Please.

 

Hawkrider is right. Lengthening the shift linkage rod will decrease throw required on the shift level and decrease mechanical advantage of the system.

it has been many, many years since my days at Georgia Tech, but the reasoning has to do with how tangential the shift linkage rod is to the center of rotation of the shift rod (on transmission). rotating the primary shift linkage on transmission shaft changes where the force will be applied around the center of rotation. the same amount of travel in shift linkage rod will apply more or less degrees of rotation to the transmission rod depending on where the along that radius the movement is applied.

imagine this - the factory setting has the shift linkage rod resting almost tangential to the circumference of the circle made by the primary shift rod around the transmission rod (force will be applied almost 90 degrees to the radius line that you could draw from the center of rotation to the end of the linkage). now take the other extreme - lengthen the rod so much that the ball joint on the primary shift rod is 90 degrees to the front of the bike. now the force will be applied almost parallel the radius line connecting the center of rotation to the primary shift ball joint. now, lets say we move the lengthened shift linkage rod a constant amount in both scenrios. moving this rod 1/2" in both cases produces more angular rotation to the transmission in the lengthened case. appling force that is more directed towards the center of the circle, rather than around the perimeter of the circle, will decrease mechanical advantage and increase angular rotation.

hope all of this make some kind of sense. if you think of changing the transmission rod by almost 90 degrees makes it easier to see the change in number of degrees travelled around the circumference versus the constant amount of travel of the linkage rod.

hope this helps!

 

I'll work it out.

 

ALTSHawk98,

I'm not shortening the shift linkage here. All we're doing is rotating it on the shift shaft. The adjustable shift rod is actually being lengthened!

You got the rest of this right! Thanks!

 

either way - moving the point of contact around the circumference of the circle (either shortening or lengthening) will decrease mechanical advantage and increase angular rotation. pushing the 90 degree example to either extreme (point towards the front or the back of the bike) will make the application of force less tangential to the radius of the circle. application of force absolutely tangential to the cirle is mechaically the most effictive and offers the least angular rotation. anything less tangential, offers less mechanical advantage and more effective rotation with less movement.

sorry for miss typing the responce with "shortening". i read through the whole thread and starting typing too quick. it will produce same results either way.

hope this helps!

 

The best advice I can give to anyone who is thying to figure this out, is to do what I did. Get out your tape measure, measure everything up, swap it to the new position, and then measure it again.

Oh, and a tip I read somewhere to add to Greg's original instructions. Before you move the linkage on the spline, take a measurement from the shifter to the ground. That way after you swap the linkage postion on the shaft, it is easy to re-set this measurement and put your shifter right back where you had it. (apologies if you said this Greg but I don't remeber seeing it)

Too easy!