Guys... there is nothing better than sharing your interest with you wife. Sometimes though it just doesn't pan out.
The best advice I can give is don't hassle them, bribe or try to guilt them into it... be understanding and maybe they will, like my wife begin to develop an interest.
Most Important... Remember that your wife is very precious and you can enjoy riding with or without her participation... so don't hassle her cos she doesn't share your passion.