Search results

  1. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    Yes, that was for banked tracks where it's possible to get even higher cornering-forces than on flat ground. So for those tracks, if you lean bike to same relative-angle to ground as on flat, you end up with even more than 2G of cornering, 3G is possible. It's the combined lateral and vertical...
  2. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    The 2G of force is inline with effective CoG and contact patch regardless of where rider's spine is located. In this example, it's in between spine of rider and axis of bike.
  3. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    Yes, that model works, but rider still experiences 2G of forces. Banking only cancels out lean-angle, but it doesn't cancels out cornering forces. While you may be able to take 1G corner without leaning, there is still 1G of gravity and 1G of cornering. Just happens that cornering-forces are...
  4. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    A more familiar model to understand this is to imagine you're standing upright and someone slides sideways into your foot. Obviously they'd kick your feet out from under you and you'd fall over them. But... what if you saw them coming? You can lean away from them at certain angle and not fall...
  5. D

    Misc. Is My Steel Square Tubing Strong Enough?

    Ideally you want guy-wires to be 90-degrees to posts. That would make for some long runs in this case. If the posts were 45-degrees outwards, then wires would be 45-degrees in other direction. One calculation you need to do is measure load based upon average wind-speeds. Can probably find that...
  6. D

    Construction Making a gong stand - will aluminium tubing be strong enough?

    Need to triangulate stand so it doesn't parallelogram and collapse laterally. Also triangulate at least one side of feet so it doesn't collapse fore & aft. Probably triangle on back side so less of tripping hazard. Sure there's some triangulation in lugs holding tubing together, but it's very...
  7. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    Yes, extra centripetal force is pushing inwards on contact-patch and bike wants to flip over that patch to outside. It's an extra force in addition to gravity. This is also static model, snapshot in time. Inertia wants to stand bike up and have bike go in straight line tangent to curve. Extra...
  8. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    Don't forget that there's actually two forces on cornering bike. Downwards gravity and lateral centripetal force. This is similar to if you hung an apple from rear-view mirror of car via string. String would have 1G when car goes in straight line. Under 1G of cornering, string would experience...
  9. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    Note that friction is not what generates traction forces on tyres. This was resolved decades ago when friction-model would only allow dragsters to reach 200mph maximum. We now know that's not true. For example, F=Nu is higher for rubber+steel than it is for rubber+asphalt. Yet going around...
  10. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    New Olympic sport: Synchronized Leg Dangling!!!
  11. D

    B Can someone please explain this paragraph from A Brief History Of Time

    Rate of expansion has been revised with Hubble's Constant now being much smaller than what Hubble himself calculated. But is Hubble's Law still valid? That looking back in time at most distant objects show they are expanding at faster rate than closer ones? That would still support idea that...
  12. D

    B Elementary question on car crashes and momentum

    Draw it as vectors and it becomes clear....
  13. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    hahahahahhahhhh!!! :-p I like this one: Rossi, the eternal jokester, is trying to see how outrageous he can make his copycats dance!
  14. D

    A How does 1-wheeled motorcycle turn?

    Here's related behavior with sidecars. Traditional sidecars that keep tyres vertical requires the motorcycle's front wheel to turn like a car's and generate lots of cornering forces. Result is sidecars must go a lot slower than same motorcycle by itself around curves. However, uncoupling...
  15. D

    A How does 1-wheeled motorcycle turn?

    Yup, I think it's the butt and hips causing changes in lateral tilt. Like riding bicycle no-hands. Tilting bike causes front-tyre to countersteer and causes bike to lean over. Seems this guy is able to teeter-totter left/right to cause tyre to lean. Throttle only affects longitudinal movement...
  16. D

    A How does 1-wheeled motorcycle turn?

    precession is not at work here because neither on bicycle nor motorcycle does front wheel reverse direction of spin in order to turn the other way. Front wheel in air has no effect on turning direction of bike either. Precession forces from 1.5-lb bicycle wheel or 5-lb motorcycle wheel spiining...
  17. D

    A How does 1-wheeled motorcycle turn?

