Water bottle boss placement

[Buzz Killington]

Maybe the lamest question ever..... How do builders decide where to put the bottle bosses on the seat and down tubes. I'm sure (?) they make a jig that determines distances from bottom bracket, but I've seen placements that seem to vary by builder's preference.
-One on seat tube as low as possible, 2nd farther up on down tube.
-One high up on seat tube, and 2nd low on down tube.
-On the same plane (approx), where the closest corners of each bottle almost come in contact ( I hate that way).

I'd think the idea would be to keep the center of gravity as low as possible considering the weight of 2 full bottles. Though maybe reach issues on the largest frames if bottles too low? Space issues on small/compact frames I'm sure factor in too. Derailleur clamp issues?

Anyway, I'd be interested to hear how these placements are determined. Too much time on my hands today.....

[UberBike]

I've seen some frames where it would seem the placement was just where they thought it looked good.
Especially a few smaller frames where 1cm lower on the seat tube and the cage would not interfere with the derailleur and would better fit a normal sized water bottle

[Peter P.]

Choice 1 gives you the lowest center of gravity but for taller riders, those cages may be too far away to reach easily.

Choice 2 I haven't seen.

Choice 3 is aesthetically pleasing.

There are many things to consider such as the aforementioned rider height, and whether the mounting of the seat tube cage will interfere with the front derailleur clamp if one is used. I actually had this happen TWICE with 2 custom frames where the bottle boss was right where the clamp wanted to go. Back the frames went for repair.

Some builders assemble the frame in a jig then position the cages where they want, mark the locations, disassemble the tubes, then drill. Others measure a specific distance from the tube end. I've never seen a jig that locates the bosses on a tube for position, other than the bolt spacing jig.

[BShow]

Well, if you're really concerned bottles inside that front triangle, you could build a CX frame.

I think each builder might have slightly different standards, but hopefully puts some thought into it so that there are not issues with FD clamps, bottles rattling on opposing tubes, or clearance to remove the bottle. Reach, I think would apply only to the tallest of riders.