mono shock under the bike

hello,
I would like to convert my ST1000 to a monoshock sometime in the future. I am kind of redoing it this spring for riding this summer. I am a certified welder, and also have a plasma cutter to make brackets.
I have seen bikes with the rear shock mounted parallel to the ground, but I cannot remember what kind of bikes they were. I really like this look, I don't like the dual rear shocks.

Has anyone done this? If not, has anyone converted to a regular style monoshock on a shaft drive?

Thanks,
Mike

maybe a buell,i think theyre mounted something like that:whistle: goodluck,happy wrenching!

Be sure you get a shock made to me mounted that way, otherwise you are in for a bad ride.

TWT, are just the oil filled shocks affected by being sideways? maybe he would be ok going with a gas shock? ...just a thought...

77KZ650 wrote:

TWT, are just the oil filled shocks affected by being sideways? maybe he would be ok going with a gas shock? ...just a thought...

No, the problem is that the shocks are not all made to take flex and force at those angles like the paralell shocks are.

Most shocks are meant strictly for linear up and down force when mounted vertically. When you mount them horizontally you have the same force but you also add forces in the other direction.

I can make a diagram if my wording is confusing (which I'm 99% sure it is! hah)

:blink:

sure, diagram would be great if it isnt hijacking the thread too much

Harley Softails have the shock mounted under the bike like your talking about. I'm putting a mono-shock set up from a GPZ with a newer shock.I welded tabs to the center stand mount for the linkage mounting and welded in a cross bar with tabs for the upper shock mount.
Mark





Post edited by: Mark Wing, at: 2006/03/02 22:46

Lower mount

Upper mount

77KZ650 wrote:

sure, diagram would be great if it isnt hijacking the thread too much

I don't think it's hijacking. It's on topic as the question was related to doing this.

Ok, here's the diagram. I hope I can explain well enough. lol



In a properly installed rear end the mono shock is setup just off of 90 degrees from the ground (assuming ground is level.) The reason for this is that when you have suspension travel it moves the bottom mount point of the shock in an arc. When you get this mounted this way at high compression (during bumps or corners) the arc places this setup in a line where the suspension is at it's most effective position.

Force A is where most of the load on this setup should go obviously as the monoshock is setup to absorb this force by compressing/decompressing in this direction. So basically, a high amount of Force A is okay.

Force B represents what some would call torsional flex, or side to side flex of this shock. Obviously, this shock wasn't made to flex this way. When you are at a high rate of compression the shock should be in a position that minimizes the effect of this force and let's the compression take over. Excessive amounts of Force B= BAD.


Now, let's say we decide to set up a shock MADE to be mounted vertically like above paralell, or horizontally like in the diagram below.



Now we have Force A still being used, and the shock is compressing and decompressing.

But, here we have a problem. Because of the position of the shock it will be more effected by Force B that it is when mounted vertically. What happens when you have more torsional force on this shock? Well, for starters the shock has to work harder and against more resistance to compress. This isn't a good thing for corner entry obviously. Plus, once it's compressed it takes more for it to decompress as it will tend to be more in a binding state. Bad for corner exit.


Now, we're not talking something that will kill you by any means right away, but you will find that the bike will not respond as well in corners, the ride will be less comfy and you will go through shocks much quicker mounting this setup like this.

This is the same principal in automotive suspension, and it's why lowering a car down to the ground improperly isn't a good idea (which is what most people do.)

When you are in a car and you corner hard you want the inside to compress to the point where the arm, is paralell with the ground, and the shock is at 90* to the arm/ground. This is where the suspension is at it's most effective... but least comfortable. lol

Now, when you slam a car to the ground, you are putting it past that point all the time, and when you corner, you are getting it even further from that point the opposite direction. What happens? You hit your bump stops, the car corners like shit, you get a really really uncomfortable ride....

A properly tuned car suspension will lower the car to the point where the geometry is just shy of that aformentioned perfect position, and tighten EVERYTHING UP so it stays as close to that position in all conditions. The loss is simple. Comfort.

When it comes to autocross cars and stuff you find out real quick that you can have perfect handling, or perfect comfort... there really isn't such thing as a "happy medium" between the two. lol

Maybe I just don't understand what you are saying, but the only "Force B" that I can see would be gravity. The shock pivots at both ends so it is always going to see a straight line force applied to it, I don't see where any lateral load would be coming from. Ok, maybe a little due to the friction of the rubber bushings on the shock eyes as it rotates, but I don't believe that would be a significant amount.

Figuring spring and damping rates to select the proper shock will be interesting, not impossible, but interesting