UIScrollView doesn't bounce

I have a UIScrollView contained within a custom UIView with a content size larger than the ScrollView's frame.

I am able to drag scroll as I expect, but the thing doesn't give me the rubber banding effect that you get with the UITableView or UIWebView. It just stops when you get to one of the extremes.

I have set bounce = YES, is there something else I'm supposed to do?

I read the docs, and they say I have to implement the delegate. I did that.

They also say I should change the zoom levels, but I don't want the user to actually be able to zoom so I haven't set these.