On WSD bicycle shouldn't the seat tube be longer and at a shallower angle?

Question

I bought a WSD ("Women specify design") bicycle for my wife which was delivered in a box.

After putting it together I took it for a ride to test it and I realised two things.

The seat tube is shorter, I don't think that an angled top tube should have anything to do with it. Saddle height is important so running out of seat post is more likely with a shorter seat tube and I don't think that is a good thing, also a seat post is more likely to flex more than a seat tube.

Another observation is that the crank length are shorter, which also means that you may have to adjust the saddle further back to make sure you can apply all your leg power when the crank hits the lowest point and starts to rise.

I also thought that a women's legs, proportionally, have longer thighs and shorter legs from knee to foot, which also suggest that the saddle should be further back.

Should WSD bike frames have longer seat tubes? Should the seat tube have a shallower angle to makeup for saddle position over the crank set?

Answer 1

A few thoughts:

• moving the saddle back to compensate for a too short seat post is not the right approach. Seat tubes have a minimum insertion length mark, it's important to respect it, but as long as you don't reach it, you can move the saddle up. If you ordered the bike with the right size and you can't move the saddle high enough, I wouldn't worry about fitting a longer seat post, especially if your wife is on the light side - small size bikes are usually rated for the same max weight as the large ones (if the bike is too small, it's another issue).
• for the seat tube/seat post height difference, it's a manufacturer choice, but nothing I would worry about in absolute terms, especially on bikes that are used gently (and when things get rough, it's common to stand, so no stress on the seat tube). To take the example of Canyon Pathlite, WMN bikes have shorter seat tubes and longer seat posts, one compensates the other. For reference, the bikes that have the shortest seat tubes to my knowledge are the trail hardtail MTBs (Canyon Stoic, Orbea Laufey,...), that is probably the worst category in terms of stress on the frame: they are used on trails that normally require full-sus MTBs, but only have a front one. So it's perfectly possible to engineer strong bikes with short seat tubes.
• Personally, (controlled) seat tube flex is something I am looking for (I replaced the aluminium one on my bike by a carbon one for that reason), it improves the comfort significantly without impacting the power transfer (unlike a telescopic suspension seat post). Women are also lighter on average, so less stress on the frame/seat tube. Having more exposed length of the seat post can be beneficial for compliance for lighter riders.
• Finally, bike fit is something that is personal: for some metrics, variation within a group (men/women) is larger than between the average of the same group, so might be more relevant to see if the fit is more appropriate to one rider than the average of the group that the manufacturer has chosen (TLDR: gender-based differentiation according to their data is mostly relevant for gloves and saddles).