Replacement bump stop for zipSTOP Brake Trolley. The Bump Stop is considered a sacrificial part that is designed to wear out over time and require replacement. The time it takes a Bump Stop to wear out will vary greatly between facilities and depends many factors including throughput rates, weather, reduction line ratio, rider trolley type, incoming speed, etc., but can be anywhere from 1-6 months. There is no way to calculate the exact life expectancy of the Bump Stop due to the individual nature of each zip line, and we recommend purchasing additional Bump Stops at the time of ordering your zipSTOP to prevent your business from experiencing any downtime during the replacement process.