Cam, I have to quote you to make this coherent, sorry.
> Are you telling me you have never experienced a difference in the feel of a rim Alex D?
The question is whether a difference in vertical compliance exists while the spokes still have tension, not whether there's a general difference in rims. Width, weight, lateral stiffness, the hub, and spoke lacing would all impact an overall impression, not to mention the terrain and the rider's inclinations at that moment. Perception isn't relevant when you can directly measure what you're interested in.
> And what do you mean about spokes contracting? As in reducing in length?
Under tension, the spokes stretch to an extent dictated by their thickness, the level of tension, and Young's modulus for steel. When the wheel is loaded, tension reduces on the bottom spokes, so they contract. A wheel with more spokes or thicker spokes will be considerably stiffer (less deflection) vertically, though perhaps only by fractions of a millimeter for most loads.
> And I guess you are calling BS on all the manufacturers who have been trying to engineer compliance into their rims?
There is a benefit to vertical compliance, it's just not to the rider. Rims that can flex when the spokes are slack are less likely to break. Fewer warranty claims. You could make a thin safety argument here. I wouldn't expect any difference in ride quality (with exception to a handful of very aggressive riders that do, perhaps, exceed spoke tension with some regularity.)
[http://www.noxcomposites.com/wheel_building ](http://www.noxcomposites.com/wheel_building);
That's a good summary.
> If we assume a similar wall thickness and construction, would you say that a rim that has a depth of 2" will feel identical to a rim with a depth of .75" assuming similar spokes and lacing pattern?
Yes, in a straight line, under loads that don't exceed spoke tension. The 2" wheel would be laterally stiffer.
EDIT: Coming back to this a year later, this may be incorrect. It depends on the spring rate of the rim wall. I've assumed throughout this thread that the rim profile is preserved when the rim flexes. If the rim walls were instead designed to flex (and sufficiently tall for this flex to matter) at a spring rate significantly lower than the spokes, that flex (and the effect on ride quality) may be perceptible.
> Was the testing you speak of applied to mountain bike rims or road rims?
Both. While the Nox article has some nice theoretical numbers, you can find out yourself; pick a wheel without a tire, measure the wheel height carefully, load the top of the rim, and measure again. I'd be surprised if your measuring instrument was accurate enough to detect any difference at all.
July 15, 2017, 10:55 a.m. - Alex D
Cam, I have to quote you to make this coherent, sorry. > Are you telling me you have never experienced a difference in the feel of a rim Alex D? The question is whether a difference in vertical compliance exists while the spokes still have tension, not whether there's a general difference in rims. Width, weight, lateral stiffness, the hub, and spoke lacing would all impact an overall impression, not to mention the terrain and the rider's inclinations at that moment. Perception isn't relevant when you can directly measure what you're interested in. > And what do you mean about spokes contracting? As in reducing in length? Under tension, the spokes stretch to an extent dictated by their thickness, the level of tension, and Young's modulus for steel. When the wheel is loaded, tension reduces on the bottom spokes, so they contract. A wheel with more spokes or thicker spokes will be considerably stiffer (less deflection) vertically, though perhaps only by fractions of a millimeter for most loads. > And I guess you are calling BS on all the manufacturers who have been trying to engineer compliance into their rims? There is a benefit to vertical compliance, it's just not to the rider. Rims that can flex when the spokes are slack are less likely to break. Fewer warranty claims. You could make a thin safety argument here. I wouldn't expect any difference in ride quality (with exception to a handful of very aggressive riders that do, perhaps, exceed spoke tension with some regularity.) [http://www.noxcomposites.com/wheel_building ](http://www.noxcomposites.com/wheel_building); That's a good summary. > If we assume a similar wall thickness and construction, would you say that a rim that has a depth of 2" will feel identical to a rim with a depth of .75" assuming similar spokes and lacing pattern? Yes, in a straight line, under loads that don't exceed spoke tension. The 2" wheel would be laterally stiffer. EDIT: Coming back to this a year later, this may be incorrect. It depends on the spring rate of the rim wall. I've assumed throughout this thread that the rim profile is preserved when the rim flexes. If the rim walls were instead designed to flex (and sufficiently tall for this flex to matter) at a spring rate significantly lower than the spokes, that flex (and the effect on ride quality) may be perceptible. > Was the testing you speak of applied to mountain bike rims or road rims? Both. While the Nox article has some nice theoretical numbers, you can find out yourself; pick a wheel without a tire, measure the wheel height carefully, load the top of the rim, and measure again. I'd be surprised if your measuring instrument was accurate enough to detect any difference at all.