Choosing The Right Stem
Choosing the right stem can be deceivingly complicated. There’s a lot to consider when purchasing a new stem. Some riders look for a reliable billet of aluminum to hold up their bars. While more incline riders seek the comforts of a precisely fitted front end!
Today, I’ll teach you about the various considerations to think of when choosing your next stem. You might learn that your current stem is serving you no good! Or best case, you walk away with a little more knowledge than before. Either way, stick around to learn all about it.
Length
Arguably the most noticeable/ impactful attribute of a stem is it’s length. This choice not only impacts the fit of the bike, but it also impacts the bike’s handling.
Stems come in all sorts of sizes, so people typically use them as band aid fixes to compensate for a poorly fitted bike frame. Is the top tube on your frame too short, purchase a longer stem. If the top tube is too long, get a shorter stem. But the conversation about stems doesn’t stop there.
Need help choosing your next frame size? Leave a comment down below to let us know if you want to see an article about proper frame sizing!
Now, there’s a reason I used the term ‘band-aid fix’ when talking about stems as correcting tools for improper bike fitment. It's a solution to be used after you have already purchased a frame or need to make a frame size last a little longer for your growing rider. It’s a lot cheaper to purchase a $60 stem than pick up a brand new frame. But this fix is not entirely free of consequences.
Stem length attributes to a bike’s overall handling profile. A short stem will make the bike more aggressive and responsive. On the other hand, a longer stem puts you further towards the front of the bike which makes for a more effective pedaling position, but at the cost of lax steering.
Keep in mind that the difference of a few millimeters between stems will not result in any drastic change or even a noticeable change. Rather, we mention this as a general rule of thumb to consider when sizing your next bike build. Should you make a big jump between stem sizes, like something over 10mm, then you will start to feel a difference in handling. But if you go from a 48mm to 50mm you are not going to feel much of a change.
However, don’t get too carried away with longer stems as there is a limit to how long you can go. In the event that you are too far forward you will start to notice a lot of rear wheel spin under acceleration. This could be a result of too long of a stem brining your weight towards the front instead of over the rear wheel. Without going too deep into a rabbit hole here, there needs to be some weight over the rear to keep traction.
Ultimately the stem’s length can be used for two different purposes, bike fit and bike handling. It’s up to you to decide which is more important to you at the moment. If you can’t get your hands on the right size frame, maybe a stem can help you compensate for the improper fitment. But if you have the right size, then start to think about how stem length can further improve the performance of your build.
Rise
Most people stop at stem length, but there’s more to consider when choosing the right stem. We also need to consider the rise of the stem and where it will put the handlebars.
The rise is how high or low the stem holds the handlebars. Similar to how we used stem length to compensate for improper frame sizing, the rise can be used to compensate for different handlebar sizes.
A high rising stem like a top load, will hold the bars a little higher, making an 8inch rise bar feel more like a 8.2 or even 8.5 inch rise depending on the stem rise. The inverse happens for a stem with a negative rise like a front load depicted below. Notice how the bars are actually clamped below the point at which the stem clamps to the steertube.
The rise is not quite as impactful as the length of the stem because you can override it through stacking steer tube spacers above or under the stem to alter the overall handlebar height. However, it’s still important to pay attention to the stem rise and understand that switching between different brands can create unexpected changes to the front end. Just because two stems are the exact same length does not guarantee they will hold your bars at the same height.
Top Load vs. Front Load
Stem’s also come in different shapes as you may have noticed by now. The two most popular being front load and top load. The front load is more popular on the Midschool style of bikes, whereas the top load seems to be the new norm for race bikes today.
A front load stem holds the bars at the front of the stem. These stems tend to have negative rises as they hold the bars much lower than top load stems. In most cases, the bars will sit parallel or just below where the stem clamps the steer tube. As a result, the handle bars will feel “lower” than when paired with a top load. The front load is a great choice for someone who has all of their steer tube spacers stacked on top of the stem and their bars to be even lower.
