Bike
MTB
Get to know MTB suspension with our jargon buster
Talk ‘bounce’ like an expert with this handy guide on the ins and outs of suspension.
Mountain biking has two opposing faces. The first is a simple one; you ride your bike, off-road, as quickly as you can. It’s a beautifully straightforward proposition. The second however is a bit more convoluted; the science behind making the aforementioned possible.
At one stage back in the dark ages (the late 1980's) suspension was viewed as a nonsense; an overly-complex gimmick which would only serve to rob the rider of the purity of off-road adventuring. That was quickly debunked thank goodness and now even an entry level suspension fork offers the kind of cultured damping and control those earlier naysayers could only have dreamed of.
Getting the right suspension settings is a fine art
© Bartek Woliński
However, this golden age of bounce has brought with it its extravagances. These often take the form of knobs and dials that a frightening amount of us just fiddle with until things feel ‘right’. Often in a car park.
Take a bit of time to understand what they all do however and any bike can be transformed into a silky-smooth, magic carpet-like ground-coverer. Here’s how:
Coil or air
Push Elevensix rear shock
© Push
Mountain bike suspension can be broken down into two camps; coil or air sprung. Coil features (you’ve guessed it) a spring, while air features (again, a tricky one...) air. To change the spring rate (the amount of pressure taken to compress the spring) a coil spring can be swapped out, while on an air-sprung model you can simply add or remove air using a shock pump.
Air was once deemed inferior due to the fact that movement would transform it into heat and that would then affect the pressure making things less than consistent. That’s all but dispensed with now, thanks to modern shock technology and many of the planet's fastest DH race bikes now run air-sprung shocks.
Travel
Greg Minnaar
© Bartek Woliński
The amount of suspension travel a bike has is often used (along with its geometry) to pigeonhole it into one of the several categories. A trail bike designed for long days meandering across scenic vistas may only have 100mm of travel, while a full-on DH bike can have over double that.
As a rule of thumb, the faster you intend to go, the more suspension travel you’ll need.
Sag
Team America for Aaron Gwin
© Nathan Hughes
This refers to the amount of travel used when the bike is supporting your weight. Too much sag and your bike will blow through its suspension before you’ve even got it out on to the first descent and too little and it won’t track the ground properly.
Too little sag and you'll be robbing yourself of the full range of travel and performance that the unit is capable of.
Most bikes are designed to sag at around 30 percent of suspension travel. The beauty of air-sprung systems is that this is easy to adjust using only a pump. Some modern frames come with in-built sag indicators as do many air shocks.
Compression
Specialized Enduro Comp Suspension
© Niall Bouzon
This controls at what rate the suspension compresses to absorb an impact. Little compression damping results in a fork or rear end capable of moving over objects with ease, but once speed increases the unit will blow through its travel quicker potentially causing a rider to lose control. Given that suspension is designed to increase control this is less than ideal.
Too much compression however and the suspension becomes less effective and the forces impacting upon it are transferred into the bike and rider.
Rebound
Anton's RockShox Argyle suspension fork
© Bartek Wolinski/Red Bull Content Pool
The rebound adjuster allows you to control how quickly the suspension resets itself to full-travel after absorbing an impact. Riders often talk about ‘fast’ and ‘slow’ rebound settings. Too fast and the bike can feel like a pogo stick, but too slow and it will progressively sink further into its travel during multiple impacts. This is often called ‘packing down’.
High speed vs. low speed
Fox DHX2 rear shock
© Bartek Woliński/Red Bull Content Pool
The more money you spend on suspension the more adjustments that you'll be able to make and on top flight machinery both compression and rebound are often adjustable across two separate parameters; high and low speed.
Low speed impacts are the type which typically line most trails. They’re the thousands of rocks and roots that your wheels will roll over that will compress your suspension to maybe halfway at most. High speed impacts are the big ones which tend to focus the attention a bit more – landings from jumps and drops or that sudden, square edged rock right in the middle of the trail that you somehow just didn’t see.
These added adjustments are fantastic for racers who need to dial bikes in to different race tracks each weekend, but to those unused to them they need to be approached with a degree of respect, as setting them up inaccurately can ruin a bike's performance.
Internal adjustments
Suspension travel is 200mm rear
© Bartek Woliński
Suspension tuning is widely-recognised as being somewhat of a dark art requiring vastly experienced riders capable of vocalising precise interpretations of sensations to skilled engineers.
But if a shock or fork festooned with clickers aren't enough adjustment for you, many modern suspnsion units can now be internally adjusted too. Air-sprung units can feature drop-in style 'tokens' or similar ways to adjust internal volumes which can help to adjust progression. Tools like Quarq's ShockWiz allow an easy interface between your smartphone and bike and greatly help with both basic and detailed tuning.
Swapping a spring is the easy way to adjust coil-sprung suspension but collecting a back catalogue of springs specific to a single unit can be costly.
