Find this on:
https://autorevue.at/ratgeber/e-bikes-recht-gesetz-regeln (Translation with "google translate"):
E-bikes and pedelecs: the legal regulations
E-bikes, ie electronically driven bicycles without pedal assistance as well as pedelecs (with pedal assist) are equal in terms of traffic law to "normal" bicycles.
Thus, both e-bikes and pedelecs must be used on cyclists, if one exists.
For e-bikes and pedelecs: The maximum drive power of the motor must not exceed 600 watts, also applies a maximum design speed of 25 km / h.
The rated continuous power is to be distinguished from the maximum power of the motor. This describes the performance that can be sustained over a period of 30 minutes. Lt. The current EU type-approval ordinance must not exceed 250 watts for pedelecs
If one of the above values (600 watts maximum power or 250 watts rated continuous power or 25 km / h speed of design) is exceeded, the vehicle is legally no longer classified as a bicycle but as a moped. (associated with, for example, helmet duty, driving license and liability insurance, etc.)
Also for e-bikes and pedelecs: 0.8-thousandths, calls only with handsfree. Incidentally, trailers may only be towed if a bicycle stand is also mounted on the e-bike.
Equipment: It applies the equipment regulations as with bicycles, duty are therefore bell, headlights, tail light, reflector and reflectors on spokes and pedals.
Minimum age: from 12 years you can be alone on the road, including only when accompanied by an adult or with a cycling license. Attention: Helmet required for children under 12 years.
A throttle grip (thumb throttle) is allowed in Austria!
Look also this: http://www.biketronic.at/images/biketronic/technik/gesetzliche-bestimmungen/e-bikes-alles-was-recht-ist-oesterreich.pdf
If you want to forego driving license, registration (including license plate) and helmet obligation in Germany, an e-bike must not bring more than 250 watts of engine power and the engine support must also switch off at 25 km / h. The bike path must be used, if one exists.
For more powerful e-bikes (or up to a maximum of 500 watts engine power / engine connection up to a maximum of 45 km / h): driving license of the class AM and approval (insurance license plate) are required, then it also applies the helmet. In addition, the use of a bike path is no longer allowed.