Yes it was.
The Milsco, Full Floating Saddle, affectionately known as the “Pogo Seat,” because of the internal spring in the seat post, was introduced in 1936 for the inaugural release of the New, Schwinn, Autocycle.
It was discontinued in 1941 for the Autocycle Super Deluxe.
The Mesinger De Luxe replaced it.
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I would imagine, that some bikes could still be supplied in 1941 with the Full Floating Milsco, if there was still any stock of them left.
It’s possible, that the decision to go with the Mesinger De Luxe in 1941 was made for them, because, Milsco could no longer guarantee delivery of that type of saddle anymore.
As cool as the Full Floating Saddle was, in my experience, the 1941 Auto Cycle Super De Luxe, was the best riding bike of the bunch, and the addition of the Mesinger, De Luxe saddle, was a big reason why.
The Milsco “Pogo” type saddle put you too close to the Crossbar Speedometer housing with no way to slide the saddle back for a more comfortable riding position.
This was not a problem, for a 15 year old kid, with a few more growing years in the bank, but a big problem for a full grown adult with a 34” inseam.
So, it’s one or the other.
Either get rid of the dashboard, or the pogo seat.
The Silding Rail, Mesinger De Luxe proved to be a better saddle all the way around, so it won out, thus making the 1941 Auto Cycle Super De Luxe a luxuriant ride.
Not to mention all of the other component improvements for that model year.