So you finally did it: ditched your car and become a bike commuter. We're proud of you (but unless your workplace provides showers, we probably wouldn't want to get a whiff of you). Then the totally expected happens: a derailleur gets out of adjustment, a wheel out of true or, Dallas streets being what they are, you break a spoke or a rim. You can hop a DART bus if it has a carrier and bring your machine to a local repair shop, but you might as well buy a bus pass, cause you're going to be waiting awhile to get your ride back. Or you can go online and book a visit from VeloFix, a new mobile bike service that brings the repairman to your home or workplace, getting you back in the saddle often in the time it takes you to have lunch. VeloFix Dallas is part of a new national franchise operation. It offers a complete range of services, from replacing chains and tires, to basic tuneups and complete overhauls.