Specialized Trekking bikes. When booking this bike you will get one of the following 2 bikes: The Sport / Trekking bike Specialized Sirrus Disc with Shimano group 24s and thin 28" wheels. Hydraulic disc brakes. Or you will get the Sport / Trekking bike Specialized w/suspension with Shimano group 27s and thin 28" wheels. Hydraulic disc brakes.