Editing Cross-country skiing (section)

===Skis===
{{main article|Ski}}
[[File:Cross-country equipment--Skate and Classic.jpg|thumb|Cross-country ski equipment for skate-skiing (left) and classic-style skiing (right). Ski and pole lengths are different for each. Classic skis have a "grip zone" in the area under the binding.]]
Skis used in cross-country are lighter and narrower than those used in [[alpine skiing]]. Ski bottoms are designed to provide a gliding surface and, for classic skis, a traction zone under foot. The base of the gliding surface is a plastic material that is designed both to minimize friction and, in many cases, to accept waxes.<ref name=oly>{{cite web|title=Cross Country Skiing Equipment and History|url=http://www.olympic.org/cross-country-skiing-equipment-and-history?tab=history|publisher=International Olympic Committee|access-date=2014-10-11|archive-date=16 October 2014|archive-url=https://web.archive.org/web/20141016185653/http://www.olympic.org/cross-country-skiing-equipment-and-history?tab=history|url-status=live}}</ref> Glide wax may be used on the tails and tips of classic skis and across the length of skate skis.<ref name="Rees"/><ref name=mec>{{cite web|title=Cross Country Skis (Nordic Skis)|url=http://www.mec.ca/AST/ContentPrimary/Learn/Snowsports/SkisBootsAndSkins/NordicSkis.jsp|website=MEC|publisher=Mountain Equipment Coop|access-date=2014-10-19|archive-date=13 August 2012|archive-url=https://web.archive.org/web/20120813113907/http://www.mec.ca/AST/ContentPrimary/Learn/Snowsports/SkisBootsAndSkins/NordicSkis.jsp|url-status=live}}</ref>

====Types====
Each type of ski is sized and designed differently. Length affects maneuverability; camber affects pressure on the snow beneath the feet of the skier; side-cut affects the ease of turning; width affects forward friction; overall area on the snow affects bearing capacity; and tip geometry affects the ability to penetrate new snow or to stay in a track.<ref name = SnowCountry>{{Citation
 | last = Woodward
 | first = Bob
 | title = Cross Country's Short Story
 | journal = Snow Country
 | volume = 8
 | issue = 1
 | pages = 127–132
 | date = January 1995
 | url = https://books.google.com/books?id=rEEo8WqmRRsC&q=Cross-country+ski+design&pg=PA127
 | access-date = 2016-01-05
 | issn = 0896-758X
 | archive-date = 6 May 2016
 | archive-url = https://web.archive.org/web/20160506044107/https://books.google.com/books?id=rEEo8WqmRRsC&pg=PA127&dq=Cross-country+ski+design&hl=en&sa=X&ved=0ahUKEwir44ns15PKAhVChhoKHdIWC4kQ6AEIRzAJ#v=onepage&q=Cross-country%20ski%20design&f=false
 | url-status = live
 }}</ref> Each of the following ski types has a different combination of these attributes:
* '''Classic skis''': Designed for skiing in tracks. For adult skiers (between 155&nbsp;cm/50&nbsp;kg and 185&nbsp;cm/75&nbsp;kg), recommended lengths are between 180 and 210 centimetres (approximately 115% of the skier's height). Traction comes from a "grip zone" underfoot that when bearing the skier's weight engages either a textured gripping surface or a grip wax. Accordingly, these skis are classified as "waxable" or "waxless". Recreational waxless skis generally require little attention and are adapted for casual use. Waxable skis, if prepared correctly, provide better grip and glide.<ref name="Rees"/><ref name="Bergin">{{cite web|url = http://www.snocountry.com/article.php/20041227133240622 |title = Back to Basics: A Quick Look at Paste Waxes, Waxless Ski Preparation and Kick Waxing|access-date = 2009-01-25|last = Bergin|first = Ron |year = 2008 |archive-url = https://web.archive.org/web/20070402051820/http://www.snocountry.com/article.php/20041227133240622 |archive-date = 2 April 2007}}</ref><ref name="REIAdvice">{{cite web|url = http://www.rei.com/learn/expert-advice/crosscountry-ski-touring-gear.html|title = Cross-Country Ski Gear: How to Choose|access-date = 2015-06-29|last = Recreational Equipment, Inc.|year = 2015|archive-date = 16 May 2015|archive-url = https://web.archive.org/web/20150516163933/http://www.rei.com/learn/expert-advice/crosscountry-ski-touring-gear.html|url-status = live}}</ref>

:When the skier's weight is distributed on both skis, the ski's [[wikt:camber|camber]] diminishes the pressure of the grip zone on the snow and promotes bearing on the remaining area of the ski—the "glide zone". A test for stiffness of camber is made with a piece of paper under the skier's foot, standing on skis on a flat, hard surface—the paper should be pinned throughout the grip zone of the ski on which all the skier's weight is placed, but slide freely when the skier's weight is bearing equally on both skis.<ref name = Mountaineers/>
* '''Skate skis''': Designed for skiing on groomed surfaces. The usual recommended length is skier length +5-15cm.  The entire bottom of each skate ski is a glide zone—prepared for maximum glide. Traction comes from the skier pushing away from the edge of the previous ski onto the next ski.<ref name="Rees"/>
* '''Back country skis''': Designed for [[ski touring]] on natural snow conditions. Recommended lengths are between 150 and 195 centimeters for adult skiers, depending on height and weight of the user. Back country skis are typically heavier and wider than classic and skate skis; they often have metal edges for better grip on hard snow; and their greater [[sidecut]] helps to carve turns.<ref name=Berg/><ref>{{cite web| title = How to choose the right ski length | work = Back Country | date = 2 September 2013 | url = http://www.backcountry.com/explore/how-to-pick-the-right-ski-length | access-date = 2014-10-22 | archive-date = 23 October 2014 | archive-url = https://web.archive.org/web/20141023055824/http://www.backcountry.com/explore/how-to-pick-the-right-ski-length | url-status = live }}</ref><ref name=Melbye/>

