Knowledge base – Drive trains 2. (vivax assist)

We presented in the last post the drive train method of the middle motor. Let’s continue with that; check out the “invisible” middle motor! 

Maybe you didn’t hear the product name “vivax” before, but the predessor’s name “gruber assist” sounds familiar to the ebike experts. The German manufacturer was founded to produce ebike kits in 2005, and the first product was announced in 2007. The engine is special, as it is hidden into the seat tube. The product was revised couple of times. The last version called Gruber Assist 3.15 and its biggest improvement was to reduce the noise of the quite loud motor. The engine is lightweight of 900 gr, and the 30 V 4,5 Ah battery weighs only 1 kg.

Parts of Gruber Assist - works quietly

The operation can be followed on that video:


The company announced this September the new product name “vivax assist”. The concept has been not changed; the different is the easier montage and the redesigned engine. You can build this into any bicycle – they say.

But how is it exactly working from the user point of view? You have one red button on the handlebar. If you push that shortly, the engine will start (or stop), and will try to reach the preassigned cadence, which can be set between 30 and 90 rounds per minute. The system extend our pedaling energy, so if we use less muscle power, the engine will support us more. If you push the button for longer time, the system is taking the current speed of the crank as new target. Plain as pikestaff, isn’t it? 😉

The engine is not too strong and the support can work for 60 minutes longest, but you have an invisible and lightweight support engine, which could help to build lightweight bicycle too, like this nice Steinbach Lodron, which is under 10 kgs: