Indeed - I had completely forgotten to show the formula(s). The calculation (formulas): π ("Pi") = 3.14 Circumference = 2 ⋅ Radius ⋅ π Diameter = 2 ⋅ Radius Circumference = Diameter ⋅ π Diameter = Circumference / π That's how we calculate the outer diameter from the measured circumference. Then, to get the ERD, we need to: - Measure the distance from the outer rim's edge to the spot where the nipple is seated. (This is noted as X1 for ERD1 and X2 for ERD2 in the video's example graph) - Substract the double of that from the outer Diameter (because we have that "extra" on both ends of the rim). So: ERD = Diameter - (2 ⋅ X) Relja
A gigantic set of calipers would be easier. Read with a ruler. Perhaps a bar clamp used for woodworking could be adapted. ERD can be looked up at various sites but can vary from published data.
If you have any questions, please use the BikeGremlin forum (I try to respond to every comment, but RUclips sucks at notifications, especially when it comes to any follow-up questions): www.bikegremlin.net/ Relja
This is the worst video I've found on the topic. You don't explain the calculation you're making with the distance you measured 🤬
Indeed - I had completely forgotten to show the formula(s).
The calculation (formulas):
π ("Pi") = 3.14
Circumference = 2 ⋅ Radius ⋅ π
Diameter = 2 ⋅ Radius
Circumference = Diameter ⋅ π
Diameter = Circumference / π
That's how we calculate the outer diameter from the measured circumference.
Then, to get the ERD, we need to:
- Measure the distance from the outer rim's edge to the spot where the nipple is seated.
(This is noted as X1 for ERD1 and X2 for ERD2 in the video's example graph)
- Substract the double of that from the outer Diameter (because we have that "extra" on both ends of the rim).
So:
ERD = Diameter - (2 ⋅ X)
Relja
@@BikeGremlinUS thank you for adding it to the description 🙏
No problem. Thanks for pointing that out. :)
Relja
As always, another useful and helpful method of doing things on our bikes. Thanks a lot.
..... and, a Happy New Year to you!
Thank you for this! It's exactly what I needed!
Great video man! And your English is fantastic. Thanks for this.
Thanks for awesome tip!!!
Thank you!
Great piece of information! Can I replace a 26*4.0 inch tyre with a 26*3.0 where the rim width of the bike is 40mm. Do I need to also change the tube?
@@BikeGremlinUS Thank you so much. Also thanks for sharing the thorough articles. Just becoming a fan of your channel!
Here's my chart on which tyre will safely fit which rim width (and what to measure on the rim):
bike.bikegremlin.com/285/bicycle-tyre-dimensions/#t2
Awesome!
I have NEVER seen such complicated and twisted method of measuring a bike wheel !
Yes - it is more complicated to do it on a finished wheel, but sometimes it's needed.
Srpska verzija?
A gigantic set of calipers would be easier. Read with a ruler. Perhaps a bar clamp used for woodworking could be adapted. ERD can be looked up at various sites but can vary from published data.
I'd also add that not every manufacturer gets it right (i.e. the way of measuring differs, so it can put my spoke-length calculations off).
If you have any questions, please use the BikeGremlin forum (I try to respond to every comment, but RUclips sucks at notifications, especially when it comes to any follow-up questions):
www.bikegremlin.net/
Relja
622 erd rim has a larger circumference than 596. I am not asking anything about the Erd. Just wondering if 622 is a bigger circle rim than 596?