Bikes with 26-, 27.5-, or 29-inch or 700C wheels are designed for adult use. Seat height has plenty of adjustment, and if you’re particularly tall, extended seat posts are available. On some models Schwinn quotes a “suggested rider height” to assist you, and on others a variety of frame sizes are offered, with charts to assist you. If you’re concerned, you might also want to check customer feedback, which often answers questions related to an individual’s height and weight.