I'm trying to decide what gear ratio to use for my conversion.
Here is the question; standard riding by myself i'm thinking 15t but when I put my sons attached bike on I'm thinking 17t (or more).
I'm using my wifes wheels off here bike (she got made that I got another bike so I took her wheels) and taking the sprocket off and picking the gear of choice but I use this bike for 2 totally different riding styles.

Has anyone ever used two gears in the back?

Will it cause a chain issue or something else?

Thank you