Boxerworks.com

I hope you didn't think I was saying anything near to the idea that motorcycle wheels can be as light as bicycle wheels. I'm the guy who will tell fat guys and big guys that the wheels on a given bike won't work out for them. Normal circumstance is for them to buy from a shop that tells them what they want to hear, that is, that they can ride on the same rims as a 150lb guy, and six months or a year later come in and tell me I was right and they had to buy a different set of wheels.

I do think that there could be some weight reductions in spoked wheels, at least for airheads. At a boutique Ducati dealership, I lifted one of their aftermarket wheels (forged?) and it was mui light. I'd love to have lighter wheels on my bikes.

Chuey

Chuey wrote:I do think that there could be some weight reductions in spoked wheels, at least for airheads. At a boutique Ducati dealership, I lifted one of their aftermarket wheels (forged?) and it was mui light.

Chuey

Yet, the modern spoke wheel they designed for the Sport Classic was not - at all. The hub was massive: much larger and heavier than their cast/forged wheel hubs, and they used 4.4 mm spokes that were not too light either. The rear hub was 7.5 lbs, just the spokes and nipples were 2.6 lbs. Of course just the damn tube was 2.4 lbs.

Total weight of the rear wheel (including bearings and tube but no tire or axle) was 20 lbs. My GT was significantly worse because of the steel rim. The weight I showed here was for the better alloy rim unit on the Paul Smart.

Here's the lovely numbers from a guy who replaced his GT wheels with Carrozzeria's (all numbers in lbs.):

Stock Wheels
Rear Wheel w/Sprocket & Rotor 28.0
Front Wheel W/O Rotors 15.25
Rear Tube 2.5
Front Tube 2.0
Total 47.75

Carrozzeria Wheels
Rear Wheel w/Sprocket & Rotor 16.75
Front Wheel W/O Rotors 8.0
Rear Tube 0.0
Front Tube 0.0
Total 24.75

Weight lost with the Carrozzerias
Rear Wheel w/Sprocket & Rotor -11.25
Front Wheel W/O Rotors -7.25
Rear Tube -2.5
Front Tube -2.0
Total -23.0

http://www.webbikeworld.com/motorcycle- ... ia-wheels/

My R68 has steel rims and heavy duty spokes.
It originally carried a chair.

At the risk of being horribly redundant ...
The forces acting upon a wheel are always context dependant.
A chosen wheel should be properly designed to respond to those specific forces.
On the road, control of lateral flexure is critical to "good handling".
The primary reason to "reinvent" the spoked road ONLY mc wheel
dealt succinctly with that particular issue of flexure.
Was production cost a determining factor or a benefit ?
Cost has never played 2nd fiddle to performance
in either the old F series or Moto GP ...
No spokes have been fitted there since the introduction of cast / forged wheels.

All thoughts, theories, and opinions aside -
This is just physics & history.

vanzen@rockerboxer.com wrote: ...The primary reason to "reinvent" the spoked road ONLY mc wheel...

snicker

5 years ago, Ken took the time to weigh some wheels.
I have no notes regarding his experimental procedure,
but I would assume the measurements to comparatively accurate.

/7 era:
Spoked wheel 9lb 10oz
BMW Snowflake 12 lb 3oz
Lester 12lb. 0oz

No Morris wheel was available,
Researching the purchase of cast wheels in @ 1980 for an R100/7
I do recall that the advertised weight of a Morris alloy rim
to be less than that of a Lester's advertised weight.

Considering @ an additional 2lb for a tube (as per Major's post)
and one might imagine that a flake
fitted without a tube
would provide both a reduction of lateral flex
and the (approximate) unsprung mass of a spoked wheel.
:)

vanzen@rockerboxer.com wrote:5 years ago, Ken took the time to weigh some wheels.
I have no notes regarding his experimental procedure,
but I would assume the measurements to comparatively accurate.

I just went out to look at the scale that I weighed the wheels on. It is an old fashioned double beam balance scale, the kind that might have been found in a dry goods store long ago. The total weight capacity of the scale is 30 lbs. The bottom beam (with the heavy weight) is graduated in pounds and the top beam is graduated in ounces. The top weight slides only, with no detents. The ounce markings are about 1/16 inch apart.

