Originally Posted by datlas

OK I will bite: but I have unusually long legs and a short torso:

6 feet 1/2 inch tall w/ 37 inch cycling inseam (yes 37 inches, 93 cm not a typo)
56.5 cm top tube, 63 cm seat tube, 10 cm stem (custom built steel frame, not compact).

Originally Posted by halfspeed

Inseam dictates saddle height which factors in saddle to bar drop which affects overall reach.

Originally Posted by Sonoma76

I got contradictory messages when shopping for a bike. A racing-oriented LBS told me a properly fitted bike ought to block my view of the front wheel hub (while in the hoods, the handlebar would supposedly block the view of the hub).

Other stores told me that's not accurate anymore.

I ride a 57cm bike, 32.75" inseam, 6'1, and a 100 mm stem. I feel a bit stretched out, but I'm new to this so it could just be me getting used to it.

Originally Posted by Grumpy Pig

I measure my reach by blocking the view of the hubs when I'm in the drops.

Originally Posted by DrPete

No, where you put the seatpost dictates saddle height. That variable can be changed. Top tube length can't. That's why, especially in the era of compact geometry, etc etc, people recommend fitting bikes by top tube length rather than seat tube length.

Originally Posted by halfspeed

The point is that you can't fit by either top tube length or seat tube length (or head tube length on compact geometry) alone.

Originally Posted by Hendley

Right. The "size by top tube" advice that gets thrown around here is just as much a misleading simplification as sizing by seat tube. You need both measurements to start with. Being long-legged for my height, I always look at HT first...I know I need at least 200 mm. After that, I look at TT to see if the reach will get me in the 120-130mm stem zone.

For example, the Cervelo R3 and RS in 58 size have identical top tubes at 58 cm, but differ in HT length by 2 cm (180 mm and 200 mm respectively). I could fit the RS fairly well, but the R3 would required a lot more fudging with spacers, flipped stems etc.

For best results, of course, you need the STA, HTA, and BB height, as well as the TT and HT lengths. Those five numbers will enable you to determine stack and reach. When ordering my last bike (impossible to test ride where I live), I used a spreadsheet to calculate stack and reach for a series of likely looking candidates, and was able to narrow my choices down to a small set of bikes that would fit well.

Originally Posted by R900

6' 1"
58.5 cm top tube
120 mm stem

Originally Posted by Campag4life

It seems for many that are 6'1" that this reach is popular. I am the same at 6'1", 57.5cm top tube and 130mm stem.

Also there is an accomodation of sorts built into the whole issue of body proportions which accounts for why guys our size run very close cockpit lengths even though our proportions maybe different. It can be explained by...those with long legs which generally means shorter torso and portend a shorter cockpit...typically have longer arms as a compensating factor. I am built this way...long legs and arms with pretty average torso length. By contrast those that are all torso typicaly have shorter legs and arms which dictates the same cockpit reach for those that are the polar opposite.

Originally Posted by DrPete

I guess I have a short torso or arms because I generally run a shorter top tube.

The fit calculator at Competitive Cyclist comes in handy here... it'll spit out a top tube/stem combination, saddle height, saddle-bar drop, etc. etc. for your given measurements and preferred position. It gives you 3 choices: The "Competitive Fit" for traditional long/low aero racing-type positions, the more relaxed "Eddy Fit" popularized by some bike racer guy named Eddy , and the "French Fit," a more upright, touring-oriented fit.

Also helpful is the TT/Tri fit calculator which gives you the "Aero fit."

Originally Posted by Campag4life

I've marked up the Hincapie riding position to make a couple of points to like minded scientific cats out there. Many know that the idea cockpit is a triangle. The key is the shape of the triangle. Triangles are strongest with a wide base. The lower the back angle the longer the reach should be or the base of the triangle is no longer steady. If you look at Hincapies' set up, there is beautiful symmetry to it that he no doubt has migrated to through exhaustive testing. His set up is the most solid for a reason. Many suggest that the ideal back angle on the hoods should be close to 45 degrees which effectively forms an isosceles right triangle with a right angle between upper arm and back. This produces a very solid platform for the arms to support the back. What one intuitively feels if their reach is too short is the arms are more in compression. This leads to a sense of feeling cramped on the hoods. Look at Hincapie. His arms are more in tension i.e. more like cables on a suspension bridge. His set up for his extreme race position looks perfect. If he were to shorten his cockpit, i.e. the red arm position, you can see how the symmetry of the triangle would be compromised and he would lose the base of his triangle and his arms would be more in compression.
The racers, though perhaps difficult to emulate to the nth degree, teach us alot about riding position. A further note is one of the reason they can tolerate such extreme saddle to bar drop is they accompany that drop with an equallly extreme reach which shallows out the angle of attack to the handlebars.

Originally Posted by Campag4life

I believe there are many factors as you allude. Type of cyclist of course including personal preference. Something a bit counterintuitive perhaps is the various fits from race to comfort associated with my Competitive Cyclist fit profile...the reach...horizontal component anyway if you add top tube and stem length is actually "less" for the competitive/racier fit. In any event, what the Competitive Cyclist calculator suggests coincides very closely to what I actually prefer...if anything stretchs me out a bit more across the board than I prefer....see below:

BTW...the above contradiction can be explained and why the CC fit calculator separates top tube and stem length. The racier fit...even though is has physically a "shorter" reach references a shorter top tube. Convention dictates, shorter top tube bikes have shorter head tubes. The result is...the shorter horizontal reach of a competitive fit will be compensated for by a bigger drop for an aggragate equal if not longer reach for a competitive versus Eddy or French (comfort) fit.

Originally Posted by texascyclist

Extending your arms will not create tension. This will increase compression. Imagine a greased up smooth wall next to a carpet floor. You lean against it with your feet directly under holding a weight. No problem. now, you move your feet out 2 feet, and it increases compression on your feet.

Originally Posted by DrPete

Short top tube = shorter wheelbase, quicker handling, and as you mentioned, a shorter top tube and greater potential for a bigger saddle to bar drop.

I set my bike up exactly according to the Competitive Fit and it's an outstanding race rig.