more expensive models are now fitted with disc brakes. Wheels are 18" but conversions can easily be made to the more readily available 16" size used by Brompton. For a long time there were no decent 18" tyres. Some owners have fitted 20-inch wheels to the bike (a 10th anniversary limited edition had 20" wheels as standard ). For folding, the rear suspension tucks under the frame, the front suspension is unclipped and hinges back under the frame, and the seat post is collapsed. Lastly the handlebars hinge downward. The front wheel can be left unfolded if the package is to be wheeled, for example when boarding public transport. Folding is relatively more complicated than for a Brompton and takes slightly longer. Available accessories are mudguards, front and rear folding racks, bags, lighting sets and some upmarket extra components sold in Singapore and Hong Kong, like gas suspension units and upgraded chain tensioners for folding. Two optional rear racks are available, the SL Carrier and the Expedition Carrier. The former mounts directly to the swingarm, and allows only the use of a rack-top bag. The latter is a folding 16mm tubular rack mounted on pivots on both the main frame and the swingarm, which allows use of small panniers (e.g. Ortlieb Front Roller) when mudguards (fenders) are fitted. The mounting pivots for this rack have only been fitted to frames since 2003. Both racks are available with rollers which allows the Birdy to roll when folded. A slightly lighter Mark 2 monocoque frame, with greater support for the seatpost (top picture), was introduced in 2006 along with new component choices. The Mark 1 continued to appear with a slightly updated frame on some models, notably the World Comfort (7 speed Nexus, and the 'Birdy Classic' of 2020. Mark 1 frames were available in Asia from a third party, badged as Rhine and produced in China or the Philippines. The standard Mark 2 weighed (2013). Some riders have reduced the Birdy's weight to 8 kg using racing components, but this was only on the Mark 1 frames. Stock bikes ranged from (for the Birdy Speed with Tune and Shimano Ultegra road components) to over , depending on the setup. The heavier bikes tend to have 3x8 gearing systems, involving an internally geared rear hub and an external derailleur. The Birdy Race () was introduced in 2013 and had dropped handlebars, and