An adjustable assembly for a bicycle includes a first support having an interior surface and a second support slidably positioned within at least a portion of the first support. One of the first support and the second support is adapted to attach to a first bicycle portion, and the other of the first support and the second support is adapted to attach to a second bicycle portion. Further, the second support comprises an expansion portion configured to be moved between an expanded position and a retracted position. The expansion portion is configured to engage the interior surface of the first support when the expansion portion is in an expanded position. In addition, the first support is configured to be selectively moved relative to the second support when the expansion portion is permitted to assume a retracted position.