Concrete canoes are a thing civil engineers make for fun [1]. Weight can come in at under 10kg [2]. That's about half the weight of a typical canoe [3].
On that basis, one might be able to build a concrete bike that is lighter than a typical bike?
In the late 70's ferro-cement sailboats were a thing. I watched one get built at the marina where we kept our boat at the time. It's mentioned here [0], the Sandpiper.
My friends live in a 80s cement boat, and have done since they built it. Was brilliant but now uninsurable, and they are stuck unable to move it and worrying about every stormy day. That said, for over 20 years it was great, but once water gets in the cracks...
Concrete canoes are a thing civil engineers make for fun [1]. Weight can come in at under 10kg [2]. That's about half the weight of a typical canoe [3].
On that basis, one might be able to build a concrete bike that is lighter than a typical bike?
[1] https://www.asce.org/communities/student-members/conferences...
[2] https://www.concrete.org/Portals/0/Files/PDF/20-1stPlace-Kon...
[3] https://paddlecamp.com/how-much-does-a-canoe-weigh/