subframe

People talk a lot about how stiff their wheels are or aren't, and we all probably know the feeling of a wheel flexing under you at times. But is there an actual scientific measurement for wheel stiffness?

I imagine one could measure deflection when the wheel is under certain loads, but I don't recall ever seeing numbers like this published anywhere.

BananaTugger

Roues Artisanales cranked out an epic wheel test a couple of years ago.

Here.

waterrockets 

Yep, RA did what you'd want to do, producing a spring constant. The rear should actually be broken down to DS and NDS stiffness, because they will be different.

Probably a really easy way to do this test would be get a hook scale and measure the force required to pull the braking surface 1cm in the bike. Fork flex will come into play, but you'd probably still get a good idea. It would also be interesting to play with different skewer tightness to see how that affects wheel stiffness.

Really though, it's not that big of a deal as long as you aren't touching your pads. Even the occasional pad touch doesn't much matter.

subframe

Yeah, I rarely worry about it too much; just got to wondering about how it's measured. If I'm super bored one day, I may try the hook scale thing.

That is indeed an epic test on RA, I'll have to sit down and read it over lunch or something.

Pedaleur

Hmmm...it's a linear problem. I don't think it there's an asymmetry here.

I will allow (for the rear wheel) that a lateral force produces both a lateral and (small) radial deflection, but that the deflection vectors are directly opposite.

I could be swayed, but it will take some math.