What in the world is average speed?

By Gordana

We all know that Venus de Miles Bike Club is a fabulous and supportive biking community. The word is out, the club is growing, and weekend rides are offering choices of distance and speed. For example, a 25-mile route may have three groups, “one going at 12, one at 14, and one at 16+ mph average speed.” The goal of dividing riders into groups based on speed is to allow for a more enjoyable and coherent ride for everyone. If you are thinking to yourself: “what exactly do they mean by ’14 mph average speed’?” or, perhaps more pragmatically: “which group should I ride with?”, you are not alone! Read on for tips and definitions that will help you pick the best group for you.

First, some definitions:

1. Average speed, as measured by bike computers and similar devices, is a time-average, NOT a distance-average, of riding speed. For example, if a rider is climbing a 10-mile hill at 10 mph, it will take her an hour to reach the top. If she then descends that same hill at 20 mph, it will take her 30 minutes to reach the bottom. A reasonable person might expect that this rider’s average speed was 15 mph, but bike computers do not think like a reasonable person. The average speed that a computer would report is (1h*10mph+0.5h*20mph)/1.5h = 13 mph. In other words, slower riding “counts for more” in the average speed.

There are two important consequences of this definition: (a) average speed on a ride that includes a lot of climbing and descending is usually lower than the average speed on a flat ride. For example, a rider who achieves 15 mph average speed on a ride to and from Hygiene may average 13-14 mph on a ride to and from Jamestown; (b) because of coasting, slowing at traffic lights, etc, average speed is usually lower than the speed one rides on flats. For example, a rider who is breezing by at the speed of 18 mph on the flats may find her average speed for the ride to be 15 mph.

2.     For the purposes of the club rides, the designated speeds refer to the average speed a rider would achieve on a relatively flat ride, such as the route to Hygiene via country roads, with no drafting or severe winds. Depending on amount of climbing, wind conditions, whether there was a club happy hour the night before, and so on, the actual average speed achieved by a specific group can vary week to week, even if all the riders are the same. So the “14 mph” group may average 12 mph on a route with a long climb, and 15 mph on a flat ride with tailwind in every direction (hypothetical scenario; it has been scientifically proven that there are only two kinds of wind: headwind and sidewind), but they remain the “14 mph” group. As you can imagine, this is not an exact science, and sometimes a group will go faster or slower than expected. As the season progresses, riders get familiar with each other and the groups somewhat settle into a rhythm. Note that in club ride announcements the words “pace” and “average pace” are sometimes used interchangeably with “average speed.” It is worth reiterating that a group designated as “X mph” will be moving faster than X mph on the flats.

OK, now that we have the technicalities out of the way, here are some tips for joining the right group for you:

–       If you are not familiar with the club or not sure how fast you would like to ride, it is best to err on the side of going slower. If you find that your group is going much slower than you would like to go, you can always join a faster group next time. Many of us know from personal experience that chasing a fast group can be a great workout, but it may not be very fun! The weekend club rides are “no drop” meaning that nobody gets left behind. Group leads and sweeps normally have a way of handling mismatches in riding speed. However, in the interest of fairness, it is our responsibility as riders to try our best to pick wisely. If you do find yourself in over your head, it is not the end of the world. Most of us have been there! Let your sweep know that you’re having a hard time keeping up, and she will devise a plan.

 –       If you would like to calibrate yourself to the “club average speed scale,” you can use a bike computer, GPS device, or a smartphone tracking app (e.g., Cyclemeter) to measure your average speed on a relatively flat ride (such as this Hygiene ride or this 16 mile route) under “normal” conditions (no drafting or severe wind). This is not a NIST-certified, 100%-guaranteed calibration, but it provides a great guideline. Your resulting average speed is most likely similar to the average speed designation of the group where you’d be happiest, unless you feel like taking it easy or challenging yourself extra hard that particular day.  

Final notes: The club has grown tremendously, and it is always going to be a challenge to balance the need for manageably sized groups with the need for trained leaders and sweeps. For the club rides, it is helpful to be somewhat flexible about riding speed and go with the flow. The leaders do their best to set the right pace, but remember that they are human and are volunteers. So, above else, remember the two most important club rules: RIDE SAFELY and HAVE FUN!