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Ventum Racing ditches the downtube to get ultra aero

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Ventum One ultra aerodynamic triathlon bike with no downtube
Photo: Troy Szczurkowski

If you’re a tri geek, it’s likely you’ve seen a few shots of the upcoming Ventum Racing bike sneaking around the interwebs. If not, its completely un-UCI legal frame shows just how far things can go when you’ve got no limitations on frame design.

Called the Ventum One, it’s the first bike from upstart Ventum Racing, a brand co-developed by professional triathlete Jimmy Seears. Here’s the story:

“I race professionally, but I got dropped by my bike sponsor,” Seears told us. “My dad and I had always tinkered with and built things, so we thought we’d build a bike. How hard could it be, right?

“We started messing with different designs, and we really liked the Lotus 110 from the mid ’90s, so we started with that. We built the first prototype in Australia in house, which we tested with strain gauges and on the road. Then we tested the second version in the wind tunnel and it was a lot faster than we expected. And that was with a rather messy home made build…the handlebars were pretty messy and jumbled together. So we continued refining the design, and will continue to into the future. So the one you see here now is close, but not quite the final version that’ll ship later this year.”

Ventum One ultra aerodynamic triathlon bike with no downtube

Seears continues: “There are some angles to the downtube that are critical for proper stiffness but terrible for aerodynamics. So the easiest way to improve aerodynamics was to get rid of the downtube. That tube is very old fashioned, from the original bike designs and was important structurally then. But with modern materials and design capabilities, there’s no need to stick with it. Look at what they’re doing with F1 racing or jets. Bikes don’t see anywhere near those same loads.”

Getting rid of the downtube was just the first step. Seears said the consistent top tube section keeps the air flowing over it because of the overall shaping from nose to tail. The cowl and fairing at the top of the fork is pointed, and then the widest part of the top tube is near the center. That silhouette improves laminar air flow over the entire top tube, which reduces drag.

Ventum One ultra aerodynamic triathlon bike with no downtube

 

The front brake is currently a TRP TTV that’s covered with a light plastic fairing that runs all the way up in front of the head tube, too. They’re working on a new fork design that may change which brakes are used, in which case they’ll look at whether an existing solution works or they need to create a new caliper altogether.

On top of the top tube is an integrated water bottle that holds 1.4 liters (47oz, or about two large water bottles worth). It’s designed to keep you tucked into the aero position while hydrating. They’re working on tool storage solutions, too, which will mostly likely be tucked under the seat.

Ventum One ultra aerodynamic triathlon bike with no downtube

“We’ve designed it to be very adjustable,” Seears said. “By using a standard 1-1/8” steerer, you can cut it and the fairing to length. That makes it easily adjustable without giving up the aero benefits. The seat has a lot of adjustment fore/aft and up/down, too. Despite the odd looks, it’s very easy to build…which is a very good thing for triathletes that regularly pack and unpack their bikes for travel. That, coupled with four frame sizes, means it’ll fit just about anyone. And it can be run with standard drop bars if you just want a very, very aero road bike.

Seears says a complete bike with Mavic CXR80 wheels and Dura-Ace group comes in at 20.2lb, but that’s a prototype frame that’s using a thicker clear coat than what’ll be used in production. The layup is pretty much final, though, and Jimmy says they’re seeing very little deflection, even after blowing through 125% of an EU safety test equivalent.

Ventum One ultra aerodynamic triathlon bike with no downtube

Prototypes are currently being raced by Leanda Cave (shown, 2nd at Ironman Texas), Kyle Buckingham, Alicia Kaye and, of course, Jimmy himself.

Retail pricing is still being finalized, but they’ll offer a frameset (frame, fork, seatpost, headset, handlebar, stem and front brake), plus Dura-Ace Di2/808 Firecrest and Ultegra Di2/Zipp 60 complete bikes. Both will get an ISM saddle.

So, about those aerodynamics…

“We (wind tunnel) tested against a Cervelo P5, Scott Plasma 30, Felt IA and others. When we swept the wind angle from 0º to 20º and averaged the results, the closest competitor was the Cervelo P5, but we were still showing an average of 33% less drag in race trim (ie. completely built and accessorized bike).”

The full test data will be published when they open up for presale in June. The first bikes should arrive in August, but they’re promising delivery in September or October just to be safe.

VentumRacing.com

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David
David
7 years ago

Indurain’s Pinarello from the ’90s?

deralex
deralex
7 years ago

looks more like the 1992-94 Lotus Sport bike by Mike Burrows.
Raced by Chris Boardman…

J N H
J N H
7 years ago

I always liked S frames, but didn’t they fall out of use because they’ve been banned from just about everything that isn’t a club triathlon nowadays?

