531colin wrote: body measurements are a poor guide to bike fit, flexibility and functionality are key.
Interesting post as always colin. To pose a possibly crude/missing the point question, does this mean that all those bike fit experts with their measurements and jigs are a distraction and that the best approach is for the rider/buyer to just sit on/test ride a load of bikes and see which, subjectively, "feel right"? And compare some key measurements on those tested bikes to the same key measurements on long ridden bikes they know they feel good on?
Honest question/s, not trying to put words into your mouth.
Consider something as "basic" as saddle height.
Read Steve Hogg here....https://www.stevehoggbikefitting.com/bikefit/2011/05/addendum-to-seat-height-how-hard-can-it-be-2/
Now Steve is using a turbo trainer with the customer's bike set up, and video cameras to the side and front/back. ....I can see a use for all that, but i would need a technician to work it for me!
I really can't see what Steve is looking at when he talks about "a small acceleration in the extension of the knee", but i'm prepared to accept that he can see something I can't see..
However, when he switches to the other view, then its blindingly obvious whats going on.
Notice that Steve never mentions the included angle of the knee, or the ratio between the length of the rider's leg and the saddle height. But he does mention that as he lowered his customer's saddle, the customer went from being a "toe-dipper" to a "Joe Average" pedalling technique.
I don't have any "equipment" at all to do bike fits, other than a selection of stems and seatposts. However, I can ride with somebody and see what they look like, and I can tell you how i think riding should "feel".....the saddle should be low enough so that you have a "safety" bend in your knee with the pedal at the bottom, so you will be smooth "through the bottom" on your worst day, when you are tired and stiff. Why a "safety" bend? Because if you are rocking your hips or standing on tiptoe just to reach the bottom pedal, you are just one step away from over-extending your knee.
I can tell you that if you are forcing the gear (pressing on in the same gear up a rising road, instead of changing down/slowing down) and you want maximum power at low cadence for a short time, you should be able to slide back in the saddle and get greater knee extension at low cadence. If sliding back a bit means you are reaching for the bottom pedal, the saddle is too high. If you are off the back of the saddle and still pedalling smoothly, then its too low.
I can tell you that the saddle should be set far enough back that you have very little weight on your hands, and if I find myself sitting on the cantle plate at the back of the saddle, it means the reach is too short, it doesn't necessarily mean the saddle is too far forward.
I think if you go looking for a bike and riding lots of bikes, you will pick the one that feels like the bike you are riding now....this may or may not be a good thing.....
People I ride with tend to come to me when riding their bikes is painful, and I think a professional bike fitter will have the same experience.