Originally Posted by
Little Darwin
As I recall reading in relation to the mixte style frame, the mixte was originally developed due to the fact that step through frames were susceptible to bending seat tubes...
i would agree that the mixte is much more rigid, just by virtue of dividing the rear triangle into two triangles. i never understood why the traditional ladies' frame design didn't include an extra tube segment (even if with very narrow tubing), similar to the mixte, to prevent this "kinking".
Originally Posted by
cudak888
First pic: Fine.
Second pic: Big-time kinked.
If your wife's Sports frame looks like the latter photo, I wouldn't use it for heavy duty work. A mixte frame would be a good starting point, or a conventional diamond frame instead.
-Kurt
i'm glad my suspicions are confirmed by someone else. she needs a step-through because with baskets all loaded up, she doesn't want to have to have to hurdle her leg over a diamond frame. perhaps a mixte is a better idea, indeed. in reality, her sports frame looks somewhere in between the two examples i posted... not quite as bad as the second photo, but visibly still kinked.
another question regarding force distribution: that kink is probably caused by the weight of the rider, most of which is between the front and rear wheels. that joint is what prevents the bike from folding up at the BB. but if she were to carry loads in baskets, that weight would be directly over the wheels, and wouldn't contribute to the force that that joint has to resist, right? would having 25 extra pounds over each wheel really increase the stress at that particular joint?