What wheel circumference #'s are you using?

update. went out and rode on a walking path with rough measured distances. I went 1.5mi according to path and 1.9 according to my computer. the path is wide and arced, but no corners. I then put in 180cm, rode the path .9mi and my computer said .87mi. i put in 183 when I got home(started raining) so I will try again another day, but I am close, but off the recommended chart. i will also try somewhere with more accurately measured distances.

Measure the diameter of your wheel in inches , multiply that number by 3.146 . That gives you the circumfrence . Multiply that number by 25.4 , that will net you mm's.

Pretty much as AZMTNS said I measure the tyre height (diameter), take off approximately 5mm (allows for the rider weight); more if I'm running low pressure; multiply it by 3.1428 (it's what my calc gives) and then set that measurement in the computer.

E.g. my Nevegals measured 655mm and the computer is set at 2.058 metres if I remember correctly.

By the way, it was nowhere near the measurements in the computer installation guide.

jerk

if you guys read my first post you would have seen that I did a roll out, w/ weight on the tire.

Don't post sh!t unless you have read the WHOLE message!

Expecting someone to have the exact same tire with the exact same pressure measured with the exact same gauge and using the exact same computer as you to respond to your thread with calibration numbers is a little silly.

Best way to do a rollout is to use a really long tape and then find the distance for 10 weighted wheel rotations (or more) and then find the average distance for one rotation. One rotation is just okay, and the tire is probably not weighted completely.

Happy New Year, jerk!

Azmtn- so in your post after you read mine, you tell me to measure my wheel in a less accurate way, and by the way, pi is 3.1415, not 3.146. which is an answer to a question I did not ask, then get butt hurt when I don't like it, what did you expect? I don't doubt you read my post but you didn't take the time to understand what I wanted. You also skipped over my update(post #2) which had more info and to get my computer close to accurate I had to shorten my wheel circumference by 23cm. 23cm = ~9in. that is a very large amount and you missed it.

-peace

The numbers you rolled out initially look to be spot on. 183 is definitely too small. Have you checked the computer is set to miles, not kilometers?

joelsman said:

i will also try somewhere with more accurately measured distances.

Click to expand...

You may have answered the question, how do you know the accuracy of the bike path markers?

what happens when you hit jumps and the wheel spins in the air?

wow I almost just said yes without checking to see if it was still on mph, I did set it originally on mph, but it was on Kph.

Thank you

should be good to go now.

Roger that, good to go.