Size recommendation advice
 

Need some advice, I'm 5'7 with a 30.5 inch inseam and currently riding a 51 (52cm top tube) caad8 with a -6 100mm stem. Looking to upgrade and pre order a 2014 supersix, my lbs is getting them in a week but im stumped which size to pick as I am in between sizes (so basically either go with a 50 or 52). My lbs doesnt have any SS's or caad10's left in either of the size so I cant even test ride. Do I go with the 50 and longer stem or 52 and shorter stem?

Try to find a older model but try it first...

If memory serves, longer stem=less twitchy and it's easier to make a adjustments to make things bigger than smaller, but have you had a pro fit to make sure?

41 forum members must be from a micro society of small things. :) So many guys ride small bikes for their size and then wonder why they can't get comfortable or need a big spacer stack. Plus, so many guys here run a lot of drop and no reach. Pros ride the opposite.

Levi Leipheimer is 5'7" and rides a 54 Tarmac SL4 with 570mm saddle tip to handlebar center with modest drop. He is also one of the fastest cyclists on the planet.

PS: the gentlemen I was helping with stack and reach in the other thread from Sweden is almost 6' tall and towers over both you OP and Levi and he rides with a shorter reach than Levi...and more drop....and bought a 54 Foil. Unbelievable whoever are doing the fittings for these bikes. Guys paying $5K for a bike and being fitted on a bike 2 sizes too small...and not racing bikes for a living.

And they do not kit their knees on the handlebar while standing and sprinting? I agree - crazy...

You shop is getting them in a week and you are pre-ordering? can't you ask them to give you a call when the two sizes are built up and test ride both? Will they really both sell right away?

Ain't it the truth! I am 5' 7 1/2" and have always ridden a 54cm C-C in traditional geometry or medium in Giant-type compact geometry. That is with a 110mm stem, and I only wear a 33 inch sleeve. What's with the clown bikes?

Not sure. I started riding in a era where everybody rode big bikes. Part of it is emulating pros...some of whom ride small bikes with big drop but a couple of notable things.
1. the average cyclist ain't nothing like a pro who is genetically blessed and spends 6 hours a day on a bicycle.
2. average cyclist oddly rides small bike + 100-110mm stem. Most pros that choose small bikes do so for the short stack and drop and some even ride custom stems because they can't get their stem long enough...for the simple reason that they need to add reach that short bikes subtract.

As the world turns. :)

If shorter stems make a bike more twitchy, do short bikes with super long stems make them hyperstable? I mean obviously you're not changing trail or anything like that.

I kind of dismiss your premise that shorter stems make a bike more twitchy. Reason is pretty simple. If your fit is correct and you are properly weighting your front wheel, and you are on a bike with a short stem, then you are on a longer wheelbase bike. Longer wheelbase bikes on average have slower steering than shorter wheelbase bikes. Most tend to think of stem length in isolation. It isn't the case. Bike geometry...you mention trail, head tube angle wheelbase and weight distribution have more effect on handling then stem aka tiller arm length.

ok, fair enough.

My lbs has a good relationship with Cannondale and can order me a 2014. They aren't receiving their shipment of 2014's for another month or so. Yes, I admit, like everyone else I can't wait. I've spoken with my lbs rep and as of right now I am going to bring in my current caad8 and we'll work from there.

I do appreciate all the comments, if anyone else can provide more comments or feedback that would be great.

I am very short. I owned a 43cm bike with a 60mm stem and a 44cm bike with a 50mm stem. The one with the shortest stem was the least twitchy. It practically steered itself.

52. I'm the same height with shorter legs and I ride a 52.