
This seems to be the most common sport seat shape that I see and also seems to be correct for the 1977 year.
The seat in this picture is off the earlier model sport (ser 1)as Norbert said

This seat shape is the same as mine but appears to be on an earlier bike.
the seat on this Strada is for a sport with mag/cast alloy wheels c.1979 to 1981'ish [
Can I ask if anyone knows which seat shape is correct for my bike model and also what other information you can offer as to the seat shown in the black and white image?[/quote]
Believe none of the seats in the photos above are correct for a 1977 spoke frt disc model