A few companies in Maipú and Chacras de Coria rent bikes, making a day tour of either area an excellent outing, and a lot more fun than the often rushed half-day wine tours on offer from Mendoza tour agencies.
Bike-hire in Maipú is seriously competitive (there have been fistfights in the street between operators) and the main companies are all within walking distance of each other. Go for a stroll and see who has the best wheels. All will supply you with a (basic) map of the area and may throw in goodies like a bottle of water, glass of wine and discount vouchers for tastings. Some travelers report poor service and bad bikes ruining their day, so be choosy.
Most hostels offer cheap minivan 'wine tours' of Maipú, including transfers, bike rental, helmets, insurance, wine tastings and visits to three wineries, lunch and transport, for around AR$800. Several recommended English-speaking tour companies, including Ampora, Trout & Wine and Mendoza Wine Camp, run wine-tasting and lunch tours to bodegas around Luján de Cuyo.