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From Nose to Tail: Factor OSTRO Gets Comprehensive Aero Upgrade

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The OSTRO is the bike that encompasses Factor and its presence worldwide. It’s the most recognizable (IMO) and appealing of its offerings and helped shape the mold for powerful road machines with a slippery silhouette. The new OSTRO doesn’t move far from the original starting point but goes all in on minute aero updates for larger gains. 

OSTRO VAM Headtube front on
(All images: Factor Bikes)

When it came time to redesign the bike, the Factor design team looked to balance stiffness/comfort, real-life aerodynamics, and beauty. The team added some cool extra bits like unique aero bottle cages and a new set of ultra-fast (and very good-looking) Black Ink 48/58 Wheels. 

 factor OSTRO VAM zones

Factor OSTRO – Aero Makeover from Nose to Tail

Developing the 2024 OSTRO, Factor looked at every tube and focused on understanding how the bike’s shape could strategically guide air around the rider. They started at the leading edge and worked backward. 

While presenting the new OSTRO, the Factor design/aero team explained that Improvements at the front impact elements at the rear, creating a snowball effect of gains and losses. The Factor design team divided this aero-challenge into five ‘zones’ to achieve the most aerodynamic edge while maintaining the bike’s overall ride integrity.  

 factor OSTRO VAM junction

Zone 1 — Fork and Headtube

The fork impacts the aerodynamics of the entire bike as the central part of the bike’s leading edge. The CDA (drag coefficient) was reduced by minimizing the frontal area and increasing shape efficiency. The newly reduced fork crown height improves the new OSTRO’s stiffness and feel. The ride feel and responsiveness are a hallmark of the OSTRO, and the team didn’t want to lose that feeling amid aero gains. 

 factor OSTRO VAM HT front

Factor then gave the new OSTRO’s headtube a more hourglass shape, reducing the frontal area. Adding a nose on the headtube allowed the team to move the leading edge of the fork forward, creating a smoother transition for the nose with the headtube.

Aero Fork on the inside: Small surface details were added on the inside of the fork leg that work with the rotating wheel to promote better flow. The dropout and brake mount surfaces are modeled to move the air from the axle. All these small details add up to create a nice chunk of aero-gains.

 factor OSTRO VAM HT tt

Zone 3 — Headtube to Toptube

The updated head tube made way for a look at the overall airflow coming to the top tube. The team focused on smoother flow from the headtube to the bike’s rear. A streamlined headtube-to-top-tube transition enhances flow attachment and creates a more slippery design. This slimmer top tube paves the way for an overall reduction in seat tube size for a streamlined profile.

 factor OSTRO VAM rear

Zone 4 — Seat Tube 

Now that the UCI has removed the 3:1 rule (about two years ago) for components and reduced the minimum tube thickness required, the design team at Factor could develop a slim seat tube that worked well with the aggressive tapering on the top tube.

factor OSTRO VAM fast front

The team’s objective was to maintain stiffness while reducing frontal area. As a result, the lower sections of the seat tube remain as wide as the OSTRO frame. It tapers into the bottom bracket zone (zone 5) and requires additional carbon layup magic to combat the dreaded torsional flex.

ostro_2024_Team Blue_detail_chain stay

Zone 5 — Bottom Bracket

The industry trend is to make the bottom bracket wider, taller, and slightly boxy (like the Trek Madone). Factor added their spin on this with the new OSTRO, creating a smooth yet boxy bottom bracket junction. The team started, “Balancing shape efficiency and maintaining volume and rigidity is key to power transfer. Here, we had to manage the pedaling forces in one plane while promoting airflow retention in the other.” 

 factor OSTRO VAM black

As for the height, the design team meticulously fine-tuned the volume above the bottom bracket, balancing airflow while keeping it tucked away from the riders’ legs. Once again, the Factor team found a slight gain in aerodynamic efficiency, adding another tick in the faster direction.

 factor OSTRO VAM white

Black Ink 48/58 Wheels:

When Factor drops a new bike, it usually means another cool wheelset, and the BLK Inc 48/58 is no exception. The newest BLK Inc. wheels feature a high-flange carbon spoke hub and weigh in at a super light (for this deep) 1270g. The wheelset is aero-designed and tested for maximal performance with 28mm tires.

 factor OSTRO VAM wheels

The increased leading-edge radius improves flow attachment at larger yaw angles, and the high-flange hub increases ride feel and lateral stiffness.

