The Ultra Light Tri Bike
article & images by Nick Salazar
Apr 5, 2011
The bike you're looking at is a lean, mean, and very aerodynamic machine. It's the culmination of our "Lighten Up" series, where we've been attempting to build the lightest triathlon bike possible, without sacrificing aerodynamics. That last bit is important. If this were just an exercise in light weight, we would have ended up with something much more like this machine. But aerodynamics require, in general, thicker tubes to make up an airfoil shape. Still, we managed to get something that's very slippery in the wind, looks like something Batman would keep in his garage, and weighs all of 12.9 pounds. That's right - it's a full two pounds lighter than is legal for Pro Tour competition. As in, Lance Armstrong wouldn't be allowed to ride a bike this light. But there's no weight limit on bikes for most triathlons, so this bike is good to go at your local tri.
Those of you who have followed our Lighten Up series have probably been wondering what frame set we would choose for the bike. You've seen a lot of the peripheral bits, but not the core. It was not an easy decision. Our focus on light weight ruled out some of the more integrated, heavier bikes. This one couldn't be a Speed Concept, a Shiv, or a DA. Cervelo has some good options, but we wanted to go a little more exotic.
X Marks the Spot
In the end, we chose an open mold frame that is most popularly sold by Planet X. It's their newest frame, and they call it the Exocet. The Chinese manufacturer called it the TT036. We just call it awesome. The frame set features aggressive but stable triathlon geometry. The dropped down tube gives it the illusion of high stack, but it is in reality fairly low, pretty much the same as a Cervelo P2C for the same reach.
This frame uses BB30 cranks, so we just got the appropriate bearing set for our compatible Lightning Cranks and bolted them on. Nothing funky there. One thing we really liked about the open-mold version of this frameset is that it has no paint. That in itself represents a good chunk of grams saved (on the order of 100-200 grams depending on how thick some paint jobs are), and without any paint, the entire bike's gorgeous 3k carbon fiber finish is exposed to view.
First up, the bars. Our original custom aerobar have been updated to feature the sweet VukaShift extensions we reviewed earlier. While they make a great platform with regular or R2C shifters, we figured we could fabricate some custom hardware to bolt on the ultralight BTP shifters used on revision one of this bar. After some careful measurement and some modeling in SolidWorks, we sent our custom models to Shapeways and got back the perfect hardware to mount the shifters. They now weigh in at just 18 grams for the pair. The complete bars are now just 505 grams, complete with shifters, brake levers, and all hardware. And with all the cables internal, and grippy extensions, there's no need for bar tape either.
How does the friction shifting work? In a word, beautifully. With the shifters in your hands at all times, it becomes a simple matter matter to trim the front derailleur as needed, and the rear deerailleur works like a charm. Dumping five gears at once is trivially easy. While R2C shifters still provide better ergonomics, these babies aren't too bad either.
The other major bit of work we did for this rig was to bond the carbon fiber Adamo we made, directly to the bike's seatpost. Eliminating the clamping hardware and saddle rails yielded a stiff, light combination that is about a pound lighter than a standard saddle and post. And getting rid of that bulky hardware probably improves the aerodynamics as well.
The rest of the bike you've already seen, from the gorgeous Enve wheels to the brake and fork details, and everything was selected for its optimal combination of weight and aerodynamics. This is a bike that will be an absolute killer on the flats, yet still climb like a mountain goat.
But like we noted when looking at the world's lightest road bike, the point of this project isn't to create a bike that's for everyone. It's to push the boundaries and open up new possibilities for the future of bike manufacturing. If we can make a 12-pound tri bike in our garage, imagine what a multi-million-dollar bike company could do with its vast resources. We hope you've enjoyed the series - this was a great project to build, and even more fun to ride. Here's to innovation!
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