I've advertised this service on CR but never explained the way we do it. We have a tool that we made about 20 years ago that does this a little more accurately and simply perhaps. It is a flat plat with pilots that fit in the bolt holes of the crankarm, a bolt to go through the center to hold the arm flat against the plate, and hardened drill guides to line up the drill to make the holes square and in the right place in the arms. One of the drill guides is a tap guide and we have a tap that goes in to tap them square. You have to move the crank around the circle once when drilling, and four times when tapping, but the end result is a perfectly drilled and tapped crank arm. After tapping I use a countersink tool to relieve the burr left from drilling on the back side of the arm. I have pretty much a lifetime supply of Ofmega bolts to bolt up any 74 bcd chainring to the arm. Some chainrings have bolt hole the size of the threaded part of the bolt, and you need to ream these to the size of the shoulder of the bolt for it to fit flush. I'll take pics if anyone cares to see it. Not easy to make, probably a $400 job from a machinist these days.
Bob Freeman Seattle
In a message dated 2/28/04 2:23:24 AM Pacific Standard Time,
> Date: Fri, 27 Feb 2004 18:26:16 -0800
> From: "Jim Langley" <email@example.com>
> To: <firstname.lastname@example.org>
> Subject: [CR]RE: Campy Triple tool final comment
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> Some of you asked for more information about the Campy Triple conversion
> tool so I've posted a photo of it on my website, here:
> And, because mine sold, some people asked if any more are available. I
> managed to track down Johnny Thess, who sold this tool to me when I worked
> at the Bicycle Center in Santa Cruz in 1983. He told me the history of the
> He was involved in the bicycle business in Southern California in the early
> 80s and he and Ross Shaffer of Salsa fame realized that there was a need for
> reliable triple cranksets for mountain bikes. This coincided with a trend at
> the time of removing Campys and installing Shimanos, which resulted in a
> glut of available Nuovo Record cranks.
> Johnny and Ross approached machinist Greg Reavis to make a tool to
> professionally convert the Nuovo Record double to a triple, and he made the
> tools. Johnny then went on the road selling them to bicycle shops. He
> believes there are still tools in shops that you should be able to find with
> a little searching.
> Jim Langley
> Santa Cruz, CA