Graduate engineer Dirk Zedler - publicly appointed and sworn in expert for bicycles and electric bicycles
MYBIKE: What are the pitfalls of a low step-through frame compared to a diamond frame?
Similar to a timber-framework the centuries-old principle is a lucky find. Every frame tube omitted reduces the riding stability. In the case of a low step-through frame the front frame area can move more easily compared to the rear area. Designers must give much more thought to stiffness and durability.
Are there differences between classic bicycles and electric-assisted bikes?
Electric-assisted bikes are equipped with heavier components, cyclists take more luggage with them and the drive unit brings more cyclists in hilly terrain at faster rides. Users of electric-assisted bikes also prefer an upright position on the bike. The requirements are therefore significantly higher with electric-assisted bikes. A battery mounted to the pannier rack is therefore extremely questionable. With a battery mounted to the central or down tube, behind or in front of the seat tube, the electric-assisted bike rides clearly better.
How is frame stiffness related to headtube wobbling?
This can be demonstrated with the intube batteries of low step-through frames: Some manufacturers only cut open the tube to integrate the battery. The down tube offers then hardly any torsional resistance. Even if everything else fits, there is a certain uneasiness of the chassis at low speeds already. Handlebar wobbling as a phenomenon, but also the dangerous riding instability when riding downhill, for example when changing the direction, are not only irritating, but also result in accidents.
How can I be sure when buying a bicycle that my desired bike with low step-through entry also offers sufficient riding safety?
The method “looking closely” is not enough. However, MYBIKE tests in which the riding stability is measured and rated during test rides help a lot. In addition, I can only advise to go on a long test ride with an adjusted seating position and definitely with luggage. It is especially the latter that sorts the wheat from the chaff.
Author: Jochen Donner
Photo: Daniel Simon
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