The current formula (P3 Heavy to P4F1 bikes for example) is a fixed number of laps (5) to the handicapped bike (P3) converted to mileage.
I will set aside the problem with the arbitrary amount for a second and deal with the calculation first.
The handicap does not take into account the amount of red flag time. For example, a 5 lap head start on a race where the winner runs 50 laps is 10%. A race with a 1 hour red flag means the handicap is 5 laps when the winner runs 25 laps. This represents a 20% handicap. The longer the red flag the more the advantage is the handicapped bike.
Suggestion 1. The handicap is prorated to the length of the actual green flag race. Eg. 1 hour red flag, handicap is 50% of full race handicap.
Second issue is the handicap does not distinguish between different tracks. EG. at Calabogie a 5 lap handicap is 11.5 minutes at 2:20 lap time. (In terms of % this is 9.6% of full race) At Mosport the 5 lap handicap is 8.33 minutes based on a 1:40 lap time. (In terms of % this is 6.9% of full race)
Suggestion 2. The handicap is calculated as a percentage of time converted to mileage. EG 6% handicap x green flag time (Per suggestion 1) x your completed mileage. We use your completed mileage because it makes little sense to run 1 lap and get awarded a percentage of the guy who finished 70 laps.
Finally, the amount of handicap. A set number is arbitrary and does not take into account actual race times at each track.
Suggestion 3. For 2019 we do an analysis of the top lap time for the top 10 riders in each sprint race at each track. Averaging and comparing these lap times to each class will produce a true differential. Other than an anomaly where one class had dry track and an hour later the other class had a wet track, the conditions and all other variables would be consistent.
So using P3/P4F1 as an example, if the P3 top 10 best riders lap at 2:25 and the top 10 best P4F1 riders lap at 2:18 then the calculation would be 7 seconds on 2:25 or 4.8%
This would be the handicap for Calabogie.
Apply the same analysis for Mosport would give the handicap for that track.
Apply the same analysis to all classes and you have a handicap amount that is objective and verifiable.