(a) On his way back home, it was a broken glass on the road. John cycled towards the broken glass, so the bicycle tyre / bicycle's tyre / bicycle was punctured.
. Vincent, you are just not looking at the previous corrections carefully enough.
X (a) On his way back home, it was a broken glass on the road. John cycled towards the broken glass, so the bicycle tyre / bicycle's tyre / bicycle was punctured.-- You cannot use 'it' without a previous refence. It is the tyre, not the bike, that is punctured