Originally Posted by
RiddleOfSteel
From what I've ascertained it is because the frame pump went there (along the seat tube). Touring bikes adopted the second bottle cage on the underside of the down tube, which makes sense when one believes the seat tube is for the pump.
Under the down tube never made sense to me for a water bottle: you can't reach it while riding, and too much road debris gets kicked up, even with mudguards. I built my 720 with three cage mounts: down and seat tube cage mounts for water bottles and under the down tube for a Sigg camp stove fuel bottle, so it doesn't have to ride in the panniers with my other belongings and stink them up.
Originally Posted by
polymorphself
That makes enough sense regarding the frame pump.
Under the top tube with a Zefal clamp-on pump peg.
If I swap this to 700c should 32mm and fenders fit fine?
My 720, pictured above, has 27" wheels and plenty of room for mudguards. 700C will give even more room.
N.B. if you have cantilever brakes on your bike, make sure you can lower the pads enough to reach a 700C diameter rim (4mm lower) before you invest in new wheels. I built my 720 for 27" wheels, because back then (1982), 700C wheels and tires could only be found in real bike shops, not the small town hardware stores I'd go through on loaded tours. Now, 700C can be found pretty much any place, including WalMart and small town hardware stores, but I can't lower the brake pads enough to use 700C wheels on that bike.
there is some concern about fully loaded performance with the reports of it being too flexible.
"Too flexible" is a subjective judgement. I haven't found it to be a problem.