Detecting threshold on force gait data

Hello,

I am analyzing data from an old Treadmill and it is quite noisy. I am using a 50-N threshold to detect the beginning of the gait cycle, which is not working on this data set because between each strike there are usually two bumps on the data and it is often above 50 N. Would anyone have any suggestion on how I can overcome this issue? I am posting a figure and an example of my data (please, note that commas instead of dots might appear as decimal separators as I am using a German computer) to help you understand what is going on. Any help would be very much appreciated.

Best,

Felipe