Comments on: A few more Taipei Cycle links

By: art

art — Wed, 21 Mar 2012 14:19:22 +0000

I’m not sure what you mean by this. Aramid fibers have an elastic modulus that’s a bit lower than steel, so I wouldn’t say that they “don’t stretch as much”. Perhaps you’re suggesting that you can make a stiffer spoke at the same weight because the density is a fifth as much? It’s true, but in this case the minimal weight savings will be offset by poor aerodynamics. (Bladed unidirectional carbon spokes, like used on Lightweights, are a different story)

As far as “stretch over time”, polymers a generally susceptible to some degree of room temperature creep, whereas steel is not. I haven’t seen any numbers for creep magnitudes or time constants for these spokes, but I wouldn’t expect much of a problem.

By: Nick F

Nick F — Sun, 18 Mar 2012 02:39:07 +0000

I love that cord-spoked wheel – I don’t know how I missed that at the show.

It’s like they built a wheel using entirely FiberSpoke repair kits!

http://www.bicycletouring101.com/getimage.php?w=800&o=no&i=JamieSpokeRepairKit.jpg

I too am a little skeptical about the long-term stiffness of that wheel due to the knots and the braids… but you’ve got to admit it has a wonderful (if slightly goofy) simplicity.

By: James Thomas

James Thomas — Fri, 16 Mar 2012 20:45:27 +0000

Hey Mike, Maybe stiff was the wrong word, but I hope it was clear that I was referring to the wheel as a whole. I have built enough wheels to understand that spokes are under tension rather than compression. My concern about these has more to do with the construction (the knots at the hub flanges) than the material itself. Interesting point about composite fibers not stretching as much as steel though. By the way, when I first saw this it made me think of the old Kevlar web Tioga Disk Drive wheel. I never had a chance to mess with one of those, but they definitely fascinanted me when they first came out.

By: Mosen

Mosen — Fri, 16 Mar 2012 20:10:04 +0000

Would love to see the other end of cord-spoke and the way they adjust it…

By: Mike

Mike — Fri, 16 Mar 2012 20:09:47 +0000

I like the Microfibre cord spokes, it reminds me of some of the kevlar / carbon systems used on high end wheels.

You should understand that spokes are strictly tension members, so when you ask about stiffness, it’s all about proper tension and then do the spokes stretch over time. In this regard, many flexible fibers and composites are BETTER than steel, as they do not stretch as much, providing a stiffer wheel.