Gents and Ladies - I have a jig that we made for this about 20 years ago to drill and tap the cranks perfectly to 74 bcd and a few years ago I was able to buy pretty much a lifetime supply of the Avocet (really Ofmega) triple bolts and spacers which is a good thing since the Campy 818 bolt spacers are pretty hard to come by now. I have done this operation a few dozen times including two last month. I like the TA rings for this as they match the quality of Campy, although a bit shinier. I currently use 26-42-47 on one the bike I rode at L'Eroica last year, but started out with 32-42-52 for regular road riding. You have to drill and ream the 8 mm holes in these chainrings to 10 mm but that isn't a big deal to do. There are some rings out there already 10 mm if you can find them. Vuelta is one brand. Either way they need a countersink for the Ofmega bolts to nestle into.
Here is the crank on my bike:
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Bob Freeman Elliott Bay Bicycles 2116 Western Ave Seattle, WA 98121 206-441-8144 Home of Davidson Handbuilt Bicycles
In a message dated 9/19/2008 8:46:11 A.M. Pacific Daylight Time, classicrendezvous-request@bikelist.org writes:
Folks,
I paid $20 or $25 to Ric and Jon Hjertberg at Wheelsmith in Palo Alto during the 1980s for one of their locally-famous Campagnolo NR crank- based "triple conversions." (They then occupied the tiny "shack" next to what was then Sierra Designs' retail outlet on Alma Street.) Because I had previously worked at Avocet/Palo Alto Bicycles, I was familiar with the conversion hardware, at least on my cranks. (There may have been other options available from Wheelsmith (WS), but could not tell you what they were.) I will forward this email to Ric and ask if he would like to shed more light on the subject of the WS triple conversions.
I have also recently checked the threading on the WS-added holes against both local hardware store stock and lots of parts in my miscellaneous boxes to verify the threading.
For that princely sum of $25, Wheelsmith drilled and tapped 6M x 1 holes in a 74 mm BCD pattern all the way through my Campi NR spider arms and supplied a set of Avocet's 6M x 1 inner chainring bolts. I then fitted a 30t Avocet inner ring (any other five-bolt 74 mm BCD ring also works, of course) to my previously-double crank with a longer Phil Wood BB. I managed pretty well dropping from a 41t middle ring (hard to find even then) to a 30t inner with my Campi NR derailleur. I do not remember whether I managed to make my NR RD work on that rig, too, but I think it just barely did.
It seems like you could re-drill and tap an existing triple spider with M5 x .8 holes and make them M6 x 1, if all you can find are the larger Avocet inner ring bolts, which have a rather conical shape to fit against the arms and maintain the correct spacing. My 1974-ish NR cranks have held up fine with the additional holes and the resulting weakening of the arms, and a more modern spider with better metallurgy would most likely do very well with M6 x 1 holes in it, too.
Since Avocet cranks and rings were manufactured (I think) by Ofmega, one might be able to find compatible hardware through Italian sources.
Having lived with a permanently weakened right leg since a 1970 rock climbing accident, I can offer Jerry and others the advice I received 30 years ago: "Don't ignore the advantages of using a triple crank. Take care of your knees--they are the only ones you've got."
(While knee replacements are now commonplace and easily available, the replacements are not as good as the OEM parts, and are very pricey. And you thought that a restored Hetchins with all-NOS Campi Super Record was expensive? :-)
The bonus was this: the very first time I climbed Old La Honda Road-- the site of regular uphill time trials in Woodside--I reached the top at Skyline Boulevard faster than I had ever managed it before, because I was spinning higher pedal RPMs with my new triple gearing. Go get them granny gears!
Jon Spangler (who is now 56, and has enjoyed this trip down memory lane, reminiscing about "back in the day") Alameda, CA USA
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