Jim’s Tech Talk
By Jim Langley
Berd probably won’t appreciate their revolutionary polymer spokes being referred to as “strings.” But, if you get a chance to hold a few, I think you’ll agree that they’re just as flexible and floppy as thick pieces of string – and entirely unlike the stiff stainless-steel spokes that all bicycle wheels have been built with for almost 150 years.
Berd spokes are actually made of a space-age fabric comprised of many tiny strands braided together. Berd isn’t the first to think of using a string-like material for spokes. You may have heard of the FiberFix emergency spoke, which has been around for many years – if my memory serves, I think since the early 1990’s.
That spoke is made of Kevlar and designed to make it easy to fix a broken spoke on the road or trail without removing the wheel or cassette – if you’re lucky. The flexible spoke fits in a little tube so you can tuck it in your seat bag. You can learn more and purchase the FiberFix here: https://amzn.to/2CUWCQR.
Berd’s spokes are not for emergency use, quite the contrary. They’re designed as cycling game-changers. They take wheel weights and maybe wheel compliance, too (shock absorption) to entirely new levels. Berd spokes weigh an amazing 2.5 grams each, compared to about 4 grams for the lightest stainless-steel spokes, such as 14/17 double-butted models.
This means that depending on spoke length and what steel spokes you’re comparing them to, switching to Berds can save from 100 to 200 grams per wheelset. That pushes the envelope for building superlight wheels to impressive new levels.
And it allows building aluminum rim wheels that are as light as carbon wheels that have steel spokes – as a way to get the weight of carbon with the durability of aluminum. Plus, a set of Berd spokes costs less than most carbon rim sets (Berds cost $8 each). Berd spokes work with J-bend and straight-pull hubs.
Quoting Berd, their spokes “are made from an advanced polymer called ultra high molecular weight polyethylene (UHMWPE). UHMWPE has 12 times the strength-to-weight ratio of steel and floats on water. It also has a significantly improved fatigue life and is impervious to the elements. This is what makes Berd spokes the lightest, strongest, and most durable spoke ever invented.”
I had not heard of UHMWPE, but I’ve heard of another super tough fabric called Dyneema that’s used to make Spurcycle’s Multi Pouch, which I reviewed here and have found to be super strong.
My friend Tony, a gear guru at REI who I ride with, is familiar with UHMWPE and Dyneema and tells me that it’s used in many backpacking products now and wears like iron. He’s so excited about the Berd spokes, he’s having them build him some custom wheels. You can, too, here: https://berdspokes.com/collections/berd-wheels/products/custom-wheel-building.
I wondered about the abrasion resistance of the spokes. For example, if you bend your derailleur hanger, don’t notice and then shift into the spokes? I asked Berd about that very scenario and they told me that the UHMWPE is strong enough to hold up to almost anything.
They said that the thing that would put the spokes at risk of breaking is two sharp edges coming together to cut the spokes, like scissors or diagonal cutters. But, for blows or strikes or rubbing, the spokes can take it.
Improved Ride Quality?
I haven’t had a chance to spend any time on the one set of Berd spoke wheels I’ve built so far (they belong to another guy here at work). And they’re mountain bike wheels anyway. With an MTB’s fat tires and low pressures, I wouldn’t expect to feel a big difference.
On deck to be built though, is a pair of 24-spoke carbon disc road wheels. Once those are ready I should get a chance to feel if Berd’s polymer spokes soak up road vibration better than steel the way they say – and some of their reviews, say they do. Gravel riders would love wheels that ride more smoothly – as would roadies for more comfort on rough pavement.
Two Observations So Far
Only a handful of people have seen the wheels I just finished which feature the white Berd spokes. A few of them pointed out that white polymer spokes might get dirty fast. Maybe being a synthetic material they can be cleaned with soap and water? I’m not sure. Though they’re not shown on their website, I’ve heard that the spokes are also available in black. If dirt is a concern that will probably be the wiser choice.
The other observation is that Berd’s round and bulky in places spokes (like at the hubs) are a complete departure from the aero and bladed metal spokes that are all the rage now on so many road wheelsets. That may make them less appealing to some riders mostly concerned with free speed. But there are plenty of roadies who would love to have much lighter wheels for conquering the climbs.
Building Wheels with Berd Spokes
In the photo is the build tool kit that you purchase from Berd in order to be able to prepare the hubs and pull their spokes through the hub spoke holes. Included is a tool for holding the spoke to stretch it and to prevent it twisting during wheel truing and tensioning (it’s the rectangular tool with the white handle stamped with “BERG”)..
The best way to understand what it takes to install Berd spokes is to watch some of the process, so I made a video to show you. The most unique thing is how the spokes are attached to the hub, so I focus on that. There are two details not in the video I need to explain.
The first detail not shown is preparing the spoke holes. There can’t be any sharp edges that might cause the spokes to break. For this, Berd’s toolkit includes two drill bits for rounding and smoothing both sides of every spoke hole in both hubs. In the video you’ll see that the black anodizing is gone on all the holes from this process.
The second detail not shown is the process of attaching the spokes to the rim. It’s actually done just like with steel spokes with one difference. Berd spokes must be stretched a little in order to reach far enough to thread the nipples on.
The rectangular tool I mentioned above and shown in the photo, slips over the built-in flats on the ends of the spokes and by pulling up with the tool, you stretch the spokes so that you can start the nipples.
The other thing you can’t see is how long it took me to finish the wheels, which was more than twice as long as regular steel spoke wheels. Mostly that’s from the hub preparation and unique spoke-to-hub attachment. Also, Berd spokes stretch more than steel so the final tensioning took more time.
The part of the process that impressed me the most was being able to get Berd’s flexible polymer spokes to the same final tension as steel spokes. Just like with wire spokes, when you’re done with the wheel, the Berd spokes become so tight that you almost cut your hand when you squeeze them.
Enjoy the show!
Ride total: 9,466
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s streak of consecutive cycling days has reached more than 8,000. Click to read Jim’s full bio.