BMC Team Machine SLT01 55cm or 53cm - help please...

kevnose Posts: 7
edited September 2009 in Road beginners
I have a 56cm Cannondale CAAD9 which I bought originally for 20-30 mile rides, but since then the goalposts have moved and the distances have gone up to 60 -70 plus. On that distance the alloy frame beats me up.

I'm looking to pick up an '09 bargain and get a carbon BMC Team Machine SLT01 which rates highly and is in budget with discount. Having looked at sizing guides for the BMC and compared against the Cannondale charts I think I need a 55cm. That said I've read elsewhere that the BMCs come out large compared to other frames and a 53cm might be a better fit.

On my current CAAD 9 I have a shorter (90mm) upright stem +16 degree as I have long legs, particularly femur, but short reach. Also I currently have the saddle as far forward as possible with no lay back on the seatpost.

One diff. I noticed between CAAD9 56cm and 55cm BMC is that the head tube on the BMC is 12mm longer than on 56cm CAAD - wondering if that will help with reach?

Anyone have an opinion to help as this will be an on-line purchase and I don't want to get wrong size as I have been there before with reach problems.