Quote:
Originally Posted by Mark McM
Clearly, all the components in the system flex to some degree - tire, wheel, fork blades, crown, and steerer. Jan Heine's test does show that there is some flex in the fork blades. but it also shows that this flex is small, and that there is far more flex in the rest of the system (particularly the tires). ...
While Jan Heine's test shows that there is some flex in the fork blades, it doesn't answer how it compares to flex in the crown/steerer. To do that, he could have mounted some type of indicator arm to the steerer tube to compare to the arm attached the fork tips, to compare the magnitudes of the total flex in the fork to the magnitude of the flex in the blades themselves. Without that, he has only shown that there is some flex in the blades, but hasn't shown how significant it is.
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Sure, he could have done a lot of things to compare with flex in other places. But he wasn’t out to do that. He demonstrated pretty convincingly what he set out to show: fork blades flex, and not an insignificant amount if they are of a certain design. Note that the low rider hoop rises about 3mm as it gets closer. That is pure vertical deflection, and not "amplified" through a large radius. And to my eyes, the video does not show there is "far more flex in the rest of the system". But that is beside the point. Even if flex at the crown is significant or greater, the fact is that fork blades do flex, thinner blades will flex more, and curved thin blades will flex more still. Most of us can feel very small amounts of frame flex in the ride. One bike has "all day comfort" while another one beats us up. Those sensations are about very small amounts of frame flex. And here we have a not insignificant amount of flex right where it has the most influence on the ride.