Are Delta brakes the ones that look really cool but don't actually give any deceleration whatsoever?
I remember when I was about 10 I had a mountain bike with the old-style top-pull brakes which were utterly shite. I discovered they were shite when I had just been given the bike, I rode furiously along my Aunt's driveway (I wasn't allowed out on the road without an adult), pulled on the brakes, not a lot happened, and I ended up mounting the door-sill, entering the kitchen, taking out the dog's water bowl, the tea trolley (complete with a pot of tea and a heavily-loaded cake stand), and ended up slamming into the Aga. I timed my entrance just perfectly to coincide with the adults sitting down and just about to enjoy a cup of tea and a slice of cake. After my Mother had made sure I was physically OK, she was livid ...