Shocks 101

FOX Float ShockIn the September and October issues of Full Sus we delved into the ins and outs of looking after and the servicing of your forks and now we’re moving on to your rear suspension. Here’s our 101 of keeping your shock in working order.

If you’re fortunate enough to be riding a full suspension bike there are a few things to keep in mind. For the benefit of comfort and added traction on climbs and descents you are paying a weight penalty (linkages, pivots and the shock weights do stack up a bit) but the performance benefits are usually more than worth it. Where the real drawback lies is in the maintenance.

The bearings in the pivots need replacing from time to time, but the major point of wear and tear – which requires regular servicing – is the active ingredient in it all, your rear shock.

Here is the Fox service interval chart (sorry if you’re running RockShox, DT Swiss, X-Fusion, or anything else space is a premium, but you can use the table as a general guide anyway).

Fox – Rear Shock

Set sag New
Check sag; reset if necessary After every ride
Set damping adjustments New
Clean shock exterior After every ride
Air sleeve maintenance Every 30 hours
Clean, inspect bushings and reducers Every 30 hours
Suspension fluid service Every 100 hours or annually


So with the fact that you should be checking your sock’s sag (or air pressure if you will) after every ride let’s get into how you do just that.

For the uninitiated sag is the amount your suspension compresses when you sit on the bike. It allows the suspension to compress and also extend in order to maintain traction when unweighting over drops, dips, or when cornering. It can be controlled with coil spring rates, coil preload, or air pressure.

The general rule of thumb is 25% of your total suspension travel should be taken up by sag. So if you’re bike offers 100mm of rear suspension travel, your shock should be 25mm depressed when you’re sitting on the saddle.

RockShox have a pretty simple way of recommending what air pressure your shock should be set at to achieve the optimal sag for your weight. They print a handy chart on their shocks so you can set your suspension up with minimal fuss. Specialized have a pretty simple system in their tuned Fox shocks, which removes all the guess work. The Autosag system does virtually everything for you, all you need to do is set the Brain fade adjust to fully open, pump the shock to 300 PSI (they say double your weight in pounds plus 15psi, but who in SA know their weight in pounds?) and let the air out of the Autosag valve until it stops, replace all the air valve caps and reset the Brain fade adjust to your preferred riding setting.

On a standard Fox shock the process is a little more complex and will require you to get the ruler out or just estimate where the quarter travel mark is. You then climb aboard the bike, sit on the saddle and get a mate to give you a gentle shake to settle the suspension. Get off carefully, so as to not move the o-ring, which indicates how far the shock travelled through its range of travel. If the o-ring isn’t at 25% travel either inflate, if it’s moved through more than 25% travel, or deflate if it hasn’t reached the 25% mark. It might take you a couple of goes to get it spot-on and Fox suggest you adjust in 5 PSI increments.

Once you’ve got it dialled in make a note of the PSI and then when you check your sag in future you can just set it back to that number.

Keeping the moving parts clean

Other than setting your sag your normal routine should involve keeping you shock, especially the damper shaft clean. Use mild soap and water only (that’s the official line) then wipe it down with a soft towel. It’s also a good idea to avoid high pressure hoses and rather use a bike friendly solvent to clean your bike and suspension pivots before spraying it down gently with water.

If you use the right stuff you don’t need high pressure.

Shock Pumps

To ensure the longevity of your fork and shock you’ll need a shock pump. All local bike shops should have a selection in stock. They need to have a pressure gauge, should be able to pump to 300 PSI and have to have the ability to release air from the shock without detaching from the shock’s air inlet valve. A good option is the Ryder DigiShock Pump, for R800.


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