I working on a hypothesis a hypothesis, which is based on simple physics. To what extent are standard shibari ties suitable for the heavier person? What we see mainly as our reference point of what is 'standard' is lithe young Japanese girls, who on average must weight about 110lbs/50kg (under 40kg if it is Ageha). The rope is around 5mm-6mm. This gives a contact patch 20mm-24mm wide, assuming that most suspension ties will incomporate wraps made of two turns of doubled rope, i.e. 4 x width. Admittedly, the length of the contact patch will vary due to the diameter of the body part tied.

Thus, in suspension, the forces (F) we are concerned with for nerve impingement etc. are width (CPW) x lenght of the contact patch bearing the load (say about 25% of the diameter of each arm in a T-K suspension) (CPW) x the subject's weight (SW). Thus, F=(CPW x CPL) x SW. If the weight of the sub doubles, F=(CPW x (CPL x X)) x (SW x 2), where X = the factor by which the length of the contact patch is increased by the longer contact area. To what extent will F increase in relation to SW? How much will the increase in CPL, due to larger body parts, mitigate his effect?

In simple terms, given the same number of suspension points and thickness of rope, how many extra wraps would be required to replicate the pressures on a standard Japanese model if yours is twice the weight? Clearly, if one keeps the points/wraps constant, the loads will increase with the weight of your sub. Thus, it is probably a mistake to do a standard two bands of two wraps on a 100kg model. It might be obvious but how many people try to recreate the same configuration unmodified without considering the physics?

NOTE: I never studied physics and failled maths a record breaking number of times, so I might have made a mistake or be talking Guests cannot see images in the messages. Please register for the forum by clicking here to see images. I'm quite happy for any closet Einstein's to correct me or refine this formula.