A plotting method for the example 'bike' class

plot.bike.R

library(plotrix)
plot.bike <- function(x, ...){
  centre_back <- c(0, x$ws / 2)
  centre_front <- c(x$ws + x$ttl + 100, x$ws / 2)
  xlim <- c(-x$ws, centre_front[1] + x$ws / 2)
  ylim <- c(0, x$ttl + x$ws/2 + 50)
  plot.new()
  plot.window(xlim, ylim)
  draw.circle(x = centre_back[1], y = centre_back[2], radius = x$ws/2)
  draw.circle(x = centre_front[1], y = centre_back[2], radius = x$ws/2)
  ttx <- c(0, x$ttl) + x$ws/2 + 100
  tty <- rep(x$ws / 2 + x$s, 2)
  stx <- rep(x$ws/2 + 100, 2)
  sty <- c(0, x$s) + x$ws/2
  lines(ttx, tty)
  lines(stx, sty)
  lines(c(0, ttx[1]), c(sty[1], sty[2]))
  lines(c(0, ttx[1]), c(sty[1], sty[1]))
  lines(c(ttx[1], ttx[2]), c(sty[1], sty[2]))
  lines(c(centre_front[1], ttx[2]), c(sty[1], sty[2]))
}