Technique

Test: crank FSA K-Force Light 2009

Details

Parent Category: Technique

Category: FSA

Published on Monday, 30 March 2009 12:01

Written by Luca Salvatelli

Stiff, light, moving, won the Tour de France, just one of the best cranks on the market

The Company

FSA was established as a manufacturer of components for the mtb and bmx, activities very popular in the USA. As time increases the production of the road sector and began to differentiate themselves from other producers for its ability to offer innovative products and breaking, in a very traditionalist like the bike. Today FSA is not only present in all major world markets, not only its products are adopted by major producers and strongest athletes in the world, but offers a complete range of products for both road and mtb.

The range FSA

FSA has been a pioneer in many technical solutions, then become customary. Among its flagships development cranks compact, integrated curves of the integrated bottom bracket and the standard BB30. Today the range is complete with the cranks, brakes, wheels, seatpost, attacks and curves, everything is on the road and mtb, without losing the time trial tests. The top range is the set K-Force Light, the highest technological expression of the House, the components being adopted by most teams in the world. The crank K-Force Light is now a classic and in 2009 is on its third version.

The crank K-Force Light on test

The crank K-Force Light is not only the tip of the diamond range FSA, but creates as many other products of the House, a series of technical innovations that have allowed to further improve a product that was already highly regarded by all valid. To improve a crank that already had established benchmarks for weight and rigidity, it has must be used a new technology, for what concerns the two carbon cranks. These are now made of a new carbon fiber, high modulus, a 3K, realized through an exclusive process, registered by FSA, which allows a higher density of carbon which results in better mechanical properties, therefore, less weight and greater rigidity. The cranks, as in the previous version, are cave inside, but have been completely redesigned, according to the new technical features, and now have a greater lateral and torsional rigidity. The only two parties in the light alloy cranks, the fixing holes of the pedals, the integrated pin and the crank in the opposite seat. These parts are not added later as in other products, but in the realization of the crank going to be a single structure with the same. We recall also that in this the cranks are hollow, but the crawler. The cranks are available in lengths of 170, 172.5 and 175 mm. The spider has a classic round hole to 110 millimeters in diameter and has a crown of 34-50 or 38-52 teeth (so traditional in fact, despite having a round hole 110 mm). The crowns are machined aluminium 7075/T6 CNC machines, while the fixing screws are ergal with head mark for Torx T-30. The factor Q, the distance between the two cranks is 147 millimeters, while the chain line is 44 mm, the crank is consistent with the changes to 10 speed, Shimano, Campagnolo and Sram. The bottom bracket bearings are ceramic caps with external anodized aluminium. Are available for bottom bracket with fillet Italian (70 mm) or English (68 mm). The ceramic bearings are not a novelty, and now are the standard for cranks and components of high quality. These ball bearings are more than 10 times harder than steel and a 3-4% reduction in mechanical friction. According to studies made by FSA with a stamp on cranks of 400 watts, at a frequency of 100 rides per minute on a normal bottom bracket bearings steel absorbs a power of 0.6 watts, while the bearings ceramic 0.02 consume watts. This is not to the decrease in reliability, because, according to the study of FSA, ceramic bearings have a life higher than those of steel from 5 to 10 times more. The total weight of crank said from FSA is 661 grams (170 mm cranks and crown 34/50), we with cranks 175 mm and 34/50 reported 693 grams by our instrumentation.

Assembly

Mounting the crank does not pose any problems but it is good to perform this procedure in the right way, or even better make sure your mechanic perform the correct procedure. In fact, too often a rushed assembly and performed superficially not only undermine the effectiveness of the crank, but also its durability and safety. Unfortunately they are still frequent cases of mechanics who continue to work without being updated on new materials and techniques for fitting; considering the cost of the crank is good to require that all stages of its assembly are performed in accordance with best practice.
1) preparation of the box of the bottom bracket: the box bottom bracket must be milled thoroughly before mounting the crank, if not already done so. The milling makes the edges of the box perfectly smooth and parallel with each other. This, of no consequence in the old central movements, it is important movements in central integrated with external bearings, because they rely on the edge of the box bottom bracket and if the two faces are not perfectly flat and parallel bearings work badly, are subject to greater wear flowing less and have a life far more pro.
2) fitting of the caps: The caps come from the FSA already locking, but to be sure you can always add the Loctite, compulsory when fitted caps are not new. To tighten the caps over to the appropriate key is better to use a key and tighten dynamometric to 39-49 Nm The torque is important to tighten up the caps, but without spoiling the equal importance of preventing the locking cap loosen.
3) mounting the crank: the crank be assembled according to the instruction being careful to use the locking and use the correct tightening torque for the two screws off the crank (tighten to 44-54 Nm).
4) installation of pedals: the pedals to make it is good to pair 24-39 Nm
Thus the assembly is unlikely crank give problems, the problems is to rely on a good mechanic who does not use the usual gimmicks. Milling box bottom bracket? Is useless; locking? Never used; dynamometric key? My experience is enough for me. Here this would save time (and very) but the editing is not done correctly, does not mean it is hurt, but it can not be 100% perfect. Given the quality of the crank, and its cost, is a painstaking assembly to be called the minimum.

