Re: [CR]Question on 1970's Campagnolo Triple cranks

(Example: Production Builders)

Date: Fri, 30 Nov 2001 14:38:25 +1300
From: "David Benson" <tech@worrall.co.nz>
To: cnighbor <cnighbor@pacbell.net>
Cc: "classicrendezvous@bikelist.org" <classicrendezvous@bikelist.org>, OROBOYZ@aol.com
Subject: Re: [CR]Question on 1970's Campagnolo Triple cranks
References: <d.1e1d93f3.29381850@aol.com> <3C06DBFB.436F43F1@pacbell.net>


According to Sutherlands handbook for Bicycle Mechanics, the bcd for the Campagnolo Triple inner chainwwheel is 100mm. DB Ak, NZ

cnighbor wrote:
> http://www.rivendellbicycles.com/webalog/cranks_bbs_c-rings/12095.html
> Then count me in. Would Willow chain ring maker make one. Looking at my triple
> it seems 32 would work as there is plenty of metal below teeth. Also what is
> the bolt to bolt dimension I know it is not 94. Maybe 96
>
> Cranks 101
>
> In England they're called "chainsets." In the U.S.,
> "crank" and
> "crankset" usually refers to the crank arms and
> assembled
> chain rings.
>
> Most decent cranks are made of aluminum, although some
> are steel, some are titanium, and at least one is
> carbon fiber.
>
> Aluminum cranks can be machined (carved), forged
> (smashed), or cast (poured into a mold).
>
> Cranks are usually differentiated two ways: 1. By bolt
> circle
> diameter (bcd), and 2. By length.
>
> 1. Bolt-circle diameter.
>
> Chainrings attach to right-side cranks by chainring
> bolts, so
> the chainring bolt holes in the chainring have to match
> up to
> the corresponding holes in the crank. If you draw a
> circle
> through the centers of all the holes and measure the
> diameter
> of that circle, thatâs the bolt circle diameter (bcd).
> The
> smaller the BCD, the smaller the chainring that'll fit
> on it.
> Here is a list of common BCDs from the past and
> present,
> and their respective minimum-sized chainrings:
>
> BCD
> Minimum chainring
> 144
> 41
> 130
> 38
> 110
> 34
> 96
> 28
> 74
> 24
> 58
> 20
>
> Most road cranks designed for two chainrings have BCDs
> of
> 130mm. A 50-tooth chainring designed for such a crank
> is
> designated thusly: 130 x 50t. Etc.
>
> Campagnolo is the odd duck here, with BCD of 135mm.
>
> Good manners suggests that manufacturers make their
> cranks (of a type, say road doubles, or whatever) to
> the
> same standard as everybody else. That way, you the
> rider
> can change chainrings and have a great selection (from
> many
> makers) to choose from.But manufacturers sometimes have
>
> bad manners, and make up their own, unique BCD so if
> you
> buy their crank, you‰ll also have to buy their
> chainrings,
> which are generally more expensive. Eventually a
> specialty
> chainring maker will see a market and make a
> lower-priced
> odd-BCD chainring, but it‰s still a mean thing to do in
> the
> first place. Standards do change over the years, and a
> manufacturer can build to its unique standard by saying
> the
> others should switch, or that theirs is better, or
> whatever. We
> don‰t buy it.
>
> Road cranks designed for three chainrings (called "road
>
> triples") have a secondary BCD to accommodate a smaller
>
> ring for an easier gear. This type of crank will have a
> BCD
> specification something like: 130 x 74, indicating it
> fits outer
> and middle chainrings with a 130mm BCD, and an inner
> chainring with a 74mm bcd. A common chainring
> combination for such a crank is 50t (outer) x 40t
> (middle) x
> 30t (inner); although that is one of many possible
> combinations.
>
> Mountain bikes cranks have BCD of either 110 x 74, or
> 94
> x 58.
>
> There is absolutely no reason why you can't use a
> mountain
> bike crank on a road bike, and one advantage in doing
> so is
> that you can use a middle ring smaller than 38t (which
> is the
> smallest you can use with a normal 130mm bcd road
> crank).
> So, you can set up your bike with a 50 x 34 double
