I believe the allen-head bold threaded into that brazeon serves to clamp the seatpost. The frame seems to lack a conventional seatpost clamp arrangement behind the seatlug. I think I've seen this arrangement before on mid-low end French bikes from the mid 80's and something similar on Japanese aero-tubed frames of the same era.
Regards,
Jerry Moos
Houston, TX
> What is the purpose of the small brazed on boss on the top back of the
seat
> tube on this Peugeot that is currently on eBay?
>
>
http://ebay.com/
>
> Thanks in advance,
>
> Eric Elman
> Somers, CT