Footballus vita est
Join Date: Jun 2002
Location: Portland, OR
Bikes: Trek 4500, Kona Dawg
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I don't see 20mm more travel putting hardly any more stress on the headtube! I do see it affecting the angle of the head tube....
It does have some effect, whether it's enough to matter or not I don't know. The headtube is design to take REALLY big axial (along its length) stress, but only medium sheer (perpendicular) stress. This also affects the steer tube and is the result of the head angle. If you don't see it, try to sketch it out and imagine in what direction most forces are applied. It can also be calculated using trig.
Sorry, yet another engineer who's gotten his hands on a bike.
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