Yup, I reckon so - and they seem to stand up to distance too pretty well judging by Cj$ on the Divide this year...

'Fat' was a consideration early on, but this bike is being put together almost exclusively for Europe / Asia (and similar distance continental) runs, so essentially tarmac & gravel. In that (wide) gamut of terrains there will indeed be places where 4" up would be useful, but for 99% of the time 3" Knard is about as big as it's as it's ever likely to need to go. (If it stops on snow /sand on those, it's time to get off & push ) Another factor is that, in my experience, tandems on thin tyres can go a lot further in those conditions than 1/2 bikes - the weight & torque means you can 'dig down' and keep moving.... that has surprised not a few people in UK mudfests in the past. Last but not least going fat ads a whole bunch of  issues like significant weight increase ('standard tyre' will be around the 2.5 mark), drive train geometry and (for touring much of Europe & Central Asia ) parts availability.

Value-wise fat is a non-market here even on singles (they're growing a bit on 'novelty value'). For 'specialised' tandems the market is minuscule - our Ventana is one of only 5 or six in the whole of the UK!

Hi All

Time has come to turn to the experts;

As our team (me & Mrs royAB) are doing less full-on off road/singletrack riding and our fire road distance riding is increasing, our Ventana ElConq is to be joined by a 29er, rigid, titanium custom tandem.

Plans are now fairly advanced, features include cable routing for 'standard' derailleur or Rohloff, S&S couplings (only one split for the moment to take account of European trains), a plethora of bottle (or frame bag) mounts, BOB Trailer mounts, tyre clearance for Surly Knards & up front a truss fork with bag support

While the last bike (29er 1/2 bike) I had built (I designed, factory in China made) worked out well, with this one, being waaay more costly and with lots more factors to consider, it would be great to have thoughts / comments from the forum. (I can wrench fine, build wheels, build bikes, but I'm only a bush engineer and by no stretch of the imagination an engineering designer!)

V.latest of frame & fork below (once change already - the 20mm thru-axle will be clamped both sides)

Thanks in advance