First off, let me apologize, because I’m sure this has been debated many times, but I’m new to this site, and don’t want to search through hundreds of posts.
Also, I know there’s probably not a black and white answer to my question, but I would like to get some input.
I race on a 650, I’m about 5’ 10" and weight 150 lbs. I use 55/11-21 setup. I consider myself a fairly strong amateur cyclist, time trialed over 26 mph for a 40K. I use a 700 road bike for training, but purely a road set up.
However, when I look at the top cyclists in both triathlon and cycling - unless I’m missing something - no males use a 650 (except Jurgen Z). Does anyone think I’m costing myself time? Am I a strong enough rider that I should be going 700 for racing? Or is the difference pretty small?
In the end, it’s all about the motor. 650’s are no faster or slower than 700’s, although some will swear blind that one is better than the other.
at 5’10", you’re in the range where either one will work well for you. Not to small to get a decent position on a 700c bike, not too tall for the bike to look like a circus machine with 650c.
I was having the exact same argument with myself last year before buying a 650c bike… I’m much like you (5’10") However, i’m a bit more of a truck at about 170 around race time.
So i’ll get the point… What eventually convinced me was a buddy of mine who turned pro last year at the Olympic distance had ridden a 650 c bike… And his splits in age group races were awesome. He’s more like you (5’10, around 155). He said the only reason he changed to 700 because he had to have a road bike for drafting races… and the money from the sale of his 650 c tri bike would help.
The only thing I can think of to take into consideration is your technique… I find I really pass a lot of people on climbs. And i’ve practiced my hill repeats using different techniques (standing, sitting aero etc.) I find with the 650 c bike… I get better results when I sit down and spin (100 rpm) However, that could just be the fact that i’m a descent sitting climber… I did read somewhere, that this approach is better due to the fact that 650 c’s accelerate slightly faster and, therefore, de-accelarate faster… So keeping the cadence up in climbs seems to be the way to go… However, even that’s up for debate depending on your style.
If you can average 26mph in a 40K time trial, you need to work on your run and swim if you not finishing in the top of your age group.
I wish I could see 26mph average in a time trial. In a triathlon I usually can only averaged around 24mph in an Olympic race if the course isn’t too hilly. I think your 55/11-21 setup is a pretty fast setup for 650s. Most people who ride 700s will have a 53 front chain ring. That said however, a 55/11 650 will be slower than a 53/11 700 bike based on gear inches.
Go to http://www.sheldonbrown.com/gears/ to compare the differences. Based on the calculations you would need to have a 57 front chain ring on your 650 setup to equal a 53 700 setup.
IMO a 55/56 chain ring on a 650 is all that is probably ever needed. I would have a hard time envisioning someone spinning out using a 56/11.