It's pretty mucky out there at the moment so now's the time to give your fork a little love after your ride.
You know how is is ... you get in from a ride, quickly wash the bike and then it's time for a cup of tea. Whilst you're supping your tea you remember to lube the chain otherwise it will be a stiff, rusty mess the next time you go to ride. Well, whilst your lubing your chain with that sweet Teflon-enriched oil, just put a couple of drops on your fork's upper tubes. Push them up and down a few times then wipe off the excess oil complete with the dirt lifted from the wiper seal lip with a clean rag. So, next time you ride, both your chain and your fork will be silky smooth before you hit the first puddle!
This one's for all you peeps with '01 onwards Manitou, RockShox, Fox & the lighter Mazocchi models. All these forks rely on oil-bath lubrication to keep them smooth.
This small amount of lubricationg oil or Red Rum/Float Fluid tends to collect at the bottom of the lower tubes after several hours of riding. It's pretty useless here as it's meant to be up between the bushings and the upper tubes. A simple tip is to leave your bike upside-down when stored. This way, the oil/Red Rum/Float Fluid can get back up between the bushings and upper tubes to give you a smoother ride. It also increases the service life of your fork. Please note that some RockShox U-Turn forks may leak from the U-Turn adjuster as this mechanisim is not sealed that well.
If you've got air suspension then here are a few pointers when pumping it up.
If your suspension uses standard Schrader valves you can damage the pump's coupling seal by screwing it in too far. As soon as the gauge registers pressure, screw the coupling ½ turn more and pump to the desired level. When you unscrew the coupling to remove the pump, the hiss you hear is the air from the pump & hose, not the fork or shock (as long as the coupling seal is good). Likewise, when you attach the pump, the opposite happens and air from the fork/shock chamber fills the pump, reducing the pressure registered on the gauge. All perfectly normal and no need to change your desired pressure settings.
On air chambers that have a very small volume (Swinger SPV, DHX Reservoir, 5th CVT, RockShox negative air on Dual air systems) the pressure drop when you connect the pump could be a much as 40-50 psi. The way to check this is to pump up the chamber to your disired pressure, disconect the pump & then immediatly reconect the pump & note the pressure. Do this 3 or 4 times so you get an average pressure drop reading & note this down, Then after 2 or 3 week riding, when you check the pressure, you know what kind of pressure drop to expect.
What do those numbers on the outside of rear shock springs mean?
Usually designated in the imperial system (well for the brands I deal with anyway) rear shocks have 2 numbers (e.g. 600 x 2.00). The first number (600) is the spring rate. The rate of a spring is the amount of force necessary in pounds to compress the spring one inch. In our example it takes 600 lb. force to compress the spring one inch. So it will take another 600 lb. (total 1200) to compress it the second inch.
The second figure (2.00) is the travel of the spring in inches and corresponds to the maximum travel of the shock.
Note: Fox confuse spring marking by quoting the maximum travel the spring will go to before it becomes coil-bound. eg 1.65 = 1.5 stroke, 2.35 or 2.38 = 2.0 or 2.25" stroke, 2.8 = 2.5 or 2.75" stroke & 3.25 = 3.00" stroke
Fork springs are also available with different spring rates but only have one number (e.g. 60). This is the spring rate; 60 lb. force to compress the spring 1 inch. Fork springs have much lower spring rates as they are connected directly to the wheel with no mechanical leverage involved. Rear shocks normally work with ratios of between 2 and 3.5 to 1. So on a bike with a 3:1 ratio, when the rear wheel moves 3 inches the rear shock moves 1 inch. If a 600 x 2.00 spring was fitted it would take 200 lb. of force at the rear wheel to move that inch. The front fork on the other hand, with its 60 lb/in spring rate would take 180 lb. to move the same 3 inches.
Spring preload is normally adjustable by the spring preload collar on rear shocks, or via the top cap adjuster on forks.
These adjusters compress the spring and should be used to fine-tune the correct amount of sag. Turning the spring preload collar to compress the spring will decrease the amount of sag, and vice versa. They will increase or decrease the hardness of the suspension slightly but should be used with care or damage can occur. Too little preload and the spring will rattle and possibly damage surrounding components, too much and it's liable to snap.
On front forks, turning the adjusters will usually increase or decrease the amount of spring preload by between 5-10mm or 0.2-0.4". So if you had a 60lb springrate you would increase the initial force required to compress the fork by 12-24 lbs and similarly the ending spring rate would increase by the same amount. This may seem like a large increase and therefore many people think adjusting the preload will make a huge difference but in reality it doesn't. So if the fork was a 5" travel mode the ending spring rate would increase from 300lbs to 312lbs or 324lbs, which is only a 4-8% increase. If however you were to go to the next spring rate, say 70 lbs, you get an increase of 14% and the ending rate would be 350lbs or with preload 364 to 378lbs.
