Unsure of frame size
I bought a pinnacle arkose 4 recently. I got it in medium, assuming it was between 54-55 cm. I looked into quite a few bikes and was told by the customer service assistants I would need 54 cm and above for the frame given my height is 5"8. Although the bike is great it did seem a bit small. I have only just noticed the medium for this bike is actually 51 cm. It does specify the medium is for people between 5"7 and 5"10. Does anyone know the reason for this? Are there other features of a bike which mean it can still be classed as medium with a small sized frame?