I bought an S40 earlier this year to replace my aging (28’ish year old) P-38 I used for double centuries/rando. I also have an M5CHR for solo vroom vroom, a Tarmac for fast group rides, and a Diverge (gravel’ish) with 32mm tires for randonneuring.
I personally don’t think the S40 climbs any better than the P-38. But man that FWD efficiency is noticeable, at least in the lack of clatter from the two extra chain idlers on the P-38 (and I do like the dual 700 wheels instead of a 406+700).
When I first got the S40 I didn’t notice a significant power difference between the M5CHR and S40 at sub-20mph speeds (as scientific as years/100+ times of doing a 2mi’ish loop on my various bikes) that would be attributable to big power train losses. I am using a dropped chain on the M5 though.
Given my own experiments with varying seat recline/BB height this is totally understandable, though depends on your height/chainstay length in case of Cruzbike. *Generaly* lower BB and less recline puts your hearts higher relative to legs on P38, hence when climbing steep stuff you don't get as much of a hydrostatic blood pressure drop in your legs, but P38 is not known to be a speed demon on flats for that very reason... unless fully faired, of course (F40).
I wonder how efficient Kervelo front hub is (likely less than a chain drive, but certainly less so than a combination of a hub gear + chain drive... Rohloff, for instance, was found to be only a *bit* less efficient than derailleur gears).
Their midracer (BB at seat level) should be a decently aero and excellently climbing bent. I didn't like their gear range though, even at 12 speeds it is kinda meh...
P.S. Since it is MBB, it should also be subject to 'bar swinging bonus'. Given extremely small effective 'boom' length (equal to offset), less pedal feedback, too... but you cannot have a DF-like shortwheelbase or will get tons of wheelspin even with seat that low.
