The (bicycle) wheel can no longer be reinvented. But every few years, new technology and techniques emerge that make further steps towards weight reduction possible. This often happens rather indirectly: if aluminium frames can be designed to withstand greater loads using hydroforming tubes, for example, material can be saved. New plastics and manufacturing techniques in tyre construction make it possible to dispense with heavy puncture protection inserts. And the higher the sales price of a bike, the more prestigious - and therefore lighter - the add-on parts usually are: Examples include Edelux dynamos, XT and Ultegra gears, DT Swiss hubs, Acros headsets and carbon seatposts. In addition, rigid but lightweight forks are back in fashion: word has got around that suspension forks offer few real advantages under normal conditions, i.e. on tarmac and paved road surfaces. Consequently, bike manufacturers are specifying entire model ranges with lightweight rigid forks again. In doing so, they are gaining both new and lost experience in frame and fork production as to what makes a good rigid fork. After all, a good fork should not be completely rigid. When used in a defined manner, a vertical flex of the fork legs provides the front wheel with more permanent ground contact and therefore better steering and riding behaviour. Vibrations caused by uneven ground are cut off at the tips and no longer reach the rider. In the longitudinal direction, however, a fork should only be slightly flexible in order to avoid wasting deceleration energy or even stuttering when braking. Disc brakes stress the fork asymmetrically and often with brute force - this one-sided load must also be taken into account in the design from the outset. In addition, there are other options such as tapering the steerer tube for stability, direct contact with the hub dynamo, optimum routing of the light cable and brake hose and visually pleasing integration of the fork into the frame - none of which makes it any easier for the designers. The great effort that goes into a modern rigid fork today increasingly requires the frame and fork to be developed in close coordination with each other. Universally usable rigid forks as spare parts are therefore almost impossible to buy.
It was great fun wagging the lightweight bikes around the test track and feeling their high riding dynamics. But you shouldn't overestimate the bike's weight: in practice, it only has an impact when starting off, accelerating and, by analogy, decelerating, as well as when riding uphill and in handling. When pedalling on level ground, which is probably by far the most common riding situation, how and where the weight is distributed on the bike is far more important. This is because heavy weight has its most unpleasant effect on the wheel: the further away from the pivot point, the more disruptive the effect of additional weight. Due to the laws of leverage, the greater the lever lengths, the greater the weight effect. The consequences are a lack of agility, sluggish riding and unsteady steering behaviour due to the high gyroscopic forces of the rotating mass. Heavy tyres, tubes and rims are therefore real fun brakes. However, stability is also required here: Disc brakes pull on the spokes on one side, luggage puts a strain on the rear wheel and every wheel should be able to withstand a kerb bump without damage. That's why sturdily built wheels are one of the most important ingredients for intelligent lightweight bicycle construction.
Conclusion:
Lightweight bikes are simply more fun - that can be said without a doubt. In general handling, when accelerating and on every ride uphill, the lack of kilos is noticeable in the form of increased pleasure. If you pack moderately, you can go on tour with a light tourer with a clear conscience: none of our candidates skidded under a test load of 15 kilos. Look out for lightweight wheels and tyres: This is where you feel the weight the most.
The complete article was published in Trekkingbike issue 4/2015.
You can download the individual articles as PDF files here.
