Stems

Run your favorite 31.8mm clamping diameter handlebar on a bike with Knock Block with the Rhythm Comp 31.8. It adds Knock Block compatibility to a durable stem with multiple lengths to let you fine-tune the fit to your ride. Get 31.8mm handlebar compatibility with your Knock Block system;Also compatible with standard headsets and spacers;Knock Block system protects frame from impacts by fork and handlebars by eliminating over-rotation of bars;Available in a wide range of sizes for today's mountain rider;See Service Parts for other Knock Block parts;

This BMX quill stem combines a steel rod with an alloy top. The 4-bolt top clamp securely fastens handlebars.

The BrickTop alloy stem is a classic style, top-mount BMX stem with a 4-bolt handlebar clamp.

The DefendR BMX threadless stem has a AL6061 forged alloy construction and a 4-bolt face clamp. - 30mm stack height - 240g

With its alloy/steel construction and 4-bolt clamp design, the MX is a trusty BMX quill stem. - Quill Length: 4-1/4-inches - Quill diameter: 21.1mm

All Box stems are engineered and crafted using our Oversized Technology. As we follow the load paths down the handlebars we have focused our attention on the stem-to-bar interface. Since the Oversized handlebars have an increased wall thickness and tube diameter in this sector we have reciprocated with an augmented stem interface with greater surface area. We’ve done this by moving material from low stress areas. This has greatly minimized twist and contributed to responsiveness. As the stem in mated with the handlebars we have contributed to increased pedaling stiffness by providing a backstop to the “lifting” phenomenon. There is no point pushing hard on your pedals if you can’t pull up on your handlebars and deliver that power. Power can easily be lost to handlebar-to-stem deflection and the consequences can be poor power delivery and steering control. When combined with Box’s other Oversized components, you’ll experience heightened responsiveness and reduced latency. Key differences: This particular model stem pushes our Oversized Technology to the extreme as it maximizes the shift of material from low stress zones to the Oversized interface. These stems are engineered for the smaller-sized racers. -Lightweight 3D Hollow Design -Front-Load Clamp Design to Fight Pull-Up Forces -Large Bar Bore -Large Hollow Clamping Bolts -Superior Strength

All Box stems are engineered and crafted using our Oversized Technology. As we follow the load paths down the handlebars we have focused our attention on the stem-to-bar interface. Since the Oversized handlebars have an increased wall thickness and tube diameter in this sector we have reciprocated with an augmented stem interface with greater surface area. We’ve done this by moving material from low stress areas. This has greatly minimized twist and contributed to responsiveness. As the stem in mated with the handlebars we have contributed to increased pedaling stiffness by providing a backstop to the “lifting” phenomenon. There is no point pushing hard on your pedals if you can’t pull up on your handlebars and deliver that power. Power can easily be lost to handlebar-to-stem deflection and the consequences can be poor power delivery and steering control. When combined with Box’s other Oversized components, you’ll experience heightened responsiveness and reduced latency. Key differences: In this particular model stem we’ve modulated the Oversized formula to emphasize pedaling stiffness. We have transferred material specifically to sectors that experience sudden stress from pulling up on the handlebars. You’ll feel a difference in your acceleration. These stems are engineered for the larger-sized racers. -Material: 6061-T6 Aluminum -Process: Cold-Forged -Hardware: Chromoly Clamping Bolts -Finish: Anodized w/Laser-Etched Graphics Weight: -48mm: 280 g / 9.8 oz -53mm: 290 g / 10.2 oz

All Box stems are engineered and crafted using our Oversized Technology. As we follow the load paths down the handlebars we have focused our attention on the stem-to-bar interface. Since the Oversized handlebars have an increased wall thickness and tube diameter in this sector we have reciprocated with an augmented stem interface with greater surface area. We’ve done this by moving material from low stress areas. This has greatly minimized twist and contributed to responsiveness. As the stem in mated with the handlebars we have contributed to increased pedaling stiffness by providing a backstop to the “lifting” phenomenon. There is no point pushing hard on your pedals if you can’t pull up on your handlebars and deliver that power. Power can easily be lost to handlebar-to-stem deflection and the consequences can be poor power delivery and steering control. When combined with Box’s other Oversized components, you’ll experience heightened responsiveness and reduced latency. Key differences: In this particular model stem we’ve tailored the Oversized strategy to favor utility and access. The geometry has been altered to allow for easy handlebar removal while at the same time scavenging material from low stress zones. Ideal for those who don’t want to compromise on user experience to gain performance. These stems are engineered for the larger-sized racers.

Hollow stems are cold forged from the highest quality 6061-T6 aluminum available. Featuring an open skeletal design and a dual mid-bolt wedge mounting system, they are lightweight yet maintain a very high level of strength. A 53mm extension stem weighs just 218 grams/7.7 ounces. By removing the rear pinch bolts and moving the mounting bolts to the middle of the stem, we reduced the weight and size and eliminated a serious hazard to the rider’s knees. These stems come with either a 48- or 53mm extension and a 22.2mm bar bore. To ensure proper clamping force, the stem must be mounted on a fork with at least 45mm of exposed steerer tube. Not compatible with forks that have carbon fiber steerer tubes.

The Box Two Front Load is a modern, 22.2 stem designed specifically for BMX racing. Box Two Front Load stem bodies are cold-forged and CNC-machined from the highest quality 6061-T6 aluminum. The lightweight front clamps are cold-forged and CNC-machined for increased stiffness and strength. -Material: 6061-T6 Aluminum -Process: Cold-Forged -Hardware: Chromoly Clamping Bolts -Finish: Anodized w/Laser-Etched Graphics Weight: · 48mm: 224 g / 7.9 oz · 53mm: 230 g / 8.1 oz