The official name for this mode is Riding Dekaranger Robo and looks pretty damn impressive. Although the Dekaranger robos were probably the smallest DX sentai bots when it comes to size, they're quite hefty in this mode.
Dekaranger Robo and DekaBike Robo, individually, are decent toys. But put them together and Riding Dekaranger Robo is arguably one of the coolest robo combinations in sentai history. If you own one and not the other, you're doing yourself an injustice.