Mongoose Goes Retro For Limited Version Stranger Issues Season Three Character Bike The others are the specialty bikes together with mountain bikes which are featured on the company web site. These are the high-end fashions and these are sold via specialty stores. On its website, it has around 24 completely different models advertised which include the ones for Dirtjump, XC, Youth, Trail, Downhill, all Mountain, and Fat Bike classes. Mongoose bikes started off as aggressive BMX bikes and have the word ‘action’ written throughout them. As far as adult bikes go, Schwinn mountain bikes start at about $250 they usually top off at round $700. Meanwhile, you’ll be hard-pressed to discover a Mongoose adult mountain bike that retails for less than $300 and some of their top-of-the-line fashions sell for upwards of $2,500.