I am sorry to say that this is amiss. The distance between bolts (c-c) on threearm cranks is half the bcd times the root of three which is 1.7320508
My 116 mm bcd cranks then have a c-c distance of 100.45894 mm. If I measure them I get 100 mm, near enough. Your distance of 112 would give a bcd of 130 mm which sounds very modern but makes me doubt your measurements.
Sure?
Olof Stroh Uppsala Sweden ----- Original Message ----- From: FujiFish1@aol.com To: classicrendezvous@bikelist.org Cc: teaat4p@yahoo.com ; freesound@comcast.net ; dddd@pacbell.net ; olof@stroh.nu ; jerrymoos@sbcglobal.net Sent: Tuesday, February 22, 2005 8:41 PM Subject: Re: [CR] Measured data, Was Re: Campag 3-arm Crank?
Ok, I have a good handful of misc. 3 spider arm cranks on various bikes, so I went down and took some measurements. Turns out I have 11 different varieties, and 9 of them measure the same! I measured simply from one bolt center to the next, and the 112mm results sound like the 116 BCD that Olaf mentioned (dunno how to measure BCD accurately on an assembled and mounted crank).
(Note: for all my photo names and dating, "~" after the date means "approx.")
1955~ Magistroni with "circus tent" logo - on a Torpado - STEEL 112mm 1959~ Magistroni with Torpado logo engraving - STEEL 112 1961~ Magistroni with "circus tent" logo, from an Olmo Special - STEEL 112 Bike boom, No name, from a Coppi low end - STEEL 112 Bike boom, No name French, from Regina France bike - STEEL 112 Early 70s? Campy w/ French b.b, from a Cilo - STEEL crank/ALUMINUM rings 112 1972~ No name, believed to be Nervar on Italvega - STEEL 112 1974~ TA with black anodized rings, from mix/match Italvega - ALUMINUM 112 1975 Campy G.S. - ALUMINUM 112 1975~ Sugino Maxy, fixed big ring holds 3 bolt sm. ring, on a Sekine - ALUM 93 Late 70s? Shimano 600 on a mix/match 3Rensho Sup.Rec.EXP. - ALUMINUM 83
Sorry to admit Jerry ... no Simplex cranks in the house to compare :(
Anyone know how to convert the above numbers into BCD to confirm the bulk of them are 116s?
Ciao, Mark Agree Southfield MI ~ ~ ~
Date: Tue, 22 Feb 2005 07:04:47 -0500 From: "Ken Freeeman" <freesound@comcast.net> To: <classicrendezvous@bikelist.org> Subject: RE: [CR]Re: Campag 3-arm Crank?
I think these Campy cranks are very similar to an old FB/Magistroni design. They may even have been sourced from Magistroni. I had the FB with a Magistroni BB on my old Rossignoli, and I've seen them in Ebay photos of old Frejus and Legnano race-grade bikes (watching for my size!). I never measured (cared?) about the BCD(s), but mine had three little Y-shaped adapters that bolted the the three spider arms, and then accepted the pair of 6-hole chainwheels. I think my adapters were marked Simplex, and the chainwheels were either Simplex or TA. I'd be very surprised if Campy-marked parts didn't exist at some time.
My bike had a classic half-step pattern, so the chainwheel BCD was not small.
The Magistroni page, accessible from the CR Main website, has some history and pictures. I have seen the adapters on Ebay from time to time.
Ken Freeman Ann Arbor, MI
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Jerome & Elizabeth Moos Sent: Tuesday, February 22, 2005 6:33 AM To: dddd; Classicrendezvous@bikelist.org Subject: Re: [CR]Re: Campag 3-arm Crank?
TA and Nervar made similar three arm cotterless cranks in that era. It's just possible they all had the same BCD, which would make the number of usable rings out there greater.
Regards,
Jerry Moos Houston, TX.
dddd <dddd@pacbell.net> wrote: Richard Cielec wrote:
I have a Campag., alloy, three arm crank, compleat - dumpster find, actually, attached to an Ishiwata tubing Trek. Are rings difficult to find, either Campag or after market? What model is this? The Gran Sports I've seen are 5 arm.
>>> It sounds like an earlier Gran Sport crank, as was fitted to the early-70's Raleigh Competition. I can remember wanting one of those. Chainrings? You've gotta be kidding, tho someone here might have something. Many of these cranks probably have narrow range gearing, so you'd be lucky to turn up a 52-42. Which ring do you need?
David Snyder