Local bike shop bike shops have begun themselves to sell products online. A recent development is the introduction of brand specific stores from bicycle manufacturers such as Trek Bicycle Corporation. Other manufacturers, such as Specialized are strengthening their channels with "concept stores". According to the National Bicycle Dealers Association, in 2007 there were approximately 4,400 "specialty bicycle retailers" in the USA; down from 4,800 in 2005. Although they sold only 17% of the bikes, up from 16% in 2005, they collected 49% of the dollars, up from 47% in 2005. In 2004, the average specialty bicycle retailer had gross sales of $550,000 per
Bicycle fork intended by the frame designer. The functional length of the fork is typically expressed in terms of Axle-to-Crown race length (A-C). Also, the axle on the wheel must fit in the fork ends (usually either a 9mm solid or hollow axle, or a 20mm thru-axle). Some manufacturers have introduced forks and matching hubs with proprietary standards, such as Maverick's 24mm axle, Specialized 25mm thru-axle and Cannondale's Lefty system. Fork steerer tubes may be threaded or unthreaded, depending on the headset used to attach the fork to the rest of the bicycle frame. An unthreaded steel steerer tube may be threaded