will the dummy hood/lever flap around if there is no cable in it?
Depends on the lever, and what steps you take to avoid flappage. Shimano SLR brake levers have a return spring, with everything else you have to make your own by one of the methods described above
I have Cane Creek SCR-5 levers on mine which also have a return spring. No flapping or rattling. Good value for money too. But seem to be discontinued which is a shame
Depends on the lever, and what steps you take to avoid flappage. Shimano SLR brake levers have a return spring, with everything else you have to make your own by one of the methods described above