Personally ,

I have a computer on my touring bike , & take the battery out when back home, dont put a new one in until i get ready for a new trip..

other bikes dont have any.


basic wired one is pretty cheap you can probably find them for $20 .. and go 1 per bike..

Some wireless types have 2 wheel size settings , have to buy spares, the magnet transmitter on the fork and the bar mount .

The spare parts will be more than a whole wired low cost, computer