Percentage of grade - gotta love these hills!

[mudmucker]

This is interesting...thanks, mudmucker, for the USGS info. I did notice that Map My Ride comes up with different results based on whether you make lots of points/clicks on the way up the hill versus just clicking at the bottom of the hill and again the top of the hill (I hope that made sense).

Actually I was just speaking of USGS data in as general terms sort of answering Mr. Silver too, since he mentioned using his county GIS data. Plus my head was in geek mode. I found and read the FAQ on the site later. And, different web mapping sites probably use different algorithms and treat the data differently. Here is a piece in the help section for mapmyride:

We report ascent and descent stats for routes when they become 'significant'. This is currently set at about 60 meters of total climb. We can't guarantee a great deal of accuracy for routes with ascents < 60m, so we don't want to confuse our users by displaying inaccurate data. For long ascents, you should see your stats appear the the right of the elevation profile.

Our ascent and descent calculation algorithms don't count every small elevation change at every point because we need to filter out 'noise' in the underlying data. Prior to our latest algorithm change, we were reporting ascents that were in many cases too high. Our new algorithm gives more reasonable results for a wider variety of routes. However, since we know that this isn't 'perfect' quite yet, we've provided the raw data in CSV format so that users such as yourself can interpret the data as you choose.

Take that with a grain of salt. I am assuming you are doing rise over run or using the percentage readout over the elevation profile info (to answer the previous post) to assess grade. So there is another level of inaccuracy based on the way mapmyride uses the elevation data.

Whatever, if your front wheel wants to come off the ground, then you are on a mighty steep hill.

[OakLeaf]

Mapmyride uses contour lines that are spaced pretty far apart. I want to say 50 ft or maybe even 100. In country like mine, with a lot of short steep hills, my Garmin registers about triple the climbing that mapmyride projects... and there are a lot of local riders who swear that Garmins underestimate climbing by about 10% compared to careful measures on specific hills.