That's the Special Lightweight tubeset. When brazed up right, these bikes will take a 27.4 seatpost. The wall diameter at the top of the seat tube is .6mm vs. the .7mm used for standard 531DB sets.
That's a great looking bike, it's probably good that it's not my size :-). The geometry looks pretty tight for a bike with cantis...
> First, look at:
> Then click the photo that shows the Reynolds transfer. Can someone
> tell me more about this? I've never seen that color combination
> on a 531 transfer before.
> Interesting bike, btw. The components seem much newer than the
> frame (if the seller's description is accurate).
> cyclist [at] dimensional [dot] com