v. s. rearsets shifter

[Greaser Greg]

Is it just me, or do the vintage smoke sets challenge anyone else when shifting?

[rodneya]

Are the linkage and shift arm parallel?
There was a post a while back about extending the pivot arms to help shifting. I think it was by Chuck

I didnt like all the slop in my linkage, so i tossed it and now I run a shift leaver backwards from the shift shaft. Just have to remember that it is now GP shift pattern,

[m in sc]

nope. the motocararra ones are way too short. though

[Dvsrd]

In my opinion, most rearsets for a 350 AC, and most likely 400 C/D/E are flawed, since they do not take into account the rather long stock shifter (180 mm IIRC)
Most rearset shifters are 120 to 140 mm long, from pivit to tip, but the linkage arm is mostly the length of the knuckle on the shift shaft, if not longer. So the leverage is reduced significantly, requiring more effort to change gears.
I definitely prefer to use a longer arm on the knuckle, instead of shortening the arm on the pedal. That reduces the forces on the ball joints, linkage and the shift shaft itself. Shortening the effective arm on the pedal (by drilling a new hole), will increase all those forces. 

[EE]

When i was a young man.... i was making a rear set set up and decided to let the bike tell me what worked best, i welded long levers to the shift arm and the lever with holes drilled every 1/4 inch i think?? long time ago... anyway longer on the foot lever, shorter (within reason) on the shift arm was better. Also as much as you can have the levers at 90deg to the linkage for optimum efficiency. check out the rearsets i made on my LSR250 good example  http://erlenbachracing.co/RD250_LandSpeed_project.htm
Oh and i could never get use to the "GP" shift pattern, downshifting to me is always down and upshifting always up lol Never had a problem with it!!

[Dvsrd]

When i was a young man.... i was making a rear set set up and decided to let the bike tell me what worked best, i welded long levers to the shift arm and the lever with holes drilled every 1/4 inch i think?? long time ago... anyway longer on the foot lever, shorter (within reason) on the shift arm was better. Also as much as you can have the levers at 90deg to the linkage for optimum efficiency. check out the rearsets i made on my LSR250 good example  http://erlenbachracing.co/RD250_LandSpeed_project.htm
Oh and i could never get use to the "GP" shift pattern, downshifting to me is always down and upshifting always up lol Never had a problem with it!!

I guess it is very much down to personal preferences, force vs throw. Your Landspeed Bike setup must be significantly stiffer, and have significantly shorter throw than a stock RD.
With my post, I was trying to describe what it would take to replicate the stock shifting action as close as possible.

[m in sc]

measurements. the arm is x long. that being said, do soem basic geometery and figure out where you want your toe to be. then, change leverage points as Ed points out and you can have it shift as smooth as stock, or slightly shorter. I like it a bit shorter throw than stock myself but mine are real close to stock feel.

easy way to figure it is if stock arm is, persay, 10 inches then

the lever is on quite a large bearing as well. made these myself from scratch.

the arm at the motor is actually an old dunstall one, i think.

[sav0r (CL MotoTech)]

Here's the lever I made for my RD. It's close to a FZR 600 lever, though I added a bit of extra length to the foot side and reduced the linkage arm a bit.





I like to orient my link so you gain a bit of a mechanical advantage in pull (up), but lose some in push (down). We humans are much stronger in down than up, at least for most of us that is the case.

That's my 2 cents. The rest have hit all the major points.

[Dvsrd]

measurements. the arm is x long. that being said, do soem basic geometery and figure out where you want your toe to be. then, change leverage points as Ed points out and you can have it shift as smooth as stock, or slightly shorter. I like it a bit shorter throw than stock myself but mine are real close to stock feel.

easy way to figure it is if stock arm is, persay, 10 inches then

the lever is on quite a large bearing as well. made these myself from scratch.

the arm at the motor is actually an old dunstall one, i think.

Hi Mark,
Looks like you got your numbers slightly mixed up. The example linkage in your sketch has the same leverage as a 12 inch direct lever.  Leverage ratio is 3 divided by 2, so 1.5. Multiplied by 8 gives 12.
I still would like to emphasize the benefits of longer levers on shift shaft and pedal. That gives less force on pedal pivot, both linkage joints, and also less radial force on the shift shaft. Less force gives less friction. Also, the effect of all play/ clearances is reduced as well. Something like the OEM 350LC linkage may seem compact and nice, but is really poor when these things are considered.
Another thing to consider. Riding footwear. When using proper motorcycle boots, with an extra pad for the shifter, slightly stiff shifting is mostly ok. But if riding in sneakers or other lightweight footwear, it is more uncomfortable. So preferred footwear should also be considered when/ if fitting or modifying rearsets.

[soonerbillz]

When i was a young man.... i was making a rear set set up and decided to let the bike tell me what worked best, i welded long levers to the shift arm and the lever with holes drilled every 1/4 inch i think?? long time ago... anyway longer on the foot lever, shorter (within reason) on the shift arm was better. Also as much as you can have the levers at 90deg to the linkage for optimum efficiency. check out the rearsets i made on my LSR250 good example  http://erlenbachracing.co/RD250_LandSpeed_project.htm
Oh and i could never get use to the "GP" shift pattern, downshifting to me is always down and upshifting always up lol Never had a problem with it!!

One of the best reasons for GP shift for racing is it virtually eliminates missed shifts.
The downward toe action is much easier and stronger to make vs the upward toe strike practically garuanteeing positive engagement.. All my race bike were converted to Gp and I rarely if ever had a missed shift.

[EE]

I know the why for GP shift but us old timers did plenty well before it became trendy, never had a problem 1 down 5 up :)

[EE]

Another great trick is to use the shift shaft and pawl (marked 2r8) out of a US Daytona or European 2r8, 2r9, better ratio.. I do that for all my bikes.

[Dvsrd]

One of the best reasons for GP shift for racing is it virtually eliminates missed shifts.
The downward toe action is much easier and stronger to make vs the upward toe strike practically garuanteeing positive engagement.. All my race bike were converted to Gp and I rarely if ever had a missed shift.

I have read that the main reason was to be able to shift up while still cranked over, like accellerating out of a lh turn. With regular street setup, the boot toe would drag.

[m in sc]

you are correct. this is what i get for trying to do basic geometry pre-coffee after a long night. 

Hi Mark,
Looks like you got your numbers slightly mixed up. The example linkage in your sketch has the same leverage as a 12 inch direct lever.  Leverage ratio is 3 divided by 2, so 1.5. Multiplied by 8 gives 12.

corrected. sometimes.. I'm a dumbass. My bad.

[Czakky]

What effect does extending the linkage have on throw distance?