BMC TeamMachine Sizing

[stefan416]

Hi all,

I'd like to get some advice on frame sizing for the BMC TeamMachine frame which i can currently get a really, really good deal on. Im torn between the 53 and 55. Everyone seems to say that they run larger than indicated on their website but im not sure. Here are my Competative Cyclist specs;

Your Measurements
Inseam: 84
Trunk: 64.25
Forearm: 34.5
Arm: 63
Thigh: 59.75
Lower Leg: 53
Sternal Notch: 144.25
Total Body Height: 178.5

My current bike is a Giant TCR Advanced in Medium w/ 110mm stem. Top tube is 55.5cm and the way its currently set up the seat is put almost all the way back on the rails with a total reach of 54-55cm (seat tip to handlebars). Im a 26yo athletic guy, moderately flexible and prefer a more "aggressive" fit. The Competative Cyclist recommended specs seem off since they recommend;

The Competitive Fit (cm) Current setup
Seat Tube Range c–c: 54.2 - 54.7 cm
Seat Tube Range c–t: 55.9 - 56.4 cm
Top Tube Length: 53 - 53.4 cm 55.5cm
Stem Length: 11.2 - 11.8 cm 11cm
BB–Saddle Position: 71.7 - 73.7 cm 72.5-73cm
Saddle Handlebar: 52.1 - 52.7 cm 54.5 cm
Saddle Setback: 5.8 - 6.2 cm 6-6.5cm


I think its sizing stuff a bit small since at a saddle to HB of 54.5 my shoulder angle is just under 90* which means it would be even less with a shorter bike no? Maybe I've been riding too stretched out all this time? It always seems that people around my area are sized way to small on their bike with too upright of a position. My back angle is about 40* which is comfortable enough.

Anyway Id love to hear some options from people my size or anyone would might be able to offer some solid advice!

Thanks

[2lo8]

Compare stack, reach, and make sure the seat tube angle is no greater than on your current bike.

Top tube is a complete red herring if you don't normalize seat tube angles. That fact that your saddle is slammed back does indicate there may be an issue with your fit. It could be right, but if anything is at an extreme it raises red flags.

[stefan416]

Compare stack, reach, and make sure the seat tube angle is no greater than on your current bike.

Top tube is a complete red herring if you don't normalize seat tube angles. That fact that your saddle is slammed back does indicate there may be an issue with your fit. It could be right, but if anything is at an extreme it raises red flags.

Thanks for the reply! Yeah so Ive quickly found out regarding stack, reach, ST angles etc which i didnt really look at for my first bike. I think my current bike would "fit" me better with a setback seatpost which would bring the seatpost clamp into the middle of the rails. The way the seat is now has led me to think larger sizing (top tube) but stack might become to high since i currently run about 2cm of spacers. I could definitely use a professional fit to see where Im at. The problem is now that the shop only has the 55cm in stock for $1999 which is a killer deal.

[2lo8]

The position of the seat rails is purely a function of the seat itself, the seatpost setback, and the seat tube angle. It has virtually nothing to do with reach, size, top tube, except for the fact that different size bikes have different sea t tube angles.