In my opinion, a simple and elegant design is always a better option than a more complex one.
It’s easy to add complexity but much harder to keep a design solution simple and efficient.
I believe a single pivot suspension design is efficient and can work as well as the best multi pivots, especially when combined with a steel swing arm.
More isn’t Better
A single pivot design has fewer bearings, not only is it better for maintenance, but this means the suspension will be more free-moving, contributing to more sensitive suspension. A badly maintained single-pivot will always work better than a badly maintained multi pivot!
Progressive vs Linear
A single pivot naturally has a leverage ratio that is more or less linear through the full travel. Due to a hard marketing push of the word “progressive”, linear suspension is deemed to be a bad thing. But a single pivot allows for a supple initial stroke with good mid-stroke support.
The linear ratio is judged to be a negative trait in that it doesn’t ramp up to provide good bottom-out capability (where progressive is deemed to be good). But, I suppose, first of all we need to be honest with ourselves and do we really huck to flat that often? Even if you do, the natural ramp up in an air spring or the big rubber bumper (or hydraulic bottom out) in a coil shock, goes a long way to helping.
But the biggest factor to a smooth bottom out capability in Starling frames is the compliance of the steel frames. There’s enough ‘give’ in the frame to acts as an extra bit of top-end suspension.
Starling is also a great believer in using coil shocks. Air shocks are not bad, but due to frame designers seeking out ‘progressiveness’ to keep their marketing colleagues happy, modern air shocks have become more linear to overcome this, good but not as good as a coil.
Air shocks tend to suffer from initial stiction. You can reduce pressure to overcome this but it results in blowing through the mid-stroke. I’m sure we have all suffered from trying to find the balance with an air shock, too much pressure and it’s harsh, too little and it has no support.
Coil shocks, on the other hand, have smaller diameter shafts and looser tolerance seals (not required to keep air in). They don’t suffer from this initial stiction and are supple at the start of the stroke. This suppleness means you can effectively run a firmer pressure than with an air shock, meaning much better mid-stroke. It’s the spring, after all, that supports the mid-stroke, not any damping.
Then as discussed as above, rubber bumpers and steel swingarm compliance give a smooth bottom out. One other thing we’veve noticed with coils is much longer service intervals, and being much less sensitive to set-up, all of which compliments the qualities of Starling frames.
To quote the EnduroMag review of the Starling Cycles Twist, “On paper, the linear suspension kinematic doesn’t look well suited to coil shocks, but whether down to the naturally compliant rear triangle or big bottom-out bumper, we never felt a harsh bottom out, despite our best efforts at finding bad lines.”
Keep it Simple, Stupid
Last, but not least, the final benefit of a linear leverage ratio is that it gives suspension tuners an easy job. They can concentrate on getting the shock to suit the rider’s requirements, rather than making it work with a strange leverage ratio.