A bicycle rack is described with a retention arm for securing a wheel of the bicycle to the bicycle rack. The retention arm is provided with a tire chock for contacting the tire of the bicycle. An adjustable tire chock may be positioned on the retention arm to secure different sizes of bicycles with different sizes of wheels on the bicycle rack. The adjustable tire chock may have latching components that can be released by a user with a single hand by applying opposing or rotational forces to the latch components or the tire chock. The latch components may be provided with a biasing mechanism to urge them into a latch or engaged position when aligned with latching features on the retention arm.