The plan this time was as simple as possible. Build the lightest E-MTB in the world! Partly out of curiosity, according to the motto: How light can you actually make it? And partly with the vision of building a bike that rides exactly like a bike without a motor, but with boost power at the push of a button. It's simple, but also somehow complicated. It's one thing to build a lightweight bike, but the lightest bike in its category that still rides well? That's another challenge.
About the person: Gustav Gullholm alias "Dangerholm"
Early on, Gustav worked in Sweden's first Scott shop in Mora. He spent the long winters tuning his bike for the next season and working out in the gym. In 2016, he posted his private Scott Spark on Instagram, also BIKE and Pinkbike introduced Dangerholm to an interested audience for the first time in larger stories. The shorts, initially intended as a joke and homage to Lemmy from Motörhead, have become his trademark. Incidentally, the extroverted Swede is rather quiet, extremely polite and modest in private.
EMTB Magazine: Gustav, how much work goes into a tuning project like this?
Gustav Gullholm "Dangerholm": It's hard to say, I don't write it down. And you underestimate how long it takes just to research the right parts. In total, 100 to 200 hours go into my bikes, with the Lumen it was probably more rather than less.
Lightweight and with integrated shock: the Scott Lumen as a tuning base
For those who are not yet familiar with the Scott Lumen: It's basically the e-bike version of Scott's race bike Spark. But not just a copy, of course. At 130 millimetres, the Lumen has slightly more suspension travel than the Spark, and the frame is shaped slightly differently to make room for the motor and battery. As with the Spark, the shock of the Lumen is hidden in the frame and the geometry can be adjusted using an angled headset. In standard trim, the Scott Lumen weighs 15.9 kilograms in size L (EMTB measurement).
EMTB Magazine: Which tuning step takes the longest?
Gustav: I remove the frame paint by hand. Very carefully with a sharp tool knife. This leaves the fibres intact. The whole process takes about 30 hours of work and saves about 150 grams in the end. I don't need to tell you that you should never do this again. Otherwise the guarantee will be void in any case and if you damage the fibres when stripping the paint, it can be really dangerous.
Scott Lumen x Dangerholm: Chassis, engine and parts
The Fox shock in the Tuning-Lumen had to make way for a slightly lighter Rockshox-Nude with lockout from the Spark. This saves 40 grams compared to the standard version. The front is fitted with a Samurai suspension fork from Intend with 130 millimetres of travel. At 1537 grams, it is not only the lightest trail fork on the market, but also has special features. As an upside-down fork, its design alone gives it a better response behaviour than conventional suspension forks, the high braking stiffness is well suited to e-bikes and the lower torsional stiffness is a matter of personal preference. Little arm pump and plenty of grip are on the plus side, but heavier riders might find the handling less precise on fast berms. Tuning is also always about customising the bike to the rider. Whether an upside-down fork suits this or not is something everyone has to decide for themselves.
The heart of the Scott Lumen in the Dangerholm edition as well as in the normal version is the HPR50 motor from TQ. It offers 50 Newton metres of torque and up to 300 watts of assistance. A good choice, especially if you want a bike with a natural riding feel. This is because the TQ drive remains pleasantly in the background - even when it comes to drive noise - has very little idle travel and is particularly easy to modulate.
EMTB Magazine: The Lumen is the first e-bike that you have tuned. Were you able to optimise the motor and battery?
Gustav: The TQ team developed a carbon sleeve for the battery as a prototype especially for this project. That's really cool and a real honour for me. That alone saves 206 grams compared to the standard version with an aluminium sleeve. We were also able to lend a hand with the motor itself: ceramic bearings from Ceramic Speed and hollow titanium bolts from Meti in Italy reduce the weight of the bike by another 70 grams. All in all, the TQ system on this bike weighs 3783 grams plus 26 grams for the remote.
From road, gravel and mountain bike: Dangerholm's tuning gears
Tuning potential also lay in the standard twelve-speed drivetrain on the Tuning Lumen. The Swede Dangerholm decided that eleven gears were enough for a sporty e-bike with a light cassette with ten to 44 teeth. But what's the best way to shift? Simply upgrade a mechanical eleven-speed rear derailleur with carbon parts? No, too antiquated.
So Gustav started experimenting and ended up combining two rear derailleurs into one. The basis is Sram's Red AXS XPLR road rear derailleur with originally twelve gears, which was combined with the electronics and friction damper of an E-Tap eleven-speed rear derailleur. Then a little polishing and calibrating - in the end, the plan worked. Incidentally, the highly polished Frankenstein gearstick is operated with a blipper converted to a toggle switch. Such blippers were originally fitted under the handlebar tape of racing bikes to allow shifting in the upper handlebar grip.
EMTB Magazine: Your Scott Lumen is now the lightest E-MTB in the world! Do you have to worry about this title?
Gustav: Of course, but worry is the wrong word. At the end of the day, I'm just a bike nerd and love coherent and elaborately modified bikes, no matter who is behind them. I met some exciting people at Eurobike in particular. From the people behind Stoll and Rotwild to many private tuners. And I think it's the same for all of us: We always want the others to be successful with their projects. We simply push each other.
Wheels, brakes and cockpit of the Scott Lumen
Weighing just 945 grams, the Pi-Rope wheels with Duke rims in Dangerholm's Scott Lumen. The special feature of Pi-Rope is the spokes, which are made of synthetic fibres rather than steel. The hubs for the wheelset come from a relatively new German brand called Nonplus. They rely on a ratchet freehub with a particularly large contact surface, making them stable enough for use on an e-bike despite their lightweight construction. Trickstuff's lightweight Piccola Carbon brakes with discs from Carbon-Ti, ceramic bearings in the head tube that do not require lubrication and a one-piece carbon cockpit from Darimo complete the design of the super-lightweight bike from Sweden.
EMTB Magazine: How does your Scott Lumen actually ride?
Gustav: This is perhaps unsurprising, but it rides like a normal bike without an e-drive. A trail version with more stable parts and grippier tyres is also available. This bike is my personal favourite and, at 14 kilos, is still very, very light.
Down-country tyres, more suspension travel and a conventional cockpit: the trail version of the record bike
Would you like a little more? The trail version of the super-light lumen from Sweden is designed to be a little more fun to ride downhill than the record bike. The chassis is identical to the XC version, but the one-piece carbon wheels of the standard bike are used again here, together with slightly grippier down-country tyres from Schwalbe (Wicked Will ) or Kenda (Karma). A slightly wider carbon cockpit with a short stem and a Fox Transfer SL seatpost with 150 millimetres instead of the super-light 80 millimetre dropper from Yep further increase the trail fun.
EMTB Magazine: Where do E-MTBs generally offer tuning potential?
Gustav: Contact points and tyres are a good place to start. At the moment, you still see a lot of bikes in standard trim, but you also see more bike nerds on e-MTBs, especially with the light bikes. I believe that tuning will increase significantly in the future.
Adrian Kaether
Editor
