artemidorus said:Magnetic aluminium? Those Italians are very crafty.
I base my statement on the following observations.
Looking at our friend's Pinarello frameset, it looks like the two cable stops on the top tube are rivetted to the frame, which suggest aluminum construction. The style of cable stops on the Pinarello in the photo are uncommon on steel frames. They are rather oversized for steel. Steel framesets, especially good quality road framesets as our friend's Pinarello appears to be, tend to use smaller (and lighter if steel) cable stops that was TIG welded or brazed in place.
Also, if you look at the rear dropout, they are solid without cut outs. It was common during the 90's to see solid forged aluminum dropouts. But not solid steel dropouts, in any era for that matter. Imagine the weight of a solid steel dropout on a "lightweight" road racing frame....
Also, if you look at the welds, it is more characteristic of aluminum TIG welds than steel. The weld seam is rather clumpy and large for quality steel TIG welding. Again, it is more reminiscent of aluminum TIG welds. Likewise, the tubing appears to be oversized compared to standard steel bicycle tubing of the era. Quality steel frameset (ie. Pinarello) of the era would have much cleaner TIG welds. See the attached photo of a steel TIG weld at the down tube junction on one of Indurain's actual race bikes of the era - smooth, tidy, masterfully finished.
Lastly, our friend mentions that the seatpost height adjustment is by a nut on the post itself. Campy and a few other component manufacturer at the time made unique seatposts that used an expander (like on quill stems) to hold the post in the frame. A number of Euro builders used this type of seatpost instead of the traditional clamp on their aluminum framesets. Pinarello appears to be one.
Again, I was looking at the clues from the photo. That magnet test is a "red herring".