In article said:"Tim McNamara" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:In article said:The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity. I
never once said I noticed anything when I was JRA, only when sprinting, or diving into a
corner. Since sprinting and diving into a corner (at least the way I do
it) produce lots of lateral loading, my wheels flexed.
You seem to be conceptualizing turning a bike to be like turning a car, with large side loads on
the wheels/tires. Do you lean your bike over in corners? What do you think happens to the forces
when you do?
-----------------------> Lateral (centripital) forces
| \ \ \ < Lean angle \ \ \ \ \
------------------------- Ground
The dashed vertical line is gravity. When you lean into the corner, from the perspective of
your wheels the forces are still vertical. The faster you go, the more you lean and the wheel
still thinks the forces are vertical. There's very little side loading when you corner a bike-
unlike the side loads a car wheel sees because the car wheel remains nearly upright throughout
the turn.
That would be true given a perfectly smooth surface, and we all know that roads are not perfectly
smooth. Irregularities magnify flex by adding to the side loads. Since Damon's test didn't include
impacts, but a smooth application of weight, neither of us know what maximum flex for my wheels
are, now do we?
How big an irregularity are you talking about? Six inch potholes? You're still not going to add
significant side loads hitting some typical road bumps- the wheels will still mostly see them as
vertical loads. If the side loading is enough to be significant, it will lift the wheel and you will
crash, unless you're riding at parking lot speeds.
Quoted message said:Quoted message said:Quoted message said:Y'all like data, I give you data. "Your" assumptions are faulty. "You" might want to recheck
them. Run tests like Damon did, proving that wheels deflect laterally as well as vertically,
then rethink "your" position on what I'm saying about a flexy wheel.
Hummm, how big are the lateral deflections again? 5 hundreths of an inch or something like that?
Try 1.7mm thank you. On top of the tire squirm, that's noticeable. It wouldn't have been an issue
if all I were doing is toodling around like some people here, but since I'm doing sprints, etc.
the flex is magnified.
Ah, Now I see. You can feel a 0.05" flex masked through the tire squirm, while you're cornering hard
and therefore paying more attanetion to the road than your bike, and you can differentiate this from
frame flex, fork flex, handlebar flex, and stem flex.
You're right, we do like to make fun of stupid stuff like this. You also seem to be oblivious to the
fact that most of the people in this newsgroup ride hard and have ridden hard for years- 30 years or
more for several of us, myself included. Many of us have raced- myself included, for 10 years.
Quoted message said:Quoted message said:Do you really think you can feel such small movements- about the thickness of a couple of dollar
bills- even if they did happen while riding?
Roll up the dollar bills into a 1.7mm stack and run over them going around a corner and tell me if
you don't feel it. Hell, run over a pebble next time you're out and tell me you don't feel it.
(just for a fair comparison, ride your 700x23c tires at 110-115psi like I
do)
I ride mine at 120 psi. At 200+ lbs, pinch flats are a problem with silly small tires like that.
Could I feel a 1.7 mm bump, on 700 x 23's at 120 psi? Possibly. But that's an acute event with a
definable edge, and might impart enough kinetic energy to cross the threshold of perceptibility.
It's the edge effect you perceive. Wheel flex is a non-acute event without a definable edge; you're
simply not going to be able to feel it at such small magnitudes. And certainly not with all the
other competing stimulus.
Whatever you're feeling in corners, it's something other than what you think it is. That's all
we're saying- your perception may or may not be accurate, but your explanation is highly unlikely
to be accurate.
Quoted message said:Quoted message said:And vertical deflection is yet another decimal place smaller than Rinard's measured side
deflections!
I never said that the wheel felt any different when JRA, only when sprinting or hard cornering.
Yes, you are obviously going so fast that the laws of physics and the laws of perception are in
abeyance. I should have realized.
ROTFL!
