What makes a wheel true? Part 1

This topic threatens to head directly into magnum opus territory, but it's worth discussing. When we talk about "true wheels," what do we mean and how do we achieve it? 

First, of course we need to disclaim that no process is 100% foolproof. In a typical set of wheels, there are somewhere around 100 different pieces (~50 spokes, ~50 nipples, 2 rims, 2 hubs) that go together with about 100 different connections (each spoke is attached at hub and rim), and on rare occasions something can get sideways. Our process aims to eliminate that outcome as much as possible. 

"True" generally defines precision with regard to lateral runout, "round" refers to precision with regard to radial runout, and "correct dish" refers to precision with regard to the rim being centered between the hub's axle ends (or off by the correct amount, as in the case of Cannondale Ai and other similar frames).

How precise is "precise"? You won't find broad agreement on that. Many would tell you that within 1mm of lateral true is fine, and within 1 to 2mm of radial true is fine. Dish is often regarded as fine so long as it's not problematic. Our standards are a bit tighter than that, and we're generally able to get wheels to about .15mm of laterally exact true. This is thickness of a piece of paper territory. Finer than this becomes difficult simply because rims vary in their external width some amount, and eventually you make one side laser straight to the detriment of the other side. 

Radial true, or round, has a small bit higher margin, somewhere around .4mm or so is a good number. Think of it this way - the wheel's runout is somewhere around 7 feet, and a round error of .4mm would mean that you rise and fall.4mm every 7 feet. That's sort of like the thickness of 2 business cards. If the radial error is stacked up in one area (as in the case of an alloy rim with a bad joint) it will be more noticeable than if it's gradual. The tire will likely absorb all of this until you get to a really big round error, but that will come at some energy cost (it's inefficient to make your tires absorb things - smooth roads are faster than bumpy ones). And then you also want your brake pads to stay on the brake tracks and all of that nice stuff.

We see a lot of frames and forks that aren't precisely aligned. Certain brands are notorious for rear triangles that are way off, and fork dropouts get weird too. In an ideal world, everything tracks along a precise centerline and away you go. In the real world, we try to get the wheels to be dead centered between the axle ends, and that's all we can do. This comes with a caveat: dished wheels (wheels where the hub's right and left flanges aren't equally spaced from the hub's centerline) move ever so slightly toward the higher tensioned spokes when you inflate a tire on them. We favor toward the lower tensioned spokes just a bit to predict this and cancel it out when the tire is installed and inflated (almost all of our customers prefer to use their wheels with tires on them). 

That's a nice place to end Part 1. For those who made it through the last blog post and watched the Tom Ritchey video, we'll go through the "I love you I love you I love you" bit next time. 

In the meantime, the January preorder for Cafe Racer, RCG, GOAT, and GX24 ends tomorrow. Get paid $100 for a bit of patience and get more performance per dollar than any wheel company in the world. Period. And yes, that's an ironic inside joke where the set of "insiders" to the joke is one. Me. It's a really inside joke!