The 60s were a decade filled with new things being introduced to the world, one of which was the BMX. Although this type of bicycle came in the 60s, it was in the early 70s that it saw worldwide spread. It took about 11 years for the International BMX Federation to be founded and 12 more for BMX riding to be integrated into the ICU (International Cycling Union). BMX made big strides in 2008 as it made its debut in the Olympics. Today there are numerous competitions and types of BMX bikes which all make use of one crucial component, the stem. This component connects the handlebars to the steerer tube which is often known as the bicycle fork. This is why the stem is important as it can affect your ride.
How the Stem Affects Your Ride
The reach or height of the handlebars is set using the stem and it also dictates the type of stem you need to get. If you want a lower handlebar position then you should go for a front-loaded stem for your setup. If you want a high BMX handlebar stem position you should consider getting a top load stem.
The stem can also affect your ride height which also affects the type of stem you’ll need to get. For a low rider, you’ll want to get a front load stem whilst for someone who wants a higher ride height you should go for a top-load BMX handlebar stem. But there are other things you need to consider when searching for the right BMX handlebar stem.
What to Consider in a BMX Stem
The material the stem is made of should be long-lasting and strong. But you shouldn’t forego its weight too. A lightweight stem will ensure you have a smooth ride. The majority of BMX stems are made fro aluminium alloy with the most common ones being 7071 and 6061. While both of these alloys are reliable and strong there is one that has a higher strength to weight ratio and that is the 7075 alloy. Keep in mind though that 7075 alloy is prone to corrosion.
The position of your stem handlebar will determine the type of stem you should get. For example, a longer stem bar goes best with top load stems and shorter ones go best with a front load stem.
The difference between top-load and front-load stems is that the former has a plate that you need to remove when installing the bars. The latter has a vertical front plate in which you install the bar hence why they sit lower allowing you to lean. If you want to sit straight up go for a top-load BMX bike stem.
Steerer Clamp Radius
This is what determines the size of the handlebars and if the steerer clamp radius is large then you need large bars. These bars go well with a top-load stem. Otherwise, you might want to get smaller bars which go well with front load stems.
The rise is the distance from the bottom of the stem to the middle of the bar’s clamping hole. The rise varies when it comes to top load stems whilst with front loads it can be quite different.
How to Measure BMX Stem?
Measuring a BMX stem starts first by figuring out its real length from the centre of the steering bore to the bar clamp. This is called the extension. There are other factors too like the stack height and extension measurements but they are not as commonly considered when searching for the right type of stem.
Afterwards, you need to measure the reach. The reach is the useful length of the stem starting from the centre of the steering bore to the centre of the handlebar clamp. This measurement is made along an imaginary line by measuring from the line vertical to the steering axis to the middle of the stem extension.
The reach won’t differ as much with a 50 mm stem reach being the most common length but there are also 48 mm stem reach lengths. A less common stem reach is 40 mm one which is made mostly for flatland riders since it helps the front of the bike more compact and straighter too. Then you measure the middle of the real steering axis tot eh middle of the stem extension. This is what we refer to the angle of the stem.
The rise is the height obtained from the function of the stem’s length and angle. The rise is measured vertically from the middle of the bar clamp to a thinking line which divides the middle meeting point of the stem extension and a vertical portion of it too. The height is the complete length of the vertical part of the stem.