Leading Link Designs - Post Pics

[Hack'dTiger]

This one isn't nearly as elaborate as some of the others posted, but it's the suspension that Dauntless built for the Tiger Rig that I now own.

[vortexau]

OEC-Temple Duplex Forks

. . . a simple diagram which shows the geometry of the system, so you can have an idea of how it works. Having ridden many miles on these machines, I can testify to how well it all works, although the worst feature is its large turning circle and poor manoeuvrability at slow speed and when wheeling the machine about. I did also have a frontal collision some years ago with the rear end of a Jeep which stopped suddenly without warning, which demonstrated the excellent impact absorbing properties of the machine!!! The damage looked far worse than it was, as I simply popped the bottom links out and more or less rode home...


Martin Shelley
VMCC OEC and Blackburne Marque Specialist

[Dr Jim]

Originally Posted by vortexau

OEC-Temple Duplex Forks

And now you all know why the O.E.C. company was affectionately referred to as:

"Odd Engineering Concepts"

Actually, this front end (one rather hesitates to call it a 'fork') was delightfully solid and stable at a time when most front forks were allowed to simply wave about loosely in the breeze, with tank-slapping and high-speed oscillations considered the norm, not the unusual.

It's weakness were the multiple bushings that defined the parallelogram which suspended the wheel - they had to be tight to prevent play, but loose enough to allow the headstock to turn easily - any dirt, grit, or misalignment and the bike reverted to classic 'Arm-Strong' steering.

Also, wheel turning angles were somewhat less than conventional forks - constrained not so much by design, but by the lever arm's strength - they're subjected to significant compression and bending forces.

Still, it's interesting to consider this front end being built with modern teflon-lined bushings (or even heim joints), and high-tensile rods. It should be no more difficult than a LL or TL design, and a delight to ride on a sidecar rig.

Cheers

Jim

[vortexau]

The strange thing is that I penned a diagram of a off-setting trike frontend some fifteen years back, similar to this O.E.C. Duplex, before I had laid eyes on the O.E.C.

My version had larger-scale geometry that would have moved the trike front-wheel to the outside during cornering . . . imitating a racecar that lifts the inside front to corner on three wheels.

Scaling a OEC-type could produce a sidecar machine that moves the frontend outboard when the chair is on the inside of the turn --- effectively widening the track to place the CG further inboard.

The same displacement of the frontend chairward, when cornering with the chair on the outside of the turn, would allow the frontend to offload some of the mass-transfer to the chairwheel; reducing chairwheel suspension compression.

That O.E.C. (in the picture) seems to use a plunger-style suspension, but I can see this geometry being used with upper & lower swingarms to make a "hub-centre" that has no actual centre steering axis. This concept would still require a wishbone-link to handlebar.

[AL-58]

Originally Posted by SCray

The builder of the links had used (say) 50mm od tube. The triple clamp internal diameter was (say) 40mm. all that he'd done was turn down that length of tube that slid into the clamps so that is was now the correct od to fit into the clamps. The top edge of the 50mm od tube was butted up against the lower face of the clamp. Probably looked great when it was all painted etc.
High load point exactly at the weakest point of the tube. The whole assembly, links, shocks, brakes, wheel, guard was flapping around, secured by the brake hoses and speedo cable. Yikes, alright. Shits were trumps, I'd reckon.

The tubes were the same size full length, nothing butted against the triple clamp, it snapped where the welded gusset was. Was well put together and everything fitted well, so it was a good fabricator, but material way too light. I know cause its my bike. It was either from South Oz or somewhere around Wollongong, never been able to find out any more.

Al

[tripodtiger]

Originally Posted by AL-58

The tubes were the same size full length, nothing butted against the triple clamp, it snapped where the welded gusset was. Was well put together and everything fitted well, so it was a good fabricator, but material way too light. I know cause its my bike. It was either from South Oz or somewhere around Wollongong, never been able to find out any more.

Al

My observations were not quite accurate then. Not the first time.
I suppose shits were trumps was pretty accurate, though?

Another lasting memory from that rally was that it was the first time I'd seen a mobile phone actually do something useful. And very surprised that it worked there.
What happened to the bike, Al?

[larryboy]

Well, I'd been toying with the idea of building a leading link for the Bandit/Ural and now I have a need since we wiped the front end off the rig on Friday.


I've pretty much got it figured out. One question..Is .188 wall in HREW strong enough for the application? My tube bender can handle .188, but not .250 wall.

[RedMenace]

Originally Posted by larryboy

...now I have a need since we wiped the front end off the rig on Friday....

[larryboy]

Originally Posted by RedMenace

I'll link you up when the kid is ready to post her story...until then, whittle down those nails.


Teaser:

[larryboy]

What was I thinking? HREW isn't the choice for this... .188 DOM is the way to go.

[RedMenace]

Originally Posted by larryboy

OW! Poor Suzi! Everyone OK, I trust? I lent my SpeedTriple rig to a freind, with similar results. Might I recommend a good sidecar class?

http://adventuresidecar.com/training06/training06.htm

[larryboy]

Originally Posted by RedMenace

OW! Poor Suzi! Everyone OK, I trust? I lent my SpeedTriple rig to a freind, with similar results. Might I recommend a good sidecar class?

http://adventuresidecar.com/training06/training06.htm

Somebody is going in for an X-ray this morning...you can handle that too I think.

Room and board sidecar class? I might hafta put her on the bus to your house.

[RedMenace]

Originally Posted by larryboy

Somebody is going in for an X-ray this morning...you can handle that too I think.

Room and board sidecar class? I might hafta put her on the bus to your house.

We might be able to work something out. At the very least I can find you a nice B&B near the class.

So when do we get the Paul Harvey( "... an that's the rest of the story...") ?

[larryboy]

Originally Posted by RedMenace

So when do we get the Paul Harvey( "... an that's the rest of the story...") ?

She has started the tale:

http://www.advrider.com/forums/showthread.php?t=343108

[Bandit Bill]

Originally Posted by larryboy

Well, I'd been toying with the idea of building a leading link for the Bandit/Ural and now I have a need since we wiped the front end off the rig on Friday.


I've pretty much got it figured out. One question..Is .188 wall in HREW strong enough for the application? My tube bender can handle .188, but not .250 wall.

.188 DOM should be fine, but the machine shop i dealt with in terms of some of the fabrication couldn't handle 44.5 mm ( 1 3/4") diameter .188 DOM tubing in their bender, and we elected to go the cut and weld and gusset method. Has held up quite well for 4 years now.

If that is a 600, the triple trees are 41 mm, so i don't know if you can use 1 5/8" DOM (41.275 mm), surface machined down at the top to fit in the triple trees and it'll bend easier in a bender..