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BERD PolyLight Spokes – The Future of Cycling

Weight Data Strength Data

PolyLight Spokes are significantly lighter than the lightest high-end spokes available. Despite their incredibly low weight, PolyLight spokes are also extremely strong. In fact, they are stronger than most spokes on the market today

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BERD PolyLight Spoke Composition

closeup of spoke

Hover over circles to see properties

fatigue logo

Fatigue life, also known as the resistance to fracture from an oscillating load, is another critical area where Berd spokes excel. Metals spokes have a finite fatigue life and will eventually fail. Since PolyLight spokes are constructed from a polymer, they don't have this inherent weakness. They have been tested to over 9.3 million cycles (about 12,500 miles) without a failure proving they can go the distance.

Moisture, UV, other symbols

Strength and weight are not everything. PolyLight Spokes are also designed to take anything you can throw at them. They are impervious to UV exposure and moisture and resistant to general wear and tear and impact.

Tools for service

Tuning and maintenance are also critical for bicycles wheels. PolyLight Spokes are easier to build wheels with because the viscoelastic properties of the polymer build tension more slowly than stainless steel. This makes it easier for wheel builders to get wheels perfectly tuned. Since elasticity is different from viscoelasticity, the spoke will still make for a high-performing ride!

Also, since the PolyLight spokes are flexible they are easy to bring on rides in case you need to replace a spoke. Try doing that with stainless steel.

Frequency Asked Questions:

Berd Spokes are flexible, so how can you make a wheel out of them?

To answer that question, we need to discuss how wheels are built. Each spoke in a wheel is pulled in tension during the wheel building process – in fact, each spoke is under ~50 - 100 kgf, depending on particular wheel build. When riding the bike, spokes at the bottom of the wheel de-tension to support the weight of the rider, but since they are pretensioned, they never leave tensile loading – which means they are never compressed or slack. Because of this, flexible spokes function equivalently to metal spokes.

How do PolyLight Spokes connect to the wheel?

Each end of Berd spokes has a connection suitable for use with standard wheels. On the wheel hub side of the spoke, an eyelet is pulled through the hub hole and secured with a small rod. On the wheel rim side, a threaded stainless steel rod is screwed into a nut. Custom hubs and rims are not required to build wheel with Berd spokes.

If the spokes are made of a polymer, won’t they feel sloppy?

Wheel stiffness is a rather complicated subject. When people think of stiffness, they are usually concerned that the wheel will not feel responsive to acceleration: torsional stiffness. In reality, this is rarely a concern for any type of spoke since the tangential lacing pattern of rear wheels distributes the drive torque evenly among all spokes. Since it is distributed, the extra force on each spoke is very small and will not result in reduced responsiveness of the wheel.

Another type of stiffness is radial stiffness: the stiffness which translates bumps in the road to the bike frame. For a comfortable ride, it is actually preferable to keep this stiffness low so you don’t feel every bump in the road. Berd spokes are similar to some grades of titanium and stainless steel used in bike spokes and therefore will not seem dramatically different in this regard.

The last type of stiffness is lateral stiffness which is how the wheel deforms when cornering tightly in a turn. This is the most complicated type of stiffness because it involves the number of spokes, spoke lacing pattern, spoke type, bracing angles, and rim properties. Wheels with few spokes or a very stiff rim are more likely to deform out of plane with the wheel when the bike is cornering in a turn which will result in the rim rubbing on the brake pads. This is very bad of course because it will slow the rider down. Since Berd spokes have a similar elastic modulus to common spoke materials, they are not inherently better or worse in this category. Ultimately, the weight savings of PolyLight spokes allows a rider to build wheels with more spokes – and therefore better lateral stiffness – and still be lighter than many other options on the market. This gives the rider ultimate flexibility to optimize their wheel design based on their end goals: weight, aerodynamics, comfort, or performance.

Can I race with Berd Spokes?

Yes! Berd spokes are legal for racing. In fact, the UCI, which regulates professional cycling, has specifically approved Berd spokes, so you can race Polylights from local crits to the Tour de France. Send us a postcard!

Berd Spokes are patent pending

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