I'm 5'11", and have a 54cm SystemSix on its way. I'm driving myself nuts with whether I purchased the correct frame size, I think a 56cm may fit better. I currently ride a 55cm Kestrel, which measures 55cm C-T.. I use a 100mm stem, with 8cm of drop, I'll probably drop to 9cm in about a month. The Kestrel Talon has a top-tube length of 55.6cm, SystemSix is 54.5cm. My cycling inseamm is 83.7cm. BB to top of seat is 74cm /w 175mm cranks, I'm going to a 172.5mm on the SystemSix.

So I'm guesstimating I'll need a 110 or 120 stem on the SystemSix, but my concern is that I might have too many spacers under the stem. Even with a 9cm drop?

Get fitted properly at the shop. Then talk to the dealer. If the bike has not arrived, they can change the frame for you.

BTW, the 56 in Cannondale is measured top tube distance. Measure your old Kestrel and see what the gap is.

The Kestrel BB to top-tube measurement is 55cm, right between the Cannondale 54cm and 56cm. Too bad they don't make a 55. Top tube length on the Kestrel is 55.6cm. The 54cm Cannondale is 54.5 and the 56cm frame is 56cm. So the problem is that I'm somewhere between the two sizes. Like I said, I ride the Kestrel with a 100cm stem.

Can't really return the frame, getting it off ebay. I guess I'll just transfer my Kestrel measurements to the 54cm, see how it works.. we're talking 1cm difference here and there. If worse comes to worse, I'll probably sell the 54 and pick-up a 56cm sooner or later.

Any folks out there with my approximate measurements riding a 54?

isnt a smaller bike easier to remedy than a bigger bike? if you dont want to go to an LBS, be on the safe side and take the 54

Ya.. that's what I'm thinking.. but, if the frame is too small, then the handle bars will be too low relative to the seat. My 8-9cm drop is mildly aggressive, I don't think I'll have that problem. Although I would be nice to calculate if the drop would work on the smaller bike (and how many spacer I would need), I just can't seem to figure out how to work the numbers.

You can always sell me the frame, I ride a 54

I'd say you made the right choice.
I'm the same height as you and have the exact inseam. I have three 54cm Cannondales with 54.5 top tubes. I use a 110cm stem with a 10deg. rise for rec. riding and switch to a 120cm stem with 5deg rise for racing. I use 20mm of spacers under all my stems. I also use a 172.5 crank on all my bikes.

I have a 55cm Serotta Colorado that has a 55cm top tube that I recently switched to a 110cm stem - I have a 54cm Serotta Al that has a 55cm top tube as well but I keep a 120cm stem on it and use it mostly for racing.

My most recent aquisition is a Merlin C110 which I have not built up yet but I went with the 53cm frame because it had the same 54.5cm top tube as my Cannondales.

Unless your alot more flexible than I am, IMO I think the 55.6 top tube on your Kestrel is to long for you especially if you have to use a 100cm stem to get comfortable.

Awesome, thanks Chaz! Very helpful stuff. How high is your seat, measured from center of BB to top of saddle, along the seat-tube? I tried riding the Kestrel with a longer stem, even all the way out to a 120, but just couldn't do it... I got crotch numbness. I assume going from the 175 to 172.5 crank will raise my seat by a very small fraction, 2.5mm?

primalcarl, I'll be sure to let you know if it doesn't work out.. but I'm hoping it does ;)

I just measured all my seat heights and they range from 74.2 to 75.
I use a couple of different saddles, some flex more than others. I generally adjust the height then fine tune on it on a couple of rides until I get the right feel while climbing in the seated position.
Your position might be slightly different depending on how flexible your hamstrings and lower back are.
Hope that helps.

Interesting, our inseam is very similar. My seat height is also 74.2. Good to hear the 54 Cannondale size works well for you. thanks!

The Kestrel BB to top-tube measurement is 55cm, right between the Cannondale 54cm and 56cm. Too bad they don't make a 55. Top tube length on the Kestrel is 55.6cm. The 54cm Cannondale is 54.5 and the 56cm frame is 56cm. So the problem is that I'm somewhere between the two sizes. Like I said, I ride the Kestrel with a 100cm stem.

