Hello...
I finally have it together and running great except for the instability in cornering abruptly.
Was wondering if anyone could suggest any options to keep all three wheels on the ground. I
thought if I moved the shock absorbers to the outside of the rear wheels; hence changing the
shock mounting location to the frame, would stabilize the high center of gravity?
XB-500 x2 Trike suspension
Wed, 06/02/2010 - 23:19
#1
XB-500 x2 Trike suspension
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Support V is for Voltage
Clean build! Except for the little problem of flipping...
Trikes are always going to be unstable, unless you work in some "auto-tilt" suspension. It's been done a few times.
http://www.google.com/images?q=tilting+trikes&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ...
The cheapest way to slightly improve safety is to widen the track, a-la the Harley trikes. You might also turn it into a semi-recumbent, which would dramatically change the stability outlook.
Mark
Thank you for the input! I'm thinking recumbent is the way to go with a front wheel drive train keeping the chain as
short as possible. (just have to come up with an idea to allow peddling through turns).
Is widening the track my only option, or will moving the shocks to the outside of the rear wheels increase stability?
It's a geometry problem. You have constructed a narrow isosceles triangle with the weight high above the lower vertices (wheels). It won't take very much lateral force to tip over. Moving the shocks outboard won't make any difference. The "tilting trikes" radically change the geometry to keep the CG between the wheels.
Now, I'm assuming that the rear wheels are on a common swing-arm. If they are on separate swing arms, it'll be even tippier unless there is some sort of tilting linkage involved.
The rear swing-arms are independent of each other.
When sitting statically the bike leans very nicely; however once mobile, there
is the tendency for the rear wheels to lift off the ground when slaloming.
As stated moving the location of the shocks will not make a difference. Several things that you could do.
1) Add a stabalizer bar to the two back wheels. to tie them together and reduce tilt of the vehicle.
2) Increase the foot print of the vehicle. THis will have the most dramatic effect on the vehicle dynamics. Widen the track width between the rear wheels.
3) Move the weight distrabution back. Want to ensure that you have most of the weight on the rear wheels. The most unstable action is breaking and turning. Will tend to roll the vehicle. Have you looked at the City Ells. A clean design, width about 36 inches, Two or three batteries directly over the axel and a very low vehicle, occupant sat down in the vehicle so very low center of gravity. So every thing done right and they still had a tendancy to roll.
4) Reduce the height of the vehicle and rider. To lower the center of gravity.
Michael
info.saccity [at] gmail.com
What about going inverted?
Well, I suppose it would mean re-desing it all, but if it doesn't reach high speed, one could go with a rear steering wheel, like forklifts do...