why light wheels make your bike turn easier

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xbacksideslider said:
It would seem a truism that if we could reduce the weight of our wheels to zero, then we would lose all gyroscopic precession effect and then lose stability.

It's just that the cast "wagon wheels" that came on those Yamahas could double as boat anchors. Those gyros were too effective.
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Yep, probably the stupidest thing I ever did to a Commando. It did not make it stable. It made it handle like a SR -dangerous.

why light wheels make your bike turn easier
 
Nope sir xbs'r, gyros on cycles may either be a nuances effect to over come with counter steer, [which tries to keep mass of bike centered bewteen two points] or a beneficial effect on stability resisting angle changes, but gryo's are not required for cycles to ride around fine w/o them. So depending on the cycle zero mass tires may be killer diller but on another they make too unstable to press around harsh. What keeps a moving bike up is the natural wobble of forks, if left alone, but if too much, must hang on or dampen down. My fast way around is to steer into the fall, but first got to get going harsh enough it actually does fall down soon as ya enter turn, which ain't something most others brave enough to do on their cripples, while I look forward to in on Peel. Some times gravity just ain't fast enough to do it in time, therefore my sign off, Throw yourself at the ground and miss. Less gryo would help Peel to do that I think. Feels like a knife of fear spike going in but the relief pulling out feels so good.

Don't need no stinking gryo's nor trail...
http://www.youtube.com/watch?v=YdtE3aIUhbU
[video]http://www.youtube.com/watch?v=YdtE3aIUhbU[/video]
 
acotrel said:
A lot of guys back in the 70s fitted 18 inch wheels to featherbed framed bikes in place of the 19 inch wheels, to get decent rubber. Few changed the steering geometry to retain the original handling characteristics. I did it to my Triton and it became exhausting in any race on a short circuit. It always ran wide. These days the replica frames have similar geometry to a Suzuki two stroke. Interestingly the fastest Manx in Victoria which was built by McIntosh in NZ and is ridden by Cameron Donald has 19 inch wheels.
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A lot of featherbed bikes were sold by Nortons as new bikes with 18 inch wheels.... ?

The rolling diam is not much different, why would you need to change the steering geometry.
Fork dive does that for you anyway....
And how would you change the steering geometry.
 
I believe an original manx handles considerably differently to a modern one. The replica featherbed frames currently being raced usually have 26 degree head angles and steer like Suzuki two strokes. You fly up to a corner and tip in rather that taking a wide smooth high speed racing line. I don't believe there is any way to modify an original wideline manx frame without ruining it, to accommodate 18 inch wheels and get the same handling as a Molnar. The yokes already have minimal offset.
When I changed from 19 inch wheels to 18s on my Triton, I was disappointed. Even though it had better rubber if felt dead and heavy and tended to run wide in corners. And worse, it was easier to ground the footrests.
I cannot remember what the head angle is on an original manx, however the guys who raced featherbeds in historic in the 80s bought the altered replica frames so they could use 18 inch wheels and get decent rubber. It is not a bad way to go, and I've often wondered that if I was buying a frame which head angle I would specify.
 
Good point Hobot, and good video too, but . . . .

Acotrel, I concur on how switching wheel diameters can harm handling; similarly I tried a switch from 18" to 17" on my '86 GSXR, did it also to fit more modern tires and had the same result - inferior handling. I couldn't put those 18" wheels back on fast enough.

Hobot, the truth is in the middle. I did not say that without the gyroscopic effect motorcycles would fall over, I said that they would lose stability. I stand by that. We've all seen flat trackers, with the rear hung out, bike upright, rider with foot down, weight on the inside, front wheel pointing to the inside, big slip angle - I think that gyroscopic precession is part of what's happening in that dynamic instance. Another part of the puzzle - engine flywheels too.
 
As far as wheel weight goes. I suggest that if you fit lighter wheels and your bike handles better, the steering geometry was not at the optimum to suit your riding style previously.
 
