I’ve seen examples of Kooka’s with multiple drillings, and I started thinking about if there were any cranks around that could be “dual holed.”
I am interested in a pair of cotterless cranks for a road/very light XC uni. I already have a UDC CrMo hub, and for what I intend it doesn’t seem necessary to go with ISIS. Except that I like the idea of dual hole cranks.
The photo’s of the Nimbus Venture cranks look like they might have some room to drill a second set of holes, or the Pro-Wheel 150’s maybe.
I saw that PDC had a machinist do the work on the Kooka’s, and it looked really nice. If such a high quality finish wasn’t that important what would the process be for doing a job like this in the garage?
What I’m imagining is a jig that screws into the existing pedal threads, and has a clamp that centers the drill guide on the crank arm in the same way that a doweling jig works. There would be a pin that threads into each crank which indexes the drilling guide so that the distance from the original hole would be consistant on both cranks. Then the drilling itself would be done slowly with a hand drill, and plenty of cutting oil.
The trick then would be tapping the new holes. I am going to check with my LBS to see if I could use their crank taps, or what they would charge to do the tapping for me.
Back when I was working in a shop we occasionally had to drill out stripped cranks, and put Helicoils in. The tapping phase of this project should be about the same as that.