Unless you live on the second floor, and will carry the bike upstairs, don't obsess over weight. For real people, not "pro" racers, bike weight is more marketing hype than a useful guide to the comfort and reliability of a bike.
The factors that are important for riding (not carrying), a bike are: correct size, correct fit, correct set-up of the seat and bars, and correct gearing. Go to a bike shop with experienced staff willing spend a couple of hours helping select the right bike for your wife, put the right saddle on it, and get it fitted exactly right for her needs.
Don't get lured by marketing hype that puts a lot of people on skinny tired bikes with narrow saddles and handlebars three inches lower than the seat. Putting the average person on a racing style bike is the reason that millions of bikes are hanging from the rafters in gararages across America.
I have a friend who is over forty years old and wants to ride an hour or so, three or four times a year. I gave her a Trek single speed beach cruiser. The ladies frame makes it easy for her to mount and dismount. The Trek beach cruiser has huge, shock absorbing tires and a wide, comfortable saddle. High handlebars. Gearing so easy that even a grandma can easily ride it up a small hill. High quality crank bearings and wheel bearings allow it to cruise smoothly with close to zero effort. It weighs 35 pounds with its wide steel fenders (double the weight of a mega-buck racing bike). The wrong bike for most folks, but exactly the right bike for her.
So, for an "around the block" rider, a one speed beach cruiser was the "right" bike. The "right" bike for your wife depends on her size, strength, experience, the distances she will cover, the degree of hilliness in your town...lots of variables other than just the weight of the bike.
Last edited by alanbikehouston; 10-18-04 at 08:51 PM.