These are the flat rickshaws which carry "affluent" passengers across the river in low-tide conditions. Every-day commuters do not use these but just wade across the thigh-deep mud and river. Tried it too, but two early slips convinced me to take the "affluent" carrier service.
These are called "autos" - sturdy old cruiser bike-fronts and engines fitted to flat rickshaws. Apart from these improvised carriers, I did not see any cruiser bike there. Do not laugh, but these are called "vans". I tried a lot to understand the reason, but the origin of this term was lost. I just know that the ride was one of the most enjoyable I have had.