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

(Example: Books)

In-Reply-To: <ab11edd00904060956j6543f2ecx7e7c333a6f50cfc3@mail.gmail.com>
References:
Date: Mon, 6 Apr 2009 13:18:01 -0400
From: "Adam Hammond" <anhammond@gmail.com>
To: CR discussion list <Classicrendezvous@bikelist.org>
Subject: Re: [CR] BBs for TA Pro 5 Vis cranksarms: old vs. new, symmetrical or not, taper styles


Apologies for missing the proper signoff (a danger of cross-posting!)

Also: a listmember has informed me that the new TA Pro 5 Vis arms and Axix BBs are indeed ISO tapered. He heard this directly from TA.

Adam Hammond Toronto, ON, Canada

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