I have been dealing with big lumber lately and I've decided it is better to carry it than transport by bike because of the stress on the brakes and drivetrain. I've been thinking of getting some 'swivel caster' wheels that pivot and attaching them to a short piece of 2x6, but I'm not sure what I would do going up and down hills except maybe chock the tires every few feet to keep them from accelerating too much.
If I was trying to build a tiny house/cottage CF, I would walk to get lumber a piece or two at a time and walk them to my lot. In the mean time, I would live in a tent. Good luck, btw, finding a lot where you can live in a tent while constructing a tiny house/cottage small enough to carry all the materials CF by hand in a reasonable span of weeks/months.