We're getting to the point where I have to make a decision on the swing-arm pivot-point height for my reverse-trike build.

I'd like to run about 110mm at the front and 130mm at the rear when fully laden.

I'm struggling though to find information about what angle a rear-swingarm should 'sit' when the vehicle is stationary, but fully laden. I'm thinking it should be perfectly-horizontal, but that's just a guess...

Can anyone help out with any suggestions!?

All thoughts much appreciated!

I would have thought that the swing arm should be angled down slightly towards the wheel at rest. The reason I think this is you want as little change in geometry as possible in normal operation and this would mean that for small bumps the effective length changes very little. This also allows the suspension to be fully horizontal when fully laden (full fuel) and also considering any aero effect and mass transfer during cornering. But I'm sure someone who actually knows something about suspension will be along soon to put me straight.

Pete

As you change things on a fairly regular basis, :-) I am assuming that it's rear wheel drive, "ala" motor cycle. If this is the case then the position of the swinging arm is dependant on the drive, so if chain, then the arm wants to stay in line with the sprockets when at normal ride height, (fully laden), so it all forms a straight line, sprocket centre - pivot point centre - sprocket centre. If shaft drive, well that pretty much sorts itself out, :-) HTH Ray

[Edited on 3-9-11 by Chippy]

Dunno but thinking out loud so to speak:-

Not sure the change in wheelbase matters one jot. However the change in ride height due to acceleration or braking could be unsettling which points to aligning the swinging arm to the centre of gravity.

Also as mentioned tou need to consider the effect the tension of the chain will have on the swinging arm. As you accelerate the chain will pull the arm towards the middle and up a bit. I guess you need to have the top of the chain as close to the arm pivot as possible.

Also you need to consider the relative angle of the swinging arm and the coilover. if less than 90 degrees this will give a measure of rising rate (a GOOD thing). lots of info and calcs on Google.

Finally I suspect you will have little choice due to the chassis mounting points so make the ride height as low as possible!

Looking forward to seeing video of it in use!

Cheers!

Cheers guys... I forgot to mention that it's a shaft-drive.

makes it simple align it with the c of g if you can and it won't sit down at the back under acceleration

Cheers!