Occassional thoughts about orienteering

Sunday, September 02, 2012

My current "rule of thumb" for MTB O trail mapping


I spent some more time working on an MTB orienteering map.  The map clip shows some of the trail network.

I've been struggling a bit with the mapping.  It is tempting to draw lots of variations in the rideability of the trails.  As a trail alternates between faster and slower (usually due to rocks on the trail), it would be easy to over map the changes.

For my current project, I'm mapping trails in three categories.  The clip above shows all three.  The dominant category is the fastest riding and is shown with the longest dashes.  Slower riding is show with shorter dashes (see the area labelled "B") and the slowest riding is show with very short dashes (see the area labelled "A").

To try to avoid over mapping the differences I'm following a "rule of thumb."  Specifically, I don't draw a change in unless it covers an area at least as wide as my thumb (on the 1:5,000 map I was using to fieldcheck this represents about 120 meters on the ground).

I make an exception for the areas that are extremely slow.  The area labelled "A" above is short, maybe 50-60 meters, but is quite rough.  If I were biking it, I'd have to get off and push the bike. I suspect a better rider would be able to ride some of the areas I've mapped as extremely slow.

Back to okansas.blogspot.com.

posted by Michael | 2:01 PM


I think it's important not to change the ridability too often. The rider wants to know how fast he can go from one trail crossing to the other and doesn't use this information to navigate.

Sometimes it might be useful to use the pink "bar" symbol too. This indicates when you have to get off the bike, usually to cross a lying tree or pass a barrier. But this weekend we also had it when we had to cross a stream (see here north of #2 or in the circle of #19). I had to get off the bike, while some riders might be able to bike it. I still found it a good way to show a technically difficult passage.

What I find difficult in the example you show is how to prevent people from cheating (thus going off trail and cutting the switchbacks). This will require very careful course planning.
I'm trying to avoid changing the rideability often, but I'm not sure I've figured it out yet.

I noticed a few places where a purple bar would have been good when I was out yesterday. All but one of those was a fallen tree (from Hurricane Issac which came through Kansas last week). I can imagine checking for fallen trees a day or two before an event would be a good idea.

I don't think cheating will be a big problem as long as I make the rules clear in advance. I'd thought I might make a few areas where cheating would be allowed - perhaps mark some places where it would be allowed to go off trail to connect to another trail. I would then mark them on the map and streamer them in the terrain.

I haven't competed in a MTB O' event. It looks like fun, but we don't have any of that going on around here (and very little in the US as a whole). I figure the first step is create some maps and do some training sessions. I've been thinking that a summer MTB O' series around here might work.

Surprisingly, in the 1990s, women want to own comfortable in designer

labels, so you see a lot of women carrying lanvin handbag become

quite popular, the grunge era upward trend. The 2000 when Gunpa, woman

or want comfort, but designers have found a way to use the material,

not only comfortable, but more targeted to fit, so again, designer lanvin bags again boarded

their peak. Comparing said: "You get what you pay", bags and many women

think that when it comes to the long duration of the brand lanvin bag.

Purple bar - I was looking at a local map with the possibility of mapping it. To do so, I reviewed the isom specs for MBO which includes no reference to a purple bar. Can you provide anything substantiating this symbol. I agree it would provide useful input for the rider, but where did it come from?

It is symbol 843 Dangerous object across tracks or paths, stairs. It is in the 2010 MTB O standards.

Post a Comment
March 2002April 2002May 2002June 2002July 2002August 2002September 2002October 2002November 2002December 2002January 2003February 2003March 2003April 2003May 2003June 2003July 2003August 2003September 2003October 2003November 2003December 2003January 2004February 2004March 2004April 2004May 2004June 2004July 2004August 2004September 2004October 2004November 2004December 2004January 2005February 2005March 2005April 2005May 2005June 2005July 2005August 2005September 2005October 2005November 2005December 2005January 2006February 2006March 2006April 2006May 2006June 2006July 2006August 2006September 2006October 2006November 2006December 2006January 2007February 2007March 2007April 2007May 2007June 2007July 2007August 2007September 2007October 2007November 2007December 2007January 2008February 2008March 2008April 2008May 2008June 2008July 2008August 2008September 2008October 2008November 2008December 2008January 2009February 2009March 2009April 2009May 2009June 2009July 2009August 2009September 2009October 2009November 2009December 2009January 2010February 2010March 2010April 2010May 2010June 2010July 2010August 2010September 2010October 2010November 2010December 2010January 2011February 2011March 2011April 2011May 2011June 2011July 2011August 2011September 2011October 2011November 2011December 2011January 2012February 2012March 2012April 2012May 2012June 2012July 2012August 2012September 2012October 2012November 2012December 2012January 2013March 2013April 2013May 2013July 2013September 2013