Editing Reuleaux triangle (section)

=== Rolling cylinders ===
[[File:Reuleaux triangle 54.JPG|thumb|Comparison of a cylindrical and Reuleaux triangle roller]]
Another class of applications of the Reuleaux triangle involves cylindrical objects with a Reuleaux triangle cross section.  Several pencils are manufactured in this shape, rather than the more traditional round or hexagonal barrels.<ref name="pencil">{{citation|url=http://www.pencilrevolution.com/2006/04/review-of-staedtler-noris-ergosoft-hb/|title=Review of Staedtler Noris Ergosoft HB|work=Pencil Revolution|date=April 26, 2006|access-date=2015-05-22|first=Johnny|last=Gamber|archive-date=2015-05-25|archive-url=https://web.archive.org/web/20150525033942/http://www.pencilrevolution.com/2006/04/review-of-staedtler-noris-ergosoft-hb/|url-status=dead}}.</ref>  They are usually promoted as being more comfortable or encouraging proper grip, as well as being less likely to roll off tables (since the center of gravity moves up and down more than a rolling hexagon).

A Reuleaux triangle (along with all other [[curve of constant width|curves of constant width]]) can [[rolling|roll]] but makes a poor wheel because it does not roll about a fixed center of rotation. An object on top of rollers that have Reuleaux triangle cross-sections would roll smoothly and flatly, but an axle attached to Reuleaux triangle wheels would bounce up and down three times per revolution.<ref name="gardner" /><ref>{{citation
 | last1 = Masferrer León | first1 = Claudia
 | last2 = von Wuthenau Mayer | first2 = Sebastián
 | date = December 2005
 | doi = 10.1007/bf02985852
 | issue = 4
 | journal = [[The Mathematical Intelligencer]]
 | pages = 7–13
 | title = Reinventing the wheel: Non-circular wheels
 | volume = 27}}.</ref> This concept was used in a science fiction short story by [[Poul Anderson]] titled "The Three-Cornered Wheel".<ref name="mj14" /><ref>{{citation|last1=Anderson|first1=Poul|title=The Three-Cornered Wheel|magazine=[[Analog Science Fiction and Fact|Analog]]|date=October 1963|pages=50–69}}</ref> A bicycle with floating axles and a frame supported by the rim of its Reuleaux triangle shaped wheel was built and demonstrated in 2009 by Chinese inventor Guan Baihua, who was inspired by pencils with the same shape.<ref>{{citation|first=Tyra|last=Dempster|url=https://www.reuters.com/article/us-china-bicycle-idUSTRE55G1GB20090617|publisher=Reuters|title=Chinese man reinvents the wheel|date=June 17, 2009}}</ref>