Can hikers and bikers share successfully on trails? - Part 2

Are you going to plaid on your trails?

In part 1 of this series , we asked  the following questions:

• Can urban trail systems share trails?
• If so, how?
• Why do some believe sharing is impossible?

This  in reference to an article from Mr. Troy Duffin of Avid Trails.  One of the reasons he mentioned for his belief sharing was hard  was that of the speeds of mountain bikers in relation to hikers.  Here is the relevant part of that quote:

​We need to accept that hikers, runners, and horses generally move at under 10 MPH (and often at 2 MPH or even slower), while aggressive cyclists often top 30 MPH. This is a massive speed differential, and creates substantial safety issues. 

Is this a true statement?  Do all trails see these type of speed differences?    Lets find out as we discuss the speeds of  mountain bikes and  why they obtain the speed they do in part 2 of  "​Can hikers and bikers share successfully on trails?"

Africa. Where all your fears were born. Except for the one about clowns.

​Travel back in human history a bit.  On the plains of Africa, most things moving with any speed toward you were doing so to gnaw on your face.  Therefore, built into our DNA, through the survivors of any face gnawing, is an internal speed limit on items we see.  Items traveling below a certain speed could be reckoned with.  Items traveling above that speed were almost always a danger and usually came with sharp pokey and chompy bits.   While few of us reading this article speed a lot of time on the plains of Africa walking among the beasts, the fact is that internal speed limit is still there, call it a paleolithic constant.  That constant is triggered when we are walking and see something coming toward us at about 3-4 times our own speed.  Even today, on a trail, if the conscious part of our brains goes, “Oh, its a guy on mountain bike”, the unconscious parts of our brains are going, “Danger!  Predator!”.

This explains why those that talk their dislike of shared trails often use terms like “nervous”, “uneasy” and “guarded”.  What they are trying to express is that paleolithic constant kicking in.  As they come across another user, in this case a mountain biker, that fight or flight response is triggered subconsciously.  If this happens in their hike more than few times the more primitive parts of their brain will just stay at full alert, even when no other users are around.  Combine this older age, maybe with a fear of injury, a lack of understanding in how best to share and the result is an anxiety borne out of the fight or flight response being triggered with every passing use.

Is this a predator?

Speed doesn't just happen

The fact is that the one of biggest contributors to the speed difference between user groups isn’t the activity, it’s the design of the infrastructure those groups are on.  As an example, if you are in a modern sports car or a classic truck, the potential speed differences might be huge.  However, the speeds you obtain would be different on highway or parking lot.  Why?  A highway encourages speed due to the myriad of signals its sending to you, and hence the sports car will be able to go much faster than the truck.  But those same two vehicles wouldn’t go faster than the other in a parking lot on Black Friday because of the myriad signals you would be receiving would be telling you to slow down to a crawl to avoid hitting anyone.  In road engineering circles , these signals to your brain are part of a concept called "edge friction".  Many engineers are discovering that to truly slow down cars and make pedestrians safer that the street needs to be narrow and chaotic with sharper turns.

The same can be said of trails.  While we don’t think of them as “infrastructure”, the fact is they are.  And through a myriad of design choices, they can send signals to mountain bikers to speed up or to slow down.  A trail that, like a highway, has wide turns and long straightaways will cause mountain bikes to go faster..  A trail that, like a parking lot, has tight corners and is narrow will cause mountain bikes to go slower.  

It’s not a function of elevation difference either.  We know this from comparing trails with the same elevation difference but with two different design styles.  We can also see this with trails where the elevation of the trail is counter intuitive to the speeds.  To illustrate this point, let’s look at 4 trails, 2 urban and in the same location and 2 more relatively close but with radically different design styles.

First, Theodore-Wirth Park, in Minneapolis, MN.  It’s the poster child of how to do urban mountain biking inside a city and share between users for a reason.  You literally cannot ask for a better “this the correct way to do this” example.  But what most people don’t know is that the trails within Theodore-Wirth all have different “feels” to them resulting in very different speeds, even with the same elevation and similar length.

