If you need a stem length beyond those extremes your bike frame is the wrong size.
Road bike handlebar stem length.
Measured vertically from the center of the handlebar clamp to an imaginary line that bisects the central meeting point of the extension and vertical portion of the stem.
Stem length will vary with the design of the bike.
In order to alter stem length you must first know the length of your current stem.
If you can see the hub in front of the handlebar the stem is too short.
Competitive racers will opt for a longer 120mm stem for optimum stretch.
This less than 90 degree angle applies to road bikes touring bikes and indoor bikes.
Stems help you achieve a proper bicycle fit.
As a rule of thumb on a road bike you shouldn t run a stem much shorter than 90mm or much longer than 130mm.
The rise angle of stem from fork to bar has quite a large effect.
Mountain and road bike stems are available in different lengths and rises to suit the needs of any rider.
For non racers of many disciplines the top of the bars may be even with the saddle or even higher.
It must also address the rider s comfort biomechanics performance needs and the steering and handling of the bike.
If the stem length is correct the handlebars should completely hide the front hub.
Stem length is one aspect of a road bike that you can alter to increase both comfort and performance.
The effective height gained as a function of the stem s angle and length.
Comfort should be your guide when adjusting the height of the handlebars.
Assuming you have a handlebar you want to marry you can use stem length to keep reach within proper fit guidelines for your type of riding but that won t do much for drop without also affecting the height of the top and hoods.
The most important consideration when choosing a road stem is the stem length considered as a key factor in the overall fit of the bike.
One good rule of thumb for choosing the correct length stem and it works for the road cc team is to sit on the bike with your hands on the top of the hoods and look down at the front hub.
Proper positioning on the bike.
The road bike racer typically has the top of the handlebars below the seat height.
Dimension 31 8 stems are fully forged 6061 t6 aluminum stems that have a 4 bolt handlebar clamp.
However most stems are not marked and must be measured in order to determine size.