Contact Devin at Lenzsport, he's building Fatillacs and Behemoths as ebikes. These are very capable bikes, short chainstays, compact, not heavy, but expect to pay 3k for a frame plus e system. He can do completes as well.
American Made bikes | Lenz Sport Mountain bikes and Ski Bikes
If you only want a hardtail, then take a look at Specialized or Haibike, they make e-fatbikes which might be able to take a 29+ tire. Keep in mind that 29+ tire capacity is a function of tire diameter, so you need longer chainstays to fit. You probably need to measure it yourself. Same option goes for a full suspension e-Fatbike.
Thanks, i like the idea of starting from a 27+ and using 29+ if they can fit. I will do some measuring on some and eventually it might be from a regular fat if not from a 27+. Pushing the BB up i can accept but not lowering it.
I am in Canada and importing a frame might be expensive.
I have a Haibike hardtail that is 27.5x3.0" and it has a RockShox Yari fork, same chassis as a Lyrik. No way could you fit 29x3.0" in the frame or the fork. I don't think any 27.5x3.0" fork is going to fit a 29x3.0" tire.
Commencal just came out with a 29er trail ebike, but it uses 29x2.35 tires stock.
I built up a Surly ECR 29+ with a Bafang BBS02B and Sturmey-Archer heavy duty 5-speed IGH. Great eSurly ride.
For the price of the pre-built eBikes (don’t know of any 29+ yet anyway) you can put a Rohloff 14-speed Gates CDX Carbon belt drive on a Surly ECR (requires frame mod), Trek Stache or Trek 1120, along with a Bafang BBS02B and your choice of battery size/range/weight. Just something to consider.
Kona Remote e-bike. Sold in the USA as a 27.5" x 3". Outside of US 29" x 3". Bosch CX motor & comes with Old Man Mtn rear rack. I'm in Oregon and have the 27.5" x 3" and love it. Photo posted in the e-bike photo thread. I searched around alot early 2018 and didn't find many offerings configured like this. A few other companies were making hard tails with 27.5" or 29" and plus size tires, but most were only offering them outside the US market. When I got mine, they were in short supply.
How odd, there is a working link to the Frey site, but it is invisible! Anyway just click the blank space above this for the link to Frey Ebikes, a rigid fatty looks to be about $2800 with a good sized battery. Endless-Sphere has a long thread with all the components and geometry listed.
Some 29/27.5+ forks will take 29x3.0 tires. I run Bontrager XR2 29x3 (Chupacabra) front tires on both my 2017 Stumpjumper and 2018 Levo which have 29/27.5+ forks. There's ~12mm clearance between the tire and fork arch on the Fox 34 of the Stumpy and ~9mm clearance on the Levo's Rockshox Revelation. No frame contact at bottom out. Sadly, neither bike will accept a 29x3 tire in the back. (The Stumpy will take up to a true 29x2.6 tire and the Levo up to a true 29x2.4 in back.)
To compensate some for the extra height of the 29x3 tire vs the stock 27.5x3 tire (~35mm diameter, ~17mm radius) I replaced the 150mm airshafts with a 140mm. The front end is still ~7mm higher, the head angle ~0.5° slacker, and the bottom bracket ~5mm higher (a benefit!). I left 27.5x3.0 tires in back, and I really like the handling of the "79er"! Rollover is improved, and the ride is noticeably smoother. The increase in trail (~1cm) also seems to add stability and makes for smoother carving. I don't sense any wheel flop, and turning remains sharp and controlled. I think the 51mm offset of both forks allows the larger wheels to handle well, whereas the stock wheels may have been better with less offset to provide more trail.
Finaly i bought a Haibike HT 120mm with 27.5x3.0.
Just had time to ride it back home with Max PSI it was rolling great on Nobby Nic.
I am reading the instructions and will try it tomorrow.
The frame is 16 in. and it is filled with the 40mm rims so i will ride it like that. It seems like i have 2 bikes, fast to get to the trails and back at Max PSI wich is great since i do not have a car. Also a fun bike to play in the trails. At 46 pounds the wheelbase is 2.5 in more than my 22 pounds 100 mm HT.
It was an unsold and the price was way down.