Video: Grim Donut Part 3 – We Made It Less Terrible

The first Grim Donut wasn’t supposed to work…and, honestly, most of the time it didn’t.sure it was fast as hell During the final episode timed test, but that was mainly because Yoann Barelli was on our steep and rocky test track. Get it on a regular trail and that’s when it feels like you’re about to land. spruce goose On a winding country road at rush hour, the only difference is that the donuts are actually a little longer.

The first Donut proved we were on to something, but was only built by Genio as a rough prototype to experiment with carefully calculated geometry. While that first Mule was a proof of concept, the new Donut was set to use a proven and well-received suspension system, was far more sophisticated, and even had bottle mounts.

What took you so long?

If it feels like it’s been five years since the first donut debuted, it’s because 2020 and beyond is slowing down. While other brands were drilling holes in their headsets and pouring all of their development budgets into e-bikes, we were working hard to perfect the geometry of the new Donut, but overnight to be exact. is not the process of…

No kidding. It only took me 15-20 minutes to settle on some new numbers that made sense. I was trying to decide whether to paint it black or go really wild and use onyx black.

Well, I’m a little behind schedule. New donuts are about a year behind. It will take another 12 months and a few months.”spy shot,”But have you seen the latest enduro bikes? Donuts may be late. produced some poor imitationsbut it’s a decade ahead of everything else on the market, regardless of where you hide your cables or how high you pivot.

To be fair, I said at the end of the first video that the next episode won’t come out until 2030, so we’re still ahead of schedule.

new donuts, new shapes

If you watched the previous episode, you already know that the first donut is unstoppable on steep, high-speed terrain. This is exactly where, under Yoann Barelli, he was 6 seconds faster than the time he put on his Enduro bike. “Chilean EWS?This bike wins by a minuteHe says racers often find nothing but anti-grip on how the first donut performs in dusty South American events.Absolutely not. The geometry is not comfortable as it is now. When you step on the pedal, it hits the ground. It can’t corner properly, but it does well when going super fast.”

Sometimes we have to overdo things a little to see what really works, but that’s exactly what the original Donut did for us.

It was listed as a bit steep on paper, but when we hit the trail, the bike’s head angle was actually closer to 56 degrees, and that’s what it felt like. The front end had more flip-flops than the presidential candidate at speeds under about 30 kilometers per hour. In his first 100 feet on the first test ride he pedaled six times. It was clearly fast – Yoann proved it – but it was also a death trap crossed by a shopping cart full of empty monster cans, not for anyone without Barelli’s skill set to ride.

The next Donut had to be a little more usable (and less dangerous) everywhere, but without compromising its ability to be really dangerous.

After about 20 minutes of intense debate, with bloodshot eyes and dangerous amounts of Fuego Takis being eaten, we finally decided to steepen the head angle by 2 degrees. This makes the new his Donut the first ever mountain bike, not as loose as its predecessor. It marks a bold new leap in geometry technology called the Turn Helper Concept. Our own innovation, his 58-degree head angle is combined with his 83-degree seat angle that worked so well on the first bike, and it’s also longer on both ends. There are three different chainstay settings that allow for a reach of 525mm, an effective top tube of 600mm and a rear end of 460, 470 or 480mm. Of course, our new geometry technology is patented.

Depending on the chainstay settings, it will have a similar wheelbase to the first bike, but with a much longer rear center, longer reach and a steeper front end.

Suspending DW link… but it’s not

The first donut is always special to me, but to be honest, I spent a lot of time thinking about the geometry, so I just called it in for the rear suspension. Conceived a high-tech dual-link system called High Pivot Virtual, it employs an idler pulley and I don’t think it’s a coincidence, but it looks a lot like the one Santa Cruz was investigating in their recent V10 development video. . The main reason was that I had no idea what I was talking about and that I spilled bubble tea on my drawing and it got pretty dirty.

What we ended up with was an off-the-shelf single-pivot and pull-style linkage design that did the job, but didn’t do it all that well. Dan Roberts very kindly pointed out in his Behind the Numbers article, with relatively linear leverage, only 16.3% progression, and almost no anti-squat, could have been a pro squat. For a non-biking scientist, another way of saying this might be, “This bike pedals like shit, why is it always stopping in the middle?” . Running the coil-sprung shock only exacerbated its worst attributes, but the upside was that it felt like a heroic amount of traction, which is always a good thing. was dangerously close to the ground.This is always bad. Considering it’s absolutely terrifying (yet funny), it’s not like I want to pedal that much anyway. Performance in a pseudoscientific climbing video.

The first donut was a reminder that while geometry is most important, suspension is next.

With Pivot and Dave Weagle on board meant the new Donut would use a custom DW Link suspension system. This is a design that has long been known for its pedaling efficiency and overall performance from cross-country rockets to serious downhill race bikes. It uses a relatively large amount of anti-squat to keep the suspension quiet while the rider is pedaling. This is the exact opposite of its predecessor. That bike was anti-his squat numbers were well below his 90%, and he fell off halfway through, but his new DW-equipped donut was still in his last three minutes of the move. is over 100 until it needs to be lowered by 1.

This, of course, means better pedaling performance, but a higher dynamic ride height means less chance of a devastating high-speed pedal hit.

If you think this all sounds dangerously good, so do we. That’s why we asked Weagle to design two suspension layouts in one bike. Both the upper and lower links and the lower shock mount have his second pivot position, as well as the DW link system. 10 minutes, another rocker link, and a few hex keys are all it takes to transform your new donut from a surprisingly efficient enduro sled into an underfilled wheeled waterbed. Amazing performance. You can see the difference in this graph.

What next for donuts?

We know it took us too long to get to this point, but the result is a bike that is far superior to everything else on the market. In 2008, while we debated for two years about which shade of black to paint the frame in, other brands were debuting features that would make the new Donuts obsolete. It’s better than any other enduro bike on the market and probably minutes faster throughout the race, but no one would buy it without headset cable routing. And I heard rumors that 32-inch wheels are the next big thing…

So the only thing we can do is start working on the next Grim Donuts prototype. Expected release date: 2030. probably. perhaps.

Want more donuts?
Part 1: I went to Taiwan and tried to build a bicycle of the future – The Grim Donut
Behind the Numbers: The Grim Donut
We Tested Bikes From The Future – Grim Donuts Part 2 (April Fool’s Day)
Spot: New Grim Donut Prototype?
Introducing the free Grim Donuts video game feat. Mike Levy (sorry)
Pivot Announces Grim Donut 2 – Sea Otter 2021