What size should I ride in BMC if I ride a M in Giant?

Aug 14, 2019
Some people told me to downsize to 51? They measured me at 53 cm at a shop and told me I'd be 54cm for a Specialized and 51 in BMC. Wouldn't it be too small? They didn't had any in stock. I’m 5’9 3/4
Last edited:
I've checked them out and the BMC's seem to have longer top tubes than the typical frame. I'm about 5'-10" also and figured I would need about 51-52. Back in the day I used to select my frames by the seat tube measurement until I figured the virtual top tube measurement was better for my own bike fit and it's worked out well for me ever since.