Don't know why, perhaps due to rising demand and production bandwidth, but be forewarned quality control is an issue. Assembly is easy enough, though have gap where back separator does not fit snugly after tightening nuts as firm as they will go (see pic). No water level sticker on tank received, so had to measure water manually according to calculations (4 gallons). Siphon was not air tight (even though release valve closed firmly), so had to manually pump instead of siphon. S4 monitor only flashes, not working as of yet and now have to take a apart top of unit to figure out why, currently not resolved after verifying connections and looking at simple solutions on website.
However, I own an air rower and have zero worries about maxing out it’s ability. I can completely exhaust myself on any type of workout. Air and water rowers are the chosen resistance type by Olympic athletes and any athlete looking to train their full-body cardio. I don’t think they would choose this resistance type if they felt they could max it out.
As far as “racing”, I said an air rowing machine is better because the Concept2 is the only model used for indoor rowing competitions, setting world records, and entering your actual scores online. It is because their monitor can calculate the drag factor of the flywheel in real time and accurately calculate distance and time. Small changes such as dust build up, air temperature, and humidity will not change the times between different machines because the drag factor is calculated every stroke.
Rowing has long been recognized as the perfect aerobic pursuit, with naturally smooth and flowing movements that don't tax the joints but do boost the heart rate. Now you can take your rowing experience to the next level with the WaterRower Natural rowing machine. Using the same principles that govern the dynamics of a boat in water, the WaterRower Natural is outfitted with a "water flywheel" that consists of two paddles in an enclosed tank of water that provide smooth, quiet resistance, just like the paddles in an actual body of water. As a result, the machine has no moving parts that can wear out over time (even the recoil belt and pulleys don't require lubricating or maintaining). More significantly, the water tank and flywheel create a self-regulating resistance system that eliminates the need for a motor. As with real rowing, when you paddle faster, the increased drag provides more resistance. When you paddle slower, the resistance is less intense. The only limit to how fast you can row is your strength and your ability to overcome drag. And unlike conventional rowing machines, which tend to be jerky and jarring, the WaterRower Natural is remarkably smooth and fluid.