Condensed Answer: A BMX stem can be mounted on a fixed-gear bike. The stem will have to be of the right size and type for the fork and the handlebars. A threaded fork requires an older quill BMX stem whereas modern threadless forks can operate with up-to-date BMX stems.
Threaded and Threadless BMX Stems
First, it’s necessary to determine whether the fork operates with a threaded or a threadless stem.
In the first case, the stem is a quill model and is secured to the head tube via a wedge system and the headset.
Threaded stems are older, and the number of available models on the market is limited, especially in the BMX segment. Nonetheless, it’s still possible to find a unit online.
Threadless stems, on the other hand, are not wedged into the fork’s steerer tube. Instead, they grab the steerer via a clamp-on bolt mechanism.
If the fork is new, it’s more than likely threadless. In that case, the user will need a threadless BMX stem (image below).
The diameter of threadless steerers is 1 1/8″. This is the case even when the forks are designed for different disciplines (road, BMX, MTB…etc.).
There are tapered threadless forks that go from 1 1/8″ to 1 1/5″, but the taper occurs at the bottom. The clamping area is still 1 1/8″.
Consequently, it’s possible to install a BMX stem even on a tapered fork.
The stem connects the steerer and the handlebars. Thus, the stem’s clamping area has to be compatible with the bars too.
The standard BMX stem has a 22.2mm clamping diameter. (BMX handlebars are made out of steel and have thinner tubing than aluminum bars.)
If the user plans to combine the stem with BMX handlebars, this will not be a problem. However, if the stem is coupled with modern aluminum riser handlebars, for example, it will not accept them. Riser handlebars as well as modern drop bars have a larger clamping diameter – 31.8mm.
In that case, the user will have to purchase a 31.8mm BMX stem. Those are rarer and harder to find.
The Advantages of Installing a BMX Stem On a Fixie
Typically, fixed-gear and road bikes have long stems.
Long stems are preferred on bikes designed for speed because they slow down the steering and make the bike more stable when descending. The “lag”, however, is considered harmful when performing freestyle tricks.
In different, a short stem makes the execution of technical stunts easier thanks to the faster input.
- Upright position
The length of a stem has a direct influence on the bike’s reach. A shorter stem brings the handlebars closer and consequently, makes the back of the rider more vertical.
The upright position is less stressful on the joints and facilitates the lifting of the front wheel during stunts.
A long stem makes the execution of tricks involving bar spinning difficult and in some cases impossible because the handlebars can hit the rider.
A long stem positions the handlebars further away from the rider but has the opposite effect when the handlebars spin. The longer the stem, the closer the handlebars come to the rider’s body during bar spins. A short BMX stem reduces the likelihood of this outcome.
Appearance is of high importance in the world of cycling. Many riders invest a lot of time and effort into producing the most aesthetically pleasing machine.
A BMX stem adds character to a bike and unsurprisingly looks neat when coupled with BMX handlebars.
The Downsides of Installing a BMX Stem On a Fixie
- Non-aero Geometry
A BMX stem reduces the reach and forces the rider to remain upright. This is beneficial because the stress on the back is reduced, but the stance isn’t aerodynamic.
The more upright the rider is, the more drag his torso creates. Therefore, a BMX stem doesn’t compliment a bike designed for maximum speed.
- Not Ideal For Descents
It may come as a surprise to some, but road bikes feel very stable during descents thanks to their geometry. A long stem helps too because it slows down the handling and makes the bike more predictable.
- Compatible with a Limited Number of Handlebars
A BMX stem makes sense only when it’s coupled with BMX handlebars or some sort of flat or riser bars. Thus, if the user wants to stick with handlebars of a different style, another stem would offer a better service.
- Non-compatible With Standard Mounts
The shape of a BMX stem does not allow the installation of accessories with mounts designed for round tubing.
If you want to place a light or a bike computer on it, an alternative mounting system will be needed.
Alternatives To a BMX Stem
A BMX stem has 3 main technical properties:
- short length
- high strength
- compatibility with 22.2mm bars
An MTB stem can offer the same features.
That said, many people want a BMX stem simply for the looks. An MTB stem comes close but does not offer the same aesthetics.
Summary: What You Need To Know
A BMX stem can be installed on a fixed-gear bike when the following conditions are met:
- The fork type and the stem should match. A threaded fork needs a threaded quill stem. A threadless fork works with a threadless stem.
- The clamping area of most BMX stems is 22.2mm. This makes them non-compatible with many handlebars on the market. There are BMX stems designed for 31.8mm bars but they’re rare.
The advantages of installing a BMX stem on a fixie are:
- Upright position (reduced joint stress)
- Easier execution of tricks involving the lifting of the front wheel (e.g., bunny hops, wheelies…etc.)
- More clearance for tricks requiring handlebar spinning
- Unique appearance
- Faster input
The disadvantages of mounting a BMX stem on a fixie are:
- Non-aero position
- Non-compatibility with many handlebars
- Non-compatibility with bike and computer mounts
- Reduced stability during descents