:The geometry of a back country ski depends on its purpose—skis suited for forested areas where loose powder can predominate may be shorter and wider than those selected for open, exposed areas where compacted snow may prevail. Sidecut on Telemark skis promotes turning in forest and rugged terrain. Width and short length aid turning in loose and deep snow. Longer, narrower and more rigid skis with sharp edges are suited for snow that has been compacted by wind or freeze-thaw. Touring ski design may represent a general-purpose compromise among these different ski conditions, plus being acceptable for use in groomed tracks.<!---We don't see these terms in English: (referred to as mountain skis or crust skis)---> Traction may come from a textured or waxed grip zone, as with classic skis, or from [[ski skins]], which are applied to the ski bottom for long, steep ascents and have hairs or mechanical texture that prevents sliding backwards.<ref name=Berg/><ref name=Melbye>{{cite book|last1=Melbye|first1=Mats|title=Friluftsliv i vinterfjellet|date=1997|publisher=Universitetsforlaget|location=Oslo|isbn=82-00-42088-4|pages=31–32}}</ref>

====Gliding surface====
{{main article|Ski wax#Glide wax}}
Glide waxes enhance the speed of the gliding surface. The wax is either melted on the base using an iron or applied in a liquid form. The excess wax is first scraped off and then finished by brushing. Most glide waxes are based on [[Paraffin wax|paraffin]] that is combined with additive materials. The paraffin hardness and additives are varied based on snow type, humidity and temperature. Since the 2021-2022 race season, fluorinated products are banned in FIS sanctioned competitions.<ref>{{Cite web|title=Flourinated Wax Ban implementation to begin in the 2021-22 season|url=https://www.fis-ski.com/en/international-ski-federation/news-multimedia/news/flourinated-wax-ban-implementation-to-begin-in-the-2021-22-season|access-date=2021-11-05|website=www.fis-ski.com|language=en}}</ref> Before the ban, most race waxes combined fluorinated hydrocarbon waxes with [[fluorocarbon]] overlays.<ref>{{cite web |last=Harvey |first=Ian |date=9 February 2011 |title=Information on Fluorinated Waxes |url=http://www.nordicskiracer.com/news.asp?NewsID=5429 |url-status=live |archive-url=https://web.archive.org/web/20120425075240/http://www.nordicskiracer.com/news.asp?NewsID=5429 |archive-date=25 April 2012 |access-date=2014-10-21 |work=A Michigan Nordic Ski Racer}}</ref> Fluorocarbons decrease surface tension and surface area of the water between the ski and the snow, increasing speed and glide of the ski under specific conditions. Either combined with the wax or applied after in a spray, powder, or block form, fluorocarbons significantly improve the glide of the ski.<ref>{{cite web |last=Swix |date=22 February 2011 |title=Information on Fluorinated Waxes |url=http://www.nordicskiracer.com/news.asp?NewsID=5482 |url-status=live |archive-url=https://web.archive.org/web/20120425080020/http://www.nordicskiracer.com/news.asp?NewsID=5482 |archive-date=25 April 2012 |access-date=2014-10-21 |work=A Michigan Nordic Ski Racer}}</ref>

====Traction surface====
{{main article|Ski wax#Grip wax}}
Skis designed for classic technique, both in track and in virgin snow, rely on a traction zone, called the "grip zone" or "kick zone", underfoot. This comes either from a) ''texture'', such as "[[fish scale]]s" or [[mohair]] skins,<ref>{{Cite web|last=Jhung|first=Lisa|date=2020-12-05|title=This Is the Winter to Invest in Cross-Country Skis|url=https://www.outsideonline.com/2419169/how-buy-cross-country-skis|access-date=2021-03-02|website=Outside Online|language=en}}</ref> designed to slide forward but not backwards, that is built into the grip zone of waxless skis, or from applied devices, e.g. [[Ski skins|climbing skins]], or b) from ''grip waxes''. [[Ski wax#Grip wax|Grip waxes]] are classified according to their hardness: harder waxes are for colder and newer snow. An incorrect choice of grip wax for the snow conditions encountered may cause ski slippage (wax too hard for the conditions) or snow sticking to the grip zone (wax too soft for the conditions).<ref name="Rees"/> Grip waxes generate grip by interacting with snow crystals, which vary with temperature, age and compaction.<ref name="Rees"/> Hard grip waxes do not work well for snow which has metamorphosed to having coarse grains, whether icy or wet. In these conditions, skiers opt for a stickier substance, called ''klister''.<ref name="Rees"/>