A Minnesota-based company called Berd has created what it claims are the world's lightest weight bicycle spokes. Instead of steel or aluminum, Berd's Polylight spokes are made from a unique polymer called ultra-high molecular weight polyethylene.
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Why polymer over metal?
Berd lists three main benefits of using its polymer-based Polylight spokes.
The most obvious is the reduction in weight, with Berd claiming that up to 250 grams can be saved on a pair of wheels. A single 265mm spoke weighs 2.3 grams.
For reference, a DT Swiss Comp double-butted steel spoke (2.0/1.8/2.0) weighs roughly 5.9g, a straight 2.0 gauge around 6.9g, and a DT Swiss Revolution (2.0/1.5/2.0) about 4.4g.
The second claim is a decrease in vibration due to the polymer's increased damping. Wheels built with Berd spokes are smoother and more comfortable than metal, Berd says.
The last is a reduction in failures. Berd claims that polymer doesn't suffer from fatigue the way metal can, reducing the likelihood of a broken spoke and improving impact resistance.
Are they stiff?
Berd claims that even though its spokes are half the weight, they're stronger than traditional spokes. The Polylight spokes are reported to be able to support 300kg (660lbs) in tension each.
Are they aero?
At average riding speeds Berd maintains its spokes are within a fraction of a watt compared to high-end spokes. The Polylight spoke width is 1.8mm.
How do they attach?
At the rim — Polylight spokes appear to attach like regular spokes. There's a standard 2.0mm threaded metal end to attach to a nipple.
On the hub side the spokes feature an eyelet which is pulled through the hub hole and secured with a small rod. Berd claims its spokes are compatible with J-bend and straight-pull hubs.
Are they legal?
Yes, Polylight spokes are UCI approved. Berd is partnering with a few custom wheelbuilders, working with wheel manufacturers and offering a service to rebuild your current wheels with its polymer spokes. More info can be found at berdspokes.com.