I would say it's too small, but it all depends of frame sizing/geometry. I am 5'8", with a 31-32 inch inseam, and have a Ghost bike which is a 53cm frame. The next size up was a 56cm, and that was too big.
This may help:http://www.merida-bikes.com/en_gb/cms/6 ... t-geometry
Alternatively, email or give them a quick call:
Email: [email protected]
Tel: 0115 981 7788
I emailed Merida and they've replied to say that according to their size chart I'm just ok for a 54cm. I think I'll ask the LBS to get in a 56cm as well so that I can compare the 2 before buying. Thanks for the advice.