Mounting a BBSHD in an Ultra frame?

[CCroft]

Long story short: I searched long and hard for a unicorn of a bike (fat tire, step-through or low stepover frame, belt drive/IGH, Ebike already or Ebike-capable with a motor powerful enough to push ~ 300lbs of rider and gear through mostly off-road terrain) and ended up with a bike that checked all of my boxes, running a M620 Ultra. I had never ridden an Ultra and assumed it wouldn’t be that much louder than my 2017 BBSHD fat bike build. I was wrong about that. It’s just too loud for me and my riding, even after disassembly/liberally greasing with Mobil SHC 100 as I did with my 2017 BBSHD bike.

I really like everything about the bike except the Ultra. How possible/crazy of an idea is it to mount a BBSHD on it instead of the Ultra? I don’t have a spare BBSHD lying around to hold up to my frame to eyeball how one might accomplish this, so it may be a non-starter. I realize it wouldn't be nicely integrated into the frame like the Ultra is, but I'm just thinking out loud a little before Plan B (= sell the bike and start looking around for a belt-drive/IGH fat bike frame that would take a BBSHD).

Thanks, Colin

 

[smorgasbord]

The BBSHD needs a bottom bracket housing in which to mount. With the Ultra frame you don’t have that mounting option.

 

[Chargeride]

Ive considered this before, I think a simple bracket bolted into the ultra mounts either side and a tube between them in the right place, once tightened up it would be plenty strong enough and youre free to adjust the crank position for the best fit and virtual seat tube angle

 

[il Munduato]

No.

 

[CCroft]

Thanks for the feedback; that's what I was suspecting. Ventana sells a BBSHD-ready fat bike frame ("El Gordo") that Cycle Monkey used to create a build very similar to what I'm looking for--sans the step-through frame (although it looks like it has a lower top tube than my existing BBSHD fat bike bike). The step-through/lower TT factor may be the one I have to compromise on. Although if I'm not gaining much in terms of a lower TT compared to my BBSHD fat bike, it might be worth exploring if converting that to the Gates drive/Rohloff is possible depending on its frame (?)

 

[m@Robertson]

What @Chargeride said. Its been done successfully. You need machine shop skills and of course a machine shop.

 

[JRA]

That seems a bit extreme to me? I have an M620 that was loud also and greased it with John Deere Cornhead and it is super quiet at all levels of engagement? There also are "quiet" gears available but I have no experience with them nor need now.

 

[Chargeride]

The ultra is also a lot heavier