Price range: $8 – $130 The seat bag is traditionally a tiny bag that tucks under the seat and attaches to the seat post or stem. It’s small in size and usually carries an extra tube and a tire repair kit. If you’re going light and fast this is the only bag you would see on the bike. But today’s cyclist doesn’t always hold to tradition. Seat bags have evolved in size from small pear sized bags to larger sizes that can carry repair kits, food, clothing, and extra gear that isn’t possible with the small traditional bag. Regardless of whichever size suits your needs the mounting area is constantly found beneath the seat or saddle.