Strida 3 seat problems

I just purchased a Strida 3, it was a floor model sold as-is.

When I attempted to ride it for the first time, my weight caused the seat to twist to the side. I tried tightening the three bolts holding the seat moulding in place with the tool under my seat, but that didn’t help.

I also notice that my bike seems to be missing the “spirol pin” under the seat, but it appears that this is only used as a guide, and probably isn’t responsible for my problem.

Am I just not tightening enough? Any other suggestions? So frustrating not to be able to ride my new bike.

Thanks for any help you’re able to provide.

I think a 4mm (or 5/16") pin is really necessary to stop the seat rotating around the seat tube. I lost a pin that can with the bike but replaced it with a long 4mm high tensile bolt with its head cut off - problem solved. When not take a trip to your local hardware or fastener store.

Never underestimate the power of a little extra friction. If you don’t mind possibly discoloring the finish, you might consider the judicious use of some contact cement on the frame. A little should add just enough friction, and yet still be easily removable, in case you want to change things in the future.