At 12:26 -0700 08.22.2006, Jerome & Elizabeth Moos wrote:
> I'm wondering if the Randonneur rings were designed to bolt to the
>three-arm steel threaded cranks, using the standard "single"
>chainring bolts. Then if one desired a second chainring, one could
>bolt it inside the first, using more modern bolt and sleeve
>attachment, and the remaining three holes. The inner ring could be
>either 6-hole or 3-hole. Of course one might ask, why not just
>manufacture longer bolts threaded to match the steel three-arm
>cranks, so that both rings could be secured by only one set of
>bolts. But in that case one needed only three holes, not six.
>
> Still it seems quite a coincidence that the Randonneur circle was
>116 BCD, same as the old three-arm cranks. So perhaps it was a
>matter of designing an inner ring for the TA "Cyclotourist" type
>cranks, but choosing a circle which also allowed the rings to be
>used on three-arm cranks.
from what i know of the 116mm 6-bolt "randonneur" pattern produced by
ta, this was not the intent. they were manufactured for mounting on
to "randonneur" pattern adapteurs, or to outer chainwheels drilled
for "randonneur" inners, which bolted to any standard 50mm bcd 5-bolt
crankarm, which was a standard at the time. chainwheels in this
pattern were produced by ta prior to its introduction of crankarms in
~1959 (see http://www.blackbirdsf.org/
the intention of the "randonneur" pattern, as i understand it, was to
provide a wider range of gearing in tas 6-arm chainwheel pattern -
wider than the "criterium" pattern intended for racing, and the
"cyclotouriste" pattern intended for touring - say, for randonneurs,
who commonly needed a wider range of gears, but who also commonly ran
double chainwheels rather than triples. perhaps they were thinking
also that there would be less flex in your lower gears with smaller
arms on those chainwheels.
> This raises the question of the sequence of introduction of the
>various "Cyclotourist" type TA cranks, by which I mean those with a
>5-pin outer ring, with inner rings attached to the outer. There has
>been a trend from WWII to the present of (more or less) steadily
>decreasing bolt circles. Did TA first offer the Criterium chainring
>set with 151 BCD (I think) inner, like old Campy Record? Then did
>they next introduce the Randonneur chainring set, retaining the
>6-hole pattern, but dropping the BCD to 116 to allow rings as small
>as 36T (actually 35T I think)? Then finally (as far as on topic
>discussion is concerned) did they introduce the Cyclotourist with 80
>BCD inner rings, allowing really small rings?
as far as i know, the 3 patterns (randonneur 116mm bcd, criterium
151mm bcd, and cyclotouriste 80mm bcd) were introduced
simultaneously, at the inception of the company in 1947, or shortly
thereafter.
> To confuse things even further, I seem to recall that one of those
>odd 116 BCD 6-hole rings that started me wondering about this was
>actually not marked TA, but rather Stronglight or perhaps Simplex.
>Anyone know of other manufacturers who produced the Randonneur
>pattern?
not that i know of - but ta chainwheel patterns were licensed to magistroni at one point... ive never seen anything but ta chainwheels in the 6-arm 116mm bcd randonneur pattern, though.
-joel
--
joel metz : magpie@blackbirdsf.org : http://www.blackbirdsf.org/
portland, oregon
==
i know what innocence looks like - and it wasn't there,
after she got that bicycle...