The grading method we use is based upon a notional calorie count for the route: the more calories used the higher the grade for the cycling.

The Grading Calculator is available as a spreadsheet, <click here>. This calculator will work on most computing devices that will run Microsoft Excel 2010 or more recent. The algorithm used in the calculator is specific to the values established using Google’s mapping tools. There is also a grade chart at the bottom of this page that has been produced using our Grading Calculator for a range of distances and height of ascent.

The algorithm used in the calculator emerged from the analysis of many hundreds of cycle rides over a range of distance and difficulty. I use a Garmin Edge200 GPS as my reference, and with it I have measured the ascent figures for a large number of rides, the results of which are then compared with the ascent values predicted by Google Earth.

A predicted grade for a ride cannot, obviously, include actual GPS measured values. The biggest problem is estimating the height climbed – all mapping systems and software have unavoidable disagreement when establishing a value for height of ascent and decent for a cycling route – a few minutes research on the web will explain the difficulties. In Cyclac, using Google Maps and Google Earth, I have found the height difference between Google and my Garmin Edge200 GPS conforms closely to a normal distribution with a standard deviation of ~190ft for distances in the range 10-miles to 46-miles. In all cases my question has been how to best bring the estimated climbing using GM and GE into line with my direct measurement using an Edge200 GPS.

Google Maps provides tools to plot routes and Google Earth can takes these routes and quickly provide a value for ascent and decent. Distance cycled and measurements of ascent are the two most important figures for grading a route. How these grades sit subjectively with the individual cyclist is down to the cyclist: an elite cyclist will have a completely different view to that of ‘ordinary folk’ (the likes of Julie and me). Therefore our cycling grades are for casual hobbyist cyclists, and try to express how much effort we feel for the cycle ride.

We grade the rides: ‘A’ (ambling), ‘B’ (bearing), ‘C’ (challenging), ‘D’ (demanding) and Ex (extreme). Each grade letter is further refined by: mild, average and hard. And the extreme grade has three levels: 1, 2 and 3 – the hardest cycle ride we have ever done provided the boundary for grade Extreme: Ex1(75W). The ride was completely exhausting! And neither Julie nor I can imagine ever doing anything harder. I’ve included Ex2 and Ex3 as extrapolations on the grading system – if you ever do a route greater than that, please let me know.

How hard a bike ride is ‘on the day’ has other factors: was it windy, were you pushing hard to test yourself, etc. Therefore the grading system assumes no wind and an average 60Watts of power used during the bike ride (60Watts is around 250kCal of exercise per hour for the average person). The bike itself is also a factor: we assume gearing of ratios you get on mountain-bikes and hybrid-bikes – in other words, rarely do you have to be out of the saddle to push yourself uphill.

Roads in the UK have a large range of ascent verses distance, but averaging around 50ft per mile. At 50ft/mile cycling power of around 60Watts ‘feels’ right. However if the average height -v- distance becomes greater than approximately 80ft/mile, then 60Watts is not high enough a power to ride the road – elevated power is needed, and the grading system takes that into account.

Below is a chart for cycle rides between 10 and 46-miles and using Google Earth for estimating the height ascended. The colour coding depicts the average power with respect to distance and ascent. Salmon colours and red are harder than 60-Watts rides, where red are rides require more than an average 100-Watts. For example, 20miles with 1500ft of ascent, grade mild-B, will most likely average 60-Watts. At greater ascent figures for the 20miles example the effort will increase: at 2800ft of ascent 85-Watts will most likely be the average power, making an otherwise mild-B route into a hard-B(85W) – bordering on a Challenging grade.

The green routes are easier (lighter the green the easier), the salmon coloured routes are harder (the darker colours are harder) and the brown and red routes are, potentially, very hard.

“Beyond pain there is a whole universe of more pain” Jens Voigt, professional cyclist and broadcast commentator.