When your scooter has a fault, you need to get an alternate. Hopefully your insurance will cover it too.
The alternate scooter is made entirely of 鉄 (てつ). It's hard and cold and not very comfortable when you sit on it. That's why you chose to keep it as an alternate and not as your everyday scooter.
Currently there are no similar looking kanji which exist in the WaniKani learning system