Thanks JimT,
That app, Bubble Level (spirit level) is perfect.
Now i know that my limit of hill climbing with the KH36 with 127mm cranks is 17.26% grade.
The local street I’m trying to acsend has a 3 meter (10 foot) section that currently eludes me due to grade. I have been attempting it a couple of times a week.
To measure average percent grade over longer distances there are a couple options:
Acquire the elevation above sea level of the start (S) and end (E) points using either an app (My Elevation is one of many) or a calibrated barometric altimeter. Measure the distance on the road (D). Then do some math:
V = E - S
V / SQRT(D*D - V*V)
Multiply that by 100 to get percent grade.
Another method is to get a GPS track of the route. Use GPS Visualizer to make a profile of the track. Be sure to select for “Add DEM elevation data” the option “best available source”.
Note that elevation values from raw GPS itself are notoriously bad.