The three types of mountain bike worth knowing
Hardtails have front suspension only and a rigid rear. They are lighter, simpler, cheaper to own and easier to maintain. For most trail centres in the UK, a good hardtail will do almost everything a full-suspension bike will do, at a fraction of the price. Buy one if you are new to the sport, ride mostly blue and red graded trails, or if you just want the simplest bike possible.
Full-suspension trail bikes have front and rear shocks and typically between 120mm and 150mm of travel. They are the most popular format for experienced UK riders because they cover the widest range of terrain. You can ride them on flat canal paths and down the rockier sections of Welsh and Scottish trail centres. Expect more servicing costs than a hardtail.
Enduro and downhill bikes have more travel, slacker angles, and are designed to go down hills fast. They are overkill for general trail riding and are genuinely slow uphill. Only buy one of these if you know you want to ride technical descents, uplift days, or actual enduro racing. A lot of enduro bikes on the used market have been ridden hard. Inspect carefully.
Wheel size, and the one upgrade worth having
Wheel size is the other choice worth understanding. 29-inch wheels roll over roots and rocks more easily and carry speed, which is why most modern bikes use them and why they suit beginners and taller riders. 27.5-inch wheels are a little smaller and feel more playful and quick to change direction on tight, twisty trails. Some bikes mix the two, a 29 up front and a 27.5 at the back, to get the roll of the big wheel with the agility of the small one. For most UK trail riding, 29-inch is the confident default.
