Review of the Thoreau Cycles Concepts pedaling technique training bike

Among the methods that can help improve pedaling efficiency, there are surprising but ingenious tools like Bruno Thoreau’s Perfec’Thor bike. A machine that has two drivetrains on each side of the bike, totally independent of each other. The goal: to force you to pedal with both legs in the same way and to eliminate dead spots. Verdict on the road.

By Guillaume Judas – Photos: 3bikes.fr

Following an accident and during the long months dedicated to his rehabilitation, Bruno Thoreau sought the best way to regain his full potential. And from a rehabilitation tool, he then made his Perfec’Thor a training concept in its own right. Thanks to his invention, the Anjou native was able to gain power and efficiency in races and time trials for himself. After finding a way to mass-produce his bike (not yet on a large scale, of course), he decided to market it. For road cyclists and triathletes, the technical and physical interest is obvious. The bike’s two independent drivetrains force you to break down the four essential phases of pedaling (pushing, pulling, and the two top and bottom dead spots) with each leg, and thus to progress muscularly and in terms of coordination.

While it is indeed enough to alternately push on both legs to turn the cranks and move the bike forward, pedaling efficiently by using the entire circumference of the pedal stroke is another matter. With a classic crankset, the movement initiated by the pushing leg conceals the inefficiency of the leg that is supposed to pull the pedal, or worse, whose own weight slows down the push of the active leg. Similarly, thanks to the circular motion and the inertia of the gesture, the two dead spots are bypassed, but not eliminated.

With a classic crankset, the movement initiated by the pushing leg conceals the inefficiency of the leg that is supposed to pull the pedal, or worse, whose own weight slows down the push of the active leg.

For a long time, it was believed that fixed-gear training helped improve pedaling efficiency, with the forced pedaling induced by an identical gear ratio regardless of the slope, or forced cadence on descents. But while fixed-gear on the track is an excellent physical exercise for cardio, positioning, and strategy, it does not help at all in working on pedaling efficiency, because it allows the leg to come up on its own and the dead spots to be driven by the movement of the rear wheel.

Systems like Bruno Thoreau’s Perfec’Thor do exactly the opposite. They prevent any driving movement of one leg by its opposite, and force you to work muscularly and technically on each phase of pedaling. We speak of systems because the principle is not entirely new. About fifteen years ago, we already discovered the PowerCranks crankset, a strength training and pedaling technique improvement device, which consists of two disengaged cranks with a kind of freewheel system between the two parts of the crankset. In case of weakness in one leg, it falls back or cannot keep up with the other leg. It is, like the Perfec’Thor, a “one-legged” type of pedaling, but either alternately or at the same time, one leg never driving the other. Quite heavy, the PowerCranks has the advantage of only retaining a drivetrain system on the right side of the bike, which allows for one (or two) derailleur(s), which is not the case with Bruno Thoreau’s bike. However, this crankset has the disadvantage of significantly increasing the Q-factor (distance between the feet relative to the frame), which can in some cases cause injuries, knowing that the muscles and tendons are heavily stressed. This is a drawback that the Perfec’Thor does not have, although we did note a slight offset in distance between the two cranks relative to the frame (8 mm).

The principle

The Perfec’Thor is a training bike, and as such, is not intended to be modified. Unlike the PowerCranks crankset which can be mounted on any bike. This exclusivity first allowed Bruno Thoreau to remain reasonable in his choices of materials and equipment. This bike has a solid and rigid aluminum frame, painted on demand. It features track dropouts, a special rear wheel with a freewheel cog on each side, a KMC single-speed chain on each side as well, and finally a crankset part with a chainring on each side again. The patent filed by Bruno Thoreau is located in the bottom bracket shell, with a disengaged axle between the two parts of the crankset, which allows each drivetrain to be independent.

With this bike, it is thus possible to pedal with only one leg, the other remaining attached to the pedal, but dangling. It is also possible to pedal with both legs joined in the same movement. But it is of course by trying to adopt a normal pedaling motion that things become difficult, but interesting, first in terms of muscular and joint work (in the case of rehabilitation or a search for muscle strengthening, for example), and then in terms of technique.

But it is important with the Perfec’Thor to choose your gear ratio carefully (the same on each side, of course) according to your level, and especially to adapt the routes well. The single speed available is indeed the main criticism that can be made of the system compared to the PowerCranks.

For the rest of the equipment and to limit costs, we have a P2R aluminum 3-spoke rear wheel, a 43mm aluminum front wheel (both are very solid but relatively heavy), Shimano 400 brake levers, Miche brakes, a Zoom Alu handlebar and stem, a Bassano Mission 3 saddle, and Michelin Dynamic Sport tires. These accessories are proven in the fixed-gear world, solid and rigid, and designed to last. The complete bike weighs over 10 kg, but it should primarily be seen as a training device to be used during the winter period, or once or twice a week during the season as a reminder of exercises already performed. Because while the first few pedal strokes are quite difficult, the technique eventually sets in, and the engagement of certain neglected muscle groups allows for increased efficiency once you return to a classic bike.

On the road

The first few kilometers are destabilizing, even if you quickly understand that to move forward you will have to stay focused and first start by mentally breaking down the perfectly circular motion necessary for harmonious pedaling. It is almost impossible to ride out of the saddle on the first outing, but it is not totally inconceivable with a little practice.

The bike is manageable fairly smoothly on flat terrain or on a long, steady climb. With the 46/16 gear ratio offered here, it is actually on the latter terrain that it is most “comfortable,” as you can adopt a pedaling cadence of around 60-65 revolutions per minute, which allows you to avoid getting carried away and maintain the motion. However, it becomes much more difficult in case of a change in gradient, a tailwind, or a false flat descent, where it is impossible to keep up the pace.

Clearly, we’re looking for a gear change, to maintain a rounded pedal stroke and especially to relieve ourselves. Because very quickly we also feel unusual pressure on the saddle, as we put more weight on it. The solution remains to occasionally practice the one-legged method, even slightly standing on the pedals and without balance problems, to relax a little under the buttocks.

In terms of the technical movement itself, we also understand the importance of having good saddle setback on your bike. Indeed, with a slightly too forward position as on this test bike, the bottom dead spot seems much more difficult to round out than with a more set-back position. It’s a bit like the movement of a rower: by positioning himself behind the oars, it is easier for him to perform a circular and harmonious movement, especially during changes of support, than if he had to pass the oars under the perpendicular of his shoulders. Here it’s the same, even if we know that many postural studies tend to move cyclists forward a lot to eliminate the top dead spot, it’s the bottom dead spot that suffers. We can verify this with the Perfec’Thor and its two independent drivetrains: to pedal well and turn “round” (because here it’s impossible to cheat), it’s better to be slightly further back.

The first session is, of course, demanding. It takes several to start getting the movement into your head, and to strengthen the psoas, hamstrings, glutes, abdominals, and lumbar muscles, but also the tibialis anterior in front of the shin. These are muscles often “forgotten” during specific training, but very interesting for improving efficiency and producing more watts during effort.

And in the long term?

Having worked with PowerCranks, we already know the benefits of this type of training: better motor coordination and more efficient pedaling, especially with a more natural cadence. The Perfec’Thor produces the same effects. It can be used for a period, but also as a reminder throughout the season. Simpler, more robust, easier to maintain, it has the advantages of a single-speed drivetrain. But it also has its drawbacks. Unless you immediately go for a larger gear ratio for trained athletes. The investment remains substantial, but not so unreasonable compared to the price of some indoor trainers, power meters, or state-of-the-art carbon wheels.

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