> chainrings, or 46 x 36 x 24 triple chainrings÷or many
> other
> combinations not possible with the road-standard 130mm
> bcd. But as a rule, cranks specifically designed for
> mountain
> bike use tend to have higher Q-factors (wider between
> the
> pedals) than road-specific cranks. There are
> exceptions,
> though.
>
> 2. By their length.
>
> In the old days, you could find cranks between 150mm
> and
> 185mm in length, often in 2.5cm increments. Even as
> recently
> as the early ë80s, any crank maker was expected to
> offer
> 165, 170, 172.5, and 175. But since then, and perhaps
> influence by the trend away from a road-dominated
> market
> to a mountain-bike dominant one, cranks outside the 170
> to
> 180 range are hard to impossible to find, and many
> makers
> offer only 170s and 175s.
>
> Conventional wisdom says shorter cranks are easier to
> turn
> quickly (spin), and longer cranks offer more leverage,
> which
> is better for climbing hills and pushing big gears.
> And, that
> short-legged riders should pedal shorter cranks.
>
> All we will add to that is the warning that riders of
> average
> height and leg length will adapt quickly enough to any
> length
> between 170 and 175; and that even experienced riders
> would be nervous if their life depended on being able
> to tell a
> 2.5mm difference in crank length; and that knee experts
>
> generally agree that shorter cranks, in some cases, may
> be
> easier on your knees.
>
> Q-Factor. Yes, Q-Factor
>
> Itâs the distance between the pedals at the outside of
> the
> cranks. In other words, it's how far apart the cranks
> put your
> feet. Are you walking a tightrope, or giving birth?
> Pedaling a
> bicycle or walking like a duck? That's Q
> (quack)-Factor.
>
> At the turn of the century, this crank dimension was
> called
> "tread," a term still adhered to by some. We call it
> Q-Factor
> because when "tread" was in vogue, tires were all
> smooth,
> and "tread" couldn't possibly have referred to the
> rubber
> pattern. But these days, "tread" means rubber pattern,
> so the
> discussion can't begin until you dig out of that hole.
>
> In any case, Q varies from about 135 to 180, with most
> good road double cranks hovering around 140mm, and most
>
> mountain bike cranks around 173mm.
>
> With the exception of Ritchey, crank makers do not list
> Q.
> Most make high-Q cranks, and would prefer that you not
> ask. There can be no arguing that a lower Q improves
> aerodynamics, but a far more compelling and practical
> reason for attending to your crank's Q is...how it
> feels.
>
> Some riders are not sensitive to it at all. Others have
>
> physiological quirks that make them better off with
> their feet
> closer together (low-Q) or farther apart (high-Q)
> cranks. In
> general, road riders accustomed to the superb, low-Q
> professional grade Campy, Zeus, TA, and Stronglight
> cranks
> have a harder time adapting to modern cranks with
> higher
> Qs. They often hate them, and don't even realize what
> it is
> until somebody suggests the Q. On the other hand,
> riders
> raised on higher Q cranks often think the whole issue
> is silly,
> because they can't tell any difference.
>
> If you're used to a low Q crank and you pedal a bike
> with a
> high Q, it's possible that you'll experience pain on
> the inside
> of your knees.
>
> © Rivendell Bicycle Works 2000
>
> OROBOYZ@aol.com wrote:
>
> > In a message dated 11/29/2001 2:33:53 PM Eastern Standard Time,
> > cnighbor@pacbell.net writes:
> >
> > << Where is source and do they fit. >>
> >
> > We are talking about maybe a group of us getting custom chain rings made in
> > the UK by Highpath Engineering:
> > http://www.argonet.co.uk/highpath/cycle.htm
> >
> > Dale Brown
> > cycles de ORO, Inc.
> > 1410 Mill Street
> > Greensboro, NC 27408
> > 336-274-5959
> > fax 336-274-6360
> > http://www.cyclesdeoro.com
> > http://www.classicrendezvous.com