Originally Posted by
bikebikebike
the 20"ers [that] have solid rear triangles and looked fine, but the 16" Brompton put a lot of stress on the rear suspension in a twisting fashion, focused on the pivot
I would recommend against trying it on the 16" Brompton and on 20"s with rear suspension
The Brommie S2L rear triangle had a lot of rotational stress focused on the rear hinge , when on my Cyclops.
The IGH on the 3/6 speeds of many make mounting an issue as well, as the shift chain comes out through the hub.
I would expect the same issues on a rear suspension 20".
They are not built with this kind of motion in mind, so I could see that stressing the welds and tubes in an unanticipated fashion.
The bigger bikes these trainers were designed around, distribute these stresses over longer spans and distribute the stress better.
Plus many trainers need $$ adapters for smaller wheels.
Roller trainers don;t have this problem, but they have their own issues that are reflected in their own lack of broad use.
I liked my Downtube NS IX on the Cyclops, but it showed these dynamics , so I just use it with my 20"trike as a recumbent trainer. where there isn't much rotational stress on the rear.