Typenschilddelete
Typenschilddelete
7 years ago

You mean the one linked to in the 4th paragraph?

boom
boom
7 years ago

When an ‘aero’ bike comes out, I think they need to post a comparison graph with competitors or STFU. Otherwise, these are all (rather lofty) claims. 33% less aero drag? Really?

Chris L
Chris L
7 years ago

Yup, the Lotus was banned under UCI rules. Sort of a non-issue since 99.99% of riders will never enter a UCI event.

Cornelius
Cornelius
7 years ago

I saw Kaye’s prototype at St. Anthony’s. Very sharp looking bike that, honestly, doesn’t photograph well. It looks much more impressive in person. If their initial wind tunnel tests pan out this thing will be smoking fast (40-80seconds faster than a P5 over 40k). They still have a lot of work to do though before production, I’ll be curious to see how it looks in final form.

MaraudingWalrus
MaraudingWalrus
7 years ago

33% less drag than a P5? Hot damn, somebody hold my drink, I’m going pro!

Jon M
Jon M
7 years ago

None of this is going to matter considering how bad the TT position of most triathletes is…

JBikes
JBikes
7 years ago

Looks nice. Like a refined version of the Lotus pursuit frame, of which they basically admit. Who doesn’t like an evolution of a great frame?

Veganpotter
Veganpotter
7 years ago

Chris, its probably more like 90% but still an important factor…99.9% if you include people that will NEVER race at all.

That said, I think the numbers are possible. Tough to believe with Cervelo spending so much money making a fast bike but possible since they had no intent on being able to make the bike UCI adaptable or legal from the beginning. Also, Cervelo’s numbers are VERY public and other brands basically confirm Cervelo’s numbers. If they say 33%, go off of their numbers. Its not like that couldn’t make a random chart and show it was 90% faster anyway. None of that will really be believed until an independent study is published which will happen. I’m a UCI guy but if I were a triathlete, I’d be all over this bike if it were faster than the others at a low speed. The P5 is a great bike but not the fastest for slow folks in a triathlon, a Trek Speed Concept is better at yaw angles over 5 degrees and its gets even better past 10 which is what most people will see when they’re riding under 22mph(most people for an Ironman and Half)

anonymous
anonymous
7 years ago

30% less drag isn’t that surprising. The lotus design is very very clever.

The entire top tube is one very long and aero airfoil section. Chainstays are also in a horizontal position, minimizing frontal area.

The seat tube is almost like a wheel fairing, so the air hits a shaped leading edge instead of the tire, and effectively lengthens the airfoil section of the seat tube/wheel combination, and was even more drastic with the disc wheels the 110 was often seen with.

That lets you omit the seat stays, and the downtube.

Comparing a diamond frame and the Lotus, above the top tube, the air hits only the seatpost. At the head tube, the air flows around the long top tube airfoil, on a diamond frame, this may not be the entire length of the head tube. On the down tube, after passing through the fork, a diamond frame the air has to pass the downtube, then the seat tube, possibly the wheels, and also the seat stays. On the lotus design, is just passes the seat tube wheel combination.

Gunnstein
Gunnstein
7 years ago

“shows just how far things can go when you’ve got no limitations on frame design”

Um, no, it doesn’t. That’s almost exactly the same as a UCI legal bike. When you’ve got no limitations, you get things like this:
https://basdemeijer.photoshelter.com/image/I0000YkegeMJgW_w

Grill
Grill
7 years ago

I’m not drinking this Kool-Aid. Remember that the Dimond tested super fast in the tunnel too. Then they put a rider on it and lost all those gains. I would also wager that their aero gains are at extreme yaw angles that most triathletes will never see (ground level people). This thing is a pig, and not even one that can be passed off convincingly in a dress.

Love that filler cap. Very aero. If I was one how gave them VC funds, I’d be seriously considering seppuku right about now. Then again, triathletes are notorious for buying any old crap.

Fastrax70
Fastrax70
7 years ago

Geez! Why not make everything plastic!

Thunderfunk
Thunderfunk
7 years ago

Grill is cranky.

Raymond Foss
Raymond Foss
7 years ago

Natascha Badmann’s CAT Cheetah triathlon bike??

John M.
7 years ago

As an aerodynamicist, I’m very skeptical of the 33% less drag than a P5. Also, a frameset only drag isn’t real world anyway. Without a rider on board, the airflow over the frame is completely different and by comparing one frame to another in this manner is a moot point. Secondly, Mr. Seear’s comment, “That silhouette improves laminar air flow over the entire top tube, which reduces drag” is incorrect as the flow isn’t laminar for even 5% of the length of the top tube due to various viscous and non-viscous flow stability (i.g. Tollmien-Schlichting waves, Orr-Sommerfeld, ect.). Due to the aforementioned reasons, the flow on the top tube as on most of the other tubes is turbulent anyway.

