Ideal Gearshifter Geometry

[Greg_imp]

I like to understand how everything works on my motorcycle. The control that is designed with the most adjustability is the gear shifter. Having this set up right makes riding easier and reduces a potential source of distraction. Besides, it's a cool little mechanism and easy to adjust to fit your unique situation.

A few years ago I had reconstructive surgery on my left foot. Several joints were immobilized and my range of motion is smaller than normal, so I have had to adjust the shifter to suit. I understood the idea behind displacing the shifter pivot away from the transmission spindle but until I did the following drawings I didn't really appreciate the beauty of this mechanism.

Displacing the shifter pivot allows the designers to position it in the right place without regard to where the spindle is, and also use differing arm lengths to control the amount of force needed to execute a shift.



Above is the normal geometry of the shifter. I would assume this is how it comes from the factory, but since I adjusted mine before taking a close look and measuring it, I'm not sure of that.



Above shows upshifting and downshifting behind the normal, at rest position.



When linkage length is about 3.86” (98mm) and the spindle dots are aligned, right angles are formed at both linkage connections; to the lever and to the arm.

Gear changes require a 10° rotation of the transmission spindle, which takes about 1.04” (26.5mm) of gearshift foot peg travel.

The spindle is splined with a 12° pitch which raises or lowers the gearshift foot peg about 1.25” (31.75mm) if the gearshift arm is moved one spline.

For finer adjustments than 1.25” you have to change the linkage length. Facing the bike, the left end is reverse threads. Both 10mm nuts must be loosened so the rod can be turned.

This mechanism is designed to be adjustable to suit individual preferences but it works best with ideal geometry.

I felt the need to disclaim this post. I hope it doesn't spoil it for you.

 

[Elipten_imp]

Great information. Thanks


Sent from my iPad using Tapatalk

 

[Rick Froscheiser_imp]

Thanks for the info Greg. That is something I did not think about much but good to know. Thanks again.

 

[CBXBob_imp]

My shift lever was way too low so I adjusted it previously. Guess The length the linkage arm ended up at? Very close to the optimum !

 

[the Ferret]

Greg, trying to understand this, but would the optimal geometry be the same for everyone? No matter the size of their shoe, be it gym shoe, work boot or touring boot? If this 3.86" is ideal, what is that in relation to the factory setting? ( length of rod)

I too felt mine was too low, and rather than mess with the rod, moved mine one tooth on the spindle which at first I thought might put my lever too high ( and still feel it might be a tad high) but I'm enjoying the extra room on my foot peg.

 

[Greg_imp]

Greg, trying to understand this, but would the optimal geometry be the same for everyone? No matter the size of their shoe, be it gym shoe, work boot or touring boot? If this 3.86" is ideal, what is that in relation to the factory setting? ( length of rod)

I too felt mine was too low, and rather than mess with the rod, moved mine one tooth on the spindle which at first I thought might put my lever too high ( and still feel it might be a tad high) but I'm enjoying the extra room on my foot peg.

Hi Ferret. The point of my post is that there is an ideal geometry for the shifter mechanism, which is when the linkage connections form 90° angles, but that of all the controls, the shifter has the most adjustability to accommodate individual differences.

So, knowing the ideal, along with knowing how the two adjustments affect it, allows you to make informed decisions about how to set it up to work best for you.

My opinion is that simply moving the arm one spline - the easy mod, which raises the shifter foot peg 1.25" - is not the best way to raise the shifter foot peg because it takes both linkage angles away from the 90° ideal. Better to leave the shifter arm with the dots aligned and shorten the linkage. Chances are good that a smaller rise distance - done by shortening the linkage - will satisfy most riders, and doing this will at least keep the linkage/shifter arm angle at 90°.

People who have moved the shifter arm one spline may find that instead using linkage adjustment to raise the foot peg will result in an easier, quieter shift. More "snick" and less "clunk", though my opinion on that is not scientific.

Like I said in the original post, I don't have good information about how this mechanism is set up from the factory since I adjusted my own before measuring my own stock set up. Even if I had, that would be a sample of one and not very reliable. I have considered going over to my local dealer, who has a couple of 2014's on the floor and measuring them. Anyone who hasn't changed their factory setup could help shed some light on this.

 

[the Ferret]

Ahhh gotcha...thanks. Really cool diagrams btw!

 

[The Spaceman_imp]

I like to understand how everything works on my motorcycle. The control that is designed with the most adjustability is the gear shifter. Having this set up right makes riding easier and reduces a potential source of distraction. Besides, it's a cool little mechanism and easy to adjust to fit your unique situation.

A few years ago I had reconstructive surgery on my left foot. Several joints were immobilized and my range of motion is smaller than normal, so I have had to adjust the shifter to suit. I understood the idea behind displacing the shifter pivot away from the transmission spindle but until I did the following drawings I didn't really appreciate the beauty of this mechanism.

Displacing the shifter pivot allows the designers to position it in the right place without regard to where the spindle is, and also use differing arm lengths to control the amount of force needed to execute a shift.



Above is the normal geometry of the shifter. I would assume this is how it comes from the factory, but since I adjusted mine before taking a close look and measuring it, I'm not sure of that.



