Re: [CR] BBs for TA Pro 5 Vis cranksarms: old vs. new, symmetrical or not, taper styles

(Example: Component Manufacturers:Campagnolo)

Date: Fri, 10 Apr 2009 14:06:33 -0700
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
To: Adam Hammond <anhammond@gmail.com>, Harry Travis <travis.harry@gmail.com>
In-Reply-To: <58dbc8400904072300o61354a37yaea1e78479788259@mail.gmail.com>
Cc: CR discussion list <Classicrendezvous@bikelist.org>
Subject: Re: [CR] BBs for TA Pro 5 Vis cranksarms: old vs. new, symmetrical or not, taper styles


The older Sutherland's editions discuss this problem. They say all significant brands of alloy cotterless cranks that used a "normal" crank axle with female threads had a 2 deg taper which is what ISO now is. The difference was the length of the taper and the width of the taper at its end. When you think about it for a moment, you realize axle tapers of greatly different widths can still have the same taper angle.

According to Sutherland's 3rd (1980) and 5th (1990) Editions, when TA crank arms were used on "many" axles, which they imply included the Campy axles of the time, the crank bolt could bottom out on the axle end before adequately tighening the crank. In this situation it was also possible to snap off the bolt head if one persisted in applying excessive force. Sutherland's says TA cranks worked well with TA, Stronglight or Phil Wood axles or with JIS axles which they called "Maxy type". A drawing in the 1990 Edition shows where the two ends of the tapers of various axles incliding an ISO axle would be positioned when inserted into the same crank. No brand shown matches ISO exactly. So I think the answer to the question as to whether Campy axles were ISO is no, but neither was any other brand. As with many items, the ISO axle specification seems to have been drawn to split the difference among the most widely used brands so as to be backward compatible with as many as possible.

Regards,

Jerry Moos
Big Spring, Texas, USA


--- On Wed, 4/8/09, Harry Travis wrote:


> From: Harry Travis <travis.harry@gmail.com>
> Subject: Re: [CR] BBs for TA Pro 5 Vis cranksarms: old vs. new, symmetrical or not, taper styles
> To: "Adam Hammond" <anhammond@gmail.com>
> Cc: "CR discussion list" <Classicrendezvous@bikelist.org>
> Date: Wednesday, April 8, 2009, 1:00 AM
> Check with Peter White. ISTR him reporting on his bicycle
> lifestyle list
> that he was confounded by unreported changes in TA cranks
> or spindles within
> production runs, but I don't recall the models. Even if
> Peter is not the
> importer, he is a major and long time seller of TA in the
> US.
>
> Harry Travis
> Washington DC
> USA
>
> On Mon, Apr 6, 2009 at 12:56 PM, Adam Hammond
> <anhammond@gmail.com> wrote:
>
> > I posted this to the BOB list this morning, but
> thought CR people might be
> > even keener at spotting the differences or
> similarities between the on- and
> > off-topic TA cranks.
> >
> > Here is my question:
> >
> > I have in my possession one of the newer TA Pro 5 vis
> cranksets -- produced
> > in 2007. I also have a TA Axix BB, which is from the
> same year. The BB is
> > 116mm wide, which I have always heard is the correct
> width for TA doubles.
> > This BB is completely symmetric.
> >
> > I ran this setup on Fuji touring bike for a few months
> last year to test it
> > out, and everything seemed in order. There wasn't
> much crankarm clearance
> > on
> > either chainstay (I was using a 135mm rear end and
> fairly beefy
> > chainstays),
> > but things seemed more or less centred.
> >
> > I was testing it for the still-forthcoming custom
> frame I expect to arrive
> > in a few months. In the meantime I've become
> interested in this question of
> > symmetricalness. For it seems TA's older bottom
> brackets for Pro 5 Vis
> > doubles were not symmetrical.
> >
> > Piece of evidence number one: this chart from Sheldon
> Brown's website:
> >
> >
> http://www.sheldonbrown.com/harris/images/ta-bb-axles.gif
> >
> > This suggests that the BB should be offset VERY
> slightly (1.5mm) toward the
> > drive side.
> >
> > And this photo of a TA 344 axle (the very one
> specified for TA doubles in
> > the above diagram) seems to show an even more
> significant driveside offset,
> > though it is the same length as my symmetrical Axix
> BB: 116mm. (It may be
> > .5
> > longer...)
> >
> >
> >
> http://picasaweb.google.ca/olivier.alonzo/Alcyon?feat=embedwebsite#5311728504161556194
> >
> > My question basically is: did TA change their cranks
> for the newer
> > production runs to make them work with symmetrical BBs
> when they used to be
> > designed for asymmetrical? If I were to have mounted
> my TA cranks onto the
> > aforementioned Fuji touring bike with one of the TA
> 344 axles, I would have
> > had one crankarm 8mm out from the chainstay, and the
> other smacking
> > straight
> > into it.
> >
> > To throw a final crankarm into the spokes: I have
> heard various rumours
> > that
> > the new TA production is designed for JIS spindles
> (and that the Axix BBs
> > use JIS spindles) -- would this explain all the
> confusion?
> >
> > Confused,
> >
> > Adam
> >
> >
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> >
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> >
>
>
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