I had a close look at the brake pads and they sit right on the wheel. Is this right? Aren't they supposed to be at least a mm from the wheel? Not touching the wheel if you know what i mean. They are not tightly pushing on the wheel but there is a screech. I adjusted on side but noticed that the other side sit closer and was not adjustable. I even tried to lengthen the brake cable but that made no difference. I checked a few youtube videos but it is hard to see the gap the brake pad has from the wheel or indeed that is what is supposed to happen. I only started riding a bike again in the last few months after 20 years of not having anything to do with them so i am learning anew and appreciate any advice.