Hey

The 170/178 isnt referring to front and rear travel, its referring to rear travel being 170mm in 29er and 178mm with a 27.5 wheel. It runs a 180mm fork, pretty sure that part is non negotiable, although maybe you could run a 190mm if you wanted?

You can see a better pic of the down tube sticker on the first page of this thread

Its the same category as the first Teewing ebike

In Andi's test i think he referenced running a 170mm fork (maybe by mistake?) and he got a fair few pedal strikes and switched to 180mm and all was fixed.
I've asked the new aussie distributor (Pushys) if they are planning to offer frame onlys of Teewing bikes, havent heard back yet.