Buyer's guide to long travel trail forks
Tough, strong and very long. (Seb Rogers©)
Want a fork that's light enough to keep your bike lively but can take the drops, track well enough to make the turns and won't restrict your steering?
Travel
Long travel trail forks are generally classed from 140-180mm in travel, so you can hit big stuff hard or drop a big one without fracturing yourself or your frame. Adding travel means adding length though, so always check what the recommended travel is for your bike before upgrading. That said, several of the forks have travel adjust features. These either let you drop the travel in small steps to tweak the bike's geometry and handling to taste, or crush it down dramatically to give a shorter, stiffer fork.
Control
The more travel you have though, the harder it is to control - which makes damping control paramount. You should at least get adjustable rebound damping so the fork returns smoothly to its natural ride height, rather than bouncing back up with a clang. More advanced forks also have compression damping to help the spring slow down and absorb the impacts.
Top line forks split compression damping into two separate circuits - low speed for controlling loads such as braking, cornering or movement under pedalling, or high speed for controlling sudden large loads such as square-edged rocks or landings. Having lots of damping adjustment is only useful if you know what you're doing with it and have the time to tune it correctly though, so be honest rather than pretending that you'll become a pro suspension fork tuner overnight.
Strength/weight
As well as travel and tuning, you need to think about how much strength you really need, or you'll just be carrying extra weight you'll never use. Getting the right balance is really important. Fork strength is hard to gauge though, so go by the manufacturer's recommendations.
As a rough guide, we'd say that any of the forks here should be fine if you occasionally blow tyres or bend wheels while riding. If you regularly crack frames, crush wheels or bend stuff like cranks and handlebars though, you'll need the strongest forks available or even a downhill race fork.
Anatomy of a fork
- Crown - There are single-crown models, with just one cross brace (the crown) holding the two legs together below the head tube of your frame. Most of them use conventional 1 1/8in steerer tubes, but some use oversized 1.5in steerer tubes for extra stiffness.
- Spring - Air springs are lighter and easy to adjust just by changing pressure, but resistance will always increase as they reach full compression. Coil forks are heavier and less adjustable without changing springs, but are invariably cheaper and they feel super smooth.
- Legs - The telescopic legs are the moving structure of the fork. The lower legs are joined together by at least one brace to stop them moving independently, and the upper legs (stanchions) have increased in sized dramatically too, with up to 40mm diameters used to boost stiffness.
- Damping - Forks rely on oil being pushed through holes to absorb the force of impacts (as heat) to stop them just bouncing up and down on the springs. Basic forks just have rebound damping, while advanced forks have separate damping circuits to handle different shaft and impact speeds.
- Through-axle - Instead of using a more standard quick release skewer most long travel trail forks use a 20mm axles that slides right through the hub and screw or clamp into the fork leg. It's a much stiffer system than conventional quick release skewers, and new cam systems such as Maxle mean they're just as quick to tighten/undo too.
Jargon buster
- Bladder - A flexible 'bag' containing damping oil.
- Blow off - A valve that only opens when a preset impact load is exceeded.
- Bottom out - The behaviour at maximum travel with the fork 'bottomed out'.
- Cartridge - Sealed damping unit in the fork.
- Cavitation - An air pocket or void in the oil causing a sudden loss of damping.
- Circuit - The routing of damping oil through valves and holes.
- Linear - A very consistent resistance all through the travel.
- Load - The force transmitted into the suspension by rocks, landings, etc.
- Open bath - System using free range oil slopping around the fork for lubrication and damping.
- Platform - Compression damping that uses a preset 'blow off' load to control when it starts working.
- Preload - Additional pressure applied to a coil or air spring to increase the load needed to start it moving.
- Progressive - Spring rate that increases as the fork compresses to full travel.
- Shaft speed - The speed at which the fork - and the damping piston shaft inside it - compresses.
- Spike - Sudden violent stop when the compression damping is unable to cope with high shaft speeds.
- Spring rate - Load needed to compress the fork.
- Square edge - A blunt-edged obstacle (like a boulder or big kerb) that pushes the fork through its travel fast.
- Stiction - Friction between the upper and lower legs of the fork.
- Top out - The behaviour of the fork when it's unloaded and extends to the very top of its stroke.
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