So… what does a bad mountain biker need? Obviously you can go mountain biking with nothing more than the bike that your grandfather welded together and has been sitting at the back of the shed for fifty years, but this will make it a great deal harder and more dangerous. So…
1. Bike. I’m not an expert (surprise, surprise) so detailed recommendations are beyond me. Ideally you want a lightweight but rugged purpose built mountain bike. I would suggest a hardtail (ie. front suspension but not rear) because they feel nice and solid, and they will be cheaper for a comparable quality bike than a full suspension model, but will still have something to absorb shocks. Mountain biking on a rigid bike is a jarring experience.
2. Helmet. Definitely an essential. Most crashes you can walk away from without any problem, a few might need medical attention, but a fractured skull is something no-one wants. It should be specifically a cycle helmet and should fit correctly without shifting around or being able to come off. There’s really no need for a full face helmet unless you’re heading straight into downhill mountain biking. Definitely replace a helmet that you’ve landed on, and theoretically replace it every few years.
3. Gloves. Maybe not quite an essential, but certainly exceptionally useful. They keep your hands warm, keep grip on the bike in wet and icy conditions, they are an extra layer of cushioning against shocks, and they save you from a surprising amount of damage when you come off. Also, they look cool. Lightweight full finger cycling gloves are ideal, but much of it comes down to personal taste.
4. Drink. Hydration is important. Whatever the level you’re riding at, you’re asking a lot of your body and need to treat it right. Get a bottle with a bottle cage on the bike. Beyond that, at this point it’s not terribly important what you drink – water, Coke, Red Bull, Lucozade. Caffeine, sugar and electrolytes all have their plus points, but the important thing is to have something to drink with you. Poor hydration means less energy and less concentration.
5. Tools. Things happen on trails. Personally I think the minimum that you need to carry is the wherewithall to change a tyre if you get a puncture. So take (attached to the bike, in pockets, in a rucksack, between your teeth…) a pump, spare inner tube, tyre levers, and spanners if your wheels have no quick releases. A puncture repair kit is also a good idea, in case of a second puncture. I also find it worthwhile to carry a small cycling multitool with me when I ride, since then I can fix a lot of minor issues that come up.
6. Phone. Don’t care if it’s terribly terribly expensive. Take it with you. If things should go badly wrong, you’ll need it.
The above is the essentials list for short rides on manmade trails. If you’re heading out onto the high hills, particularly alone, then the list is a great deal longer. For longer and more remote rides, you should always take: a waterproof, warm clothing, map, compass, more drink, more tools, more spare inner tubes, food, and ideally other emergency gear such as a whistle and emergency blanket. Most of the time you’ll be wondering why you’ve bothered to take so much extra weight. Just occasionally you’ll be glad you did.