Suspension Guide

Words by George Shipman

on 23/05/2019 16:39:42

Read our simple guide to quick suspension set up.

Want to know a little more about recommended suspension set up? We've tried to simplify things and created a quick guide to assist with the most common tuneable properties on suspension forks and shocks. Enjoy a quick set up then get out and ride!

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The primary function of front & rear suspension on a mountain bike is to increase rider control. Your tyres and the pressures you run them at will take you so far – but a correctly set-up and serviced suspension system will vastly improve your available traction.

It’s more important to have a suspension system that delivers ride qualities such as predictability, stability, traction and feel. But comfort doesn’t necessarily trump those things – a common misconception.

Having the ability to tune your system remotely on the fly, allows the rider to select a suitable setting for that particular moment in the ride. Having such a functionality greatly enhances both rider control and comfort. The majority of fork and shock models available arrive from the factory very well tuned, offering a certain range of adjustment variables. This ensures that the rider cannot stray too far away from optimum suspension performance.

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One of the biggest misconceptions about suspension components and systems is that they’re difficult to set-up properly.

Manufacturers will supply information online or in manuals supplied with the component or new bike. We’re always happy to share our knowledge with customers looking for a little assistance! For air-systems, recommended pressures are often displayed on the component!

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Air Pressure

Select your suspension components pressure relative to your body weight. Ensure you have a high-pressure shock pump! The maximum pressures for shocks can exceed 275psi. Lighter riders will generally require lower pressure and heavier riders will require higher pressure. Recommended pressures can often be found on a table on the lower fork leg. Rear shocks do not have charts because the air pressure varies according to the frame they are in. The same model and size of shock can fit in two very different frames with different leverage linkages. Rear shock pressure is always determined by SAG, so it matches the SAG on the front suspension. Usually 20% for most brands. It is of course paramount that this is never exceeded. For example, I ride a Trek Fuel, with of 130mm travel. I weigh a fraction under 70kg. My recommended pressures are 75psi in my forks and 180psi in my rear shock. Luckily Trek have a very handy calculator online. Trek Suspension Calculator (Only relevant to Trek models.) You may wish to add a fraction more or less, dependant on your own preference.

Sag

Setting sag is the first thing you’ll need to do – and it’s important that you set it correctly first. Thankfully it’s a straightforward task! Sag is how much your bike settles into its suspension when you get on your bike and take your feet off the ground. Suspension is optimised to work at its best between 20% sag. An example would be that on a 100mm travel fork you want to aim to have 20mm of sagged (used) travel when you sit on your bike. Our pro-tip is to perform this check with all of your usual riding gear on, stood up, leant against a wall squatting (attack mode!) – not in the saddle. You can measure your sag with either a zip-tie or the rubber O-ring. Ensure your compression and rebound is in its lowest/fastest setting for best results! Regarding rear shocks, just because you have a 6” travel bike doesn’t mean you’ll have a 6” stroke length. Measure the stroke length and aim for the same 20% sag. 8mm of travel used on a shock with a 40mm stroke length would indicate that your shocks sag is set up correctly.

Rebound

Indicated on components by a red dial button - Rebound defines the speed at which your suspension returns to full travel after compression. Faster rebound will make your suspension pogo with force back to its full travel. Slower rebound will cause your suspension to be unresponsive and unable to utilise all of its travel. This is important in trail scenarios where big hits may occur in quick succession, for example rock gardens.
Rebound often comes down to personal preference – some riders like ‘fast’ suspension and some prefer ‘slower’ – it’s a wide spectrum. Consider the area you’re riding in and the trails you’ll be riding most commonly. It’s simple to adjust, often taking the form of a dial. To set your rebound damping, find a curb. Select the fastest rebound setting. Ride off of the curb, in a standing position at a jogging pace. Your suspension will likely compress, then extend to full extension in quick succession. Perhaps even a second time! The goal is to gradually introduce slower rebound settings until this ‘pogo’ effect is minimised. You may need to repeat several times!

Compression Dampening

Not all suspension forks or rear shocks have adjustable compression damping so this section may not be applicable to you. Compression dampening utilises a blue dial button for adjustments. Compression damping controls the speed in which your suspension compresses.
Too high a compression damping setting will result in suspension that ‘bobs’ and ‘dives’ through its travel. This is especially noticeable under braking. Too much compression damping will do the opposite – too low a setting will prevent your suspension from absorbing impacts effectively. Compression damping is again, a thing of personal preference. Some riders like supple reactive suspension, whilst other riders prefer stable and less reactive suspension.

Preset Compression Damping

Many rear shocks (it’s less common to find on forks) have dial-controlled presets for compression damping. Fox forks and shocks designate their modes as ‘Climb’, ‘Trail’ and ‘Descent’ for example. ‘Climb’ mode results in the highest level of compression damping - resulting in a firm ride that resists pedal bobbing and uses minimal suspension travel. ‘Trail’ mode uses less compression damping - but enough to avoid excess pedal-bob but still able to absorb large hits. It’s the best “all rounder”. ‘Descent’ (Party) mode uses the least amount of compression damping. The ride will be super plush, allowing you to utilise all of your travel. Rider pedalling efficiency is significantly reduced - so best combined with a helping hand from gravity. RockShox and other manufacturers utilise similar presets. Commonly three settings are offered.

Low-Speed Compression

If you’re able to fine tune your low speed compression (as opposed to using the built-in presets) then it’s worth familiarising yourself with how it works. Low-speed compression affects how the suspension compresses at lower speeds. Gradually increase the level of low speed compression until your suspension doesn’t bob about excessively under pedalling. You won’t be able to totally eradicate all bobbing. Bear in mind that your tyres will be absorbing the smallest bumps. A primed low speed compression setup will allow your fork to resist diving and sinking through its travel during steep descents or heavy braking. Low Speed Compression Damping - Open / Too Soft The fork compresses low into the compression stroke through the low point of the terrain. Suspension travel is used quickly, the rider's weight may shift forward, and bicycle momentum may be reduced. Low Speed Compression Damping - Mid to Firm The fork resists compressing, remains higher in it's travel, and helps the rider maintain speed into and through the rolling section of terrain.

Tokens

Modern suspension units are able to accept manufacturer-specific volume-spacers or ‘tokens’ to modify the behaviour of the fork through its travel range. This adjusts the suspensions ‘spring rate’. For example, adding spacers to a 120mm fork could result in a tune that is super supple through the first 40mm of travel, getting progressively stiffer through the next 40mm of travel, before reserving the final 40mm of travel for bigger hits! This is an extremely popular upgrade, with manufacturers supplying spacers with new components ready for installation!

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The other common misconception is that they are totally maintenance free.
A suspension fork and rear shock will require routine servicing to ensure that they continue to run at their optimum performance.
For the best experience - we recommend forks are serviced annually or after 100 hours of riding. We recommend rear shocks are serviced every 6 months or after 50 hours of riding. (Figures are quoted in alignment with manufacturer guidelines.)
In May, we launched our fork & shock servicing programme ‘CR Tech’. Our workshops now have the capability to service forks and shocks in house, for a highly competitive rate. We continue to offer our longstanding pivot bearing services and replacement service. Read more about our CR Tech servicing programme here!

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