Dave,
I recall from a similar discussion on another forum that the transition in the PX-10 design was in the 1976/1977 time frame. But I have a 1968 or 1969 PX-10, and while it is laid back, it's not as laid back as the Gitane you mention or my early '70s UO-8 (cheaper Peugeot at the start of the Bike Boom).
Model, seat tube c-c, top tube, chainstay, wheelbase, seat tube angle, head tube angle, offset, trail, BB drop 1968/9 PX-10: 52, 54.5, 42, 100, 73, 73, 50, 50, 7.2 1970/4 UO-8: 55, 57, 45, 106, 72, 73, 57.5, 42, 7.1 1973 Super Course: 52.5, 56.5, 44.3, 105, 73.3, 72, 50. 54.3, 7.3
Eyeballing the UO-8 and the 1936 picture, I'd guess the geometries are very similar, except the 1936 bike seems to have the head tube slightly laid back compared to my UO-8. Clearly from my measurements the 1968 bike (well, 30 years newer!!) is much closer to what we'd see as a racer, than is the 1936.
Your reference to the International note is interesting. After I read that many moons ago, I started looking for geometry similar to a late '60s Internat, and found the 1973 and earlier Super Course (also a Carlton bike) to be very similar, in terms of rake, angles, and chainstay. However, this couldn't be a true apples to apples comparison, since I couldn't measure an International.
At the Ann Arbor Vintage Bike Show and Swap a few weeks ago, I saw a 1955 East German Diamant racing bike - very similar to the 1936 Peug! If it had been $200 ...
I definitely concur the 1963 geometry is tighter, but I wouldn't make any numerical guesses. It does look like my 1968, proportions/wise. Clearly any bike that can host a frame pump behind the seat tube has a few cm more chainstay than one that cannot!
On Tue, May 11, 2010 at 2:04 PM, Mann, Dave <damann@mitre.org> wrote:
> Short version of the question is this:
>
> Does anybody have access to a pre-war Peugeot racing bike
> and could they document the frame geometry of it?
>
> http://www.peugeotshow.com/
>
>
> The longer version of the question is this:
>
> I'm interested in understanding more about when the classic
> road racing geometry began to emerge and separate itself
> away from the longer wheelbased designs. Many 50 vintage
> British bikes (Mercian, Raleigh) used 73 or 72 parallel
> angles, longer stays in the 6.0cm range and longer stays.
>
> This longer, more relaxed geometry appears to have persisted
> into the 70s being sold as a light tourer, amateur racer,
> semi-pro racer or it would seem among production Gitane
> Tour de Frances.
>
> In the write up on the Raleigh International, the author
> (Ray Chong or Sheldon Brown?) states:
>
> "While the Professional was patterned after the popular Italianate style
> popular in the early '70s, the International harkend back to an earlier ear.
> The International frame was built for comfort, lightness and verastility,
> while the Professional was built for stiffness and maneuverability. The
> Internationals had very generous tire clearanbce (hence the need for the
> long-reach Weinmann calipers) and relaxed angles."
> See: http://www.sheldonbrown.com/
>
> The 1936 Peugeot's I posted a link to are interesting to me
> in that they *appear* to both have the longer, more relaxed
> geometry.
>
> By 1951, it appears that Peugeot was discriminating between
> "sport", "course" (racing) and "course professional" (pro racing).
> http://www.peugeotshow.com/
> Unclear what the geometries are here too.
>
> Again, in 1963, Peugeot makes the distinction between the
> amateur racer and the professional racer and again, it would
> be interesting to know if the professional was starting to
> tighten up and steepen. That rear triangle looks shorter to
> my eyes.
> See: http://www.peugeotshow.com/
>
> In like manner, the Raleigh Professional looks to be a steeper
> shorter layout by 1969.
> http://www.sheldonbrown.com/
>
>
> The real question here is where did the short wheelbase
> racing geometry start and when did it find it's way into
> the mainstream in both British and French production bikes?
>
> NOTE: A Gitane collector submitted specs for the 70s vintage
> TdFs that are definitely pretty stretched out: 72.5 degree
> parallel, 5.5cm of rake and 45cm stays.
>
>
> -Dave Mann, Boston, MA
> -------------------------
> THE BIKE GEOMETRY PROJECT
> A community effort to document and compare bike geometries
> http://home.comcast.net/
> -------------------------
> _______________________________________________
>
--
Ken Freeman
Ann Arbor, MI USA