This applies to both the forces and the external conditions that act on our gear hub. Experience has shown that the stress on bike components is particularly high in winter. And it is these requirements that we have focused on in our latest series of tests.
Freestyle in the test program: 3X3 NINE in the freezer check
Icy temperatures, moisture, mud and the material-eating salt used by winter road maintenance services can really take their toll on gears, chains and belts. We know that our gear hub can easily withstand these common impacts. But what if it were to freeze completely? What if it was exposed to extreme temperature fluctuations? To find out, we literally shock-froze the bikes to minus 25 degrees and then thawed them back to room temperature in a very short period of time. A temperature difference of over 40 degrees Celsius in a very short period of time pushes materials to their physical limits – keyword: thermal expansion.
Large temperature differences can lead to considerable component fluctuations, e.g. due to the thermal expansion of different materials. In order to really determine whether or when the 3X3 NINE is affected by extreme temperatures, it went on the roller trainer for long test laps both after shock freezing and after thawing. The gear hubs were then tested for proper function, e.g. with regard to shifting or freewheel behaviour. Conclusion: Our 3X3 NINE can even cope with huge temperature differences in a short period of time – so winter can come!
The Bowden cable in the ice jacket
It’s not just the derailleur itself that is exposed to extreme weather conditions. The connection between the rotary shift and the gearshift control via the Bowden cable also has to withstand a lot of climatic and mechanical stress. We therefore also wanted to find out how the Bowden cable reacts to the permanently icy temperatures in the cold chamber. To do this, we flooded it and also shock-froze it so that it was completely iced in. Here too, our test results were positive. The shock-frozen Bowden cable shifts just as precisely and flawlessly as when it is defrosted again in no time at all.
The “duty” in the test program: winter endurance tests
Our 3X3 NINE is particularly popular with bicycle courier companies. Because this is where the pedals of the mostly electrically powered cargo bikes are put to the test. Some of the most powerful cargo bikes can carry loads of up to 150 kilos and have to prove themselves in tough city traffic. Our “endurance test cargo bikes” are travelling in Amsterdam, for example, which gives us an insight into the long-term effect of the typically salty, humid air of a coastal city on our gear hubs. The knowledge we gain from these endurance tests and the feedback from our customers gives us valuable insights into the merciless effect of the combination of moisture and salt on the various materials.
Endurance tests are also running in other major cities with bike delivery services, which can hardly save themselves from orders, especially in the run-up to Christmas. The components are used almost around the clock and are therefore exposed to the conditions of a typical city winter with its mix of frost, snow, rain and unexpectedly mild temperatures. Here, it is particularly important for us to find out how permanent continuous stress from heavy loads affects the hub and its components. The cargo bike riders constantly demand maximum performance from their material in order to be able to keep to their tight time frames.
The conclusion so far:
Our 3X3 NINE are made for the tough demands of inner-city cargo bike logistics and many other extreme applications.