Tried & Tested

Ride & Revise

After manufacturing, initial frame prototypes are lab-tested to achieve required strength and stiffness at all junctions and load points. Then we start test riding all frame sizes with elite and pro riders to get their perceived feedback. Having ridden hundreds of frames in their lives, these riders can tell us how a frame climbs, sprints, corners, and “feels” overall.

Based on our findings, multiple iterations of the frame’s layup are generated to balance stiffness, vibration damping, perceived road feel, and of course, overall strength. Even with all of our high-tech testing software and feedback from the world’s best riders, it takes a minimum of five iterations to optimize all parameters and, sometimes, far more. With the final layup determined, we conduct a number of destructive lab tests (with multiple samples for each size) to verify that the layup is stable and predictable.

Layup Development Through Testing

Each frame goes through this layup process to achieve engineering targets.
Layup Process Diagram

Test Methods & Data

With one of the world’s foremost testing facilities housed in our Morgan Hill, CA, headquarters, our engineers and technicians can perform countless hours of testing in all phases of fatigue, ultimate strength, impact strength, stiffness, and vibration. For competitive analysis, we publish data on the two most universally accepted modes of comparison: weight and stiffness.

There are a number of commonly accepted stiffness measurements that everyone in the industry uses, but we’ve also adapted our own proprietary tests to further analyze and fine tune specific parts of the frame. Here we will focus on torsional and BB stiffness-to-weight, module BB stiffness, rear triangle stiffness, and vertical compliance.

Note: Since the Tarmac SL3 is our flagship road race bike for 2010, we use it most widely as our basis for comparison against competitors.

Module System Weight

The test for weight is simple. We take a finished 56cm or equivalent frame and put it on the scales. Module weights include frame, fork, hardware, seatpost, crankset and BB (53/39), and Dura Ace 7900, unless the frame is sold with a proprietary crankset.

Module System Weight Diagram

Testing Stiffness-to-Weight

Stiffness-To-Weight Torsion Testing

This is an overall torsional measurement from head tube to rear dropouts—it indicates how well a frame will handle in turns and how stable it will be at high speed. The higher the number, the stiffer the frame.

The frame is fixed at the rear dropouts and a single point support at the middle of head tube that allows the head tube to move. By weighting the bar extending from the head tube (acting as a fork) at the point of tire contact, this test measures the torsional deflection (twisting) along the entire length of the frame, not just a single section. To deduct stiffness-to-weight, the numerical results for torsional stiffness are divided by frame weight.

Stiffness-to-Weight Diagram

Stiffness-to-Weight BB Testing

Stiffness-to-Weight BB Testing

Just like torsional stiffness-to-weight, a higher number indicates greater stiffness. Generally, the stiffer the structure is to the rider’s pedaling forces, the faster the frame will respond to rider acceleration. With the SL3, we shot for a high stiffness number, then focused on maximizing torsional and rear triangle stiffness, while reducing weight.

For this test, each frame is fixed at the head tube and rear dropouts and angled slightly to simulate the side-to-side motion of a bike during heavy sprinting loads. Weights are applied at the pedal through a simulated crank arm and chain at the power-stroke position, then the deflection at the BB is measured and the results are divided by frame weight.

Stiffness-to-Weight BB Testing Diagram

Vertical Compliance Testing

Vertical Compliance Testing

This test measures how a frame responds to loads applied in a vertical plane, which correlates to ride comfort. As a frame gets more compliant, it becomes less stiff. A higher number represents more compliance. This is an isolated vertical compliance test, independent of torsional or BB stiffness.

Each frame is positioned vertically—allowing it to roll at the front and rotate at the rear dropouts—and a vertical force is applied at the saddle. The distance between the BB center and the top of the seatpost is kept constant on all frames. The deflection measures the ability of the frame and seatpost combination to absorb shock in a vertical plane.

Vertical Compliance Diagram

Module BB Stiffness Testing


Module BB Stiffness Testing

Some of our competitors have made slanted claims about the superiority of wide bottom brackets, and we wanted to set the record straight: Using an ultra-wide 90mm BB, in contrast to a proprietary system like our 68mm OSBB or even the standard BB30, doesn’t in itself make for a stiffer frame.

