Flywheel

[909]

"A bike wheel on a mountain bike should be more difficult to spin than one on a BMX bike just because it's taller but once it's moving, the taller tire should spin longer than the smaller one {assuming same weight}. "

 

 

This is true as long as you are spinning from the hub and not from the rim.

 

 

The best thing to do is develop one that can be easily spun and stay spinning the longest.

 

This is exactly what this discussion has been about. The "best" flywhel is exactly what you stated above. Its the "getting" that has been the discussion.

[Holyman]

"A bike wheel on a mountain bike should be more difficult to spin than one on a BMX bike just because it's taller but once it's moving, the taller tire should spin longer than the smaller one {assuming same weight}. "

 

 

This is true as long as you are spinning from the hub and not from the rim.

 

 

The best thing to do is develop one that can be easily spun and stay spinning the longest.

 

This is exactly what this discussion has been about. The "best" flywhel is exactly what you stated above. Its the "getting" that has been the discussion.

And the clouds part and a chorus begins to sing :lol:

I was wondering if anyone has tried the weight reduction in the center and compared it to the one with the weight only removed from the rim. Maybe even a dyno ???

I guess we'll need to leave this up to Ron since he seems to be the only one that's brave enough to take some weight off from there.

[boonman]

I don't think a dyno would show the needed results. It is more of a throttle response issue when you lighten the flywheel. It doesn't get the bike to make any more power. It may show however, where the power may come on earlier. I don't know though. I do know that I like the mod. It works for whhat I want it to.

[FORMULASPEED]

I just seen the FlyWheel theory page.

I could be missing the point but I have these Ideas.

Why not create A lightweight metal hub to mount to the crank (like an 87 rear sprocket hub design) and machine a heavier outer rim to mount on it.

This for tight course.

And then have lightend rim for WOT.

Then sell an intechangable fly wheel setup.

If im getting what you guys are saying.

[909]

you guys got the jist of it. The problem though with the interchangable design is how to keep the outer rim from just spinning off? I'll post what i'm doing as soon as my RZ flywheel is back from getting cut.

[FORMULASPEED]

To keep the rim on example On the hub part. lets say its 1/2 inch thick

crank end to crank end going that direction. You got the hub arm with a hole through it. Machine 1/2 the hole off at 1/4 in depth. thus leaving 1/4 inch on one

side of the hole and a half inch on the other. Then create the opposit pattern on the rim

creating a puzzle fit. Then bolt the holes . Then the hub arms would be pushing it and holding it at the same time.

Im trying to type it out of my head it would be easier to draw.

But do you get what im saying?

 

 

(edit )If you think this is a good idea I have a ton more.

There almost room for improvement on anything.

The sick thing is I understood that Flywheel theory. I couldnt do the mathmatical

equasion though and Im far from collage material

[Holyman]

I think I finally got it!!!

Imagine a flywheel like a mini sled clutch. At low RPM's when you need the improved moment of inertia when your engine power output is low, the weight would be closest to the center. When the RPM's build, the weight would shift to the outer edge to sustain the higher RPM's and reduce the effects of changing engine loads. Different springs or weights could be used to ultra fine tune the flywheel for maximum benefit for very specific riding conditions.

YEAHHHH. That's finally it.

[FORMULASPEED]

Thats a good idea too HOLYMAN.

[banshee04le]

I did not read all of this, and it may have already been

covered, but flywheel design is application specific.

As a rule, for constant speed applications you want a heavy flywheel

to help maintain rpm's during load changes. Generator, pumps, and

compressors are examples of constant speed applications. Obviously

the banshee engine is not a constant speed application. As long as you

have enough flywheel inertia to maintain smooth

engine performance at low rpm, that is all you need, no more no less.

 

 

Distribution of mass is important. A 2 lb flywheel can produce more force

than a 10 lb flywheel...it depends on the distribution of mass.

As a rotating mass is moved further from the center of rotation, inertial

force increases exponentialy.

 

To alter a flywheels inertial characteristics in the pursuit of better throttle

response obviously involves the removal of material. The actual weight

reduction is not as important as the location that weight is removed from.

Two flywheels lightened by the same amount will have different inertial

characteristics if the material was removed from a different radiused plane. This again gets back to the exponential factor of distrubition of mass.

