Berd PolyLight Spokes. Silly-light Polymer Spokes

[oldpotatoe]

Originally Posted by ergott

Actually Tiagra is a better value.

Sent from my SM-G950U using Tapatalk

Yup and Veloce....really nice stuff

[torquer]

Originally Posted by Birddog

Macrame makes a comeback on bicycle wheels!

And bicycle wheels start appearing on Etsy!

[MaraudingWalrus]

Update -

I'd been building these for a customer of mine who is off the bike for quite a while. I got the front dialed pretty quickly. The rear I had significant difficulty lacing. I had been unable to get I think the last three of the rear wheel laced, despite many rounds of my best effort on that (tensioning the rest of the spokes to stretch them, then loosening, etc).

It was a bit of a back burner project for me with other things going on, and my customer being off the bike, but eventually shipped it back to Berd a week or two ago to see if they could get it, or if the spokes I got were slightly too short.

It wound up being that the spokes were maybe a smidgen too short, but they were able to sort it out.

Brad@berd has improved their spoke length calculator a bit, as well as including several more things in the builder's kit to aid in the wheelbuilding process.

At any rate, the front wheel weighs in at 615g (down from 675g) and 742g for the front (down from 805g). So a total weight of 1357 down from 1480. A savings of 123g, which is an amusing number. For what it's worth, this took the wheels from 5.2 watts to 4.4 watts to accelerate from 0-30km/h on my recreation of the device described here. They're now the second best wheelset by that number I have tested, behind only a set of Extralites laced to Kinlin XR200s (2.2watts, 1140g for the pair), with the worst being a set of Bontrager Race Lites at ( 17.1watts 1721g weight for the pair). One day I compile that data in a somewhat more viewer friendly form and post the findings.

Obviously that 0.8 watt saving is very much very small when compared to the total energy required to accelerate the whole system, but not technically zero. Over the course of a long ride or race it could add up to several fives or tens of watts of energy saved. Which I guess for my customer - who has missed out on the top step of podiums @Nats repeatedly - is the sort of mythical marginal gain. Hopefully it works out for them. Will probably be rebuilding those Kinlins/Extralites using these puppies in the next few months. I guess the numbers say it'll hit right at 1020 or so grams for a pair of aluminum clinchers.

Also worth noting, I cannot attest to the accuracy of the formula described on the WheelFanatyk site, that has been discussed in other threads and argued about by people with a more math sciencey background than I. However the information is from one of the leading authorities on the bicycle wheel, Ric Hjertberg of Wheelsmith & MadFiber fame, and I generally believe what he says on things regarding wheels.

[ergott]

Thanks for the follow up!

[Bob Ross]

[oldpotatoe]

Not something I'd tackle but thanks for the review, followup.

[benb]

Yah no way I'd touch these with a 20ft pole without there being some serious engineering data on wheels built with these. Not data on how great the material is for other applications, data about how this specific use case holds up.

How different is this than the Mavic wheels which seemed great but blew up and caused serious injuries?

Seems like it's a weight weenie thing anyway? When does that 123g become significant? When you're Phil Gaimon or something hunting KOMs or riding an unsanctioned hill climb where they don't care if your bike is UCI legal and you can reduce the weight well below the usual limit?

If the rider isn't stupid fast/strong/light and needs that last 1% to win the race than I don't see the point. That's not me so no freaking way.

And if it's 0.8w or something that seems small enough it could get negated if there is an aero problem?

How is this material for resisting weakening from unknown chemicals which ALWAYS get on the spokes when riding in the real world? What cleaners are safe for it?

[MaraudingWalrus]

Originally Posted by benb

Seems like it's a weight weenie thing anyway? When does that 123g become significant?
If the rider isn't stupid fast/strong/light and needs that last 1% to win the race than I don't see the point.

At least in the case of the particular rider these are for, the rider and bike combined weigh maybe 125lbs, so certainly more relevant than for me, a 225 person with a 23lb bike. And given they have actually needed that last 1% to win their races before, and lost by that 1% before, for certain people, it's most certainly a great application.

Some things I've read on the material indicate it has decent abrasion resistance, enough for road bike usage. Similar indications on a couple things I've read about it for general chemical resistance....

Definitely a weight weenie thing. Even for this customer these are going to be race day only type things, so long term durability for riding through chemical spills isn't as relevant as for someone who wants to ride them daily.

[benb]

I'm curious is your customer riding races where the weight limits on bikes don't come into effect?

When I raced I never could have afforded a bike that weighed the UCI limit, much less one that would have broken the limit. But in the amateur levels I did no one was ever inspecting bikes at all, except maybe looking for illegal handlebar configurations.

It's just if you are going to this degree to save weight off the bike is it only necessary if you're trying to reduce weight below the limits since we repeatedly read about top level CF frames having to be ballasted to meet the weight limits?

I guess another question would be... maybe it's hard to break a spoke on these but if you manage to, how many does it take before the wheel fails catastrophically enough to cause a season ending crash? How do these deal with the rim cracking at the nipples?

[pasadena]

These remind me of the Spinergy PBO spokes. I had a few sets of those wheels.

I have to imagine the aero drag on these is huge compared to a conventional bladed 20 spoke front/24 rear.

maybe on the rear, it would help with weight but not affect aero as much.

Interesting concept. I checked my calendar because I thought this was an elaborate April fools joke at first!

[Tickdoc]

is it pioneering, or folly?

[cachagua]

Sorry if you mentioned this already, but how do they respond to a tension gauge?

[MaraudingWalrus]

Originally Posted by cachagua

Sorry if you mentioned this already, but how do they respond to a tension gauge?

Not sure that I mentioned. Berd gave me a target range of corresponding readings on specific tension meters.

[Mark McM]

Originally Posted by benb

How different is this than the Mavic wheels which seemed great but blew up and caused serious injuries?

If you are referring to the Mavic R-Sys wheels, the Berd spokes are very different. The Mavic spokes were made out of a brittle material (carbon fiber) and the wheel was designed so the spokes were loaded in compression. Berd polymer spokes are not brittle, nor are they loaded in compression.

I don't think there is inherently anything wrong with polymer spokes, but I think there may be some practical aspects that may make the wheel a bit harder to build and maintain, and may also introduce new points of failure (for example, the bond between the fibers and the threaded metal end).

[MaraudingWalrus]

Originally Posted by Mark McM

here may be some practical aspects that may make the wheel a bit harder to build

and may also introduce new points of failure (for example, the bond between the fibers and the threaded metal end).

I can attest, certainly harder to build.

Ric @Wheelfanatyk expressed concerns about the bond between the fiber and the treaded end. This is also my concern with their longterm survival. No idea how that will hold up.