Frame Technology

Understanding Frame Efficiency

Butted Tubing
Tubing Refinements
Relative Weight Index


The IsoGrid® Story



Lighter bikes:
How much faster?

This age-old question—and the resulting debate between engineers and enthusiasts—has finally been settled. Engineers had claimed weight was relatively unimportant. They insisted that any bicycle, even one weighing 100 pounds, would be equally fast on a totally-flat century. Armed with cryptic formulas, engineers wanted us
to believe a heavier bike was only a disadvantage when accelerating or climbing. Cycling experts (including magazine editors, lionized builders and winning racers) knew better. A lighter bike, they declared, was the true path to speed and performance. Want to ride faster? Buy a lighter frame and equip it with lighter components! Saving a pound of rotating weight (wheels and pedals), they told us, was as good as saving two pounds of frame weight. Better yet, we were assured, saving two pounds at the frame was as good as saving four pounds of body weight. Whose argument won? Most of us (this writer included) sided with our heroes and ignored the engineers. After all, which is more fun: dieting, training, or shopping for lighter wheels?

After we invested in our carbon frames, titanium hardware and featherweight wheels we felt hours faster. At the very least, we convinced ourselves, our finishing times were improved by dozens of minutes. Now that thousands of enthusiasts are using watt me- ters that accurately record rear wheel power output, however, repeated 32 real world testing proves that those darned engineers were right. The effect of bike weight on speed is easily quanti- fiable, and conforms to Newtonian Physics. Even on an exceptionally long ride a lighter bike is only a few seconds faster. Minutes faster? That was an impossible fantasy.

Watt Meter Findings

• On a totally flat 100-mile ride, a pound of extra weight will slow a cyclist by about 8 seconds (due to increased rolling resistance).

• On a challenging century, a pound of extra weight will slow a cyclist by about 30 seconds.

• On Alpe d’Huez, where the gradient averages 7.9% for 8.6 miles, pro riders using watt meters have verified what Isaac Newton proposed centuries earlier. On this famous climb, the energy required to lift a pound by 3,500 vertical feet will cause solo competitors to reach the summit about 30 seconds later.

The difference between a pound of frame weight and a pound of wheel weight? Less than a second. Excess body weight, which needs to be both lifted and nourished, has a bit more impact than excess bicycle weight.

Discouraged by this news? For tandem riders it only gets worse. When engineers insert doubled power, their formulas confirm that
a tandem’s frame weight becomes half as important. If your tandem’s frame is a pound overweight, for instance, you and your partner will finish a challenging century (or reach the summit of Alpe d’Huez) about 15 seconds slower. Unless you can escape the laws of Newtonian Physics, on most tandem rides the speed advantage of a pound-lighter frame won’t exceed 10 seconds.

Can Lighter be Slower?

While a lighter frame can’t possibly save you more time than the aforementioned examples, it might actually make you slower. If your frame doesn’t adequately resist pedal-induced flex, energy that could have propelled you forward will instead be wasted in lateral frame distortion (which creates heat instead of propulsion).

Because the faddish “open” tandem frames are undeniably flexier, these suddenly popular designs with their missing frame tubes are apt to reach the summit behind a pound-heavier frame with all tubes present. (Legs are also heavy, but finding a tandem partner with missing limbs won’t cause you to win races.)

Although the advantage of a lighter frame is less than most of us formerly believed, the energy required to accelerate and/or lift excess weight cannot be denied. While your body weight is difficult to control, and the lightest bike components may fail or wear out, a light and well-designed frame should provide decades of reliable performance. Because a lighter and more efficient frame
is more enjoyable to ride, you’ll use it more often. Extra use is the factor that easily justifies a frame’s expense. If you spread the cost over a number of years, Santana’s lighter and more efficient frames become a healthy bargain and a superior long-term investment. Since the effect of weight is relatively small (and the lightest frames from leading tandem builders are all within a two-pound spread), is it possible to believe a new frame will allow you to keep up with faster couples? Better yet, some might ask, is there a new technology that will allow you to finish ahead of teams that are younger, thinner or stronger? Actually, there is. We call it Bilaminate Damping™.

