What Frame Size for Cannondale SuperSix Evo

Im exactly 175 cm and i ride a 56 super six. in my size, i can swing between 54 and 56 but i prefer the stability that a 56 can give on sprints. The difference in weight is negligible (13 grams) but the additional cm or two of wheelbase along with the stiffer tubes (bigger sizes have bigger tubes) mean that the 56 is both more comfortable and arguably faster. just go with what you like, but remember that on a test ride, the stem, bars and seat height may influence you more then the actual frame.

I'm 172 cm with 79 cm inseam, so I'm just a tad shorter than you and the 52 cm Cannondale fits me perfectly! I'm a little older (mid 50's) so the extra spacers on the stem work well for me as I am less flexible than 30 years ago As far as the SRAM Red22, I have both SRAM Red and Shimano Ultegra group sets and they both work great! I prefer the SRAM system when shifting up (more definitive feeling), but prefer Shimano when shifting down (less missed shifts). I always recommend riding any bike before you buy. What's good for one may not be good for another...great bike by the way!

new SRAM works well. Nearly as good as Shimano and lighter. The double tap system annoys occasionally when going for a gear that is not there on a climb(in top gear already) and shifting into a harder gear by mistake.

I also missed Shimanos system for allowing braking and shifting simultaneously when riding in town.

SRAM also looks great!

As to sizing, you have to arrange a test ride, it is quite an aggressive/low stack height geometry compared to many more sportive style bikes Cevelo R5 for example

I'm 170cm and have the 52 SuperSix, fits me like a glove, Lots of room for adjustment via head spacers if you are flexible you can slam her. If you are between the 52 and 54 ride both and pick the 'one'. It will depend greatly on the differential between leg and body length. I've got stumpy legs and a 'normal' length body so the 52 felt best for me.

I'm 174cm with 79cm inseam, rode a CAAD8 54cm. Your longer legs will tilt you forward on the bike - which may work because the Evo is lower at the front.

Test ride essential.

I'm 180cm and ride a 54cm supersix (not evo, but same geometry). When i tried riding it in the shop i came to the conclusion that a 54 suited me better than a 56. I think i may have been wrong as the ridiculous amount of spacers stacked in the stems gave me the wrong impression of the bike. I've remedied this by sticking on a 120cm stem.

As above try it out.

I rode a 54cm Evo for a few weeks (holiday hire) and am about the same height as you. Given the chance again I would possibly go for a 52 just to be "on" the bike more, but its entirely personal taste.

My home bike has SRAM rival, but the hired Evo had Ultegra Di2, and I've been lusting after that ever since. Again, all down to personal taste but I preferred the absolute certainty of electronic shifting. When using mechanical shimano Ive found the lever throw a bit offputting especially when shifting to a bigger gear on the back. For mechanical shifters I'd always go SRAM.

TL;DR: Ride some stuff, go with what feels best.

Have you tried one in the shop? SRAM included? See if you like the levers?