On rear shocks, the spring preload collar is infinitely adjustable (with a little help from some pipegrips!) so in theory you could get the ending rate you want. The only problem here is the limited space for the spring. As you screw the preload collar down to compress the spring, the gaps between the coils become smaller. These gaps must add up in total to a value higher than that of the shock stroke. Ideally they should be 10% greater otherwise premature failure of the spring will occur. This is why all coil-over shocks have a maximum amount of allowable preload. This amount is usually between 2-8 turns and is counted from the moment the spring collar contacts the spring and begins to compress it.
As most suspension is supplied for Joe Average who is 170lbs or 70kg you will usually need to take different springs if you are more than 10% ether side (assuming the manufacturer called the spring rate right in the first place!) if you want the ultimate ride.
sSag is the compression of the front or rear suspension caused by the rider's weight & is the most important suspension setting (especially on the rear). Correct sag allows the wheels to follow the contour of the terrain as you ride and has the biggest effect on how the bike feels.
By having the correct amount of sag the wheels will not only be able to rise up over any obstacle it will also allow the wheel to fall into most holes. In this way the rider should not feel much variation in bike movement as you track across rough ground.Sag is expressed as a percentage of maximum travel.
Sag is very difficult to measure on front forks as it is difficult to know where to centre your weight on the bike. Some people ride with their weight way back over the rear wheel whilst others attack the trail & have their weight over the front. It is therefore difficult to make specific recomendations on spring selection or air pressures for forks apart from to go with the manufactures guidelines in your owners manual intially. If you find on the trail that things are too soft/hard adjust the air pressure or take another spring.
On Rear shocks sag is expressed as a percentage of maximum stroke and is best set at 20-30% for XC (firm), 25-35% for Enduro and 25-45% Downhill. The better damped a shock the more sag you can usually run because the compression damping will prevent the shock from blowing through it's travel. This allows you to run deeper in the stroke without blowing through the travel giving better control over braking bumps & cornering stability (due to lower centre of gravity).
The table below can be used to determine/set the correct sag on your bike. To set/check your sag you are going to need the help of a friend. Wearing your normal riding gear sit on your bike with your feet on the pedals (do this next to a wall so you can prop yourself up with your elbow). Push up & down allowing the the shock spring/air pressure to push your weight back up until it settles. Now get your friend to measure the eye to eye of the shock (distance between the shock mounting bolt centres). Check this distance with the table below to see if you have the correct sag.
| |
Eye to eye (mm) with percentage sag |
| Eye to Eye x Stroke |
20% |
25% |
30% |
35% |
40% |
45% |
50% |
| 6.5 x 1.5" |
165 x 38mm |
157 |
155 |
153 |
151 |
149 |
147 |
145 |
| 7.5 x 2.0" |
190 x 50mm |
180 |
177.5 |
175 |
172.5 |
170 |
167.5 |
165 |
| 7.875 x 2.0" |
200 x 50mm |
190 |
187.5 |
185 |
182.5 |
180 |
177.5 |
175 |
| 7.875 x 2.25" |
200 x 57mm |
188 |
185 |
183 |
180 |
177 |
174 |
171 |
| 8.5 x 2.5" |
216 x 63mm |
203 |
200 |
197 |
194 |
191 |
187 |
184 |
| 8.75 x 2.75" |
222 x 71mm |
208 |
204 |
200 |
197 |
193 |
189 |
186 |
| 9.0 x 2.75" |
230 x 71mm |
218 |
214 |
210 |
207 |
203 |
199 |
196 |
| 9.5 x 3.0" |
241 x 76mm |
226 |
222 |
218 |
214 |
210 |
206 |
203 |
Coil Rear Shocks: Spring preload fine-tunes the amount of sag & is done with the spring preload adjuster collar. Adjust the spring preload adjuster up or down to achieve the desired amount of sag. If you reach the manufactures maximum spring preload & the sag is too much, then go to the next harder spring. Turning the spring preload collar to compress the spring will decrease the amount of sag & vice versa.
If you need a new spring or advice on the selection of the correct one see spring calculator or call with details of your bike, style of riding & your weight.
Air Rear Shocks: To increase your sag reduce the main air spring pressure. To reduce sag increase the main air spring pressure.