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Discussion in 'GS Boxers' started by Dorsicano, Feb 3, 2011.
Spoked wheels very desirable IMO. Never know when you're going to peg something.
Although the chances off going off road aren't that high, I still want the cross spokes on the off chance. Wouldn't want to be restricted should my riding mates decide to venture down some tracks
Cast wheels are fine for casual off road.
This comment from a Brit bike journo on the Guzzi Stelvio launch I thought interesting.
The latest Stelvio comes in two versions in Europe, one with spoked wheels (NTX) and one with cast (8V), and they had both on the launch:
"Swapping between the two and riding through mountain roads it's the 1200 8V version that I wanted to stay on. It's the keener of the two bikes and much easier to throw around. Admittedly it's not carrying an extra 22kg of extras around with it but it's the wheels that make the biggest difference.
"Although the 1200 8V's alloy wheels and the NTX's spoked wheels weigh the same amount, the NTX's carry most of their weight on the rim and this inertia makes a big difference when it comes to cornering. It's not that the NTX is bad at turning on its side, it's just the 1200 8V just feels so much better."
(Quotes from 2012 Stelvio piece at visordown.)
Can't say whether the same applies to the GS wheels, but it may well do.
That's interesting, as I will be predominantly riding on road. I may have to give this a little more thought.
So, is the journo saying that the Stelvio's cast and spoke wheels weigh the same but that the lighter of the two motorcycles (8v) is the easier to maneuver/flick around? No surprise if so. Or is he talking about the construction of each wheel and how the weight is distributed amongst them (hub, spokes, rim versus one cast piece)?
He is acknowledging the NTX carries more weight, but attributes most of the steering difference to the wheel construction, with the cast wheels carrying a lower proportion of their mass at the perimeter.
So, the gyroscope effect was less pronounced on the cast wheel, he believed. This made for lighter steering, which he greatly preferred on twisting tarmac prevalent at the launch.
Whew! Good on ya for being a good sport!
And the Stelvio licenses the spoked wheel patent from BMW, so the construction is similar. Another factor to consider aside from rotating mass is stiffness...the spoked wheels are stronger offroad because they have some flex...which I would think would be a negative for paved twisties.
Someone keeps reading my mind
Another good point. I've never noticed any handling issues on my current GS, and that has spokes, so am sure I'll never ride to the bikes limits. As long as they are priced similar to the current spoked wheels, and the bike is priced sensibly, I'll go cross spoke, otherwise my decision will be made for me.
I wish this spoke vs cast rim issue was just as simple as picking colours.
I was going to do some physics calculations at higher accuracy (not involving the effects of tire and flexing of it at higher speeds along with the effects of gravity due to vertical alignment), but I decided for later if time permits.
Here's what I think: Assuming total weight to be the same for either rim, the geometry of weight distribution are quite different. Spoke rims will weight higher at the ends, because of total weight minus the small weight of sum of spokes. While the Cast rim will have weight distributed across the wheel due to weight of cast spokes. Hence, I suspect the centripetal acceleration to be different, while the centrifugal force may remain somewhat the same (it could also change). Due to increased centripetal acceleration for a spoke rim at a given constant speed, the effects of turning on a curve would be pronounced as we increase the angle of lean.
This effect translates to a feel and handling of a bike on a paved curve. Scientifically, it would be there, however, once you start riding your own bike, you get accustomed to its handling, and you make adjustments to it without even knowing. This is what I call your "style" of riding. We ride bikes that we own, unlike journo's who tests them against another.
So, IMHO, I think get the wheel you want, spoke is great because it has tendency to flex if you were to go off-roading or unexpectedly go over big bumps, it will be far more forgiving. It also means about $500 more as an option!
I don't think the spokes create an issue, its just a question of whether the cast wheels handle slightly better on pavement.
Wow, thanks for the detailed response.
That was funny! I liked the summary that Montauk gave though, I knew the was a more scientific explanation
Just saw this, knew about it but hadn't seen this clip before! I just really love the sound of the wet head :)
Who wrote their script director? I like what Charlie says at the end... NOW, you can conquer the world...
Nova Scotia on Explorer
This is why I love the ADV forum.....can't imagine reading this response over on the vtwinforum where I, from time to time, tune into the latest "hadda lay 'er" down harley threads. lol
Very detailed and it forced me to think back to my college Calculus-based physics class.
Official Fuel consumption as taken from press release:
90km/h l/100km is 4.1 L (57mpg)
120km/h l/100km is 5.5 L (51mpg)
The 120km using 5.5 L (51 mpg) of gasoline seems high fuel usage. I would expect this machine would run leaner, so I would expect it more like 53-54 mpg at 75 m/hr speed. What do you guys think?
I don't own a recent R1200GS, therefore I cannot relate. For my current bike the difference lies about 2-4 mpg at those speeds in approximation and mine is not leaner at all.