Above shows upshifting and downshifting behind the normal, at rest position.



When linkage length is about 3.86” (98mm) and the spindle dots are aligned, right angles are formed at both linkage connections; to the lever and to the arm.

Gear changes require a 10° rotation of the transmission spindle, which takes about 1.04” (26.5mm) of gearshift foot peg travel.

The spindle is splined with a 12° pitch which raises or lowers the gearshift foot peg about 1.25” (31.75mm) if the gearshift arm is moved one spline.

For finer adjustments than 1.25” you have to change the linkage length. Facing the bike, the left end is reverse threads. Both 10mm nuts must be loosened so the rod can be turned.

This mechanism is designed to be adjustable to suit individual preferences but it works best with ideal geometry.

I felt the need to disclaim this post. I hope it doesn't spoil it for you.

If we have threads on hacking the ECU without disclaimers, we can probably safely have a thread on adjusting a lever...

 

[the Ferret]

My shift lever was way too low so I adjusted it previously. Guess The length the linkage arm ended up at? Very close to the optimum !

Describe how you adjusted yours Bob. With the rod or by moving the arm on the spline?

 

[shdwghst457_imp]

Was that done in SolidWorks?

 

[redbirds_imp]

Thanks Greg for the info and diagram. Going to put my bike on the lift and check.

 

[Greg_imp]

Was that done in SolidWorks?

Adobe Illustrator

 

[Red Mist_imp]

Greg, trying to understand this, but would the optimal geometry be the same for everyone? No matter the size of their shoe, be it gym shoe, work boot or touring boot? If this 3.86" is ideal, what is that in relation to the factory setting? ( length of rod)

I too felt mine was too low, and rather than mess with the rod, moved mine one tooth on the spindle which at first I thought might put my lever too high ( and still feel it might be a tad high) but I'm enjoying the extra room on my foot peg.

Hi Ferret. The point of my post is that there is an ideal geometry for the shifter mechanism, which is when the linkage connections form 90° angles, but that of all the controls, the shifter has the most adjustability to accommodate individual differences.

So, knowing the ideal, along with knowing how the two adjustments affect it, allows you to make informed decisions about how to set it up to work best for you.

My opinion is that simply moving the arm one spline - the easy mod, which raises the shifter foot peg 1.25" - is not the best way to raise the shifter foot peg because it takes both linkage angles away from the 90° ideal. Better to leave the shifter arm with the dots aligned and shorten the linkage. Chances are good that a smaller rise distance - done by shortening the linkage - will satisfy most riders, and doing this will at least keep the linkage/shifter arm angle at 90°.

People who have moved the shifter arm one spline may find that instead using linkage adjustment to raise the foot peg will result in an easier, quieter shift. More "snick" and less "clunk", though my opinion on that is not scientific.

Like I said in the original post, I don't have good information about how this mechanism is set up from the factory since I adjusted my own before measuring my own stock set up. Even if I had, that would be a sample of one and not very reliable. I have considered going over to my local dealer, who has a couple of 2014's on the floor and measuring them. Anyone who hasn't changed their factory setup could help shed some light on this.

Yes, that's the best way to adjust the shift lever, not to move it over a spline. In some kind of extreme case a spline offset might be needed but at that point, better to go with a different set of controls, such as might be needed to accommodate a very large foot or boot.

 

[DAC]

Very useful post, Greg. My gear lever feels fine but the brake lever might need some fiddling. This post at least makes me think a little more about the geometry - a challenge since i haven't considered that particular subject much since high school!

 

[CBXBob_imp]

I ADJUSTED THE ROD. Did not re-index the splines. There is a large range of adjustment just using the rod.

 

[Cormanus]

Useful post, Greg, and great diagrams. Thanks.

 

[the Ferret]

BTW I went back and forth moving my gear shifter 1 splines worth. The first was too low for me, the second a smidge (Australian for small amount I've learned) too high. With the bike on the center stand, measuring from ground to center of shifter with it on marked dots it was 12". Moved 1 spline, it was 13" or 1 inch higher. So I realigned the dots on the spline/shifter and loosed the lock nuts on each end of the shift rod. The one on the left towards the front of the bike is the one that's reverse thread, so loosening that one is like tightening any regular nut. Anyhow, with both nuts loose, a couple turns on the rod raised the shifter until the measurement from ground to center of shifter was 12 1/2 inches, halfway between the too high measurement and the too low measurement. I locked both nuts down (again remembering the one on the left, towards the front of the engine is backwards). A short 20 mile test ride confirmed this is a very good spot for me and I intend to leave it this way.

Thanks for all the info Greg and by suggestion CBXbob.

 

[Greg_imp]

I'm glad people are finding the post useful!

Part of putting it together was labeling the names of all the parts down there, but I did miss "Toe Peg" somehow, calling it Foot Peg, which is confusing.

 

[Cormanus]

Nice usage of 'smidge' Ferret.

 

[shdwghst457_imp]

Smidge is Australian? Blimey, I knew I was adopted!

Was that done in SolidWorks?

Adobe Illustrator

Adobe Illustrator
Ah. SolidWorks is amazing; you could reproduced a working 3D model of the mechanism, test it's limits and whatnot. It would even give you a bill of materials!