After much faffing about, I releasing my first set of bicycle frame tube wall thickness measurements. You can find them here:
Included in this first data set are an interesting selection of Rawland, Rivendell, Surly, and other production bicycles.
I've spent a goodly amount of time with a crashed Centurion Ironman frame (Tange #1, 4130) taking ultrasonic measurements and then cutting up tubes, deburring, carefully sanding away paint, and then re-measuring with a high quality set of Mitutoyo digital calipers. I've also spent a great deal of time comparing other frames against tubing manufacturer and frame manufacturer specifications. I am now confident my measurements are reasonably accurate for bikes made of 4130 steel, which is most bikes. Let's say within 5%, probably better. They should also be fairly representative for bikes made of other alloys, more testing to come.
Note: I am providing these results at the full resolution of the device I used to measure, but please don't get too hung up on hundredths of a millimeter. I recommend rounding up. Or down. Whichever makes you feel better.
Thanks to everyone at the Bicycle Quarterly Un-Meeting last weekend who let me measure your frames, to Eric Keller who originally suggested ultrasonic measurement, to Joshua Horowitz who provided the crashed Centurion, and Charles Vasta who donated a damaged Reynolds 531 frame for testing and calibration.
A very special thanks to Jan Heine, Mark Vande Kamp, Alex Wetmore, and Hahn Rossman for their work in identifying, researching, and teaching about the concept of planing.
Things to do better going forward: Carry a caliper to measure tubing diameter and a tape measure to measure frame size. If anyone knows any of the folks whose bikes I measured at the Un-Meeting please put me in touch! I'd love to get their frame sizes.
And if you're able to make it to San Francisco with your bike, please drop me a line, I'd love to measure your frame. Even if I've already measured another one of the same type, it would be ideal to confirm those results.
San Francisco, CA