Frame

Like any bike, a downhill rig lives and dies on the quality of its frame. These are developed with the help of the fastest racers in the World Cup series and have pure speed in mind. Most top end downhill frames are now at least partly carbon but some, like the Nukeproof Pulse, are still fully aluminium.

The main advantages of carbon are lightness and stiffness, but it comes at a cost. The benchmark for weight is still the Mondraker Summum Carbon at 2.8kg (6.25lbs) which would translate to roughly 15kgs (33lbs) for a full build, but in all honesty weight doesn’t play as big a role in these frames as it would for an all-day trail cruiser. There’s nothing wrong with an aluminium frame though, the technology is well tested and durable – it’s been good enough for years so why change a winning formula?

Instead you want to focus on the geometry. You’re looking for a bike that will be stable at speed – so generally longer and slacker is better – but bear in mind if you go too long or low then you will start to sacrifice manoeuvrability, especially in slow sections.

A head angle of 62-64°, a bottom bracket height around 350mm and a wheelbase in excess of 1,250mm will be a good start. Geometry sheets can lie though and they mean nothing without the rest of the package coming together. Unfortunately, the only way to get a true feel for how a bike handles is to book on to a demo day and try out for yourself.

If you ride a trail frame, then a downhill frame will probably feel lower and longer – you should feel like you’re sitting “in” the bike rather than perching on top of it. There’s not an exact science to finding one that’s the right size so it’s probably best to stick to the manufacturer’s guidelines.

Suspension

Downhill mountain bikes have suspension at the front and rear. Typically they will have 200mm of travel – that means the suspension provides 200mm of cushioning on any impacts. Suspension set up is crucial for downhill bikes, have it too hard and it will feel like you’re riding a shopping trolley – too soft and there’s not much point in having it at all as you’ll just blow right through it. You can also adjust how the suspension performs throughout its travel, for example how fast it rebounds after it has taken an impact.

Forks – Most downhill bikes will use double crown forks that extend alongside the headtube. Downhill bikes need to take massive impacts so the forks are clamped in three spots to add stiffness. These forks will have around 200mm of travel, stanchions up to 40mm thick and tend to provide far plusher performance than a trail fork.

Double crown forks are stiffer and more sturdy, however they will not allow you to turn your bars as much as you are used to if you’re coming from a single-crown set up.

Shocks – Coil springs used to be ubiquitous in downhill but recent advancements in air shock technology have made them a viable option too. As it stands we still favour coil shocks in terms of pure performance but it can’t be denied that air shocks offer more extensive set up options and are lighter.

At World Cup level Fox and Rockshox adorn the bikes of the top teams for forks and shocks but there are also capable offerings from BOS, Marzocchi, X-Fusion and more

Wheels

Downhill bikes were the last safe haven of the 26 inch wheel, but even these are starting to disappear now – in fact a 26 inch bike hasn’t won a World Cup race for two years. Instead 650b rules the roost but there are rumours of bigger wheels appearing in the near future…

Carbon wheels are both available at downhill level but their combination of high strength and low weight means they won’t come cheap. Aluminium ones will serve a budget rider better and many years of development have left them able to take the big hits associated with the sport with a consistent feel.

Downhill tyres tend to favour grip over rolling resistance so will be fatter, stronger and more aggressive than your trail tyres. Look for tyres between 2.35 and 2.5 inches. They are also heavier than you may be used to but this is a trade off for the added strength – otherwise you’d be puncturing everywhere.

Different tyres offer different compounds – some are more grippy while others are more durable. There are also different tread patterns for different conditions. If you’re in the UK you’ll at least want a set of dry tyres and a set of mud tyres.

The rest

As you will be going faster on a downhill bike you need to be able to slow down quickly too. Brakes will often be four piston affairs bolted onto 203mm rotors for maximum stopping power.

Gears may not seem important when you’re mainly free-wheeling but top racers use them more than you might realise. A compact seven speed cassette will probably be sufficient for most riding but there’s no harm in having more.

For the rest of your hardware you want as long-lasting and durable kit as possible. Bars are often 760mm+ with short stubby stems. Both flat and clipless pedals can be used depending on your preference, although most riders will switch to flats in muddy conditions.

Downhill bikes have saddles and seatposts, but often they are slammed right down into the frame to protect a riders…erm, undercarriage, from a big impact.

Where do you buy a downhill bike?

You’re going to be looking in one of two places for your downhill bike – a local bike shop or the internet

A reputable, downhill leaning shop will get you most of the way to purchasing your first downhill bike and you can rest assured that their advice is more valuable than an internet expert’s. There’s also the added benefit of being able to test a bike before you buy it, this should give you peace of mind that it fits you correctly and feels fun to ride.

We have to be honest though, direct order bikes have really shaken up the market recently. The YT Tues, for example, won our downhill bike of the year for two years in a row and remains a serious contender for its superb value. But that’s easy for us to say, we’re aren’t putting down the hard cash to ride it.

While a bike bought off the internet will undoubtedly offer better value, you don’t get the chance to test it out beforehand to see if you get on with it. Also, if you do happen to have an issue with it, sending it back under warranty is a lot more difficult than just popping in to a local brick and mortar store.

The third option is to buy a second hand bike off a forum or eBay. Because they take a lot of abuse, downhill bikes depreciate rapidly, this is bad news for those of you buying one new but great news for someone in the hunt for a prospective bargain. Again, this will get you a great value (less than half price of R.R.P) but you need to be aware that it will come with a few scuffs and some of the components could well be shagged.

It’s definitely worth seeing the bike in person before you buy it and, if you are new to buying bikes, take someone with you who can spot any potentially chronic dents, cracks or rattles. Don’t part with your money unless you’re sure you’re not being ripped off.

Click here for more information on where to buy a mountain bike

Click here for more information on how much to spend on a DH bike

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