Perhaps the biggest problem for those who own treadmills is discipline. How long will you regularly use it, before it becomes a place to hang clothes? The second problem is how much space they take up.

A Chinese company called King Smith Fitness makes a treadmill that folds away for storage. Their X21, which runs $1,000, collapses down to a thickness of just 8.9" (226mm).

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However, if user reviews are anything to go by, this product does highlight the danger of purchasing expensive tech objects from companies with poor or nonexistent customer support. Somehow, we as a society have grown comfortable ordering $1,000 objects from companies we've never heard of, with the naïve expectation that we will receive what we paid for. About 13% of reviewers on Amazon gave the X21 one star, reporting that the unit stopped working, from its first few minutes of use up to about 8 months. The 1-year warranty stipulates defective units must be shipped back to the manufacturer, in its original packaging, at user cost ($280).

The design is neat.

Buyer beware.