live don't tell your DD then that my DD is currently sat in front of a film nursing quite a deep gash to her knee, a scraped bum/thigh, cut to her chin and ripped trousers
having just got back in from a super fast crash.
Seriously though, thank goodness she was wearing her helmet, make sure your DD always wears hers. It would have potentially been much worse as she landed on her head as well as the rest of her, but she should have been wearing her knee pads. I felt like such a bad mother - it was down a loooong hill, she had gone down it fast a few times with me at the top. A little girl said 'ooh she's good!' and then she promptly wobbled at top speed (had taken her feet off the peddles) and fell off in a spectacular roll that had a zillion mothers going
. I was almost in tears as a stranger got to her before I did because I couldn't run to her (and looked at me in astonishment as it looked like I was not at all bothered as I was sort of nonchalantly strolling down the hill) She told the stranger she was fine, and that her mummy was coming, and as soon as I got to her ran into my arms and burst into tears! Then I had to walk with the bike and DSs scooter, and the helmets to the car which was miles away with blood dripping from her knee!
She is actually ok, milking it by having a film, getting ice cream for pudding etc
I on the other hand am not so ok, having picked her up and cuddled her, dragging her bike a way to the car, then carrying her from the car to the door. I know, I know, I shouldn't have done that, but sod it, it was bad enough I couldn't carry her to the car, and that I could not run to her and be there straight away, that she had to stand there holding back her tears until I hobbled to her. So I am just gonna have to suck up the pain. But, ouch!
Sorry, that was very self indulgent 
It is amazing when they ride their bikes for the first time though without help. Makes me realise how grown up they are!