On The Pedals
By Jason Giacchino

Pedaling Racecar Style

One of the fringe benefits of hanging around the MBT editorial grounds is access to the abundance of literature that finds its way here. Of particular note was a piece I uncovered recently from GT; in it was a brief but very interesting history development of their patented iDrive system. One fact that stuck with me was a line about the reality that what makes the system so effective is that it’s one of few suspension platforms designed entirely from the ground up to address the specific demands of mountain biking (as opposed to those that borrow their core concepts from motorsports applications).

Good point- I suppose regardless of how smooth you believe you are at spinning the cranks, it’s tough to compete with the near endless rhythm of an internal combustion engine’s output. In that regard mountain bike engineering is faced with an additional obstacle in that suspension has to be weary of force being extruded by the rider almost as critically as the force being transmitted by fluctuations of the terrain itself.

This line of reasoning got me to thinking about some of the unique means and methods established throughout the years to address the issue- you’ve heard them all even if you haven’t the faintest idea of the science behind how they attempt to battle pedal bob: Virtual pivot points, four bar linkages, inertia valves, s-shaped axel paths, and the list goes on. Perhaps you’re more familiar with the marketing lingo: dw-Link, Maestro, VPP, FSR, Brain, etc. In any event, the bottom line is that mountain biking demands some clever thinking and slick engineering so as not to suck up precious pedaling-power before it can reach the ground.

While such thoughts occupied what little span of attention I call my own, I happened upon a report from the automotive world that if I’m not mistaken, just may find its way into the shocks of mountain bikes in the near future. The news came from Porche as a revolutionary innovation designed to eliminate tiny fluctuations caused by the powertrain that could actually affect the GT3’s handling at high speeds. The answer was to surround the drivetrain’s mounts with magnetorheological fluid, which could thus make the mounts solid when needed and free-floating when the speeds start to get intense.

This is accomplished through a pretty wild yet simplistic concept: Magnetorheological fluid is a fancy term for an oil loaded up with microscopic iron particles. When exposed to an electrical current (in this case a magnetic field) the iron particles align themselves into chains. These chains obviously increase resistance of the oil’s ability to flow and as a result create viscosity change on the fly.

Think about it- Filling a mountain bike shock with this fluid would mean all that’s required is an onboard electromagnet (which could be powered by the reciprocation of the cranks) to spur infinite control over the internal valving. With enough voltage, the fluid can become so thick that it cannot flow through the valves in which case you’ve essentially established lock-out (a tactic that requires a separate circuit in current suspension designs).

Best of all still is the speed at which these viscosity changes can be accomplished- essentially the speed of light. Since the moment the magnetic field is altered, the particle chains begin to crumble or rebuild as required.

Now I don’t pretend to be an engineer but I do suspect this technology could find a home on mountain bike suspension in the near future. Costs aren’t quite as exuberant as one might expect either- $1000 for the dynamic drivetrain mount option added to the $113,150 base price of a 2010 Porche 911 GT3.

The bad news is that brochure boasts of cutting ties with motorsports suspension design will suffer should this technology arrive but in all, I think that’s a pretty small price to pay.

Questions? Comments? Love letters? Send 'em to Editor@mountainbiketales.com.