What do you do when you're stuck in hospital with tonsillitis and nothing to do? For most of us, it would probably involve buckets of ice cream and watching shreddits
, but for Andi Jakoubek from Munich, it was the perfect opportunity to design his dream bike. Unable to find the 29er downhill bike to fit his 6'4" frame at an affordable price and high on a fever and antibiotics, Andi got inspired and, 18 months later, the Shredmaster was born.
Andi has no background in the bike industry, beyond 17 years of riding, but he's a graduated Pinkbike armchair engineer and avid reader of linkagedesign.blogspot.com
Shredmaster DetailsFrame Material:
7020 aluminumIntended Use:
29 inch front and rearTransmission:
Pinion 6 speed gearboxHead Angle:
17.5kg without pedalsPrice:
N/AMore info: @project_shredmaster
He combined this with a drizzling of inspiration from the 77 Designs Kavenz project
and got to work dreaming up kinematics and linkages. It wasn't long before he'd roped in Peter, a high school friend and engineer for a German car manufacturer, to help him with the finer points of the design and the project started to take shape.
There were a few key points that Andi and Peter wanted to bake into the design to create their perfect bike. First, it had to have a high pivot design to allow for a rearward axle path, an idler pulley to eliminate pedal kickback and a leverage ratio that was progressive enough for a coil shock but not too progressive that it would sacrifice mid-stroke support. The bike also had to be aluminum as carbon was too expensive and the weight and aesthetics of steel were not to their liking. These aluminum tubes also had to be straight for simplicity and strength. Finally, the bike had to have adjustable geometry to switch between a regular 29er and a mullet set up.
The linkage is driven by this one-piece machined rocker that was glass pearl blasted and black anodized.The Gearbox
Andi and Peter admit that the final product does bear a more than passing resemblance to a GT Fury but there's one huge difference, the Pinion C1.6 gearbox. This provides six speeds, which they believe to be enough for a downhill bike. When asked about the added weight, Andi said, "1kg on my DH bike doesn’t really bother me. As far as I know, there is a whopping 2kg difference just in frame weight between a Supreme and a Gambler, and both frames are winning World Cups and I would love to ride them… So long story short, I don’t care.
He continues, "You save 450g of unsprung mass on the rear wheel, since the derailleur and cassette are gone. And since 'suspension performance first' is my agenda, that is a killer argument pro gearbox. Also, the weight sits perfectly low in the bike, giving a super planted feel. The ratio of unsprung to sprung mass further improves, so let’s just say the suspension should work really well. I can also remember Orange fiddling with extra weights
to achieve this."
The Pinion housing is also machined from a solid block.
As for the drag of the gearbox, Andi compares it to running a chain guide on his regular downhill bike and he and Peter have also designed a custom chain tensioner with a sealed spring that reduces the drag of the standard box. Currently, the gearbox uses a grip shift but is soon to be replaced by a trigger shifter designed by "another nerdy soul from the IBC-Forum."Geometry
The frame is designed around Andi's 6'4" proportions but smaller versions are being worked on too (more on that below).
The chainstays were the most difficult part of the process for Andi and Peter, not because they were that technically complex but because finding somewhere to source them in a pandemic took a lot of time and effort, especially as neither of them knew who to even ask about finding aluminum bicycle tubing at the start of the project.
Andi explains, "We had 4 months of waiting after the design was already finished around May 2020. We had a supplier for the chainstays that well, did not have the chainstay tubes in the end and everything else was machined or ordered at that point. We tried to get matching tubes from all the European manufacturers that we knew where making Alu 7000 frames in Europe, but no luck. So, we had to order tubes from Taiwan, which obviously took some time (thank you Nancy, you are the best!). So, everything went to the welder in October and we got the frame end of November, perfectly timed for the summer riding season!"The Future for Shredmaster
This is version one of the frame that initially only intended to be a three frame run - one for Andi, one for Peter and a spare that they would have given away to a friend. However, after the bike blew up on Instagram, they have decided to refine their design before running a small production batch next year. The next frame will use a 225 Trunnion shock so the standover can be lowered plus some further refinements. Andi says, "We don’t want to rush it. This will require more bike park testing and fatigue-lab tests before anything is offered. Don’t wanna see our chainstays bend in the huck-to-flat test! Rough costs? Not at this stage, I’m afraid."
When asked about the potential for some other designs, Andi replied, "Other bikes? Let’s see where this is going and then I guess, we just have to figure out a sick business model!" Watch this space.
To keep up with their progress, follow Shredmaster on Instagram, here