Hi, I am using 165 mm cranks for years. I didn't try shorter, only on other riders' bikes. Too short feels like riding a kids bike (ha!) for me. As long as your chainstay lenght is not below 13" I would say it is enough out of the way with 165 mm. And of course for all pedal tricks (also pedal five or other front wheel stuff) your center of mass will be higher which in theory should make it more difficult to balance.You are working on pedal time machines, don't you? I could imagine (I can not to this trick) that with shorter cranks it will be even more difficult because you stand even more far away from the peg. But in the end you might get used to it and of course they are lighter...Maybe a view on the scene helps. Look at the pros. I hardly see any rider with cranks below 160 mm (at least what I can see by eye). I would say some years ago people were experimenting with it and then 160 mm or 165 mm became a standard more or less. You can not go so wrong with these sizes.