This^^^^^.
There’s a load of wasted space right there. How about brackets to hang the bikes there? Failing that have a look at strong stay brackets from tool station. A fiver each and they accommodate 6 lengths of batten as per my shelf as below.
Bikes could be hung like so in that space. I just tied it with cord which was hung from screws. I’m sure you could fab a few brackets if you find the beams above.