The Road test

We tested this thoroughly crank adopting several frames, in particular on a carbon frame wrapped in high-end, a carbon fiber monocoque chassis range of medium/low and an aluminium frame of medium range. It came out a full test which has shown all the qualities of this product, but also the limits. The crank K-Force Light is made of impeccably, with its glossy finish and the plot of carbon in fine choices. Even the aluminium parts are perfect. The installation is simple and intuitive, good instructions provided by the House. A good crank being mounted on a bike because it is refined to the smallest details and transmit a sensation of great quality and solidity, but it is moving that this crank is appreciated. The less powerful are not soon to understand the high rolling bearings ceramic early cycling. Nothing distort, but it is noticeable the significant increase. The advantages are the more obvious the more increases the speed of pedalling, for this was the most powerful benefits will be felt most. The low weight, however, helps to achieve pedalling cadences higher than usual and in particular allows changes faster pace. The real strength of the crank, however, is in its rigidity, each has a strong ride decided step forward, with the clear feeling that all the power expressed by the legs is transmitted to the rear wheel. The more powerful is the better the positive sensations, as in the fly, the action raises, or uphill, when you are standing on the pedals. Undermine these cranks is truly impossible and the stiffness goes perfectly with the bottom bracket, scale, capable of supporting the power transmitted by the same cranks. The ceramic bearings not transform a normal person in a sample, but, as mentioned, give a smoothness that only a crank, and, overall, has to make the winning product is perfect. In those two qualities together lead to benefits of the most important among the best, if not the best ever, between the cranks. Of course there are marketing products even more sophisticated (and expensive) but here we are in front of a product but not the display or for short outings and fleeting, but a mature and reliable object to be used every day in training as in competition. Its adoption, however, to be really noticeable, it should be weighted in the sense that it should be used on frames with rigid bottom bracket and dimensioned and pedals and shoes with the same technical level. Otherwise we risk that the high stiffness of the cranks is then dispersed from the frame and thus the smoothness of the bottom bracket with pedals thwarted by bad bearings. Certainly those who think such a crank also has an allocation of remaining technical level, but it is worth pointing out that although good feel for the benefits the rest of the components must be at the top. In ideal conditions, however, this enthusiasm for lightweight crank fluency and rigidity, allowing all athletes to express themselves at the highest and utmost satisfaction. Very good, then the choice of the two crowns options, so as to meet all the athletes and you are at ease in any type of journey. For example, you can take the 38/52 fast in races and in the period of greatest shape, but can be left in the period 34/50 to resumption of training after the winter break, in races with long and significant slopes or where yet form is not the top. Compared with the previous K-Force Light the differences are almost imperceptible, and so the lucky owners of the previous model can calm star, while compared to other high-end cranks, that there seems to be winning weight fluidity and rigidity. Especially the latter two aspects there appeared to be the best ever for this product.

Conclusions

The crank K-Force Light has reconfirmed the crank at the top who already knew. The third edition did not make it as technical development started years ago and the FSA, with pride, continue to perform. The patent with which the structure is made in carbon, is associated with the other innovations introduced by the crank during the previous editions, we recall the structure of hollow cranks and ceramic bearings, but it is the care with which every detail is made to create an unique and successful. Light weight, stiffness and fluency are true to the absolute category, but this did not go to the expense of longevity and reliability. There are lighter components, but not as usable as FSA. Its high performance, is more exploitable by the most powerful athletes, but everyone can feel the increased stiffness and fluency. In conclusion we feel that this new K-Force Light reaffirms its undisputed superiority in weight, reliability, strength and smoothness. The only defect can be found in the choice of the length of the cranks, because of absence of cranks from 177.5 and 180 mm lengths, but taken from other athletes, obviously the market was too small to start production of these products.

Price

The crank has a cost of 680,00 Euro, not cheap in absolute terms, but justified by the performance and quality of the product.

Is suitable for

Athlete: light, stiff, sliding is the best crank to be taken on a bike for an athlete.
GF-cyclist tourist: the aesthetics and exclusivity of the product only make the bike where it is adopted, an amateur will not be able to fully appreciate the features, but its unquestionable quality they can justify the purchase when you want to create a particular bike.

Positive aspects

Construction quality
Stiffness
Fluency
Weight
Aesthetics

Negative aspects

Missing cranks from 177.5 and 180 mm

For further informations:

Full Speed Ahead, US
12810 NE 178th St. Suite 102
Woodinville, WA 98072
Tel.: 425 488 8653

Full Speed Ahead, Europe
Via Del Lavoro, 56
20040 Busnago
Milano, Italy
Tel.: +39.039.688.5265
Fax.: +39.039.682.3336
Web Site: www.fullspeedahead.com