Bikerumor has a nice new update on Ted's crank: http://www.bikerumor.com/2012/12/21/cia ... more-53011
We’ve posted a ton on these recently, and I started this as a mere update to the post earlier this week. But, the more I spoke with Ted, the more info came out and, well, here we are with lots of great details on the construction of his Gravitas cranks.
First off, they’re shipping. The first few units have mailed to some of his long-standing customers, and more will trickle out each week until they’re up to full speed. Orders placed now will likely ship in five or six weeks. Second, given the overriding theme among the comments, I asked directly about the stiffness of the design and why use carbon tubes. Here’s Ted’s response:
“We’re shooting for a sub-400g crankset that’s as stiff as or stiffer than Dura-Ace. The tubes are made by a company that specializes in hi-mod carbon tubes. We started this process by reverse engineering other cranks on the market, and this three-tube design can be made stiffer. The engineer designed these tubes to be 1.5x as stiff as the Rotor cranks, and the end result is slightly less than 1.5x because of the alloy parts interface. But, all we have to do is slightly increase the wall thickness and/or diameter of the tubes and we can make this the stiffest crank on the market without adding any weight. I wanted to have the lightest component in that arena without compromise.”
Read on to see how it all comes together, and get a promo code to enter to win a set of these and his brakes!
The Gravitas crankset's pins can be anodized or powdercoated in a variety of custom colors.
A two part process connects the carbon tubes and alloy ends. First, they’re bonded together. The bonding agent fills in any gaps, providing a solid connection. Then holes are bored through both the alloy parts and carbon tubes, and pins (blue in the top pic) are threaded together inside the holes. It’s called PTS for Pinned Tube System. These both lock the carbon tubes in place and prevent them from rotating.
The other side of the story is customization. This design lets them very easily make custom lengths and Q-factors without needing a ton of size-specific tooling. To get the exact length a rider needs/wants, they simply cut the tubes accordingly. Depending on the frame’s BB width, they have a range of spindle widths they can use, too, with spacers taking up any slack. A narrower 68mm BB shell would give you a wider range of customization than an 86mm one, of course.
They can also change the spider’s mounting width to tweak the spacing between chainrings to accommodate different rings in both 10- and 11-speed. The spider is interchangeable, letting you run standard or compact with the same arms.
Several spindle options will be offered to accommodate all modern bottom bracket sizes, BB30 first. A 24mm BSA spindle should be available in a couple weeks, which is likely to be a bit heavier because the spindle’s wall thickness will have to increase.