Disusbat

9 May, 2012 — by Orbea — Investigation & analysis

Disusbat is the original mountain bike rear suspension mechanical design project carried out by Orbea and the Center of Studies and Technical Research (CEIT) from 2006 to 2008.

Goals: To improve software-based design methods, considering rider comfort, safety and pedaling efficiency for better designed rear suspension bikes by Orbea.

The Disusbat project comprised four stages:

1. Mathematical tests to analyze the behavior of bicycle components (wheels, forks, shock absorbers, etc.) and how they affect mountain bike performance

Goals: To develop mathematical models for simulations with real data.

Analyses and studies were performed on each of the components, to see how they affected bike performance. Different types of tires, wheels, forks and shock absorbers were tested at different pressures to check their effects on dynamic bike performance, pedaling efficiency, etc. Do you think a lighter wheel with lower lateral stiffness is good or bad for riding performance? This and other issues were considered in an effort to take as many variables as possible affecting bike performance into account. Do you think the pressure of your suspension system (hardness) may have an influence too?

2. Dynamic simulation software development for full suspension bikes (Advanced Dynamics)

At Orbea we asked these questions, looked into lots of variables and laid them open to come up with the best software tool available. In a 3D environment, we took rider comfort, safety and pedaling efficiency into account to improve the design of our bikes. Where other analysis programs left the most important variable out, that is, the rider (crucial to any calculation and accounting for the largest percentage of mass in the analysis), Advanced Dynamics was a comprehensive platform to perform all sorts of tests and trials with the rider’s weight on the bike. Climbs at a given slope, potholes, bumps of a certain height… All of them were analyzed to assess and determine how they affect bike performance as accurately as possible, and how the bike responds to these challenges.

3. Database creation with the leading full suspension bike models on the market, oriented towards the bike prototype to be developed

Some of the leading rear suspension systems were analyzed, considering variables such as simplicity, efficiency, complexity, and so on. Single-pivot systems like those used by Cannondale, four-bar systems such as that of the Orbea Rallon, active breaking pivot (ABP) systems with a Rocker Link design (rear pivot placed above the rear wheel axle) like that of the Trek Remedy, FSR-Horst Link systems as in the Specialized Enduro, virtual pivot point (VPP) technology as in the second-generation Santa Cruz by Nomad, DW-Link suspension in brands like Ibis, and so on. The variables analyzed included riding comfort, pedaling efficiency, rear suspension absorption and safety. They were analyzed in individual graphics for, say, a rider with a certain weight at a constant cycling cadence of 90 rpm. The results were surprising, bringing into question some of the traditionally appreciated suspension systems while proving that others, like the well-designed single-pivot systems, were technically on a par with or even better than more complex technologies, which in fact were found to have no particular advantages.

4. Development of a new full suspension bike model out of the original Rallon 2004, now redesigned into the Rallon 2010 – the new reference in the 150mm travel category

The studies led to the redesigning of Orbea’s flagship enduro bike, the Rallon. First launched in 2004, the Rallon underwent changes in the main pivot point (which went 37.3 mm back and 15 mm up), the joint between the swingarm and the link (which went 2 mm forward), and the point where the link and the top tube are held together (which went 33 mm back and 25.7 mm up). Why all this? These changes improved the bike’s kinematics and, as a result, also its pedaling efficiency and rear suspension absorption. The frame was redesigned along with the tube structure (now square) and a new development with FOX for an exclusive shock absorber setting. The result was the new, second-generation Rallon, launched in 2010. The Rallon 2010 was launched to ravishing reviews in specialist magazines and other media. Experts considered it to be the ideal multi-purpose enduro bike in the 150mm travel category.