Gryroscopic or flywheel effect

[Draxsr]

Oddball question - As most are well aware, when doing slow maneuvering with a v-twin motorcycle, some stability can be generated by revving the engine and applying some trailing brake while playing in the friction zone. Very slow speeds are achieved with the help of the forces created by the spinning parts of the engine (the flywheel?).

Now, I'm an operator, not a maintainer and can't really speak to the accuracy of the parts involved, but know it does work. I wonder though, if the flat-6 in the F6B (or any Goldwing for that matter) gains similar benefits at higher RPMs. Or is the engine oriented differently?

Any thoughts on this would be appreciated.

[53driver]

That's a great question!

By design the HD V-Twin has "more" stuff spinning in the North-South plane than a flat 6 - flywheel, crankshaft, plus the primary and clutch plates.
However, I think that most physicists will agree that stuff spinning in ANY plane will stabilize as much as long as it is equivalent mass at equivalent speed as long as that plane is not messed with too greatly.
At slow speeds, almost no angle of bank, dragging the rear brake (or as close to that as we can come with linked brakes) I would say that any RPM increase that you can maintain steadily will help.
Cheers,
Steve

[shortleg0521]

Also there is what's called Fud,s 2nd law.
That is to say , If an object is pushed with surfactant force it will
become horizontal.

[Travelor]

I think the gyroscopic forces developed by a spinning mass are applied at 90 degrees to the "axle" of the spinning mass. Hence, a spinning wheel remains vertical. If you hold a bicycle wheel by the axle and spin it, it resists an attempt to rotate the axle either in a horizontal or vertical rotation. But if you are holding it vertical (axle horizontal) straight out in front of you and raise your arms, there is no effect on the wheel. Likewise with a "V" twin - the mass of the flywheel is spinning in the same plane as the wheels (axle side to side) and thus provides stability in a vertical plane (helping to keep the bike from falling over). However, a flat six, with the "axle" of the rotating mass (flywheel, crankshaft, alternator and trans gears) in a longitudinal direction (front to back) does not provide any gyroscopic stability along its axis so there is no vertical stability provided as the bike leans from side to side. If all the rotating parts of the flat six are spinning in the same direction (which Honda does not do), you get a torque twist when twisting the throttle or down shifting. This has always been the issue with BMW Boxer twins until the latest engine iteration in 2014 where the redesigned engine rotates the alternator and clutch counter to the flywheel, greatly reducing the torque effect.

[53driver]

WELL PUT! Great example with the bicycle tire!
So, if anything is spinning there will be stability, but the issue is 'along which axis.' Got it.
Since the bike doesn't tip forward or backward, but rather to the left or right, the flat 6 gives no stability whereas the HD design does.
It also means the HDs are more resistant to leaning over...lol.

Thanks Travelor!

[Retired Army]

One of the basic principals of the gyroscope is they remain stable in space. This is the reason they are used in air craft instruments so level flight can be maintained when the natural horizon is not visible.

[Travelor]

WELL PUT! Great example with the bicycle tire!
So, if anything is spinning there will be stability, but the issue is 'along which axis.' Got it.
Since the bike doesn't tip forward or backward, but rather to the left or right, the flat 6 gives no stability whereas the HD design does.
It also means the HDs are more resistant to leaning over...lol.

Thanks Travelor!
:cheers:

[53driver]

One of the basic principals of the gyroscope is they remain stable in space. This is the reason they are used in air craft instruments so level flight can be maintained when the natural horizon is not visible.

That's exactly the approach I was coming from! The gyros in aircraft utilize 3 axes (or more) to keep a balanced reference for instruments and pilots.
However, Travelor made me recall that while aircraft tilt in all three axes, our bikes tilt (fall over) in only one, so as long as the axis of rotation is perpendicular to the path of travel of the bike, that axis of rotation would apply to motorcycles.
I think I need more coffee, I burned through all the brain cells awakened by the first cup...lol

[P.Sutton]

On all my previous bikes, both dirt and street, I was able to “creep” forward as opposed to coming to a stop by increasing rpm and sliding the clutch against the brake. Even coming to a complete stop for a moment or intermittently without putting down my feet. With the F6B I immediately noticed how much harder this was when I first started riding it. I attributed this to the gyroscopic effect as all the other rotating assemblies were transversely oriented. I have learned on the B, not to focus just ahead (for instance, on the red light about to turn green) but to look as far down the road as I can and focus on a fixed point. This helps with balance and keeps me from having to put my feet down in some situations.

[DaWadd]

This is all great reading:yes:

[Frye]

On my Valkyrie, keeping the revs up while slipping the clutch and pushing the engine against the rear brake created much better low speed stability. A large percentage of the time I was able to come to a complete stop at stop signs without dropping a foot using this technique. The only downside was nearly getting rear ended by cagers who didn't realize I was stopped a time or two. During a slow race in (I think Paducah Kentucky) I saw a Valk rider keep his bike stopped for several seconds, several times while using this technique. This rider only had one arm, by the way.

Although the Valk and the B both sport horizontally opposed 6 cylinder engines the technique doesn't work nearly as well on my B. I attribute the difference to the linked brakes.

My company sent me to Bike Week in Daytona a few years ago to help man a Hog Halters/AirFX booth in the Bruce Rossmeyer area at Daytona. (Yes, I parked my Valk in front of the booth everyday;) ) Jerry the Motorman of Ride Like A Pro fame had an area next to us so I watched them ride and talked to them daily. They said they rode HDs to this event and Goldwings to non HD events and it sounded as if both bikes worked equally well. These folks are true artists when it comes to the "slipping the clutch and keeping the revs up school of riding" since they teach it.

So, I do know the technique works well on other flat sixes but not so well on our B's which is why I blame the linked brakes. Really wish there was a fool proof way to stop the front from coming on with the rear with the flip of a switch. Both for slow speed riding and for riding on gravel roads.

[Retired Army]

I overcame the necessity of having to put the feet down by adding a third wheel to my F6b. How ever gyroscopic procession is still a factor. The handlebars have to be held in the turn until completed.