Trainers that lock in the rear wheel are heavy, and full-length rollers take up a lot of space in the car. And as dedicated cyclists, it's all about getting in the workout as conveniently as possible; and Feedback Sports has a solution with the Omnium Zero-Drive Portable Trainer. The folding design is a scant 13. 3 pounds — compared to the typical 40+ lbs of rear-wheel resistance trainers — and fits most wheelbases, and accommodates 16 through 29-inch wheel sizes. Feedback Sports designs the Omnium to offer no resistance other than the rollers' inertia and allow the rear wheel to move about a bit more naturally and mimic normal riding. The trainer totes easily to races for a quick warmup or for hitting key, high cadence drills that are more skill-based. The trainer comes with a durable, water-resistant carry bag, and thru-axle adapters for boost and non-boost bikes, and 9mm quick release. Cannondale Lefty, 20 x 100mm, and folding bike adapters are available separately.