Can't really return the frame, getting it off ebay. I guess I'll just transfer my Kestrel measurements to the 54cm, see how it works.. we're talking 1cm difference here and there. If worse comes to worse, I'll probably sell the 54 and pick-up a 56cm sooner or later.

Any folks out there with my approximate measurements riding a 54?

I'm 5'10" and ride a 54. At one time you could get a 55, but I opted for the 54 since the headtube length was the same and I wanted the smaller Top tube. I use an 11cm stem and I think my fit is pretty good. Just a note, cannondale measure there top tube lengths as "Horizontal Top Tube" length, which for a 54 is 54.5.

I considered a 56 at one point, but felt the frame would be too large, even with a shorter stem. The headtube would require less spacers for me, but I feel I'm ok with 2.5cm.

results are in.. IT FITS, what a relief. I might even have to go 10mm shorter on the stem, I've got a 120mm stem on there now. Need to get narrower bars too, 42cm.

With Fulcrum Racing 1 wheels (clinchers), Hollowgram SI crank and a full Dura-Ace build.. the bike weights in at 16.4lbs.

Initial impression on my first really short ride.. stiff and responsive. Every ounce of energy I put into the bike is delivered to the rear wheel, quite a dramatic difference compared to my Kestrel Talon. The cornering is amazing, bike tracks with huge confidence.

Good to hear it worked, I was afraid myself the 54 inch would not work for me and I am 69 or 70 inches tall. It felt good today when I road it, glad I di dnot order the 56.

Well all this talk about the system6, got me to order myself a size 54 ! Looking forward to the upgrade from my caad7 size 54. Hope the fit is identical as I love the way my 7 fits.

sweet.. it's an awesome bike, I'm really happy with my purchase.

After much more tweaking with the fit, if a 55 existed, I think it would've been a better fit for me, but oh well... with the 56 I would've ended up with a 90cm or 100cm stem, my preference is 110 or 120. Although I think the 56 would've fit fine too.

I think 5'11" with a slightly shorter torso or arms is the upper limit of the 54 frame.. that is if you can handle a 7cm plus drop. I'm at about 8cm drop, and have 2cm of spacers.

ipaul: what size is your 7?

I use 2.5 cm of spacers on my caad7 and its fine. I could flip the stem, but don't feel its necessary. I wasn't sure how things will change with the system6 and the headset system. I do notice the headtube is about .5 cm shorter. Will see. The 55 7's still had the same headtube length, so I saw no point in gaining the few mm of top tube length for me. If it was slightly longer (headtube) I would have considered the 55.

I'd be suprised if you fit a 54cm.

No question, I fit on a 54.

Now I am confused. I am buying a used six13 to do crits with and it is a size 56. I have been riding a 58cm R1000 for 3 yrs and is much too big especially for racing. I was properly fit to it a year ago and have had no pains whatsoever. I am 5'11 and 3/4 with a 33in inseam and just rececently ordered a LOOK 585 55cm(Size L). LOOK does not make a 54 and Cdale only makes the 55cm in team colors. I was confident in buying the used 56cm until I read this thread. Will the cm and 1/2 make that much of a difference? I am getting a good deal on the 613 frame and fork.
Help.

Cheers

I think you'll be fine.. you're a little taller than me, and I know I can fit a 56 too. Although I'd be riding a 100mm stem, probably with no spacers and way less seat post. How long is your stem on the 58?

JayTee: don't be surprised, I fit the 54.. it's my short torso.

The stem is 80mm with an incline. I bought the 58cm three years ago and had no aspirations of ever racing. I finally went to the LBS at got a proper fit for it and started riding easier without pain. They shortened the stem and made a steeper incline. After dropping 40lbs and racing last season with it and doing very well I decided I needed something better suited for racing. A team member is selling his 1 yr old 613 frameset at a good price and I just purchased a LOOK 585 and will not be racing it. Bottom line, I want something suitable for racing. The price is good on the 613, but could keep my eyes open for a 54cm on ebay, but would pay shipping and not know the person. Thanks for any more advice.