More Important than Weight

Even though most cyclists haven’t yet heard of Bilaminate Damping™ (Santana’s specific application of a phenomenon engineers refer to as Constrained Layer Damping or CLD), this exciting technology is a game-changer that’s helping engineers at Boeing and Ford to define the next generation of airplanes and automobiles. Santana became aware of constrained layer damping after we tried to understand dozens of reports received from owners of our Beyond frames built with IsoGrid®* carbon tubing. Most of these couples had upgraded from a previous Santana, and nearly all reported longer rides at higher speeds. Especially intriguing were reports from competitive seniors who claimed their Beyond had “turned back the clock” and was allowing them to regain performance they’d lost through aging. Because Santana’s design team knew these fantastic reports couldn’t possibly be explained by the 6 lb. weight of our Beyond frame (which is only a pound-and-a-half lighter than our frames built with titanium or scandium), we challenged a group of engineers to provide an explanation. Their three word response, constrained layer damping, encouraged a surprising path of discovery.

Following four years of additional research and ride testing, Santana understands constrained layer damping well enough to explain why you’ll feel younger. Further, we realize how an advanced version of this technology (i.e., Bilaminate Damping™) is actually more critical than frame weight, and can enable you to enjoy longer rides and finish minutes faster.

Interested? Continue reading to discover an unexpected source of cycling performance months before your bike-racing buddies read about it in their favorite magazines.

What's the Buzz?

If you place your fingertips on your frame while you ride, you’ll sense the vibration that occurs as the result of your wheels rolling along the road surface. Experts confirm that all materials resonate, and that thin sections of high strength materials will continue to reverberate indefinitely. Your bicycle frame not only resonates like a cymbal, the lighter and stiffer the frame, the greater the vibration.

This explains why a resounding wind chime can be produced from the same materials that create light bicycle frames (i.e., aluminum, steel, titanium, carbon and even bamboo). The difference, of course, is that the sustained notes of a wind chime are pleasant. Sustained road vibration isn’t. While the vibration we sense through our fingertips seems innocuous, miles of exposure to road buzz has a debilitating effect on human joints and muscles. The faster the speed, the greater the road’s impact. The lighter the bike, the greater the reverberation. Even on the smoothest courses, competetive speeds and bikes take a toll on performance, limit your endurance and makes you feel old.

Doesn’t a carbon frame damp vibration? Although certain materials won’t resonate as efficiently as others (which is precisely why discerning cyclists prefer the comfort of titanium over carbon, and carbon over aluminum or steel), the degree of vibration damping between various high strength materials is comparatively small. A light and stiff racing frame built from titanium or carbon can be less comfortable than a recreational frame built from aluminum or steel.

How Bilaminate Damping™ Works

When two materials that resonate at different frequencies are bound together, each inhibits the other’s ability to resonate. Engineers call it “Constrained Layer Damping.” Additionally, if the weights of the materials are roughly equal, the two frequencies cancel each other. The effect of Bilaminate Damping™ is immediate and profound. Vibration is terminated. Boeing’s initial plan for their 787 Dreamliner was an “all-carbon” stucture. Partway through development they changed the design to approximately equal weights of carbon and aluminum. Through careful engineering and the use of constrained layer damping (CLD), weight did not increase. Instead, vibration disappeared. A flight in a 787 will change your perception of air travel. Because the quieter plane is more comfortable, flights are less fatiguing. Once you’ve experienced the difference, other jetliners become second rate.

The Ultimate CLD

Bilaminate Damping™ is Santana’s term for an advanced adaptation of constrained layer damping. Typical CLD is acheived by bonding structural and non-structural materials (usually elastomers) in unbalanced ratios. With this simple approach, vibration is merely reduced. Employing VyaTek’s patented ExoGrid® and IsoGrid®* technologies, Santana eliminates the bonding layer by using extreme heat and pressure to fuse together a proportioned and complementary pair of ultra-strong materials. In short, other CLDs add weight to reduce vibration. Santana’s Bilaminate Damping™ eliminates vibration without adding a single gram of non-structural weight.

*IsoGrid® and Exogrid® are trademarks for Vyatek's patented, cutting edge method for creating the world's finest hybrid composite carbon/metal tubes.