read the dimensions which are written on the tire?
the size on the side of my tire says 26 and when i use the tape on the ground it's 2600cm, so maybe you can
I am little bit confuse here, where is coming for 25.4. I understand 85cm but how I know how to X 25.4. Please explain.
1 in = 2.54 cm = 25.4 mm
if your gooing to do it that way why wouldnt you measure the back tire instead since your puting most of your weight on your back tire sitting down unless i guess your a speed racer standing i suppose idk seems like you would be putting most your weight on the back tire anyway
It would depend on which wheel your sensor is on. But you've got the right idea.
I got the same measurement as you
There is 25.4mm in one inch not 25.9
You need to do this with your weight on the bike or you will be off by a few %