From Bulbapedia, the community-driven Pokémon encyclopedia.
Miracle Cycle (Japanese: ミラクルサイクル Miracle Cycle) is the number-one producer of bicycles in Kanto and Johto. Initially beginning business in Cerulean City, Miracle Cycle expanded to Johto after about three years, with a second shop in Goldenrod City, where they became popular with the help of the player.
Miracle Cycle apparently has little to no presence in Hoenn or Sinnoh, where Rydel's Cycles and Rad Rickshaw's Cycle Shop dominate business.
The company name was not mentioned in non-Japanese versions of any games it has appeared in for unknown reasons.
In the games
Miracle Cycle's Cerulean branch can be visited in Generation I and III, where a bicycle is on sale for 1,000,000. As the player can only carry 999,999 at one time, this makes it impossible to buy. However, several vouchers for the expensive bicycle have been given away; the player can obtain one from the Chairman of the Pokémon Fan Club in Vermilion City and trade it in for the bicycle instead.
In Generation II, this branch of Miracle Cycle is shut down, possibly due to the limited space the games had for Kanto locations. In Generation IV, however, the shop is still open, though nothing is obtainable here.
Grass and caves
The sign with the notice about its closure in Generation II reads:
There's a notice
The BIKE SHOP has
moved to GOLDENROD
CITY in JOHTO...
The Goldenrod branch of Miracle Cycle can be visited in Generation II and its remakes, where the owner will give the player a bicycle for free temporarily so that he or she can advertise Miracle Cycle, stuck in an isolated corner of Goldenrod City, to the people of Johto. After a certain amount of time, the owner will call the player via the Pokégear, allowing him or her to keep the item as thanks for bringing in so much business.
In Generation II, it is mentioned that the owner moved shop from Cerulean, shutting down the old shop in the process, while in the remakes, he recommends that the player visit the still-open shop in Cerulean.
In the manga
Miracle Cycle also exists in the Pokémon Adventures manga.
It was first mentioned by the Tripokémon Bike race organizer as the sponsor of the race in Wake Up--You're Snorlax!. This mention was not removed from Viz's English translation of the manga.
Whitney owns a Miracle Cycle bike which she used in the Gold, Silver & Crystal chapter in a race against Gold. The race was designed as a promotion for the bikes but Gold adapted his into a scooter.