Hello Winfried,
I mean it is hard to tell a certain dimension for the distance between steering and middle of the saddle - due to the unusual seat height adjustment of the Strida (seat molding sliding on seat tube) will this distance depend mostly on the leg length of the rider. The higher the seat, the shorter the distance - though the effect can be mildened by moving the seat a few cm’s back and forth within the clamp of the molding.
Overall maybe ~ 40 to 55 cm.
The wheel base of Strida frames will be ~ 895 mm.
According to this page has Brompton before 2003 a wheel base of 1.02m (40.2"), since then 1045mm (41.2").
brompton.zendesk.com/hc/en-us/a … heel-base-
Could you find info about the Brompton saddle - steering distance?