Hey Folks. An update on The Strongest Coker Wheel in the World.
I’ve been able to increase the average tension in the spokes by another 60%, to about 175 kg. This leads to significant spoke wind-up issues during truing but also results in a stronger wheel. I’m almost at the limit of the spoke wrench / spoke nipple interface so that’s probably it for spoke tension. Working with even higher tension would mean ruining the nipple surfaces. I’m sure that the rim could handle more, though.
The higher tension also appears to have made the wheel significantly stiffer. All my brake rubbing issues have gone away, even though I am using just the stock Coker frame. With the lower tension, I was still having problems with the brake pads rubbing the wheel on torquing ascents and on idling. Those problems are now gone. It appears as though brake and frame rubbing issues are primarily due to wheel flex. Before increasing the wheel tension, I couldn’t tell if it was the wheel or the frame. I don’t know yet if a narrower hub with everything else the same would be as stiff, but I doubt it, since the brace angle is at work here too.
I have also been able to improve the braking surface by filing and sanding the rim weld. Although the manufacturer grinds the weld, it is still a braking problem because they do not finish off the weld that finely. In addition, some of the Airfoil rims are not suitable for braking because the join is too misaligned. The rim is still extremely strong, but if you are planning on using a brake be sure to inspect your Airfoil rim weld before you build it into a wheel. I put a picture in the Gallery of the improved braking surface in the weld area (link is above).
We haven’t repeated the 3-person test with the higher tension, but we have been able to add a couple of drops: approximately 24" and 27", and a long side-hopping descent of a set of stairs. Brave David Kaplan of the Unatics was the test pilot of those tests, which can be seen in the Gallery with the other photos. David is about 145 lbs, an intrepid trials rider, and a skilled juggler. We are hoping to do some higher drops soon.
Tom Miller of The Unicycle Factory has produced some fine wider hubs to supplement the GB wide hub that was used in this wheel. So if you are looking for a wide hub you’re not up a creek while the GB hubs are out of stock. They are more expensive, though. I have a picture in the Gallery.
In the Gallery you can also see Bill Ryan of the Unatics zooming around on the Coker while juggling 3 clubs.
Thanks to all the testers, and especially to Dave Kaplan for being the test pilot!