Ajax
Ajax
7 years ago

So what? Chris Boardman had a frame like this 20 years ago.

spinbob
spinbob
7 years ago

What about Chris Boardmans Lotus and there have many others this is not new

Marc
Marc
7 years ago

Gunnstein : +1

the weirdest – and most awesome – are the rear facing (drived with a mirror!) models of Damjan Zabovnik. His best one have a 0.0125 m² CdA
http://www.eivie4.com/bikes/eivie-iii/
and I trust that, the light aircraft company he works in is one of the best, and his design have the hour record at 91.556 km.

Gary McDonald
7 years ago

Disappointed we did not even get a mention, built the prototype in house??? Should read built at Paint My Bike in Brisbane and FOC.

Veganpotter
Veganpotter
7 years ago

Everyone saying this is nothing new is partially right but what about any new aero bike. They all have double triangles and how have hidden brakes. Why make any other new bike with those things? Easy…small differences in tube shape give huge gains. There are enormous wind tunnel differences from a Cervelo P5 and a regular, round tubed frame, even though they really have basically the same shape/foundation. This bike likely acts VERY different than the lotus in the wind tunnel. That Lotus bike is VERY fast, even now. This could be much faster with the cable routing, front brake, better shaping, modern aerobars etc

Cowtown Cyclist
Cowtown Cyclist
7 years ago

The biggest innovation Chris Boardman had on his side was his body position. His Lotus was fancy, but the reason no one is even close to his 56.375 km is because the human body represents the vast majority of the drag. Frame aerodynamics are really just window dressing.

fred
fred
7 years ago

If only I was an aerodynamicist, like John M, I could for sure use my big brain to run the picture of this bike in my brain wind tunnel and figure out if their claims are bogus or not. But my brain is pretty small and the only thing I can kinda comprehend is that the boundary layer over the top tube is probably not laminar because the length of it and a typical speed of a bicycle put it above the critical Reynolds number (>4000) which means that it is probably turbulent. I can’t possibly comprehend how Tollmien solved the Orr-Sommerfeld equations to describe that unsteady flow and arrived at those wave thingies that John mentions, so I will not cite them to demonstrate how smart I am. As a layman, I also believe that some of the bicycle remains upstream of the rider and is thus mostly unaffected by the rider and I do believe that there is value with testing without a rider on board, mostly because there is no other way. If only I was as smart as John then maybe I would figure out how to make non-rigid, pedaling manequins of various sizes that are fully adoptable for all the small variations in bicycle fit and geometry. Also I would figure out how to make millions of currency so that I could pay for weeks of wind tunnel time to study different manequins with different prototypes and production bikes of various sizes and configurations.

Anyways, sorry for this off-topic comment towards John M. People that know everything make me upset. I wouldn’t mind if this comment gets moderated out. But the bike looks nice. What’s old is new again.

out for a ride
out for a ride
7 years ago

I know Seers says that they derived the bike from the Lotus design in the beginning of the article, but I’m gonna pretend that he claimed it to be revolutionary and then scold him for it. I can’t be bothered to read anything, but damn if someone won’t let me spit my opinion all over the page!

John M.
7 years ago

@Fred, sorry I made you upset, go have beer or something to make you feel better. The intent of my post wasn’t to show how smart I was, but rather it was made to address a key point Mr. Seears made about aerodynamics that wasn’t true. If you don’t like that sort of discussion and you’re willing to accept yet again another manufacturer trying to market a product with dubious claims, then go right at it. I’m sure this bike will help you achieve 22 mph PR on your next time trial or bike leg of a tri.

Gunnstein
Gunnstein
7 years ago

@Cowtown Cyclist “…the human body represents the vast majority of the drag. Frame aerodynamics are really just window dressing.”

Yes, unless the frame includes a fairing. I looked up some hour records:
91.556 – Francesco Russo, faired recumbent, 2011
56.375 – Chris Boardman, Lotus upright, 1996 (UCI approved, then reclassified)
52.074 – Aurélien Bonneteau, unfaired recumbent, 2009
49.700 – Ondřej Sosenka, conventional upright, 2005 (UCI approved)
45.055 – Francis Faure, unfaired recumbent, 1933 (UCI approved, then reclassified)

One should be aware of these different categories when discussing the “hour record” – it means a lot of different things.

Andy
Andy
7 years ago

The (liquid) storage piece and the stem-to-handlebar part could be much more streamlined. That gap is ugly and goes against the whole concept.

Rixter
Rixter
7 years ago

(90’s Pinarello) Exactly what I was thinking. Didn’t Ulrich ride one on a TT around Euro Disney, crashed in a cross wind?

