Originally Posted by
mrrabbit
It does have an upside I like:
It will measure accurately a rim that is warped - because it's measuring circumference to arrive at an ERD estimate.
That's similar to the benefit of a dishing tool - with a dishing tool you don't have to worry so much about axle locknut imperfections or warped axles and the effect they have on flip flop dishing.
=8-)
Yep, you're absolutely right about that. The device has a built in averaging feature so only one measurement need be taken to get the best average diameter. That is neat. But on the other hand doing it that way you don't get an appreciation for how good or bad the rim is. You don't see how round or not the rim is based on multiple diameters taken at different points around the rim. Flatness of course is easy. Just lay the rim on a flat surface to see any rises and dips.
My main complaint is how expensive it is compared to other wheel building tools that provide more necessary functionality like a spoke tensiometer. For about $20 less than this device you can get a Park Tensiometer that is essentially indispensable for good wheel building, at least for most mortal humans who can't feel or hear spoke tension accurately. For the higher price of this device you get something you don't need in the first place. Your traditional method of measuring rim diameter works just fine even if it just a wee bit less convenient.