So are there 'riding styles' where much heavier wheels are an advantage ?
 
i don't really know what or why Ms Peel can take me beyond anything you'all or the elites can even describe on what wheel mass will do or not do when leaving what's published and demo'd behind in the dust but don't think we with our vintage sizes can loose enough weight to hurt w/o going to 26" carbon fiber bicycle wheels we'd collapse at first throttle hits or going to 17" size balloon tire rims, so we can lighten up as much as we can with technology we can actually fit and expect better everything on handling. That is - no danger of hitting too little gryo mass in a Commando as some the 17" shod elites have hit in references I've found. I know what .5 sec difference means in neck and neck contests, night and day differences on pecking order joys to die for. Lightest combo for our sizes would be a supercross-MX hub with necked down spokes on sealed tubeless rim, if ya can pull that off and not leak down in hours or even faster to crash on aired down tire upsets. Again tarmac is so so conquered by Peel its about the last thing on my mind to take on 200 hp 200 mph bikes when any leaning involved at all, so its the touchy off road stuff that fascinated me now and to a man all off roaders run spoked rims so that's what I'm sticking with and see how the pecking order falls someday. If ya have to think-worry about how fast and low and powerful to enter a decreasing radius w/o any thot of brakes in a pavement turn, then ya no idea how thoughtless eager Peel takes on those absolute delights. If ya ain't making every turn a sharpening decreasing radius turn for the shear increasing G thrills of it then sorry ya missing out on the G force joys before ya gone-dead. i now think-feel-experienced - its likely only possible on a isolastic linked Commando on narrow tires.
 
Why some go to see at races

[video]http://www.youtube.com/watch?v=rkMfI8UII2c[/video]

[video]http://www.youtube.com/watch?v=Eqsytcz7g0c[/video]

[video]http://www.youtube.com/watch?v=moAfIYmV4E4[/video]

[video]http://www.youtube.com/watch?v=gxiAfI6XQB4[/video]

[video]http://www.youtube.com/watch?v=sFJ9mNpZ1Ms[/video]
 
Luck or skill saves

[video]http://www.youtube.com/watch?v=lHqmty-Oinc[/video]

[video]http://www.youtube.com/watch?v=0AyFzQg4i0Q[/video]
 
acotrel said:
As far as wheel weight goes. I suggest that if you fit lighter wheels and your bike handles better, the steering geometry was not at the optimum to suit your riding style previously.
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Having raced a TZ350 Yamaha with both lighter Campagnolo mag alloy wheels and the weightier wire spoked wheels on the same bike, I cannot say that I noticed much difference between the two. Other riders on the same TZ350s won both the season long Champion of Snetterton and Brands with the heavier wire wheels, at about the same time I was racing. Even Damon hill won the Champion of Brands on a TZ.
Obliviously, the lighter wheels would help contribute to a great deal of total bike weight saving, particularly when used with tubeless tyres.
 
Dances with Shrapnel said:
xbacksideslider said:
No. And, IMO, lighter wheels are always better.
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+1

That is the take away point on this whole thread.
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You are probably correct, however I believe my bike is at the safe limit of quick steering. These days if I crashed, I would probably end up as a skin bag full of bone chips. Obviously anything which reduces the total weight of the bike helps the acceleration in the forwards direction. If you don't stay upright, the good effect is negated.
 
It's really not about the forward acceleration and decleration that lighter wheels are all about. The big benefit is better opportunity for road compliance.

If you think about it, with a zero mass wheel and zero mass (unsprung) suspension components the wheel would always be in full contact with the road no matter how severe the bump and with full load on the tire patch. You want to get as close to that as practical.

Unfortunately, in the real world, there are compromises such as wheels that have mass :cry: and unsprung suspension component that have mass. :cry:
 
Dances with Shrapnel said:
It's really not about the forward acceleration and decleration that lighter wheels are all about. The big benefit it better opportunity for road compliance.

If you think about it, with a zero mass wheel and zero mass (unsprung) suspension components the wheel would always be in full contact with the road no matter how severe the bump and with full load on the tire patch. You want to get as close to that as practical.

Unfortunately, in the real world, there are compromises such as wheels that have mass :cry: and unsprung suspension component that have mass. :cry:
Click to expand...
These come pretty close to zero mass:

http://www.dymag.com/?q=products
 
You want 19" ? 16.5" and 17" isn't good enough for you? They do come "in a range of colours" after all. LOL
 
Carbonfibre 19" wheels for Harley's are 3" wide for ~ $1300, on sale.
Scooters are famous for easy handling on their light wheels but both Wes and I know what happens about 90 mph on scooter size wheels so some of them now come with 16.5" size to help stabilize in a straight-ish line as they turn great and slide and drift nicely on tiny tires. Imagine the size market needed to work up a cf to DOT approval in our sizes to sell to public. Implies too light of available wheels for our vintage bikes' power/mass/speed is both academic nonsense plus oxymoronic. Those who can't read English will think I just wrote against Comstock's wisdom, that heaver smaller wheels-tires helps all motorcycles, especially vintage to take on elites.
 
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