This is almost certainly 70's vintage. Probably mid to late 70's. By the mid-70's the once top of the line Stronglight 49 and Mafac Racer had been supplanted by newer models on the top bikes, and these older models had been pushed down to less expensive bikes. A 1020 frame in the early 70's or before would probably have had a cottered steel crank. Motobecane did use a lot of Japanese stuff in the 80's, but the rest of the components don't seem to fit with the SunTour derailleurs, so I still think the bike is 70's vintage and you are right about the derailleurs being replaced. I wouldn't feel at all bad about stealing the parts for other projects. The very small outer bolt circle on the Stronglight 49 was very common in the 50's and 60's when the mod 49 was the top Stronglight model, and survived into the 70's and 80's. TA Cyclotourist, Zeus Competition, Some Nervar models, and even Lambert chainrings used this pattern. However, these cranks usually had different bolt circles where the inner chainring bolted to the outer one, so you could switch a pair of rings from one crank to another, but couldn't use an inner of one brand with a different outer. The inner bolt circle of the Stronglight 49 is 122mm, same as the mod 93 and 104. I'd be interested to know what the inner circle of the Nervar rings is. Perhaps 128mm like the Nervar Star?
Regards,
Jerry Moos
Karl P Frantz wrote:
> This isn't bike anyone would consider a classic, I don't think, but it is
> kind of interesting (and French!). It's a rather oridinary Motobecane
> mixte-frame (followed me home from the recycling center), but what caught
> my eye was the Stronglight 49D crank. Some interesting features:
>
> The Mafac Racer brake levers have the half-hoods, and the cable anchors
> ride in J-shaped slots that appear to be intended as a quick-release
> device. One the levers has little plastic knobs on the ends of this
> anchor; the other has lost its knobs. Is this really a quick-release? It
> seems very hard to operate.
>
> The wheels are alloy, with high-flange hubs (unmarked, presume Atom), and
> the Atom QR levers are straight.
>
> The tubing sticker is mostly illegible, but appears to have a four-digit
> number starting with a "1". I bet it's 1020. The sticker assures me that
> applies to the "Tubes, forks, and stays".
>
> What strikes me is the realtively nice wheels, cranks, 460D pedals (I
> think, maybe should recheck those) on a high-tensile frame. The Pivo stem
> is rather crude, and seems more in keeping. Derailleurs are SunTour, so
> you know *that's* been changed.
>
> So... how old might this thing be? Should I feel guilty if I raid it for
> parts? The crank might be fun on my Riv... though I may need rings (I
> have some Nervar rings that would work - how's that for odd).
>
> Oh yeah, one of the stamped emblems on the Pivo bar is driven in really
> deeply. Did these ever break there?
>
> Karl Frantz
> Sterling, Massachusetts
> -------------------------------------
> Karl.Frantz@juno.com
>
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