Re: [CR]re: TA triples


Date: Mon, 2 Oct 2006 08:11:08 -0700 (PDT)
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
Subject: Re: [CR]re: TA triples
To: john@os2.dhs.org, classicrendezvous@bikelist.org
In-Reply-To: <45212324.6050004@new.rr.com>


In fact, the Cyclotourist arms supported a wide variety of ring setups, single, double and triple. In addition to the 80 mm Cyclotourist inner circle there was the 116 mm Randonneur circle and the 152 mm Criterium circle. The potential for warping the inner/middle ring is highest when one uses a ralatively large ring with the 80 mm circle. But it can be argued that TA did not intend customers to use such a setup on a double, but assumed those using larger inner rings would use the Randonneur or Criterium setup. Of course a triple will usually have a relatively large 80 mm middle ring, so this may be a real weakness in the Cyclotourist design. But perhaps TA did not anticipate triple users really hammering on the middle ring - don't think the concept of a "racing triple" had occured to anyone when these cranks were designed.

I have a now 30 year old photo book with a picture of the great Beryl Burton hammering along on a TA Criterium setup on a Jacques Anquetil bike. Beryl probably applied more pedal force than most any CR member, male or female, and evidently she found the TA cranks quite adequate.

Regards,

Jerry Moos Big Spring, Republica de Tejas

John Thompson <JohnThompson@new.rr.com> wrote: sachshm@cox.net wrote:


> First, let me agree strongly that the TA "cyclotourist" units had
> design defects. The business of 6 spindly arms supporting a large
> chainring can be best described as "nuts."

If you had it set up as a triple, those "six spindly arms" would have to support all three rings!
> My touring bike of the era had such an arrangement, and the middle
> cog warped backwards substantially, while remaining nicely in plane.

I've never had that problem, but I'm much more a spinner than a masher. As evidenced by the 45-49T large rings on my bikes -- I found I never used the higher gears so I got rid of them.
> For the next set-up, I installed a supplementary ring of machine
> screws and spacers, at the radius used for one of TA's other styles.
> I used flat-head machine screws, head outside, and the slight nub of
> the 1/2" screws that stuck out to the inside was easily filed off.
> Never had a warp again - but maybe I was getting older and weaker.

Some of the larger TA outer rings were double-drilled to allow bolts both at the smaller Cyclotouriste attachment point (accommodating rings down to 26T) and the larger Criterium (44T minimum) attachment point. You'd have double the bracing on each arm, at least for inner rings >44T.

--

-John Thompson (john@os2.dhs.org)
Appleton WI USA