CompuTrainers have two lock nuts on each side (see photo) that have to be twisted to tighten and untighten to lock the bike in place. These two handles or wrenches are designed to reduce hand pain and fatigue by changing the force from gripping to levering. Slide the large one past the small nut and use it to turn the large nut. 

I would appreciate any feedback and improvement suggestions, as I have designed these for a friend who owns a bike studio with 10 of units.

Update upon user feedback, I have modified the smaller wrench to be a dual handle and lengthened the handles. See new version in blue and also in use on the CompuTrainer handle.

#computrainer