Whether it is online or in town, the number of bike stores can be amazing. Some believe that you must physically go into several road bike shops to get the bike that was built for you. They believe that the only way to truly know that what you are paying for is the right sized bike for your build is by sitting on it. While this maybe a very helpful tool, a resourceful biker can obtain just as good or higher quality bike through an online store.
Often people will walk into a store, see a few bikes they like and the extent of their fitting is to stand over a few tubes of different heights to get an idea of what would work. This may be effective or may not. Reputable online road bike shops will offer an extensive fitting area that teaches one how to size a bike for the correct fit. When one just stands over a few tubes, the fitting for knee position is lost, top tube or stem fitting is left out, then there are the handlebars and crank length that have not been considered.
During an online version or instruction, all of these areas will be covered. Going into great detail about how and what to measure, the formulas necessary to obtain the correct numbers and then how to put it all together. This is not to say that there are not some physical road bike shops that offer great fitting sessions, but when they do, the cost of the fitting is usually applied to the purchase of one of their bikes. However, just because one is unable to walk into a place and touch the bike, does not mean that it is impossible to acquire a quality, well-fitted bike.
So the preference is yours, are you more comfortable walking in and having someone take all the measurements and then point you to your options or are you resourceful enough to follow directions and obtain the measurements for yourself and then search road bike shops online for the bike that fits your body and needs. Regardless of your approach, the most important thing is to be fitted for your road bike.
