Don't mistake CityRow for a Peloton wannabe. Both companies launched about the same time a decade ago. But CityRow started as a network of boutique HIIT (High Intensity Interval Training) studios that only started selling connected home exercise machines several years ago. And for co-founder Helaine Knapp, the growing physical presence is the brand and marketing special sauce. As she tells Brand Insider this week, that omnichannel "flywheel" drives the two achievement metrics every D2C trains for - cost of acquisition (CAC) and lifetime value (LTV). As Knapp explains it, from lower-key content marketing to laser-focused performance advertising, D2C brand …