With a top load, the bars are held at the top of the stem. Top load stems have a much more aggressive rise than the front loads. It’s important to consider handlebar sizing when opting for a top load as it can change the overall height of your handlebars. But again, as mentioned before in the “Rise” section, you can override this issue with steer tube spacer stacking. But if you are currently running a lower rise stem, keep in mind that a higher rise will change the placement of your handlebars a bit.
Also growing in popularity is the slant stem. This is a hybrid between the front load and top load stems. They hold the bars at a slant from the steer tube. These aren’t quite top loads but also not front loads. These have become a popular shape for the newer 31.8mm stems.
Clamping Diameter (31.8mm vs. 22.2mm)
In recent years, BMX manufacturers have moved towards Oversized stems. This term refers to the width of the stem’s clamping surface. Traditional stems have a 22.2mm clamping area, where as newer stems feature a 31.8mm clamping area.
The 31.8mm is a larger clamping, hence the nickname, Oversized. Keep in mind, that whichever size you choose, you will have to purchase the corresponding handle bar size. Handlebars with a 22.2mm clamping area will be too small for the 31.8mm stem to clamp. Make sure you consider whether or not you will have to replace your handlebars before purchasing either one of these stems.
Not much to be said about the 22.2mm handlebar/ stem combo. It’s the standard in bmx racing and does the job without too much flash. If you aren’t familiar with the 31.8mm stem then there’s a 99% chance that you’re running the 22.2mm stem/ handlebar combo right now.
The reason for a 31.8mm stem is that the larger clamping area makes for more grip. The stem has a better hold on the handlebars so the bars are less prone to slipping. This is something you would want should you come up short on a jump or just want more security knowing your bars are less likely to move. The 31.8mm also makes the front end stiffer to lateral forces. There’s more material and larger tubing making for increased reenforcement of the handle bars. You’ll really notice the advantages in the corners; and less importantly, you’ll experience less side to side wiggle in the bars when balancing in the gate. The increased material of the 31.8 will keep things rigid and not flex as much as your weight shifts from side to side.
Stem Material
Like many BMX Racing products, stems can be constructed of various materials thus allowing for varying production methods.
Not all alloy stems are created equal. Just because two stems are of the same material, it does not promise equal performance. Some stems are produced through CNC machining, while others are Forged.
The majority of BMX Racing stems are CNC machined. It can create more intricate designs allowing manufactures to cut out portions of the stem for better weight savings all without compromising structural integrity. This is something that can’t be done with a forged stem. 99.9% of aftermarket BMX Racing stems will be CNC machined, every stem we offer is included in that category!
Forged stems are considered to be stronger, but they also weigh more. These stems are forged from a raw block of material using heat and pressure to alter it into shape. Forged stems are simple in design because of their manufacturing process. It’s a bit of a double edged sword in that they are cheaper to produce, but you need to produce mass quantities of them to be cost effective. You will most likely see forged stems on complete bikes as they are more cost effective to outfit large quantities of bikes.
There’s also differences between the aluminum used to produce stems. The two most commonly used alloys for BMX Racing stems are 7075 and 6061 aluminum.
7075 is a stronger and lighter material, but it’s also more expensive. While 7075 is superior on paper, in terms of a stem’s performance, there is little to no noticeable difference between a 6061 stem and a 7075. It really comes down to build quality and the fidelity of the stem that makes the biggest difference! A poorly built stem made of 7075 is far more likely to fail than a well researched 6061. Again, the difference between the two alloys is hardly noticeable out on track. I put this here so that you can know and understand ALL aspects of stems going forward.
What It All Means
As you can see there are many things to consider when purchasing your next stem. But choices are a good thing! The vast array of options between stems allows you to find a truly tailored fit. It may take some testing and tinkering to finally find the perfect stem for you.
Remember that the stem can do a lot more than just hold your bars! There’s plenty of functionality to be had. And if you’re in the market for a stem, we have plenty of options on our webstore. Speedline have just about every size, style, and color you could want. Click here to get shopping!
Still Have Questions?
No worries! Leave a comment down below with any questions you may have. We’d be happy to reply back with ways we can help. But if commenting isn’t your style, shoot us an email with your question and we’ll be sure to get back to you!
My Personal Set up is as follows; 48mm Front Load Supercross Stem Flipped Upside down w/ 8 inch bars