World’s most aero UCI legal bars?

John Cobb’s new wind tunnel optimized position for me has my arm rests 5cm lower than my 3T Ventus LTD bars, and has my elbows much closer to each other. My choice was to either buy a new Cervelo P4 with a shorter head tube, or to use a crazy dropped stem with some non-integrated bars, or to have some bars custom made. You know where this is going…

I also want to have UCI legal bars, which means not exceeding the 3:1 aspect ratio. The most aero commercially available bars I could find were the Tula Aero Bars, which are 17mm thick and 50mm deep. They come in a narrow version that’s 38cm wide. Al Morrison’s “rule of thumb” says that:
0.001 square meters of frontal aera is equivalent to 1 watt, which is ~ 4 sec in a 40 km TT.

This had me tempted to do the aero-or-die position as it would be removing the entire frontal area of the wing section of the bars. But there are two issues with using aero-or-die bars. The first issue is that the UCI could very easily make this illegal; there’s a rule that says something like “bicycle handle bars must supply sufficient control to safely steer the bicycle”. So far it doesn’t seem that anyone has been banned for using aero-or-die bars, but quite a few people say it’s only a matter of time, and I’d hate to be that guy at Nationals who gets told that his bike isn’t legal in the starting gate. My friend Matt Johnson, who is the president of the Garmin-Transition Professional Cycling Team laughed at me when I told him about aero-or-die bars, and said “I’m sure they wouldn’t allow those in the Tour”. The second reason for not going with the aero-or-die bars is that I have a wife and two young kids, and the “die” part of that name was inserted for a reason.

The frontal area of the Tula bars is 380mm (the width) times 17mm (the thickness) which comes to .006460 square meters. To lower that number there were two things I could do — I could make the bars narrower and I could use thinner tubes. The thinnest aero tubing I could find that would still be structurally sound for making bars came from the wonderful frame builder Dave Tiemeyer who recently made a custom TT Tandem for me. It’s the tubing he uses for his seat stays. It is 13mm x 38mm, meaning it’s UCI legal, and it’s thinner than the 17mm thick carbon wings on the Tula bars. Then I decided that I’d make the bars as narrow as possible. I came up with 28cm as the right number, pretty much by experimenting with holding my hands on the tops of my regular road bars. I can’t yet tell you whether this is sufficient as I haven’t ridden these new custom bars yet, but it sure looks safer than the aero-or-die bars.

Back to the math… The frontal area of my new bars is 280mm wide times 13mm thick which comes to .003640 square meters. That’s about .003 square meters less than the narrow Tula bars. According to Al Morrison’s rule of thumb, this should save me 3 watts or 12 seconds in a 40k. The Tula bars do have the inline brake levers, and I opted for traditional brake levers on my custom bars, so I have to add back a little frontal area. My lazy math says that I might give up 2 of those 12 seconds by using some really thin 3T time trial levers, so now we’re down to a 10 second savings. That’s 10 seconds over the Tula bars — not 10 seconds over my now illegal 3T Ventus bars. Once these bars are done I’ll do some frontal area calculations and see if I’m really back to where I started. The 3T Ventus bars have remarkably thin wings and very little frontal area.

These initial prototype bars are being built by my great friend, master frame builder JP Boylan of James Frames here in Boulder. Thanks JP!

If you’re interested in having some custom bars made, let me know. I’d consider making more, depending on how well these work. These are not adjustable at all, and are probably best for people who have done wind tunnel testing and know exactly what they want.

John, maybe you can send us some customer’s measurements and we can make them some bars?

13 thoughts on “World’s most aero UCI legal bars?

  1. Check the UCI regulations carefully: I think there is already a specified minimum handlebar width of around 35cm

  2. Indeed, I googled it after I said that too. UK CTT regulation is 35cm, but the UCI don’t seem to be specific. I wouldn’t fancy 28cm if there is any technical riding to do, but hey, it’s your funeral :-)

  3. I sure hope these don’t bring about an early funeral! These are prototype bars — I’m definitely going to test them out and make sure I feel safe with them before I go do a technical TT course. And it’s possible that I’ll decide they are too narrow, and I’ll either make a wider set, or I’ll reserve them for non-technical races. But from my previous experience, having really narrow bars doesn’t make handling the bike difficult, rather it makes riding out of the saddle difficult. Until I get out on the road with these, I’m just speculating.

  4. the uscf has a minimum width for brake hoods.

    pretty specifically does not apply to your bars. because they aren’t used in a road event and because of the lack of hoods.


    …attachments that point upward on the brakehoods of road bicycles are allowed if the distance between them is greater than 25 cm…

    nice bars.

  5. Update: I’ve raced with this first version 5 times so far this year and they actually feel better than I thought they would. It’s not a problem at all to control the bike, even on sharp corners, despite the super narrow bars. Climbing out of the saddle is where they don’t really work, so as long as the course doesn’t have many steep hills, they work great. I also tend to be more efficient remaining in my aero bars while climbing so I don’t see this as much of an issue.

    Small things that bother me are:
    1) The extensions are so close that it’s hard for me to see my PowerTap head, which I have mounted between my forearms.
    2) My elbows occasionally bump into the stem part of the bars, which is a little higher than it needs to be.
    3) We didn’t drill a hole for the front brake cable to exit the wings on the bottom, rather it comes out of the rear of the wing. This makes for an awkward cable route. This will only take 20 min to rectify, but I haven’t gotten around to it yet.

    I’m planning on filing the welds down more, to make the bars smoother, drilling a new front brake cable exit hole, and having them anodized or painted. And I’m working on the drawings for V2, which I hope to have done in a few months.

  6. cool project. looks similar to vision trimax integrated. what about chopping the inner half off each arm rest? or, buy the carbon arm rests from an easton attack and bolt them onto the tops of your wings and/or extensions.

    i would like to see a design which fully integrates the arm rests into the base bar (instead of having them surface mounted). this would force the uci to accept a deeper cross section as the arm rests are a structural necessity, no?

  7. Lovely!

    You have got me thinking about doing the same… But in carbon, I don’t trust my alloy welding capacity.


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