    Riding no-hands on bicycle still uses front-tyre for steering though. As it's completely different behavior than doing wheelies and steering. How does countre-steering cause wheel to turn in opposite direction? I'm pretty sure when wheelieing motorcycle, he leans towards direction he wants to...
  18. D

    A How does 1-wheeled motorcycle turn?

    At first I thought unicycle too. Which steers like a car with an upright wheel pivoting around vertical axis to aim in new direction of travel. However, in this case, there is no vertical steering of back wheel that I could see, it's aimed down the road at all times. The only dynamic change I...
  19. D

    A How does 1-wheeled motorcycle turn?

    I've witnessed 1st-hand with my own eyeballs this guy riding an S-shaped path through chicane at Thunderhill East+West 5-mile combined course with front-wheel IN THE AIR! I believe bike is a Yamaha TZ250, 100-120bhp and 200-lbs weight. I conducted an experiment to document behavior of single...
  20. D

    I Glasses and problems with chromatic aberration

    Sure, most glass has less CA than plastics.
  21. D

    I Power spent to keep a spring compressed

    Electrical power going into solenoid is dependent upon force that it is required to push. This is then dependent upon the spring's rate constant multiplied by compression amount (displacement) needed. This is similar to how peak-n-hold fuel-injectors work. A larger burst of power is needed to...
  22. D

    B Calculate the speed of the flywheel for my drone motor

    This looks like basic gearing calculations. Motor is attached to flywheel, which spins propellers. Let's say propellers are spun from flywheel's edge with belts or gears and they need to spin at 5200rpms in order to generate 900g lift. Simple enough to calculate ratios of 18" flywheel diameter...
  23. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    Need to clarify the dirt stuff. For motocross and supermoto stuff, the foot down is for balance. When cornering over uneven surfaces, front tyre can slide after coming off bump mid-corner. The hanging foot then 'steps' down to keep rider upright, then throttle and steering keeps bike up and...
  24. D

    I Glasses and problems with chromatic aberration

    With amount of correction dioptre you need, lens need to be thick with short focal length, which increases CA. It is difficult to have low CA with single material. As mentioned an achromatic doublet lens with two materials and opposing focal-lengths are needed to cancel CA. Since resultant CA...
  25. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    heh, heh... yeah many riders have crashed into T1 @ TH by missing their braking markers while staring at their clocks to see if they broke +180mph! I actually use digital Trailtech Vapour unit with bar-graph tach (speedo disconnected). It's mounted higher than stock and I can see it in...
  26. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    "net inwards torque" will always occur due to knee puck being inside of tyres' contact patch around curve. However, there are two rotations to consider here: 1. rotation of bike+rider around centre of curve 2. rotation of bike+rider around knee-puck contact (think moon rotating around Earth)...
  27. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    academic discussions need numbers to understand various magnitudes of forces involved and their contribution to entire system. bike = 315 lbs (48/52% F/R distribution) rider = 180 lbs with full gear (helmet, suit, air vest, gloves, boots) speed through T1 & T8 @ Thunderhill = 105mph cornering G...
  28. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    There IS a lot of squirming of contact patch when cornering because radius of tyre at edge is smaller than towards centre. When cornering, outside edge of tyre is forced to travel longer distance while centre is forced through smaller distance. Somewhere in middle is neutral. As I pick bike up...
  29. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    the last video is mine and it was track-day practice with Pacifc Track Time. Unfortunately, Keigwins is no more. Done in and bankrupted by idiot rider who crashed and sued them and Laguna Seca. However, it has been revived as Carters at the Track with previous GM as new owner. :)
  30. D

    I Can a cornering motorcycle go faster if the rider puts a knee down?

    It was mentioned earlier that putting weight on knee would jack up bike, lowering vertical-loading on tyres and reduce grip. While this is true, you'd have to have super-human strength to push your knee out that hard. What's more common is some hard non-yielding parts will touch down, such as...
Top