the "trust" factor when cornering

[Hoon]

Yep Counter steering and gyroscopic precession can be very tricky to understand (and even harder to explain). I often use my "simplified" explanation even though it isn't entirely accurate but does make it easier to understand and convinces people enough to believe in it (as opposed to rambling on about angular momentum).

Basically I tell people that you turn the handle bars in the opposite direction i.e. left, which causes the lower part of the bike to shoot left.  As a result the top part of the bike falls to the right, like someone kicking your legs out from under you....kind of what KK was trying to say (for the record I believe countersteering is the product of the above, angular momentum, gyroscopic precession AND the rake angle of the front).

The best way to see how a spinning front wheel affects lean is to grab a kids bicycle, lift the front wheel off the ground and spin it.  Turn the front wheel near the axle and feel how the bike wants to tilt to either side.

A few more interesting things about gyroscopic forces.

- The spinning wheels of your bike keeps you upright, not the speed you are moving.  An example of this is an olympic cyclist riding on stationary rollers staying upright.

- The heavier and faster the wheels are spinning the more stable (or resistant to lean) the bike is.  Thats why its harder to keep the bike balanced at low speeds and also why light weight rims improves high speed turning response.

- The gyroscopic forces of the back wheel does most the work keeping you upright as it is fixed to the frame.  That is why when you lock up the rear the bike falls quickly and loses all balance whereas locking up the front you can still stay upright (if you aren't leaned in a turn that is).

Another interesting observation is that you could mount a spinning wheel to your bike and it would be just as easy to balance at low speed.  But be careful because if you spin the wheel in the opposite direction it would cancel out your bikes gyro effect and at high speed the bike would be just as unstable as if you were stationary!  Boy would that be a nasty trick!

[bluninja]

FYI a chap rode around the Isle of Man Circuit doing a wheel stand all the way. One of the mods to his bike to achieve this was to fit an electric motor to the front wheel to keep it spinning whilst in the air. Woner why he did that?

TTFN

PS I don't really want an answer I'm just increasing my number of posts

 

[Kwaka-Kid]

Originally posted by HO-Hoon

- The gyroscopic forces of the back wheel does most the work keeping you upright as it is fixed to the frame.  That is why when you lock up the rear the bike falls quickly and loses all balance whereas locking up the front you can still stay upright)

hey thanks for all that Hoon, makes sense apart from this bit.. which i spose might and its just my lack of skill.. but i find.. i can lock up rear wheel quite happily and slide to a stop.... however when i lock up front wheel it always wants to "tuck under" like, slam down... know what i mean?even if i thought i was steering straight and was trying to keep it that way. Am i too week to hold the front end straight? or could it be that my wheels aint alligned? or another reason making KK's bikes defy the laws of gyrocollaptic collision? or whatever that was?  (lest just call it simple physics)

[Coldkiwi]

not sure if I follow the ho-hoon logic of front wheel lock ups! There are other forces involved with stability and directional change that I'm pretty sure will take precedence (i.e, no more steering!) when you lock the front than the loss of gyroscopic stability.

as for the Isle of man front wheel rotation; that would be the only way he could steer with the front wheel in the air. I wouldn't be surprised if he'd had a variable speed drive on the electric motor too to help with stability and control.

 

[Hoon]

Yeah my explanation about the front thing wasn't too great....Keith Code does a way better job in one of the Twist books!