​Notice the speed difference (from Strava) on these two trails, the North Loop and the SW (Glenwood) Loop, both in Theodore-Wirth Park:

Theodore-Wirth North Loop Strava KOM

Theodore-Wirth SW (Glenwood) Loop Strava KOM

​One might be tempted to conclude that the faster one has greater elevation difference or is longer.  You would be wrong on both counts, as the slower one is longer and they both have the same elevation difference.  Yet the speed difference for the 5 fastest riders between trails is nearly double.  Why?  Because the SW Loop trails were designed to be more open, less tight, and have more relatively straight stretches.  The North Loop trails, in contrast, are very tight, routed around every gopher hole and tree out there with hardly any straight stretches.

Now, let’s look at the Portland, OR where trail safety "advocates" have suggested for years that 8 foot wide trails should be the standard on shared trails for safety.   We will be looking at Firelane 1  in Forest Park, a 8 foot wide trail along a fall line.  We will also be looking at Hide and Seek, a modern singletrack gravity flow trail at Sandy Ridge.  It should be noted that Hide and Seek is not designed to be shared.  We are using it because its a very fast mountain bike trail.  Here is Firelane 1 and Hide and Seek  from Strava:

Sandy Ridge Hide and Seek DH Full Strava KOM

Forest Park Fireland 1 Strava KOM

​Here on a singletrack downhill, a type of trail known as a gravity flow trail, designed for high speed mountain bike use with bermed turns (not for sharing), the fastest speed  on the trail was a third less that is currently being obtained on the fire lane within Forest Park, a trail that is supposed to be shared and "safer".  It’s worth noting here that the elevation drop and length of Hide and Seek compared to Firelane 1 is about 3:1, meaning Hide and Seek is over 3 times as long with 3 times the vertical drop.  So even with 3 times the length and 3 times the vertical drop, its 2/3 as fast.  Again, it’s a singletrack (albeit a gravity flow trail made for speed) versus a more open double track descent.

This understanding of speed also explains why the sharing debate is nowhere near as loud or vibrant in the eastern half of United States.  These trails tend to be relatively sinuous.  Combined with that is the fact that a lot of the topography east of the Rockies involve steep sloped, but non-uniform hillsides that force trails to switch directions often as they climb or descend.  Therefore, the history and topography are imposing limitations on the trail designers.  Add to the fact that public lands in East, Midwest and South tend to be smaller than those in the West.  This adds another set of limitations and forces trail designers to create tight trail routes to maximize trail mileage.  Tight trails with lots of corners means a lack of straightaways.

All this history and physical limitations of design mean lower average speeds of mountain bikers.  Lower speeds of mountain bikers means they are not approaching or passing hikers with a great speed difference.  That lack of a speed difference doesn’t trigger the paleolithic constant of the hikers as often, if ever.  This lower speed also allows both parties to communicate verbally or otherwise their respective intentions.  Ultimately, that greater amount of time to know what the other party is doing and the ability to communicate means less issues sharing.

We’ve managed to tease out a few simple truths of sharing:

• Speed really influences how users feel about sharing.
• The user group that is the least comfortable with speed is the slowest speed: hikers.  
• Trail layout, not elevation  , the determining factor in the resulting mountain bike speeds.

Therefore, if we want to create trails that are shared between user groups successfully, the speed difference has to be kept in a window that has maximum average of 3 or 4 times the hiker speed average.  If the average hiker is going 3 mph that means for a successful sharing in an urban trail, we don’t want mountain bikers going faster than 9 mph to 12 mph.  If we have determined that trail layout is more important than elevation for speed, that means if we want lower speeds, we need a tighter layout, regardless of how much elevation we will gain or lose.    No amount of directions or signage will lower the speed of mountain bikers as much as the layout of the trail.  If we open up the layout, we raise the speeds of the mountain bikers.  As those speeds climb, hikers get less comfortable with sharing.  

This article is part 2 of a 5 part series about sharing.    Next up: How sightlines affect mountain bike speeds and the ability to share.