Exercise 3: sample answer

The mountain bike grew out of many people modifying old heavy balloon-tyred bikes in the 1970s, mainly in California, to ride down rough tracks, then adding gears, better brakes and later suspension. Several riders, builders and companies each took part and each is credited by different sources (check who and when), and there was no single moment of invention or patent. Like earlier chapters' "first" claims, it needs a qualifier: first to be sold commercially, first purpose-built, or first to use certain features.