Generally speaking, how do bike fitters know what stem length to choose on a road bike setup? I’m going to replace the stem on my road bike soon and was thinking about experimenting with a longer stem length. It seems like I could get more stretched out that way. Any way to figure this out on my own or do I need to see a fitter? Thanks.
Ideally you get fitted so you know what length/height you want your bars at. An old rule of thumb was that when riding the hoods, the bar top should block your view of the front hub (that’s not precise, but is in the right ballpark). Another option is if your LBS has some demo stems they can lend you to try out (or an old Look Ergostem). This way you can experiment before dropping some $$ on a nice stem. Make sure that the stem produces a comfortable position that holds up for an entire ride.
See a fitter for right length, also remember that stems come in different angles and that may also affect your position and how much power you’ll be able to produce.