This saddle from a bicycle used for travelling to school has become worn out.
This bicycle has a brand name of "Bobby Town". We also have a Bridgestone Villetta bicycle which is no longer used because the back wheel's spokes broke, and the previous user bought a new bicycle, so I decided to use its old saddle.
However, the Bobby Town bicycle has a shaft of 25.4 millimetres (one inch):
But the Villetta bicycle has a shaft which is slightly bigger:
So the Villetta saddle can't be used in the Bobby Town bicycle. Looking at the bases of the saddles, they seem quite similar in construction.
I wondered if the shafts could be changed somehow. It turned out that the top part of the Bobby Town's shaft was exactly the same size as the top part of the Villetta's shaft.
This is the Villetta saddle with the Bobby Town shaft inserted. I forgot to take photos of the intermediate stages.
The Bobby Town bicycle's shaft was a bit rusty so I put some of this lubricant spray from D2 on the shaft so it would slide in easily.
Here is the finished bicycle with the new saddle.
If you look at the big version of the photo on flickr, you can see the bicycle name "Bobby Town".