Quick Answer: The Dimond Marquise is a beam-design triathlon bike handmade in the U.S.A. It uses a wishbone (beam) frame instead of a traditional seat tube to reduce aerodynamic drag across straight-on and yaw wind angles. The Marquise is the stiffer, higher-power-transfer evolution of Dimond’s original Brilliant, with integrated top-tube nutrition storage and a bottom-bracket tool compartment, available in rim and disc configurations.
SPECIAL THANKS TO THE PROS CLOSET FOR THE IMAGE CONTAINED IN THIS ARTICLE!
Dimond entered triathlon in 2013 by reviving the beam-frame concept ZIPP experimented with years earlier. Rather than a conventional double-diamond layout, the beam design removes the seat tube entirely, suspending the saddle on a cantilevered carbon beam. Dimond bet that the concept could be refined beyond its original form, and a decade of fastest overall bike splits at races worldwide, including the Kona World Championships, has validated that approach.
The Marquise sits near the top of Dimond’s range and is a direct evolution of the original Brilliant. The frame uses revised carbon layups and tube shapes to increase lateral stiffness, which translates more rider input into forward drive rather than frame flex. Both rim-brake and disc-brake versions are offered, and the frame carries a large nutrition compartment integrated into the top tube plus a second storage bay near the bottom bracket sized for tools and a flat kit. For long-course athletes, on-bike storage of this scale removes the need for bolt-on aero bottles and bento boxes that disrupt airflow. A quality tire repair kit stows cleanly in that lower compartment.
Aerodynamically, the Dimond frame posts industry-leading wind-tunnel figures both head-on and across a range of yaw (crosswind) angles. The beam architecture reduces the frontal surface area and turbulence that a standard seat-tube-and-rear-triangle cluster generates, particularly behind the rider. That advantage holds up in real racing conditions where wind rarely arrives perfectly straight on, which is why the platform repeatedly produces leading bike splits rather than just favorable lab numbers.
Recommended Gear Dialing in your position on a beam bike starts with reliable aero extensions and a clip-on bar that holds its setup. |
This particular build is a 2021 X-Small with an original MSRP of $6,000.00 and a full carbon Dimond frame and fork. The drivetrain is a 1×11-speed setup, pairing a Shimano Ultegra alloy crank with a 52-tooth Rotor chainring at 165mm with a Shimano 105 HG700 11-32t cassette and a Shimano Deore XT M8000 rear derailleur. The 1x configuration drops front-shifting hardware to clean up the cockpit and reduce weight, while the wide 11-32t cassette preserves climbing range despite the single front ring. Total weight is 20 lbs 1 oz.
Braking is a mixed setup typical of beam-frame triathlon builds: a TriRig front center-pull caliper paired with a Shimano Ultegra rear caliper, actuated by a Microshift right shifter and Shimano left shifter, both mechanical. The cockpit runs a Profile Design Prosvet carbon base bar with T4+ carbon aero extensions in 42cm, mounted on a 110mm Profile Design alloy stem with 7 degrees of rise. Keeping a small torque wrench on hand is worthwhile, since carbon base bars and extensions require precise clamping force to avoid damage.
The wheelset is a Profile Design 58 TwentyFour carbon tube-type clincher set, shod with Continental Grand Prix 4000 S II tires, 23c front and 25c rear. The deeper 58mm section reinforces the frame’s aero intent, though the tube-type construction means these wheels are not tubeless compatible, so ride with the right inner tubes and a backup. Axle spacing is the older 9x100mm front and 10x130mm rear quick-release standard, consistent with a rim-brake frame of this era. Finishing kit includes a frame-specific Dimond carbon seatpost, a Cane Creek headset, and a JCOB Delta Thirty Eight saddle on Cr-Mo rails.
Cosmetically, the Master Mechanic notes light scratches on the brake levers and shifters, and light scratches on the fork lowers, head tube, and chainstays. None of these are structural, and on a handmade U.S.-built carbon frame of this caliber they represent normal use rather than a concern for a rider seeking a proven aero platform.
Frequently Asked Questions
What is a beam-frame triathlon bike?
A beam frame replaces the traditional seat tube and rear triangle with a single cantilevered carbon beam that supports the saddle. The Dimond Marquise uses this design to reduce frontal area and airflow turbulence behind the rider, lowering aerodynamic drag across straight-on and crosswind (yaw) angles compared to conventional double-diamond frames.
Are the wheels on this Dimond Marquise tubeless compatible?
No. This build uses Profile Design 58 TwentyFour carbon tube-type clincher wheels, which are not tubeless compatible. They require standard clincher tires with inner tubes, such as the fitted Continental Grand Prix 4000 S II in 23c front and 25c rear.
Where are Dimond frames manufactured?
All Dimond frames, including the Marquise, are handmade in the U.S.A. The brand launched in 2013 reviving the beam-frame concept and has since produced fastest overall bike splits at major triathlons worldwide, including the Kona World Championships.
James Hickman is a former USA Cycling Expert coach and Platinum finisher at El Tour de Tucson (sub-5-hour century), who has coached riders of all levels, including Team In Training century riders.
Sponsored · Competitive Cyclist
We are an Amazon affiliate and earn from qualified Amazon purchases with no cost to you. This is for ANY product that you purchase through our links. We are also an affiliate for Competitive Cyclist and JensonUSA. This way we can provide you with competitive pricing and products.
