When looking for a new bike, the frame shape often gets lost in the mass of information. However, it not only determines the look of a bike, but also has a decisive influence on its area of use. However, the choice is not particularly difficult. The classic "men's frame" has many technical arguments in its favour, but if you have a child seat or basket on your bike, it is difficult to swing your right leg over the saddle when climbing or descending. Older cyclists are happy about low step-through heights because they make it safer to get on the bike. Many female cyclists don't want to do without being able to cycle in a skirt or dress. This is simply not possible with a classic diamond frame, so only a step-through or ladies' frame is an option. We explain the disadvantages of this in detail here.
Sophisticated design: the diamond frame
The traditional "men's frame" consists of several triangular constructions joined together - the optimum way to build a load-bearing, low-torsion chassis from a tubular composite. If you want to be light and stable at the same time, this frame variant is the way to go. Ideal for a fast riding style, but also for touring and travelling bikes with luggage transport. Depending on the material, tube diameter and shape, there are also big differences in the lateral stiffness of diamond frames. Rule of thumb: The more voluminous the tubes and the greater their support width at the tube nodes, the more stable a diamond frame will be.
Trapezoidal frame looks light and elegant
If the top tube of a diamond frame is lowered at the seat tube, the result is a trapezoidal frame. This shape has many variations and allows you to step through with your foot in front of the saddle instead of swinging your leg over the rear wheel onto the other pedal. The women's frame can therefore be ridden well with a skirt or dress, but also with a basket on the back. Disadvantage: low lateral stiffness due to increased torsion between the seat tube and head tube. This can impair riding safety when transporting luggage or with a child seat. It always depends on the tube quality and design, but for the same models, the women's frame is always less laterally stiff than the diamond frame due to the design. The classic "ladies' frame" or "gooseneck frame", as used on retro Dutch bikes, is even easier to get through, but also less laterally stiff.
Low entry
On bikes without a motor, single-tube frames have a bad reputation due to poor riding stability, especially with a loaded pannier rack. Lateral stiffness at higher speeds is often poor, even to the point of being a safety risk, which greatly relativises the advantage of comfortable access. At a leisurely pace and with a payload of five or six kilos, the design is justifiable.
The situation is different with modern pedelecs: since the motor and battery have been integrated more and more fully into the design, aluminium box modules are increasingly being used in frame construction: angular profiles, large diameters, thick walls - thanks to the motor, weight does not play a major role. E-step-through bikes built this robustly can therefore often easily keep up with the structurally more stable diamond frame in terms of rigidity and riding safety. These bikes are often advertised as "unisex" models and are practical when frequently getting on and off the bike or when mobility is limited.