In weighing the wheels I made sure that the scale mechanism operated smoothly and that at the zero position for the weights the beam pointer was midway between the top and bottom stops. So I figured the accuracy/error to be plus/minus one ounce. At the very worst they should be plus/minus two ounces.

I was deliberate in making my measurements. The bottom sliding weight was kept on one position for all the measurements, though I can't absolutely say so for sure. All three measured wheel weights should be therefore directly comparable.

What Vanzen didn't mention is that the Snowflakes don't need tubes, And from a safety standpoint tubes are less safe than running the tire tubeless. There was a marathon discussion between Vanzen and Rob Frankham about the advisability of running tires tubeless on snowflake rims. Cogent arguments were made pro and con. As I read the arguments I (perhaps reluctantly) came to the conclusion that Vanzen was correct and I changed my original opinion.

That discussion centered on stock Snowflake wheels vs stock spoked wheels. IIRC Lesters and Morris wheels weren't discussed, though I see no reason why the arguments wouldn't apply to them too.

The whole reason I brought up this arcane bit of Boxerworks history is the implicit conclusion that to go tubeless on snowflake wheels provides an automatic 2 pound edge in figuring the unsprung weight when discussing cast vs spoked wheels.

That memorable discussion, along with Lonnie Walker's discussion about why a Harley Davidson motorcycle was his best choice for a new ride were the top two discussions of all time here on Boxerworks. Other notable lost discussions include Duane Ausherman's argument that safety bars/motor guards are more dangerous to life and limg than going without. Also ranking high were multiple discussions about proper alignment and adjustment of airhead forks vis a vis tank slappers and major wobbles. One memorable memory (?) from a Boxerworks rally at my place was regarding the value of countersteering as a useful concept for teaching motorcycle riding. I (with the help from some friends) won that one.)

Ken

" What Vanzen didn't mention is that the Snowflakes don't need tubes, And from a safety standpoint tubes are less safe than running the tire tubeless. There was a marathon discussion between Vanzen and Rob Frankham about the advisability of running tires tubeless on snowflake rims. Cogent arguments were made pro and con. As I read the arguments I (perhaps reluctantly) came to the conclusion that Vanzen was correct and I changed my original opinion."

Just to be clear:
A BMW snowflake rim profile is designed for tubes.
DOT regulations require a different rim profile for tube-less use.
Using a flake without a tube, then,
will be an "at your own risk" proposition.

AND

I believe Lester and/or Morris made a few BMW wheels with the safety bead toward the end of that production - that is, they were designed for tubeless tires - just like a BMW Y-spoke or newer is.

vanzen@rockerboxer.com wrote:"Just to be clear:
A BMW snowflake rim profile is designed for tubes.
DOT regulations require a different rim profile for tube-less use.
Using a flake without a tube, then,
will be an "at your own risk" proposition.

To be clear, I believe that your personal decision, considering all the tradeoffs, was that you would choose to run tires tubeless on snowflake wheels. (And in that old thread you then, as now, made no reccomendations.)

There were many other things talked about in that discussion. I seem to recall that one concern is that a tubed tire that picks up a nail will not typically loose air slowly. Typically, the nail will shred the tube and then you have the rough equivalent of a blowout at speed, and the tire will flop about on the rim, sometimes causing the wheel to lock up. Whereas a nail in a tubeless tire, even on a snowflake, will more commonly result in a leak allowing the rider to slow with a modicum of control.

Be that as it may, right or wrong, In the limit, if you run tubed tire on a snowflake wheel, and you have a problem, that's at your own risk too.

But I'll quit here. I have no real intent to revisit that old discussion. My post was more nostalgic than anything else. It's just too bad that we have lost that discussions and many more that would be of interest for many now. (There are also many old discussions that were full of rancor and pissing to which I would say, good riddance.)


Ken

It seems then, that for this discussion, there is the supposition that tires do not vary much in weight. Are tubeless tires generally lighter or heavier than non tubeless in a given size? That is, not including the tube.

Chuey