I'm normally a 54 but boardman suggest 53 would fit me. 55.5 is probably too big for me.
Does anyone know how boardman cx bikes fit? I think i read before they are a little bigger than they the sizing would suggest
Not sure if this is of any help but I've got a hybrid version but I think the sizing is similar, I'm five nine and on a medium which believe it or not they call a 49cm the large was way too big for me. I usually ride a 54 Road bike or medium mtb.
They're closer to normal road bike sizing. Some CX bikes are quite a bit taller (or shorter reach depending on your POV) to give as much height in the front triangle for shouldering as possible. So a 58 might have a 56cm top tube. The boardmans are closer to normal sizing with equal toptubes and seatubes.
The 55.5cm CX Team fits me well (even with my weak lower back), I'm ~179cm tall with a cycling inseam (not trouser inseam) of ~81cm, I have short legs and a long torso for someone my height.
To buy, the CX Team is a bargain right now, £720 if you have British Cycling membership. You could use the money saved to help buy some nicer wheels, such as http://www.wiggle.co.uk/cosine-23mm-alloy-clincher-disc-brake-road-wheelset/.
But bare in mind that a replacement 10-42 XD driver cassette is ~£80. 😯
Depends on geo I think. CX bikes tend to be a larger frame size number than you might expect from a road perspective. If I was running into a conflict of my preconceptions and the company's sizing chart, I'd go sit on one and then have a hard think about it. I bought a 58 Cotic X a few years ago because I thought I was right on the crossover between 56 and 58 and the 56 looked like it was running a lot of post. Result was a bike that worked well as a stretched out tootler but wasn't very sprinty fast.
When I was looking for a replacement I spotted a 54 Crosslight5T and tried it anyway, expecting it to be silly small and had an 'it fits!' moment. I'm 2cm taller at 178 than the recommended range on the size chart, but it's perfect for me.