RPM (均輝企業有限公司): 5月 2015

Simple shock absorber:

Design with no reservoir, with oil and gas mixture, shock absorbers will allow gas compress simultaneously to balance the pressure within body tube. RPM body tube design with gas-oil separation mechanism; although no difference in appearance and design cost is higher, but you can effectively prevent the shock absorber oil mixed with nitrogen at high pressure, avoid damper fade with short time period.

When shock absorbers working, shock absorber oil flow through the piston within the cylinder in between chamber A and chamber B, through piston shims, it creates different level of damping resistance. When shock absorber compression and rebound rapidly, shock absorber oil flow back and forth through different holes on the Pistons, resulting in different compression and rebound damping effects.

Piston with shims, control piston holes of opening and closing, due to oil flow speed changing, lead to shock absorber compression and rebound at different speeds and achieve stable performance.

Damper adjustable shock absorber:

Shock absorber interior mainly consists of a piston rod, piston, shims, oil seal, and valve. In addition to the shock absorber oil viscosity, temperature and shims on the piston hole opening and closing will affect the damping rate, and damping-adjustable shock absorbers hard and soft control mainly determine through the valve orifice size which is located on the axis of the piston rod, opening more of the valve increases shock absorber oil flow, shock absorber is relatively soft, and vice versa.

When shock absorber receive equal amount of force, valve open bigger will create less resistance, damper is softer, and vice versa.

In General, shock absorber Hi/Low speed knob is often misinterpreted as vehicles moving at a low speed adjust the low speed knob adjusting hi speed knob at high speed, in fact, this is wrong. High speed correctly interpreted is not the speed of the vehicle moving, but the shock absorber oil flow rate.

Hi/Low speed damping principle is basically similar with rebound damping, are using valve size to control shock absorbers of soft and hard damping rate, low speed valve has two-way oil passage, it can flow in and out, but high-speed valve has only one-way valve, only flow in, oil will then flow via low speed valve and back to body tube.

Low pressure oil flow, less resistance, L valve activate, H valve Closed (small holes on pavement or gravel road)

High pressure oil flow, L and H valve both activate (Pavement road surface with large potholes)

When vehicles travel in continuity of small pit hole surface, such as gravel road, then shock absorbers device travel is small, oil flow speed is low, the high-speed valve will not open, oil only circulate in low speed mechanism, when vehicles travel on surface that has big hole or uneven pavement, then shock absorbers device travel is big, oil flow speed become high, pressure is big enough to open high-speed valve, oil will then flow through high-speed valve and low speed valve.

Gravel road, shock absorber will actuated in small stroke, small, oil flow pressure is low; Potholes can cause a sudden pressure rise, causes larger stroke, oil flow pressure become high.

High speed damper effect:

Low speed compression damper-L is control with "continuous moving small travel of piston rod", is in charge with range of piston rod travel, how much does it effects the travel range? The answers is "Loading weight" and "cornering" stability!

High-speed compression damper-H is in control of the "sudden moving big travel of piston rod" is in charge with range of piston rod travel, how much does it effects the travel range? The answer is "holes on road surface"!

Hi/Low damper adjustment instruction

High or low speed damping adjustment adjust the damping is actually a very time consuming task, the reason lies between high low speed mechanism affect each other, and everybody's riding style are not the same, so that each rider’s preference adjustments are not the same. Thus provides a simple way for your reference below.

First of all, please remember that clock wise direction click is hard adjustment, anti clock wise direction is soft adjustment , this applies to Hi/Low compression adjustment.

Turn low speed knob in clockwise direction to the end, high-speed anti counter clockwise to the end. At this moment low speed mechanism is completely close, high-speed mechanism is completely open. Intended to adjust the low-speed compression clicks, because low speed is the easy adjustment, and is the most commonly used! Low speed knob is close at this time, represents minimize of damping rate, with hardest rate. So, when you encounter a pothole, your vehicle will vibrate like electric massage chair, this is a normal phenomenon, do not panic! if you do not want this, you can adjust low speed knob 5 clicks in counterclockwise direction, then repeated the adjustment until you feel comfortable with the setting.

Taiwan road surface is not in good condition, the adjustment test can be done anywhere anytime, or test on unpaved asphalt pavement or gravel pavement! When you feel the shock absorbers in "continuous motion and less travel" condition, has obviously absorbed and actuation, represents the low-speed compression damping adjustment is successful!

When low-speed compression damping adjustment is completed, then it is time to adjust the high-speed compression mechanism, the so-called high-speed damping is in control of the "sudden actuation and dive deep stroke" when travel over pavement "potholes". Or recommend way to find out the setting tip is to ride faster on road, when it comes to "sidewalk" or "pavements with potholes", apparently feel the jumps represent you must adjust the high-speed compression damping. Actually high-speed compression adjustment is not an easy task, because you must repeatedly test damping on poor road condition, such as you can find a sidewalk, ride with certain and constant speed, then you can obviously feel shock absorbers in "sudden actuation and dive deep stroke" situation, the shock is obviously absorb and moving, and not let you of shock absorbers bottom out, it represent you have completed high-speed damping adjustment. Of course, we do not recommend this method to abuse your ride!

Frequent Q&A

Q: Riding with low speed, feel vehicle vibrating

A: It means you will need to adjust low speed compression more open flow .

Low speed compression too hard will slow down oil flow, and not able to absorber vibration.

Q: When riding with lower speed on potholes feel vibrating and bottom out?

A: It means you will need to adjust High speed compression more open flow.

High speed compression too hard will slow down oil flow, and not able to absorber vibration.

Q: When riding with high speed, feel vehicle vibrating?

A: It means low speed damper is necessary to increase.

Low speed compression damping gap is too open, at high speeds, tire contact with pavement movement is large and continuous! Lead to vehicle vibration and instability.

Q: When riding with high speed, going over potholes and feel vehicle jump?

A: It means high speed damper is necessary to increase.

High speed compression damping gap is too narrow, lead to damper oil flow slow down, thus unable to absorber sudden impact.

Q: When travelling high speed corner, feel vehicle is vibrating and unstable?

A: It means LOW speed damper is necessary to decrease.

A: It means low speed damper is necessary to increase.

Low speed compression damping gap is too open, damper oil flow too quick, lead to vehicle vibration and instability.

Q: No matter how I adjust, still cannot get correct hi/low setting, the vehicle is still unstable and vibrating. Jumping and bottom out?

A: Before compression damping adjustment, make sure spring preload and rebound are correctly adjusted.

Although a minor variation of spring preload, or rebound damping, it can also be correct by adjust compression damping! But incorrect adjustment ~ such as adjustment of spring preload is too tight, too loose. Or rebound damping rebound too fast, too slow, and so on. Will lead to incorrect adjustment of high/low speed compression damping, so if there are such problems, is not to do with your adjustment process, but before compression damping adjustment, rebound adjustment and spring preload adjustment are already adjusted incorrectly!

* Note:

prior to adjustment of high low speed knob, you should first adjust spring preload and rebound damping to appropriate setting, to adjustment that are unable to meet demand, regarding detail rebound damping and spring preload adjustment mentioned on RPM website, by the way, on the bottom comics provided allows riders to quickly review how!

Spring Preload Adjusment Comics