 

I'm good at saying a WHOLE lot of nothing

[909]

OK guys, you asked for it...... The optimum flywheel on a banshee in particular is the lightest hub possible with all the weight necessary to run the bike on the rim. With todays materials and manufacturing costs etc.... I'd say the best you could do is either aluminum or titanium hub and the necessary magnets to run the stator as the rim weight. You don't need ANY weight on the crank to keep it running. Here are a couple pics of my MSD fluwheel to put this into perspective. This is for rag only as there is no provisioning for electrics, just a flying magnet. Dees is all you need!!!

 

 

 

 

As you can see the rotating mass of the crankshaft is sufficient to accomplish the job. All the flywheel is there for (really) is to run the electrics and fire the coil.

 

The bolt onz idea has 1 makor flaw. The weight of the puzzle needs to be perfectly balanced so you'd have to ake the weight from somewhere in balancing. Where? If the hub is superlight you won't have enough meat to do it there so you'd have to remove from the rim working against the whole idea.

 

The moving mass is a great idea however carrying out the task is another. Not sure if you noticed or not but the variable clutches never spin at crank rotation speed. Any mechanism spinning 12000 RPM is going to be dangerous if any piece doesn't stay exactly in balance all of the time. Notice the 2 small holes on the flywheel. Those are the magnets that go by the trigger firing off the coil.

[Holyman]

I don't want start a circular argument here {no pun intended} but how well does the "button" flywheel perform in a trail riding situation where the engine is put under vastly varying loads in succession?

Does it tend to stall easier or because of the lighter flywheel does it perform better because of the ability to rev quicker?

[boonman]

Have you ever seen a sled primary clutch come apart at WOT??? I have. Not a pretty site. Needless to say, it totaled the sled. I have also watched a BELT on a sled blow right through the bellypan when it came apart. not very pretty. I too however would like to hear how the "button" style flywheel works. I don't think it would be good for most riders, because the power for the ignition is battery supplied. The flywheel on the shee serves a dual purpose. One to do what a normal flywheel does, and the other is to house magnets to supply power to the ignition and lights. For that, you need a stator and magnets to provide the magnetized field.

[BdBanshee]

I think I finally got it!!!

Imagine a flywheel like a mini sled clutch. At low RPM's when you need the improved moment of inertia when your engine power output is low, the weight would be closest to the center. When the RPM's build, the weight would shift to the outer edge to sustain the higher RPM's and reduce the effects of changing engine loads. Different springs or weights could be used to ultra fine tune the flywheel for maximum benefit for very specific riding conditions.

YEAHHHH. That's finally it.

 

Not trying to be a no-it-all, but......... you have it backwards. The weight should be to the outside when at low RPM's.

[909]

I think I finally got it!!!

Imagine a flywheel like a mini sled clutch. At low RPM's when you need the improved moment of inertia when your engine power output is low, the weight would be closest to the center. When the RPM's build, the weight would shift to the outer edge to sustain the higher RPM's and reduce the effects of changing engine loads. Different springs or weights could be used to ultra fine tune the flywheel for maximum benefit for very specific riding conditions.

YEAHHHH. That's finally it.

 

Not trying to be a no-it-all, but......... you have it backwards. The weight should be to the outside when at low RPM's.

bzzzztt! guess again, you want the weight closer to the center at low RPM to allow for the quicker revs, then the weight further away to hold them longer. This is an energy store approach. We've already determined that the energy is not needed to make the bike run. with the idle weight outside the bile will be slower reving and the weight transfer to the center will slow it down quickly, totaly against what holyman was suggesting.

[909]

I don't want start a circular argument here {no pun intended} but how well does the "button" flywheel perform in a trail riding situation where the engine is put under vastly varying loads in succession?

Does it tend to stall easier or because of the lighter flywheel does it perform better because of the ability to rev quicker?

The small fly i'd imagine would suck on any motor producing low torque and not on the pipe. The banshee does this stock though. This type of flywheel/crank trigger is purely for drag only. I imagine, my bike on a trail would ride the same if it had a stock flywheel on it or the button. My motor doesn't start producing enough power to move it below 7000 RPM.