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Dortmund frame builder Uwe Marschall got the idea from a customer. Back from a trip to America, the customer showed Marschall his new 200 millimetre long cranks, which he had bought from American frame builder Lennard Zinn. Marschall himself is not a giant at 1.85 metres, but has a stride length of 93 centimetres and therefore very long legs for his height. He was able to borrow the cranks and trialled them for a year. After just a short period of familiarisation, he felt very comfortable with them: "It took a few rides to get used to them, but the long cranks felt very comfortable from the start, even though they were much longer than my normal ones." Marschall made an interesting observation: "I used to have to stretch after every ride. Since I've been riding the long cranks, that's no longer necessary. I'm also faster and perform better in races, which I still do occasionally." The frame builder also wants to offer his customers the freedom he has experienced and therefore had engineer Stefan Reher design the "Big John" crankset. The long things are produced on a modern CNC machine by a German specialist and are available in lengths from 150 to 220 millimetres. They therefore not only cater to the needs of particularly tall but also particularly short people. This is because the cranks normally on offer usually only range from 170 to 175 millimetres, in exceptional cases from 165 to 180 millimetres.
The Big John cranks are milled from a solid piece of high-strength aluminium alloy "7075" and are available in four anodised colours. The visual references to Campagnolo's "Super Record" of the 1980s are no coincidence - that was Marschall's golden age as a racing cyclist. Nevertheless, the cranks have been completely recalculated using modern software and, according to Stefan Reher, designed in such a way that the material stresses are uniform and low. "This also made them very stiff," explains the designer. The weight, on the other hand, was not so important to Marschall and Reher. The 200 millimetre long cranks weigh 962 grams with chainrings (55/42). The fact that the cranks only fit on the classic square axle is mainly due to the small series. Marschall: "We would have needed broaches (a special production tool, editor's note) for the current connection systems, which would have driven up the costs too much. The square is a good compromise for my purposes."
The feeling - just right
But what does it feel like to ride such long cranks? Marschall provided us with his own suitable racing bike for our self-experiment. The bottom bracket of the frame is raised so that the ground clearance is maintained despite the long cranks.
The first ride doesn't feel as strange as I feared. Once the saddle height has been adjusted downwards by 2.5 centimetres - the difference in length compared to the 175 mm cranks we are used to - we make good progress, with wide-ranging pedalling. It feels free and expansive. A little unusual, but not wrong. More like just right. Of course, after a while some muscles have to change their ingrained movement patterns, but it's not unpleasant and there are no sore muscles afterwards.
The cadence doesn't drop as much as you might expect, instead levelling off just below the usual values. One hundred revolutions per minute are possible at the first attempt if you want to. Marschall has fitted a powerful gear ratio: 55/42 chainrings, sprockets from 12 to 23 - an indication that he wants to use larger gears.
pedalling slower. This initially causes a bit of a frown, as the test course is littered with poisonous climbs with a gradient of 14 per cent. But when pedalling in the cradle, the long cranks reveal a clear difference. The big gear is much easier to move than usual, and your legs don't get sore as quickly. It feels like climbing a staircase with the right step height instead of stumbling over standard German steps that are far too low. Big John gives you the feeling that the step height is just right. Even when seated on the mountain, significantly higher gears are possible. It should be noted that these are initially very subjective impressions and not confirmed findings that a longer crank actually makes you faster. But it makes you curious.
Hardly researched
What does science have to say about this? Very little so far. There are hardly any studies on the subject, and the few that do exist do not come to any clear conclusions. No miracles are to be expected: the continuous performance capacity is primarily dictated by the maximum oxygen uptake, and this does not change with the length of the crank. And since power is physically the product of speed times force, the same power can be achieved with very different combinations of force, crank length and speed. Nevertheless, there is clear evidence that you are faster with the optimum length crank - in other words, you achieve better efficiency. Pedalling technology expert Wolfgang Petzke, who has already caused a stir with revolutionary approaches to the round pedal stroke, is of the opinion "that tall riders need proportionally longer cranks in order to use their muscles efficiently." Petzke compares the crank length on the bike with the stride length when running: "Tall runners take longer strides than short ones, but their stride frequency is lower. To a certain extent, however, the stride length is also freely selectable." The expert's advice: "Experiment with your stride length when running. It's easy to do and gives you a feel for the subject."
Common sense tells you that leg and crank length should be in a certain ratio in order to achieve the same joint angles for the same movements in small, medium-sized and tall people. After all, you wouldn't sit an adult on a children's chair. The preferences of tall racing cyclists support this theory; they favour long and extra-long cranks. Rolf Aldag (1.90 metres) rode 180 mm cranks on his normal road bike. The Spaniard Miguel Induraín (1.88 metres) even used 190 mm cranks, which Campagnolo manufactured especially for this purpose, for his world hour record in 1994.
The crank formula
Based on their experience, frame builders such as Marschall, Zinn and others believe that 20 to 21 per cent of the crotch length is a good guide for the crank length. According to this, commercially available cranks of 170 to 175 millimetres would just about fit a body size of 1.70 to 1.84 metres (which corresponds to a stride length of around 81 to 88 centimetres). If you are shorter or taller or have above-average long or short legs, you could benefit from customised cranks. The larger manufacturers are less flexible. The cranks do get longer with increasing frame size - but not proportionally, but within the narrow range of 170 to 175 millimetres offered by the major component manufacturers. The available crank lengths have become even shorter in recent years. Campagnolo and Shimano now only supply the top models "Super Record" and "Dura-Ace" with lengths over 175 millimetres, while SRAM offers 177.5 millimetres even for the cheaper models. Fritz Baumgarten from Campagnolo Germany explains why this is the case: "There are mainly economic reasons for the narrowing down. On the one hand, it is expensive to produce different crank lengths, and on the other hand, it is expensive to keep all conceivable combinations in stock." According to Baumgarten, the best-selling length is 172.5 millimetres.
This may make sense from an economic point of view, but not in terms of content. After all, the product policy of the major manufacturers provides niche suppliers such as Marschall with an interesting field of activity. Crank lengths beyond the usual standards require significant adjustments to the frame geometry - otherwise the ground clearance suffers or the cranks or even the shoes collide with the rear stays and front wheel, to name just two handicaps for extra-long cranks. On the other hand, it's hard to find a better argument in favour of customised frame construction.
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