Middleton Link and 3-in-line STV

3-in-line STV: A prototype to test the concept, built mid 2002.

Made from a Suzuki 80 step through (free) and a couple of 10” scooter wheels (20 euro). The idea is to test if any of the supposed benefits can be achieved, and what problems there might be in applying these. Middleton Link is a solution to a bump steer problem in this concept.

Benefits are: increased contact patch to unsprung mass ratio, increased contact patch to tyre width ratio, effectively reduced unsprung mass for a given contact patch area, contact with the road with at least one steered wheel on sharp bumps, second tyre running in drier road surface under straight line braking conditions, lower propensity to front wheel traction loss in cornering, potentially lower frontal area and un-steered suspension. Actual mass of the complete system is less than a single Kawasaki GPZ500S 16” front wheel and tyre.

All were demonstrated as being achievable, but measurement is difficult.

I invented the Middleton Link to eliminate the severe bump steer inherent in a system where the handlebar axis and the steered axis varied with respect to each other by a significant amount, and the 2 axes are not aligned with suspension pivots. Alternatives like cable(s), hydraulic and complex linkages were considered, but all have more problems than this system.

The pictures of the hinge itself show how rusty something gets when left outside unprotected for a couple of years!

Arthur Middleton 2005.

twin wheel 1.jpg95.63 KB
twin wheel on bumps.jpg59.53 KB
Steering_hinge_1a.jpg110.46 KB
Steering_hinge_2a.jpg114.09 KB