27.5 mountain bike

27.5 mountain bikes are mountain bikes which use a large volume tire that is approximately 27.5 inches in diameter, 56 mm wide (ISO 56-584 / 27.5 × 2.25) on an ISO 584 mm rim.

[1][2][3][4][5] 27.5 mountain bikes are also called tweeners,[6] since it "fits between" the traditional 26-inch wheels and the newer 29ers".

[7] The wheel size is sometimes erroneously called "650B"[8][9] as a "marketing term" by some manufacturers for their 27.5", but the 650B size has traditionally been a designation for a 26 inch diameter (ISO ~ 40-584 demi-ballon tire) using the same ISO 584 mm rim[10] used by French tandems, Porteurs and touring bicycles.

In 2007, 27.5 inch wheels for mountain bike use was popularized by Kirk Pacenti,[6][12] and in 2013 at least 10 companies had launched models with 27.5 inch wheels,[3] with some parts manufacturers following suit.

[1][4] In 2012, Nino Schurter won the World Cup event at Pietermaritzburg, South Africa,[5] and placed second in the Olympics in 2012 on 27.5 inch wheels.