As a follow up to the Pivot Mach 429 first rides, here's some updates after putting some miles into it.
First, that bottle cage issue. This frame has so much custom shaping from what would appear to be extensive engineering and design work, and for it's boutique brand price, not having enough millimeters to functionally use a water bottle is a gross oversight. Its just not acceptable. A 750ml bottle straight up doesn't fit. A smaller bottle will fit, but is usable only with one of those side entry style cages. That's exactly the reason things are drawn up in AutoCAD or whatever bike designers use, and is entirely unacceptable for a product of this supposed design spec. If you're a CamelBak'er, no problem. If not, be forewarned.
On to the positives... What continues to impress is the longitudinal stiffness, the smoothness over terrain, the plush without mush feeling. My suspended riding history is Turner (the Horst link designs), Specialized (basically the same 4 bar), Cannondale (soft tail) mostly. Each have their pros and cons. Suspension performance wise, this beats all. Same with longitudinal rigidity. Weight wise, partly due to it being stiffer with bigger wheels so there needs to be more material to keep it stiff and reach back to the hub, it gives some up. The three settings of the Fox forks/shocks are not unique to this frame, but this frame uses them well. They transform the bike from taught climber to plush downhiller, within the confines of what 4" of travel and 29er wheels can do. The 2.25" Nobby Nic I've elected for up front is consistent with the performance of the suspension - feels not under or over the capability of the rest of the bike in delivering traction.
Beautiful bike if you understand the water bottle issue.
Addendum: so I was actually challenged on this claim, without providing pictures. Here's the pics. Note this is a Specialized side entry style cage, and I have jerry rigged it by a few millimeters. I'm now reasonably happy, one of those mid size bottles (two actually if you use the lower cages and swap them) makes using this for long rides or stage races actually feasible. So if you're willing to do so, you can attain an adequate result. Three test bottles. Small, medium, large.
Fit of small is fine.
Fit of medium is just possible down to the nanometer, by jerry rigging the mount by drilling out the cage a bit. Keep in mind, you're going to be retrieving/replacing bottles while riding, and presumably not smooth trails with this bike. Now possible, even adequate, but not ideal.
Large doesn't fit. Photo doesn't really show depth well, but essentially this bottle is protruding to the right of center by a couple inches as obviously its bumping up against the shock adjuster.
Lastly, I've now just tried to supplement with the lower bottle mount this morning. Only a small even fits to start, but the small is within the front wheel travel path, so that is entirely and completely useless. Pivot guys what on earth were you thinking?