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"Lead" question on installation
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blueflu
Posted 4/12/2005 3:12 PM (#7257)
Subject: "Lead" question on installation



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Posts: 23
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Location: SouthEast Ohio
Some of the sidecar installation articles I have read and downloaded state there should be approx. 8-10 inches of lead on the sidecar. How important is this, right now am only able to get roughly 4.5 inches of lead. Is this okay??
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Hack'n
Posted 4/12/2005 6:37 PM (#7261 - in reply to #7257)
Subject: RE: "Lead" question on installation



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Posts: 4833
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Location: Boise, Idaho
The 8" to 10" lead numbers are just an arbitrary figure. (Starting point?)
Harley doesn't use any lead and some high speed rigs have the wheel half way between the bike's wheels. There is no "One size fits all" number.
The farther back the sidecar axle is (to 0" lead) the easier the steering is at slow speeds. Farther ahead seems to give more high speed stability and less tendency to stub it's nose into the ground on left turn decceleration or braking.

Lonnie
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Posted 4/13/2005 3:46 AM (#7264 - in reply to #7257)
Subject: RE: "Lead" question on installation


"Farther ahead seems to give ... less tendency to stub it's nose into the ground on left turn decceleration or braking."
That's the important point - and "lead" is basically the wrong measure.
The crucial question is: "Where's the COG within the magic triangle and what's it's height and it's distance from the line between the contact points of front and sidewheel?"
Imagine a given and well adjusted outfit and now you replace the rear swingarm by a shorter one. This would shorten the lead but it wouldn't change anything at the situation described above.
After some consideration one comes to the conclusion that a small track-width and a high COG both require an increased lead value.

some lead values for the K100 (Monolever)
Wasp Sport 280mm
Jeaniel Lynx 250mm
Lefévre 420mm
HMO 310mm
HGT 390mm
EZS TPS 390mm
EML Speedline 390mm
EML GT III 355mm

Compared with these values your 4.5 inches (= 114mm) appear very short.

Best regards,

Clemens
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claude #3563
Posted 4/13/2005 6:57 AM (#7266 - in reply to #7264)
Subject: RE: "Lead" question on installation



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Clemons makes a good point. He also states that 4.5" is not much lead. I totally agree. The 8-10" figure that is often spoken of is a good compromise for all practical purposes. Personally I to see more lead rather than less. In a left hand turn (or a turn away from the sidecar) it is easy to build confidence real early by a new sidecarist. This is well and good but be warned that left handers can bite you real quick, especially on a lighter rig. When the rear tire comes up it does so quickly and the operator is basically at the mercy of the cornering forces that caused it to happen to beginwith. Much diferent than a right hander.
Most times the rear wheel will simply go back down just as quick but it is possible to flip the bike over the sidecar. It is not that uncommon for a new sidecarist to smash the nose of the sidecar into the road due to getting a little to frisky in left handers. Those 180 degree spins can be fun but costly.
So, be warned. More lead will add much stability, especially when a passenger is on board.
TIP FOR ALL RIGS:
Always try and add any loads to the rear of the sidecar and not the nose.

NOTE THAT WITH ALL OF THAT BEING SAID I NOTICE YOU HAVE A MOTORVATION FORMULA II. Motorvation does not suggest that much lead be run from what I understaND. You may want to check with them. They are a great company and offer great servie.
I have a formula II as well and do run a lot of lead with no ill effects. Check it out.

Edited by claude #3563 4/13/2005 7:02 AM
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hahnda
Posted 4/14/2005 2:49 PM (#7297 - in reply to #7257)
Subject: RE: "Lead" question on installation



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Posts: 38
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Location: Cameron, WI
I also have a Formula II sidecar. I'm running about 10" of lead. Seems ok by me.

Kevin
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