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 aluminum
Intended Use: Downhill
Wheelsize: 29 inch front and rear
Transmission: Pinion 6 speed gearbox
Head Angle: 63°
Reach: 500mm
Sizes: 1, custom
Weight: 17.5kg without pedals
Price: N/A
More 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 GearboxAndi 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."
GeometryThe frame is designed around Andi's 6'4" proportions but smaller versions are being worked on too (more on that below).
The ChainstaysThe 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 ShredmasterThis 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.
Also, 170mm enduro bike next please.
Next Step: A v2 proto in CF to shave a bit more weight and tune stiffness.
The Ed Masters' ShredMaster Enduro Master?
I like it!
Please guys built an Enduro
My prediction is that enduro and freeride bikes will go back to short cage derailleurs and a 46t cog somewhere in the future, but it should be a gearbox.
Kisses
www.google.com/search?q=which+country+use+metric+system&client=ms-android-huawei&prmd=ivbn&sxsrf=ALeKk01qXcd1WJtSdZVo6iO1aqELbjbgtA:1609881288128&source=lnms&tbm=isch&sa=X&ved=2ahUKEwi6o7yS24XuAhUE7aQKHX0zDVgQ_AUoAXoECAMQAQ&biw=360&bih=518&dpr=3#imgrc=zZ_i_Pw_u_BprM
I just : "Send it Billy" !
Now teach me inch / feet / yards / miles and whatever else you can find on some parts of the world ????????
If you can be more understanding maybe i can answer to you !
1 yard = 3 feet
mile, depends on the kind (Swedish, land, sea... loads of them)
"Once upon a time, was a King, and he was asked where the road that connects two cities would go! The King, not knowing his blindness from such matters, simply on the map united the two cities with a straight line! His servants went and carried out his orders, and cut a whole mountain in half to cross the road"!
"The road must exist even today"!
"Just because someone once had power - influence, doesn't automatically mean that his opinion was right"!
I hope to understanding my thinking ! (Friendly)
"Right lads, lets walk 2.3km to the pub for a pint"
That is one of the annoying things about being in the maintenance field; never knowing if you are working on something that is SI or metric. My 1995 and 2012 Ford's are nearly all metric, but HVACR is all SI.
we break inches into 1/16ths
12 inches in a foot
3 feet in a yard
5280ft in a mile.
It's not my fault!
This is a beautiful bike! No gimiky crap . Solid . Thanks for pic details on fabrication. Six speeds are all you need! 7005 Al. Sweet!
Just kidding, I can't believe how good some of these home projects turn out! This looks really well sorted, but most importantly did they like how it rode?
Excellent work.
The bike is seriously cool and they've done a great job with it.
I’m sure with an effective trigger that can multi dump gears you will be nearing nirvana - bring on an enduro rig.
Just as badass as this bike.
Do not even need many gears as a DH e-bike?
One for going UP & maybe 3 for going down, Please make it happen?
nsmb.com/articles/3463-readers-rides-lahar-m9
Imagine if things had gone better business wise and things still going ok, what the bikes would be like now?
To shift into an easier gear you need to unload.
A week's worth of adjustment overcomes this "issue" and work around the quirks.
www.youtube.com/watch?v=VmkN8pxKe-A
29
High Pivot
Gearbox
Rare
Nnnaaahhh
images.app.goo.gl/twB9WR6VcirA58LYA
@Project-Shredmaster : What's the chainstay length like at SAG? The frame design looks incredibely clean!
Or 459, if you are going for the 440mm base setting.
Or 456, if you go for the Mullet set up