Laverda 1000/1200/ Jota braced swing arm

[GregT]

Modern MotoGP bike chassis have become so stiff that a certain amount of flex needs to be introduced in certain areas to regain traction and feedback for the rider.  Don't know how much of this technology is transferred to road bikes, maybe electronic traction control devices are simply a lot cheaper...

piet

Some of them certainly are too stiff to work well with the ordained electronics in MotoGP.
Couple of years back i had a yarn to Mike Sinclair - over the top of Magoo's YZR500 which he was working on. Mike's an old mate from the early 70's.
He was telling me about the testing of the Yamaha frames they did. Holes everywhere eventually to work out which bits actually added to stiffness and which didn't.
Then back to back testing of frames with known stiffness figures.
That was how when they built the Roberts KR3's they could go to a specialist structural engineer and specify they wanted a frame this stiff - between a high and low specified figure. And it worked.
Then Yamaha got directly involved - and stuffed it up. According to Mike the last YZR's were simply wrong. Shows how easy it is to screw up at that level.

Now, steel arms. As a frame builder myself, the formula is - build it as stiff as you can. 99% of the riders can't pick whether it's too stiff or not. But they can feel flex - and don't like it. then you look at where it's going to flex - frame or arm. Surprisingly to some but as has already been suggested here it's more often the frame which is the source.
I'd suggest that if an aftermarket arm alone fixes an apparent flex problem, it may well be a better bearing or stiffer pivot pin setup.

 

[Grant]

Mine has a triangulated swingarm, necessary for the monoshock.
Standard swingarm, modified.
But it also has double-skinned swing arm pivots and a 16mm swing arm spindle instead of the usual 14mm one on triples.
Hard to say what made the biggest improvement as I went through the bike as a whole, rather than improving isolated areas only.

IMG_5611 by Grant Duguid, on Flickr

IMG_5667 by Grant Duguid, on Flickr

IMG_5665 by Grant Duguid, on Flickr

 

[1200 JOTA]

Mine has a triangulated swingarm, necessary for the monoshock.
Standard swingarm, modified.
But it also has double-skinned swing arm pivots and a 16mm swing arm spindle instead of the usual 14mm one on triples.
Hard to say what made the biggest improvement as I went through the bike as a whole, rather than improving isolated areas only.

Very smart (well thought out) and nice work!