What makes the bicycles in Amsterdam suitable for riding with jeans on? What makes the bicycles in Amsterdam suitable for riding with jeans on?

The Dutch are known to wear regular clothes while cycling rather than cycling specific clothing.



In cycling forums, people often say that jeans are uncomfortable for cycling especially in the rain. When jeans are wet, friction increases which can cause chafing and increase the wear and tear on the jeans and the saddle. The Dutch must have a way of wearing jeans comfortably since regular clothes include jeans. Cycling friendly pants tend to be silkier and thinner so that friction decreases, and more flexible so that there's less pressure on our perineum. Even with a saddle cutout, the seams on jeans can put too much pressure there.

I'm thinking that these are the possible factors:


Saddle height
Saddle setback
Upright posture 
Cadence
Power
Coasting percentage
Saddle shape
Pants sold in the Netherlands tend to be more cycling friendly such as
jeans with softer seams
The commuting times are too short for the discomfort to develop


Also, can you have a fast or powerful human powered bike that's jeans friendly? Like hybrid, cyclocross, MTB, and road bikes.

Someone who's into fitness and speed, bikes to work, and wouldn't want to carry an extra pair of pants would be interested in getting that answer.
In places where there are lots of bikes, most people who are riding them are making short journeys purely for transport. For a short ride of a few kilometers, it really doesn't matter what you're wearing. Any clothes that are comfortable to wear in general will be comfortable to wear on a bike for fifteen minutes.

People who are riding longer distances, pushing harder and aiming for fitness rather than just getting from A to&nbsp;B will start to consider clothing that's more oriented towards exercising and people who are going even farther and pushing even harder will start to wear cycling-specific clothing.

I see this exact thing when I cycle at home in Oxford. If I cycle directly into town, most of the people I see on bikes are just wearing whatever clothes will be appropriate at their destination. If I take a more circuitous route around the outskirts of town before heading into the centre through an area where not many people live, I see a lot of people wearing "general exercise" clothing. If I head away from town, out into the countryside, most of the cyclists I see are wearing clothing designed specifically for cycling.