RE: [CR] TA Triple

(Example: Framebuilders:Tony Beek)

From: "Bob Hanson" <theonetrueBob@webtv.net>
Date: Sun, 1 Oct 2006 23:23:26 -0600
To: mhoffman0@snet.net, mike@bikespecialties.com, magpie@blackbirdsf.org, classicrendezvous@bikelist.org
Subject: RE: [CR] TA Triple


Mark Hoffman wrote:

While browsing ebay for stuff TA, I came across a triple crankset. I did a double-take, thinking I saw 4 rings, rather than 3. Now I have seen a quad TA franken crank, but this was a web connecting the "spokes" of the inner chainring. All my TA triples lack this webbing. Is this something atypical? I imagine it might stiffen-up the chainset a bit.

ebay item:130032261374

Mark Hoffman New Britain, CT USA

-------------------------- Mark,

I don't know if that was a "common" option or alternate style, but I do have one inner ring (42t) which has not only the secondary support band but also has wider arms arms (18 mm. versus 13 mm.) than is found on most. If you look carefully at the auction photo, this appears to be the case with that middle ring, as well.

I would say it definitely makes for an altogether stiffer chainring set. I think one of the concerns with this small BCD crank style, with no massive rigid Spider forged directly to the crank arm, was that the rings could tend to flex a bit - especially under torque, and particularly with a chain on the extreme inner cogs of wider (say, 7-spd) freewheels. They'd never break, but they could gradually bend slightly off of from their original perfectly flat plane.

I have noticed that this was especially true of some larger middle rings I have seen (as used with half-step gearing) since they were only supported by the narrow dural arms reaching all the way out to perhaps 48 or 49 teeth from the 80 mm. bolt circle.

I'm actually curious too whether these more massive chainrings were perhaps intended for a specific style of bike. I have only two rings with the 18mm wide arms; the 42t which I already mentioned, and also an outer ring (also for the 80mm BCD) which is a huge 60 tooth ring. That monster chainring also happens to have a much earlier TA logo - so the wider chainring arms would not have been simply a later development.

I wonder if these rings were ever used on motor powered bicycles or even mopeds? Perhaps Joel Metz or another List Member has observed such a set-up during their travels in France?

Bob Hanson, now, like Alice in Wonderland, "curiouser and curiouser" in Albuquerque, New Mexico USA