It’s important to note that both 90mm and 68mm bottom brackets allow for a larger diameter down tube and seat tube, which will inevitably increase stiffness. But since our OSBB system is designed in tandem with our FACT carbon crankset, we can achieve even greater module BB stiffness than the 90mm designs, while still remaining BB30-compatible.

To illustrate this concept, we created a new test called “Module BB Stiffness”. It’s set up just like a standard BB stiffness test, but the frame is paired with the real crankset to better measure the BB stiffness of the overall system. As you can see, we clearly out-perform the other guys.

Note: The competition’s modules are tested with a Dura Ace 7900 crankset.

Module BB Stiffness Testing Diagram

Rear Triangle System Testing

Sometimes stiffness and weight measurements are too general. So we conduct several proprietary tests on select parts of the frame to help us analyze variables that might otherwise get overshadowed. We won’t reveal too many details into this process, but one such test is rear triangle stiffness.

Rear Triangle System Testing Diagram

Bike as Ride-able Transducer

The Bike as a Ride-able Transducer


We’ve made rapid advances in the last several years in terms of the performance and ride quality of our carbon frames. It’s not just our commitment to testing that pushes us forward, but our constant drive to get inside the bike (metaphorically speaking, of course) and determine exactly what’s happening in each tube under real riding and racing conditions.

Stiffness tests are a great benchmark for frame development, and finite element analysis allows rapid prototyping, but the act of riding is so dynamic that it can’t be fully duplicated with a static test or computer simulation. Naturally, we saw these limits as opportunity. After a long, arduous process, we found a way to turn the bike frame into a ride-able transducer, capable of gathering bending and torsion data along each tube.

The transducer frame was ridden in every possible manner—sprinting, climbing, descending, pedaling while turning, etc. From the tests, we gathered mountains of data that illustrated the relationship of bending vs. torsion in each tube and how each tube relates to the other. We mapped the load paths through the entire bike frame in every riding situation.

The numbers we pulled from the transducer frame allowed us to optimize the shapes of our bikes to resist the specific loads they would encounter in the field. Take a good look at a bike like the Tarmac SL3—think about how each tube is designed with variable diameter, shifting from circular shapes to flatter, more rectangular ones, yet all blending together—these subtle changes are no accident.

S-Works SL FACT Carbon Crankset

S-Works SL FACT Carbon Crankset


Our 2nd generation S-Works SL FACT Carbon Crankset is one of the best examples of the merits of systems integration. This proprietary crank is designed together with our oversized bottom bracket shell (also BB30 compatible) to deliver superior stiffness, strength, and balanced performance at only 597 grams—that’s lighter than even the biggest names in components.


  • – Lightest and stiffest crankset on market; see charts
  • – FACT carbon removable spider
  • – Self-adjusting 42mm ceramic cartridge bearings
  • – Smooth-shifting S-Works SL aluminum chainrings
  • – BB30 compatible

Creates best weight and stiffness with better fatigue life.

The S-Works SL FACT Carbon Crankset uses a patented integrated construction that’s functionally different from traditional configurations. Typical carbon cranks cut fibers at the BB axle/arm interface, which creates a potential weak spot in a very high-stress area. But the SL’s integrated crank design allows the carbon fiber to transition seamlessly into the bottom bracket with only one connection point at the center of the BB shell—eliminating the typically independent BB axle.

Since this design optimizes the layup of carbon fiber within the bottom bracket, we can engineer the SL crank with completely hollow crank arms for greater stiffness and lighter weight and even add material at the center connection for more strength (without a weight penalty). Finally, replacing the typical steel bearings with new ceramic bearings adds durability and offers less rolling resistance.

Balances stiffness and gives the rider more options.

Most crank spiders are integrated into the right crank arm and create big discrepancies in crank arm stiffness from left to right—a fact that’s often hidden by overall weights and measurements that don’t take side-to-side balance into account. The SL’s removable carbon spider balances stiffness from left to right, adding to the efficiency of your pedal stroke. At the same time, it gives riders interchangeability between different spider and chain ring sizes and also enables the use of SRM and Quarq power meters. The S-Works SL crank is found exclusively on the S-Works Tarmac SL3, but is also available aftermarket.


Crank System Weight Diagram


Crank System Stiffness Diagram