dual sporting

vanmar27 said:

yep...pretty awesome indeed....you order one yet??? Might be tough on Jesse's single track stuff though......

Where do you find this stuff???? I am glad you do.....

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palica found it above.

but i've had a unit like this in mind ever since trike conversions started coming out... you know, something for my retirement when i am too old and weak to hold the bike up anymore.

this thing would plow over/through almost anything we rode in the LBL200...

it looks like an awesome product, definitely visit their web site. built in norway, i think you'd have to sneak it into the US.

maybe ship it over in sections via UPS?

Makes me think of that ole Johnny Cash hit..."I got it one piece at a time...and it didn't cost me a dime"

I would like to see you gettin up that hill from the creekbed!

There is a guy in the USA, Bob Mighell, who has been working on tilting trikes. He converts a two-wheeler to three by adding a new front end with two leaning wheels. This was covered in the latest issue of Motorcycle Consumer News, although he's been around the Northwest for several years.

I've been offered a test ride on one, but just haven't put together the timing, yet. I think I need to make this a priority for 2011.

For more information, contact Tilting Motor Works, 3915 152nd St. NE, Marysville, WA 98271. www.tiltingmotorworks.com or 360 657-7900.

The latest unit is based on a Harley-Davidson, and so far I think the development has been for street use. But I suspect he'd be willing to discuss a "dual sport" rig based on something like a BMW GS or KTM.

When you see an offroad sidecar rig drifting around turns, it may seem that it's only partially under control, but that's an illusion. With enough traction, a sidecar rig can be drifted left or right. A tilting trike can also be drifted with much less risk of a fall-down than a bike. But remember that with a tilting rig, balance and direction are controlled by steering. If both front tires lose enough traction, balance will be lost. A rigid rig can slide sideways, or (if the system allows) lock the wheels and slide in a straight line, without falling over.

However, I think the TMW design has some merit, and who knows? Maybe I'll build one for myself. I'd really like something less complex than the Spyder, and with more performance than the R100/Ural.

pmdave

Dang. This thread got interesting agin!

Visian said:

ok, i'm calling this thing flat awesome!

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Best way to kill a video is a soundtrack like that one.

I couldn't hit the mute fast enough. Sheesh.

Chopin would've been better!

I'm curious about traction with two front wheels vs one. Total traction is a function of the normal weight pressing down the tires. Supporting the same weight on two tires would theoretically halve the traction of either tire. So, theoretically, in a quick stop, the stopping distance would be the same for two wheels or three.

But, in the real world, we know that traction is not just a matter of friction of rubber/pavement, but also a matter of some toothing of the rubber edges against sharp protrusions in the pavement. IOW, the tire can be more like a gear, where tread blocks are prevented from lateral movement by the "teeth" of the bumps and dips in the pavement. That's why motorcycles can often produce g forces greater than 1.0.

Also, in the real world, the surface is not equally tractable from point to point. Right here, the tire/surface might have traction equal to 1.4, where over there traction might be 0.6. On a two-wheeler, if the front tire happens to roll over the 0.6 area while leaned over or braking, traction might be lost, and the bike goes BAM!

But if one tire is on the 0.6 area, while the other tire is on the 1.4 area, one tire can lose traction, but the other tire continues to hold, so the trike might slide a bit but not fall down. (the tractable tire is still able to produce steering force to maintain balance)

We also know that tires usually have a slip angle in turns. That is, the direction of the wheel doesn't match the direction in which the wheel is pointed. The slip angle can increase quite a bit before the tire loses rolling traction. The problem for front wheels is that if the tire loses all rolling traction, the wheel will slide off on a tangent without regard to which direction the wheel is steered.

So, what is it really that gives an MP3 or tilting trike greater stability than a bike?

pmdave

After a bit of thought about traction, I'm realizing why I don't like leaning sidecar outfits. There is just one steerable wheel. The sidecar tire will have some resistance to sliding, since the articulation will allow continuous weight on the sidecar wheel. But if the single front tire slides, steering/balance will quickly degrade.

On any 2F 1R three-wheeler, the rear tire can slide or be drifted to control direction, tire slip, and balance. And it's easier to control rear wheel thrust with a single wheel drive, than if there are two wheels with a differential. (note; H-D/Lehman 1F 2R has no differential.)

Whether a 2F 1R trike is rigid or free leaning, the outside wheel in a turn will be loaded by "centrifugal force", which will add traction to the outside tire. If the outside tire loses traction, the rig will slip more in that direction, bringing the inside wheel down.

If the driver is hanging off in turns, there will be more weight (and therefore increased traction) on the inside tire. I wonder if it makes any difference which front tire on a 2F 1R trike slides first... In any case, increasing slip angles reduces rollover force. Watching the Norwegian tilting trike video, I was wondering why the driver wasn't hanging his butt off toward the inside rather than counterleaning. Maybe he just wanted to show off the extreme lean angles possible.

Just thinking here...

pmdave

pmdave

I find ABS on dirt/gravel/fire roads annoying.

Visian said:

palica found it above.

it looks like an awesome product, definitely visit their web site. built in norway, i think you'd have to sneak it into the US.

maybe ship it over in sections via UPS?

Click to expand...

I wonder what USA import laws say about modified vehicles? It would probably not be possible to import the whole rig, since that would be a motor vehicle, and the base motorcycle would likely be a Euro spec, not a USA spec. Even if it's the same basic motorcycle as sold in the USA, it would need all the appropriate DOT equipment and stickers.

However, I suspect the front end kit could be imported as a "motorcycle accessory" since it doesn't have a motor, and isn't licensed. There would probably be a healthy import duty, plus shipping, documentation, etc. I think customs would treat it the same way as a sidecar imported from a European country.

Years ago I bought a Unit leading link from Hedingham sidecars in England. They boxed up the various parts in suitable packages and mailed it. Apparently, sending it by post, it just arrives, and there is no import duty. As I carried my heavy clanking packages out of the post office, I kept looking over my shoulder, expecting someone to shout, WAIT, yes you--we have papers to sign!

By comparison, when I bought some panniers and rack from the UK, it had to be shipped freight (apparently because of the size). I had to pay the crating company, the shipping company, and a document company, then meet the customs guy at the warehouse and cough up import duty before I could get it released.

pmdave