By Tom Jow
Mountain bike suspension is a continually improving facet of bicycle technology. From the first two inch travel RockShox fork to all of the current four, five, six and eight inch suspension systems, improvement never stops. Many of the ideas, and consequently testing, come from sponsored racers. They are always looking for the most efficient way to the finish line. It is for this reason that bicycle suspension systems have developed “lockout”.The purpose of the suspension lockout is to reduce or “lockout” the fork or rear shock travel to provide a platform for the most efficient transfer of the riders power. Anyone who has ridden a full suspension bike has experienced pedal “bob”, the power sucking movement of the suspension, while either powering up a short steep hill or sprinting. Until recently, suspension lockout mechanisms have been a lever located either on the component itself, or mounted on the handlebar operated manually with a cable. However, mountain bike suspension is now being blended with another wonder of technology, electronics, to not only eliminate the cable, but also provide automatic adjustment between locked and open suspension. Could this combination be the best ever?
For several years now, suspension makers have offered a handlebar mounted, cable operated lockout lever for the fork or the rear shock. During the last couple years, Fox Racing Shox has offered a single lever system to control both the front and rear suspension. In 2013, Fox introduced their iCD electronic shock lockout system. The iCD, with one flick of a switch, locks or unlocks the front and rear suspension simultaneously. The advantage to using electronics over a mechanical cable is two-fold. First, the electronic system requires minimal physical and mental effort to complete the task. Second, the electronic action is much faster, essentially instantaneous. Thus, the lockout is used much more often during a race or ride.
The German fork manufacturer, Magura, has taken the electronic concept further. By using both a processor and a three dimensional accelerometer, they have developed a system that automatically senses when suspension or lockout is required. In order to function optimally, the fork is first calibrated on flat ground. The positioning sensor then locks or unlocks the fork based upon whether the rider is traveling up or downhill. It does not, however end there. The accelerometer portion of the sensor is used to sense upward impact, which will allow the fork to absorb the impact. The accelerometer will also sense if the fork is traveling downward, as in free fall from a jump in order to provide suspension for the landing. A wireless switch mounted on the handlebar provides toggling between automatic, locked and open modes.
Another concept in electronic suspension control is the “electronic intelligence (e:i)” suspension system available in North America on Lapierre bicycles. Developed in conjunction with RockShox, the e:i system, rather than provide control of the fork, adjusts the damping of the rear shock based upon what the fork is doing. The rear shock adjustments are made by a processor based upon information provided by an accelerometer on the fork and handlebar stem, and a cadence sensor inside the bottom bracket. The e:i system consists of five automatic modes, plus manual control for locked, open and medium modes.
The basics of the automatic mode are as follows:
Pedaling = Locked
Pedaling plus Light hits = Medium damping
Pedaling plus Big hits = Open damping
Not Pedaling = Open damping*
In other words, when the rider is pedaling in automatic mode the shock is locked out until the fork contacts an obstacle. When the fork compresses, a signal is sent to the system and the rear shock unlocks. If the fork were locked out, however, it would not compress and therefore, the rear shock will remain locked.
Modern mountain bike suspension has allowed riders to travel farther and faster with more control than ever before. While the suspension absorbs shock from below, it can also absorb pedaling energy (real or perceived) from above. As suspension travel has grown component designers have worked hard to reduce any inefficiency. The solution was dials or levers to “lockout” the shock to keep it from compressing and therefore, absorbing energy. Having the shock locked out, however, does keep it from doing it's job of absorbing shock. For the recreational rider, it's no problem to slow down or stop when it's time to change modes. The racer though, does not have that luxury. For them, every split second counts. A handlebar mounted lever is more convenient but still takes time and energy to operate. Electronic control may be the answer. It is both faster and easier than a cable operated lever. Automatically controlled systems are in place and will only improve. Could the electronic “smart” shock system be the “Holy Grail” for suspension bicycles?
*(adapted from http://www.lapierrebicycles.com/technologies-ei-shock)
Got a bike question? Email Tom at [email protected]