Factor design team explains: “The increased radius creates a more gradual rate of curvature change, promoting flow attachment at larger yaw angles. In addition, the rounder profile and more gradual change in curvature means that the aerodynamic stall onset is gentler, giving the rider a better feeling of control in gusts and strong crosswind situations.”

 factor OSTRO VAM bottle design

Aero and Tube Specific Water Bottle Cages 

Not only are these new Factor/BLK Inc cages aero, but they are tube-specific. Unlike other aero cages, they do not require a specific bottle or an attachment.

 factor OSTRO VAM bottle air flow

Black Ink–Tube Specific Bottle Cage: The BLK Inc OSTRO downtube cage bridges the gap between the downtube and the water bottle. It promotes longer flow attachment and reduces localized drag — plus, it holds a water bottle!

 factor OSTRO VAM bottle cage aero

Ostro Sprint Cage: The Factor design team chose a different aerodynamic approach for the Sprint Cage. It acts as a high-speed flow management device. It’s most aerodynamically functional when a rider ejects their bottle before the final sprint. The foil profiles and precise spacing with the seat tube funnel air tightly across the tube and transition it to the rear wheel. Making you faster for the times when it’s absolutely needed — like a tour stage or a town line sprint.


The Full Picture — Factor OSTRO 2024

So, how much faster is the new Factor OSTRO compared to the previous generation? The new design saves 7 watts. Now I know what you’re thinking: “All that for 7 watts?!” But that’s a lot when it comes to an already super-aero bike. 


The Factor design team explains: “As for aerodynamics, the net gain is roughly a 10% improvement in aerodynamic efficiency with all variables controlled and normalized in a wind tunnel. This is, on average, a 70-gram reduction in drag vs. the original OSTRO. This is about 7 watts at 48km/h, which converges with our simulation data. In addition, the aerodynamic benefit increases as yaw angles become closer to real-world expectations (5-10 degrees).” 


Factor OSTRO VAM — Prices and Availability

The new Factor OSTRO VAM is available exclusively from factorbikes.com and authorized Factor dealers worldwide.

factor OSTRO VAM pricing

The Factor OSTRO is available as a frameset, a ‘rolling frameset’ with Black Inc 48/58 disc brake carbon wheelset, or a complete bike.

Sizes: The New Factor OSTRO is available in sizes 45, 49, 52, 54, 56, 58, and 61cm.

Paint options: Gloss Chrome, and Pearl White


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2 months ago

That’s a lot of words to say “made rim wider, added carbon spokes; updated tubes due to rule change”

We’re truly stuck in a flat loop since 2016

2 months ago
Reply to  Evan

What were you expecting? This is a top-of-the-line race bike that has to conform to UCI rules. You realize that, right? So what can Factor do? As for the changes listed, well, isn’t reasonable list what changed, especially when there aren’t many or any “revolutionary” changes that can be made?

I don’t think the UCI will allow the use of electric discharge to further manipulate flow, and I doubt Factor has access to or would even want to use radar absorbing materials. Sure, radar propagating in the opposite direction of the Ostro would technically cause the bike to slow a little, but we’d be talking about the effects of a force on the order of somewhere in the nano- to femtoNewton range.That’s gonna be tough to resolve on the road. So what else is there?

As for being “stuck in a flat loop”, what was it called when steel frames were the norm? I’d say there were decades of “being stuck in a flat loop” with respect to steel bikes.

2 months ago
Reply to  Robin

Exactly, and some are still stuck in that flat loop with steel. inevitably one will chime in here. The operative point as you allude to in the first sentence is Uci rules are holding back bike design. It’s super easy with modern computing power to run ever possible variant of the allowed trouble and tubing and check the performance and weight advantages of this vs that aw nd that is why we have been “stuck in a flat loop” but not since 2016, more like about 2019. Specialized hit peak aero with the last version of venue and all they can do now is get a little weight out of it and add pretty impractical bar stems. And still get about the same drag. And this is why all bikes are pretty much the same now and will be until UCI allows bigger changes. Probably the biggest change with this is one is the freaking bottle cage, and I’m seriously doubting a 7w gain vs old ostro. But no one should blame Ostro or specialized or BMC or whoever. The problem is UCI, the sock regulators.

Robert Miskines
Robert Miskines
1 month ago

Wow does it look aero! Love the hourglass headtube. I see a combination of the Cervelo S5, Giant Propel and Scot Foil RC (mostl front fork). The color and component options are incredibly diverse compared to other manufacturers too, a real plus for those that want to really dial in their performace.

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