Originally Posted by
fietsbob
Locate pictures from the actual Inspection ..
I was somewhat skeptical, but this motor is now available and will fit in a 31.8 seat tube.
While not completely hidden as it comes, it could certainly be hidden by a competent mechanic.
vivax Assist, Gruber Assist E-Bikes (Fahrradantriebe, Elektrorad )
The special design of the drive unit allows it to be built into any bicycle frame with the requisite seat tube internal diameter of 31.6 mm or 30.9 mm and is therefore invisible on the bicycle – except the on/off switch, which is unobtrusively located on the bar end.