Reverse Rotating Brake Rotors

**oldrider** · 22nd February 2006, 08:44

That guy went the way most people expected. Oblivion! April fools prank really.

I try to remain optimistic. You never know what some bright spark will come up with next.

I am a Myers-Briggs "ENTP". I just can't help myself being optimistic.

Cheers John.

**Mental Trousers** · 22nd February 2006, 09:51

Originally Posted by WINJA

to make it simple .
buy 2 gsxr600s , pullthe motor out of one and put a 1000cc in its place , add ballast to the 600 to make it weigh the same as the 600 with the 1000 motor.
the one with the 600 motor in will turn faster in general

Easier to just go around a corner in 6th (say at 80kph) and then go around the same corner in 2nd but doing exactly the same speed. Doing it in 2nd would be harder as the engine is doing a lot more revs.

**ManDownUnder** · 22nd February 2006, 09:58

Originally Posted by bluninja

Also if it cancels the gyroscopic forces on the wheels then the only gyroscopic stabiliser would be the crankshaft and flywheel.

Which raises the q... would that be enough to stay upright on the road?

At what speed would you be able to stay upright? I can balance at approx 4 or 5kph... what if it did cancel that gyro thingy and I couldn't balance till 20 - would I have to run alongside holding it up?

My thoughts is that's it's a crock. It won;t cancel anything. A spinning wheel is stable due to gyroscopic effects... irrespective of which way the wheel is spinning.

One part going one way, and another part going the other way wouldn't affect the over all level of effect. They don't negate each other as they are actually complimentary forces.

*ding* next!

**TygerTung** · 22nd February 2006, 11:33

It would reduce acceleration and braking as your wheel has a lot more centrical mass, as it has to spin up the brake disc twice as fast now= more centrical mass= more power used to spin it up etc.

**Ixion** · 22nd February 2006, 12:08

Originally Posted by Mental-Trousers

Easier to just go around a corner in 6th (say at 80kph) and then go around the same corner in 2nd but doing exactly the same speed. Doing it in 2nd would be harder as the engine is doing a lot more revs.

Or, familiar territory, it is the reason that opening the throttle and increasing revs coming out of a corner helps to stand the bike up.

**jonbuoy** · 22nd February 2006, 20:43

Those little disks would have to be spinning bloody fast to counteract all the mass of the tyre and wheel as they weigh a lot less. I'm guessing they would only do it on the front wheel?

I 'spose you would loose the "tail wagging the dog effect" from a tankslapper, i wouldn't think it would stop them from hapening though. I thought they were caused by short wheelbase, sharp steering angle, ripples in the road and a fistfull of throttle

Hope the boffins get there sums right before the poor bastard rides the bike.

**Milky** · 22nd February 2006, 23:09

Originally Posted by ManDownUnder

My thoughts is that's it's a crock. It won;t cancel anything. A spinning wheel is stable due to gyroscopic effects... irrespective of which way the wheel is spinning.

One part going one way, and another part going the other way wouldn't affect the over all level of effect. They don't negate each other as they are actually complimentary forces.

*ding* next!

That was the first things I thought too... I am not sure on the specifics of the physics involved, but I didn't see any reason why having one wheel rotating backwards should reduce the overall effect. You still have to change the angle of both wheels, and it doesnt take a negative force to tilt a clockwise rotating wheel to the left, a positive force to tilt it right. Hence surely the rotation direction of the wheel has no effect.

There is a little voice reminding me that when I held a wheel and tried this, the wheel wanted to yaw when tilted... Maybe this is the effect that they are looking to exploit?

**zooter** · 23rd February 2006, 23:22

Dammit you are making me think aloud: Leaning a wheel rotating forwards requires a torque on the axle in the direction of the lean eg anticlockwise "left hand down right hand up". Imagine someone looking at it from the other side seeing a wheel rotating in the opposite direction leaning in the opposite way by virtue of opposite torque ( leans clockwise, left hand up, right down). Now turn the reverse rotating wheel around it's vertical axis so it is the true counterrotating twin of the original, the forces being applied to it :

this is straining my underutilised brain...

turning the imaginary wheel around has reversed the forces and lean direction so the lean direction is the same as the original but the forces are

somebody PLEASE complete this.....

on another tack the gyroscopic tendency of a spinning wheel I recall being something to do wth conservation of angular momentum, being that the twin wheels are counterroating there is zero system angular momentum to conserve so no gyroscopic force

But even if they were sucessful all they would acheive is a big bike that handles like a scooter! All good fun but it takes a real man to make one of them fang!

**Milky** · 26th February 2006, 12:36

right.

I got a bicycle wheel from downstairs, and if I spin it forwards, then go left hand down, it wants to push my left hand towards me too. The reverse is true if it is spinning backwards - left hand down, and it pulls my left hand away from my body. Hence, the addition of reverse rotating brake rotors means that less effort is required in the bars to change the spin axis angle of the wheel. This will inherently make the bike less stable. Tank slappers will be less voilent when they occur, as the wheel doesn't contribute as much to the severity as before, but they will be easier to initiate as the wheel is less stable as a stand alone item.

Braking should require less torque at the brake rotors due to the gearing. The rotational inertia of the wheel system will increase slightly due to the extra mass required to reverse the disc rotation, as will unsprung mass. As for rider feel and usability, only time will tell I guess

**thehollowmen** · 26th February 2006, 13:52

Originally Posted by k14

I doubt one disc would have enough inertia

They'll gear it up to have enough inertia

**crash harry** · 26th February 2006, 16:09

Originally Posted by bugjuice

yeah, i can't really see how it works..
you'd have to have more balance at low speed than every before. If the effect of doing 200kph is like turning at 20kph, then what's riding at 50kph going to be like? Standing still? I can hold my balance at the lights for may be 30 seconds if I do it right (which isn't often), but then my foot has to come down.. Fuck me am I doing that at 100kph

I think it wouldn't be that bad, you'd still have the gyroscopic forces from the rear wheel. It'd be a bit like balancing a unicycle with a front trainer wheel - maybe more like riding a penny-farthing but not quite as dangerous or ridiculous looking...

It's the rear wheel that does most of your steering anyway, the front is only used to get the bike leaned over in the first place. I think if they got the ratios wrong the steering would get horribly light though - like some of the early Jap power steering on cars. There was no feel cos the steering was too light.

It sounds over-complicated and mostly irrelevant to me though - litre bikes fall into corners easily enough these days...