Originally Posted by
Campag4life
If you are saying that lighter wheels are faster in a TT I think you are missing the boat with your unscientific testing. Sorry. Unless you post all wheel parameters, defining differences...which is a very long list...you aren't being true to whether weight is a big factor.
Common knowledge on a road course in particular a TT, that tire selection..even tubes or lack thereof, tire width, wheel width, pressure and in particular wheel 'aerodynamics' trumps difference in static weight. Physics support this and not what you wrote. You are experiencing a difference in time and speed based upon your testing...you just aren't doing a good job in assigning cause as to why. The wheels that you test to be faster simply happen to be lighter...that doesn't mean lighter wheels/tires are generally faster. But aero wheels are generally faster FWIW on the flats.. Weight if taking say 100g/wheel or so is probably one of the smallest contributor to speed.
So far...I'm the only one I've read hear that is testing. And so far, no one has dealt with the physics on the side to side movement. If I provide the SIN wave formula for the front wheel road trace and give the speed, trail and wheelbase of the bike, few can tell me the formula of the rear wheel trace. If I add the offset from hitting a pebble or bump and recovering, well - too hard. If someone can do the math I'd be happy to read it. But right now, we are not at that place anymore.
We went out again this afternoon. Worked on seats and front wheels and a bit of shoe covers.
I was going to video, do something that looked scientific, but decided it was time for feel and there was nothing to video. We were testing 900g trispoke vs 980g trispoke both 22mm wide rims (complete wheel). Both wheels had the same tire and we selected the heavier one with the lower MOI and a bit more flex due to course. Because - he liked it.
These are 33mph runs. I was a bit surprised nobody commented on 33mph runs.
I've been doing unscientific trials on my son for 7 years. I can bring up test data on my wife 20 years ago and test data on me 30 years ago. I don't think my sloppy testing that happens almost weekly has given me the wrong view of what actually is happening. I just have hundreds of tests and I can't do formal tests every ride. The inmates rebel.
Rather I take the actual cycling out of the lab and into what is closer to what actually happens.
You can see I was pretty much a nutcase 7 years ago in the video below - still recording times, HR. The front wheel here were made by a mathematics prodigy that graduated college in his mid teens. We know the maths and we know the physics. It just was never as good as a test. Which is why they build wind tunnels - even though they are not as good as the real road.