McClain
McClain
7 years ago
ginsu
ginsu
7 years ago

The only bike that WILL show a substantial improvement in aerodynamic drag WILL COME FROM OPTIMIZING THE POSITION OF THE RIDER, NOT THE FRAME. If you were really determined to design a bicycle that had the BEST AERO you would obviously invest most of your energy in getting the rider into a better position.

Even if this frame has aerodynamics that are 33% better than it’s competitors, you will destroy the advantage when you ride it!

Bryin
Bryin
7 years ago

First, triathletes WILL buy anything… they are a marketer’s wet dream, stupid people with money. Second, frame aerodynamics mean nothing to everyone that can’t ride 27mph for an hour. Which means if you need an aero frame you will be given one by your sponsor. Otherwise suck it up.

Lastly, wind tunnel testing means little in the real world. In cycling 98% of the time wind is coming from 2 directions- from the front and from an angle. Wind tunnels can not replicate this. In testing higher speed subjects like cars this does not matter as much.

Aero is baloney, marketing designed to separate stupid people from their money.

John M.
7 years ago

@Bryin, you sound angry and misinformed (or you’re just a troll). But hey, if you want to ride whatever bike you’d like, be my guest. Aero bikes are an advantage (for anyone who races either TT’s, criteriums, road races, and triathlons) with or without a direct head wind. And you don’t need to be riding 27 mph as you say to benefit from an aero frame. You can gain a benefit from riding one at 20 mph, although the power savings from the drag reduction are of course less. In addition, wind tunnels can and usually are used to replicate the wind’s yaw angle by using a rotating turn table and measuring the drag at various increments of yaw angle. So I am glad to be stupid and to be relieved of my money for an aerodynamic bicycle and a proper aero fit to make the whole rider-bike package optimal for racing.

DT
DT
7 years ago

Yes, it’s positioning AND the bike AND fitness AND whatever else! If you have perfect positioning, a more aero bike will simply make you faster! Period.
And I gotta mention the “Flying V” bikes by Softride and lesser known and more aero Cycpro prototypes that are also non-UCI legal bikes that have optimal aerodyanmics similar to this one. And you can get the Softride ones under $1000!

slinger
slinger
7 years ago

i knew my Slingshot was good for something. turns out its TT’s.

Fraser Cunningham
Fraser Cunningham
7 years ago

I scanned and didn’t see any comments on the biggest disadvantage of this design, so apologies if it’s already been stated, but here it is:
Aero advantage versus hysteresis loss. While this design may reduce drag, it WILL incur an efficiency loss due to the frame twist (lost energy, does not contribute to propulsion). Period. I became convinced of this after following a fellow triathlete on his Softride (I had a carbon frame Softride at that time) and observed his rear wheel twisting several degrees each way as his pedals went over the top of the stroke. This was frame twist, which costs energy but is completely lost when the other leg engages the geartrain. Interesting how there is little said about this phenomenon when discussing these types of frames.

anonymous
anonymous
7 years ago

@Fraser
That energy is not completely lost, in fact no one has actually done any real testing as far as stiffness and power loss goes. The wheel “twisting” could have simply been poor form, and lack of seat stays to track the wobble to.

And the fact of the matter is, the aero benefits already proved themselves 20 years ago, which is why they got banned in the first place. This isn’t voodoo, it’s race proven 20 year old technology.

Joe R.G.
Joe R.G.
7 years ago

You won’t see frame twist on any new-school beam-bikes…
But what about the drive train and gearshift stuff? Why not implement some kind of gearbox like a Rohloff to get get rid of this crap. And the drive train (chain or cardan shaft drive) integrated in a mono-chainstay? Depending on the course weight doesn’t matter that much.

JV
JV
7 years ago

“That tube is very old fashioned, from the original bike designs and was important structurally then. But with modern materials and design capabilities, there’s no need to stick with it. Look at what they’re doing with F1 racing or jets. Bikes don’t see anywhere near those same loads.”

Not true, the diamond or triangulated frame is a very efficient way of creating structural integrity. It’s true that in the old days, there was no other way of achieving this, and that nowadays we do have material with which we can achieve high stiffness and strength and have interesting shapes and forms, but just look at the sheer amount of material needed.
If you use a current state of the art material (such as high modulus carbon fiber composites), in the “old fashioned” way of making a bicycle frame, you end up with something which is lighter and stiffer than the bike shown in the article.
And yes, perhaps such a bike has more drag, but do not mistake “traditional” with “old fashioned”. It’s engineering requirements and trade-offs that drive design, and apparently aerodynamics were given a higher priority than weight or stiffness.
And looking at the design of F1 racing cars is indeed worthwhile. You’ll see that the area with extreme stresses, front wheel suspension, looks exactly like the front triangle (or rear) of an “old fashioned” bicycle frame 🙂

JV
JV
7 years ago

But kudos for taking on such a giant engineering job with such a small scale team!

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