Downhill mountain biking is definitely a dangerous genre because of the speed, the obstacles and the elements you should pass through. On the second hand, it is the most exciting, fun and self improving sport. I have tried various extreme sports (Snowboarding, wakeboarding, surfing, kite surfing, skiing and some more..) and this one satisfied me the most.
Things to do before starting DH on a regular basis:
- Buy all the protection accessories that you need: Full-Face Helmet, Goggles (are much better then glasses), Gloves, Knee Guards (you can buy it with shin guard), Cycling shoes (for better handling, very important!), Neck brace (recommended for higher speeds and jumps) and for the beginning I would recommend a kind of Pressure suit for the hole upper body.
- Kids learn very fast but still it's important to go step by step and not diving into extreme trails before you know the basics. Start riding some Cross-country / All-mountain trails and after gaining some experience try to go and ride a downhill track.
- I think that taking a few private lessons with a MTB guide will give your kid the basic skills and put him on the right way.
- If you think that it can be too early for your son (and it can be), you can look for some group courses for children that ride together with a guide on a regular basis. If you have DH tracks in your area than you should have groups and guides also. And I didn't mention it because its obvious - never let him ride alone.
Kids get injured much less than adults do but still it is important to explain them that they shouldn't take unnecessary risks. They should progress at their own pace and be careful when comparing themselves with their friends.
In conclusion, this is the ultimate sport! You meet great people, learn how to overcome obstacles, you get fit, and all this is in the nature! And there are many more advantages. I would recommend you also read some articles about mountain biking, it's great and very interesting! And how could I forget?! Buy a DH bike!!! :)
I hope that was helpful, sorry for my bad English (I am Israeli and I'm practicing it :)) and feel free to contact me privately for more questions :)
ILAN.