If you don’t have this adjustment, it doesn’t mean you don’t have rebound damping, but rather that the manufacturer has decided what works best and they don’t want you fiddling with it . . .
First, get a feeling for the effect of the rebound damping adjustment before finding the right setting. Find a place where you can repeat a simple five-minute loop – nothing special, a car park will do fine. Ride the loop twice at the two extremes of the rebound damping adjustment to get a feel for the effect of changing the settings. Then set the rebound damping in the central position; for example, if it has a total 12 clicks, start with six clicks. Find a clear, flat space without cars with a single baby dropoff – 50mm (2 inches) or 100mm (4 inches) or so – to ride repeatedly. The idea is you ride over the dropoff, the shock compresses, rebounds further than it started, and returns to its original position. If the shock springs back and kicks you on landing, the rebound is too fast, and you need to increase the damping. If you wallow on landing, it’s too slow and needs to be reduced. At first you may want to make radical changes to the adjustment to learn its effect. Whatever you do, remember to keep a clear and constant note of all changes you make, and resist the temptation to fiddle randomly with combinations – if playing with the rebound damping, leave the sag alone.
Now for the test ride. Go out and play. You should bottom out the shock about once every ride. If not, you are not using the full travel, which is a waste. Play with the sag, a little at a time. This is where your personal taste and riding style come into play. If you stand a lot, up and out of the saddle, you may prefer a stiffer ride, at the lower end of your recommended sag range.
Maintaining rear suspension
Rear shocks have two levels of servicing: they need to be kept clean; and the moving parts need regular lubrication. The bushings that allow them to move must be kept clean and must be replaced when worn. They need to be checked regularly to ensure they’re working properly. You can kill a shock very quickly by continuing to ride when something internal is broken. All this can be done with a few simple tools, and it is worth learning to do regularly.
Rear shocks often sit directly in the firing line for mush thrown up by your back wheel and their performance deteriorates quickly if you ignore them. Conversely, keep them clean and greased and they last a whole lot longer – see page 208 for air shock servicing.
Deeper, internal servicing and tuning must be carried out by a shock servicer. Don’t be tempted to continue ripping inside the shock once you are confident with the outer parts. Depending on make, the internal parts may be filled with nitrogen or stored under high pressure. Don’t get involved. It’s too easy to hurt yourself, and the action voids the warranty. Post the shock to the service centre.
Luckily, there are enough specialists to do the job and, luckily again, once you’ve taken the shock off the bike, it is small enough to post easily. If there’s one thing you can do to help this process, clean the shock before packaging. It is cleaned at the other end, but it’s polite to wipe off last weekend’s fun before putting it in a box. The correct service centre depends on the make of shock. Servicers are quick too. You can usually get a shock back in the time between weekends.
- When opening up the shock for regreasing, clean the bike before you start. Otherwise mud drops into the body of the shock – the rebound characteristics of mud are notoriously variable.
- Air shocks: DON’T forget to discharge all the air in the shock before you start working it. Open a unit that is still pressurized and it releases suddenly, flying into the air. Usually it hits you because you are undoing it. It hurts and you feel stupid.
- DON’T open up the damping cartridge inside the shock.
- Occasionally, air shocks get stuck in the squashed position. Let all the air out of the valve, then reinflate to the maximum pressure the shock is rated for. If this doesn’t work, deflate again and send to the servicer. DON’T open the air sleeve – let the specialist deal with it.
Coil springs have a pair of numbers printed on the coil: the first is the spring rate (stiffness); the second is the travel in inches. You need to know the vital statistics of your spring to change it for a stiffer or softer one.
“Now for the test ride. Go out and play. You should bottom out the shock about once every ride”
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES
See also bike maintenance tips, tricks and techniques “Setting up sag”