elcruxio

So far I've usually had pretty good results from the fit calculator.
My MTB is spot on with the calculator.
Also my road bike specification works... Well, it works but also gives me a bit short top tube length on the competetive fit. Eddy and french are more on the money.

I'm 6'5" with 37.5 inch inseam and the top tube lengths I'm given are 57-59cm. I use a 59cm with a 130mm stem and lots of setback. Also the saddle heights the calculator gives are seriously too high in all but the french fit. Competetive fit would like to put me on bb-saddle top 87cm when I actually ride 83-84cm.
Also the suggested setback is 7-9cm when I use 12cm. My saddle is a contributor to this situation, it being on the short side so my actual setback might be somewhere in the 10.5-11.5cm region.

Now this is where this get strange. I did the calculator with a friend of mine.
He's 6'2" with a 36.6 inch inseam. We checked and none of the measurements we have are radically different. A few cm here and there but the fit the calculator gives him is pretty radical. 62-63cm top tube with 130mm stem. Normal setback of 7-8cm.
So he is shorter than me, but needs a frame that is 3cm longer. I could never ride a 62cm top tube with a 130mm stem.

We checked and double checked the measurements and did them twice. so nothing should be off.
Could there be a glitch in the calculation formula? has anyone got similiar results with just small differences in body size and proportions.

acckids

I tried it recently and I would have to stretch out and lay on my belly on the top tube to reach the handlebars. The numbers made no sense.

fa63

I played with it a while back and it doesn't work for me either; puts my saddle too low (by about 2 cm) and my saddle too far forward (I run 10.5 cm setback, it recommends 7 cm).

rpenmanparker 

OP, in your case your preferred greater setback could explain all. With greater setback you need lower saddle, so once you have changed the setback suggested by CC, it makes sense that the saddle height is also different (lower). And this may be controversial, but many of the measurements are very difficult to get just right. So a cm or two off here and there is only expected. For example, exactly how tight up against the pubic bone? Where exactly does that bone or joint start that you have to measure from? Do you have fat padding the bone or joint to cause error in the measurement? The calculator is supposed to be a starting point, not a universal directive. As for your friend, you don't mention whether he has a nominally different build than you do, you know, longer legs but shorter trunk, or long arms, etc. What differences in bike size between the two of you would a casual observer expect besides just a shorter seat tube?

topflightpro

A small difference here and there can lead to a huge difference in fit. For example, my wife is just a half-inch shorter than me, but rides a full frame size smaller with completely different bar position and reach.

Also, the Competitive Cyclist calculator is a good estimator of fit, but it is not perfect. For one thing, it relies on you to take accurate measurements of your body, which if you are by a little bit, can throw off the calculations.

Flexibility can also affect fit tremendously. The CC calculator kind of takes that into account with the three different fit options, but again, that is not based exactly on individual flexibility.

vesteroid

I am 6' 5" and am comfortable on a 59.5 tt with a 120 stem and a 60 tt with a 110.

I dont need the crazy setback you do either. Not sure what my cycling inseam is but just wear standard 34 pants.

SpeshulEd 

I would double check the measurements. It's a calculator, put junk in, get junk out.

Also, a competitive fit is going to be on the small side, that's the point.

Looigi

I'm an very average 5'9" 34" bike inseam and find the Wrench Science fit calculator generates a fit very close to what I already know works, unlike the CC calculator, though I bought my bike from CC.

Fiery

Competitive Cyclist generates a very short fit for me, 3+ centimeters (2+ inches) too short. Saddle height they recommend is OK, setback around 1 cm/0.5 inches too short. Funny that Wrench Science is also mentioned, they give me a fit that's too long, though not as far from what I'm riding as Competitive Cyclist.

CC has definitely not changed their algorithm recently; I've just entered the same numbers I used a couple of years ago and I got the exact same results.

CrankAndYank

Check your measuring tape. Some of the cheap ones can be way off.

spectastic

I'm 6', and both fit calculators, one of them being competitivecyclistfit or something, that I've used says I belong on a 52 cm frame with a 58 cm top tube and 13 mm stem. That can't be right...... I did the measurement myself, but it shouldn't be that far off. Will double check the tape measurer isn't stretched or anything.

TrojanHorse

I'm just going to guess here that anybody who is that far outside the "norm" for cyclists bodies is going to have trouble with a measurement system that relies on averages. 6'5" is definitely going to be on the skinny end of the bell curve.

spectastic

It's more of a body proportion issue. And the calculators make a lot of assumptions - all calculations like that do. I'm just going to go with my gut feeling of 56 cm, even though I'm supposed to be riding a 58 or 60.

Looigi

FWIW. Both calculators use a lot of measurements, 8 in the case of CC and Wrench Science. These include the lengths of: inseam, trunk, forearm, arm, thigh, lower leg, sternal notch, and total height. They give specific instructions on how to perform each of the measurements. Taken together, these measurements account for variation in length proportions. The calculators use these measurements and straightforward geometry to put you into a given nominal position on the bike with pretty good accuracy. (CC offers three choices of fit, I believe). It would take observation of you riding in that position, or prior knowledge of what specifically works for you to improve upon it, IMO. Such things as flexibility, bar position preference, fitness and core strength, riding goals, etc. all come into play at that point.

A "pro fit" starts with measurements and setting up a nominal position pretty much in the same way. It then continues with the second part of interviewing and observation, and then ideally follow-ups periodically after that as your fitness and preferences change.