Originally Posted by
GhostRider62
Interesting comments, unfortunately most of them are made to statements that I did not make. For instance, I did not say, "Fitters who don't measure angles are still measuring angles" ....I said, "
They did not measure a single thing on me...." meaning they did not care about static measurements like distance from tailbone to floor or length or arms, etc. Not a single static measurement.
WRT foot length, toe angle, and cleat mounting position, it most certainly matters at the top of the stroke although not as much at the bottom of the stroke. Like most fitters, you are wrong.
I'm glad you have a decade of experience.
You are 5'4''. When you get to be more like 6'4'', you might appreciate why 73 degree can be and is often a bad starting point. Pinarello and Trek for instance do understand that, they have more like 72 degrees on big bikes. That was my point. Obviously, some prefer to be more over the pedals and might have a shorter torso.
You are telling me the back half is different from size to size? Interesting. The STA is identical as are the chainstays on all three of these very popular bikes. Are you not aware how costly molds are or that using the same mold for the back half saves a lot of money? Or that manufacturers don't like to save money.
https://www.canyon.com/en-us/product...etry/?pid=2893
https://www.cervelo.com/en-US/bikes/s5
https://www.bmc-switzerland.com/intl...c-grey-23.html
Okay, try this again:
Fitters generally don't take static measurements. I don't. However, I have had occasion to compare inseams to the final product and found that the .883 or 109 formulas tend to come out within 1cm of where the fit process using knee angle observations tend to put most riders. To me, that validates a home fit using those formulas - not fitters.
No one seems to be overly concerned with the top of the stroke, otherwise they wouldn't ignore it by lowering the saddle to match longer cranks. Anything can effect the pedal stroke, but your insinuation that foot length has an obvious and predictable effect on saddle height in particular doesn't match the reality. Someone moving their cleats far forward or aft is going to move their saddle set back accordingly, just as someone with a short leg is going to fix their saddle to pedal height on the one side with a cleat spacer. This part fit is elementary arithmetic. There is no "My feet are size 12, therefore my seat needs to move X." Foot size and the like might be factors in fine tuning, but not gross metrics.
I don't have a decade of experience. Please read again.
Trek has 72 STA on big bikes and 76 STA on small bikes. The small bike numbers are especially insensible. I've fit plenty of tall riders and there doesn't seem to be a trend of needing more proportional set back than anyone else. Small riders certainly don't need less, and are often screwed by companies like Trek faking short top tubes with steep STAs. Seat tube angle is better fixed because a triangle with the same angles is proportional. Tall riders don't have different proportions, and when you are tall more of your butt is going to be behind the crank automatically, just like you have more in front. You are making it sound like tall people don't scale up from shorter people. They do.
I already said that a few companies do or did use 73 STAs as a matter of choice, not cheapness. Cannondale did so in the '80s on their aluminum frames that were hand made and didn't benefit sharing parts, and Cervelo was the other company I was thinking of. Since Cervelo's have had seat stays that are whatever angle required to match the height of the seat cluster, clearly the whole back end is not identical because sizes change that angle. So you're barking up the wrong tree - especially if you saw the sub-frames that bikes are typically assembled from - the size specific angles are built into parts - like a BB that has the chainstay, seat tube and down tube ends sticking out 8" in each direction. So you have observed a trend in geometry I happen to like, and drawn the wrong conclusion about it.
As I said, tall people and short have relatively the same proportions, and therefore require similar postures on the bike. Taller people need more reach, but they automatically get more set back, so proportionality takes care of both.
Keep in mind that the difference in formulas and fits isn't that of broad trends - they both produce fairly similar overall riding postures when applied to symmetrical people with normal flexibility, For those folks, the fitting process both arrives at the same basic posture and adds refinements for even greater comfort and efficiency. This is similar to how a custom suit fits better than one off the rack, but both are still roughly size 44.
For people with asymmetry, atypical proportions and/or injuries, the fit process is hugely beneficial because it safely adapts the cycling posture to what their bodies can do. And sometimes that means a custom frame, because just moving seats and stems will never address the issue alone.
For people with alternative theories about cycling postures (like having your cleats full forward or aft), fitting isn't going to automatically validate your theory by automatically putting you where the hot new trend says you should be. Fitting just provides a framework to take what you want to do and make that as physiologically sound as possible. Fitting isn't really part of the ridiculous wheel-reinventing that has people buying 180mm cranks and then a decade later 160s, or using zero set back posts, or slamming their cleats all the way back, or using oval rings. Those are just fads that come and go. Meanwhile the way people sit on road bikes remains about the same as Major Taylor's fit 120 years ago. That's why road bike geometry hasn't really changed in at least 50 years, except that there is now a much greater range of head tube lengths.