weight_weenie.R

library(tidyverse)

adj_ftp <- function(rider_kg=70, watts_kg_ftp=3, extra_kg) {
  watts <-  watts_kg_ftp * rider_kg
  adj_wkf <- watts / (rider_kg + extra_kg)
  return(adj_wkf)
}


tibble(extra_kg = seq(0, 5, .1),
       rider_55kg = adj_ftp(rider_kg = 55, extra_kg = extra_kg),
       rider_85kg = adfj_ftp(rider_kg = 85, extra_kg = extra_kg)) %>%
  data.table::melt(id.var='extra_kg') %>%
  ggplot(aes(extra_kg, value, color=variable)) +
  geom_line() +
  theme_light() +
  labs(color='Rider weight', y='Adjusted watts/kg',
       title='Influence of extra weight on effective watts/kg',
       subtitle = 'for heavy and light riders with same base watts/kg')