Funn RSX Direct Mount Bike Stem 35mm - Adjustable 45-50mm Extension

In this review the Funn RSX Direct Mount Bike Stem is assessed for riders who run dual crown forks and need a stiff, reliable connection between bar and steerer. The single biggest reason to consider the RSX is its combination of a 35mm clamp option and precision CNC 6061 alloy construction, which delivers notable rigidity without adding unnecessary weight. For downhill and aggressive off-road use where clamp strength and durability matter, this stem stands out as a purpose-built choice.

Key Features

• 35mm Bar Clamp: Provides a wider clamp engagement for added stiffness and secure handling on rough terrain.
• Direct Mount Design: Made specifically for dual crown forks so alignment and fit are simplified for downhill setups.
• 6061 Aerospace Alloy: CNC precision manufacturing gives a strong, lightweight structure that holds up to hard use.
• Adjustable Extension: Offers both 45mm and 50mm lengths with 20mm and 30mm rise options to tune reach and bar height.
• Split Two-Piece Construction: Two-piece layout makes installation around dual crown crowns straightforward while maintaining clamp strength.
• Multiple Colors: A range of finishes lets riders match the stem to their bike for a cohesive look.

Who It's For

The RSX suits downhill and aggressive trail riders who run dual crown forks and want a stiff, reliable stem with a 35mm clamp for improved control. Riders who value a lightweight CNC alloy part that gives both 45mm and 50mm extension options will appreciate the adjustability for dialing in reach and rise.

Less suitable are casual riders or those who use single crown forks and 31.8mm bars, since this listing is the 35mm-only version and is tailored to dual crown systems. Also, riders who need integrated headset functions or a full-service cockpit may prefer a different stem design.

Pros & Cons

Pros

• Solid clamp strength and a wider 35mm hold improve front-end stiffness and confidence on rough descents.
• Lightweight yet rigid thanks to CNC 6061 aerospace grade alloy construction.
• Built-in adjustable extension gives practical tuning between 45mm and 50mm without swapping parts.
• Easy installation on dual crown forks with its split two-piece direct mount layout.

Cons

• Available only in a 35mm clamp version here, so it will not fit 31.8mm handlebars.
• Designed for dual crown forks only, so it is not universal for all mountain bikes.

Specifications

Our Verdict

The Funn RSX Direct Mount Stem is a focused choice for downhill and aggressive off-road riders who run dual crown forks and require a sturdy 35mm clamp. Its CNC 6061 construction, adjustable extension, and split mount design deliver good value for riders who need stiffness and easy fitment; just confirm your handlebar diameter before buying.

Frequently Asked Questions

Will this fit my 31.8mm handlebar?
No. This listing is the 35mm clamp version only; check for the 31.8mm model if that is your bar size.

Can I use this on a single crown fork?
It is designed specifically for dual crown forks, so it is not intended for standard single crown setups.

Does it come with adjustable reach settings?
Yes. The RSX offers built-in adjustment for 45mm and 50mm extension with two rise positions.