Hi I’m poundering on the shape of the piston rings from my 29 flyer.
Is has a concave curve on the internal edge of the piston ring. Is it to keep the stress profile the same around the circumference and therefore keeping the wear circular ? and why is the end ground to an angle of 30 degrees ? It is of no consequence because I’m going to take Rodger’s advice and reengineer the piston and rings to take Triumph 5TA rings, but I’m interested to know the thinking behind the design, any thoughts ?