Santa Cruz Bicycles - Santa Cruz Trials

The Danny Bike

The Story

The story behind Danny’s carbon trials frame dates back to the time he first rode a carbon mountain bike.

In early 2014, Danny asked if he could borrow one of our carbon Bronsons for a little project he had cooking on Skye that summer. He said he might be a little rough on it. We said OK, and never expected to see it again.

56 million views later, we’re almost tired of seeing that old Bronson now. None of us expected “The Ridge” to bring mountain biking to the masses the way it did. It was great for the sport, the Scots, and the beginning of our relationship with Danny.

“I wasn’t expecting to be able to do the stuff I did on that bike” Danny points out. “It opened my eyes to what carbon was capable of. The lightness, stiffness and durability is perfect for taking trials to the mountain and I was already thinking about my next project.”

At this point, Danny was still just borrowing bikes from us. And to be fair, he was returning them too. A bit scuffed, but still fully rideable. He was like a one man test rig. So we effectively asked him to join us in that capacity.

His first project: Reserve wheels. In 2016 we gave him a pair of the first Reserve wheelsets to secretly test throughout the summer. He said he might do a wee bit of filming on them. We said OK. A few months later those secret wheels were thrown completely into the public eye. Fourteen and a half million public eyes to be precise. “Wee Day Out” was another hit, but we were still 8 months away from production. We braced ourselves for a barrage of questions we couldn’t answer, and then…

Nothing.

Not a peep. Even when Danny appeared on the cover of 2 million copies of Red Bull’s The Red Bulletin, the phone stayed silent. It was pretty weird. It seemed like nobody really noticed, and yet here we all were at Santa Cruz getting mega excited at the potential of these things.

Bulletin Cover Hay Bale

“I rode that one pair of wheels all summer” says Danny “Some of the scenes took more than 150 attempts to get right. A 1000lb hay bale rolled over them a few times and they still only needed a quarter spoke turn the whole time*. It was pretty unbelievable really. That’s when I started talking seriously to Santa Cruz about what other stuff we could do with carbon.”

(*Despite this, Danny had actually failed us in finding the breaking point for the wheels.
So we sent him back out again on the streets of Glasgow to finish the job.

“Danny wanted us to make him a carbon trials bike” explains Nic McCrae, composites engineer at Santa Cruz. “I had no idea what kind of journey that was going to be, but it sounded like there’d be a whole lot of new stuff to learn working on a project like this so I just said yes, and used it as an opportunity to take our in-house R&D facility to the next level.”

The in-house composites lab at Santa Cruz was initially set up for the wheels program. The testing here is what resulted in the distinctive spoke reinforcement profiles found on Reserve rims today. It features all the equipment you’d expect in a carbon lab—cutting table, prepreg freezer etc.—but also a few things you won’t find anywhere else, like a heat press we designed and built in-house.

Resembling a panini machine built by Egon Spengler, the press is an invaluable piece of custom machinery whose infinite adjustability allows us to fine tune the ideal curing sequences.

All the gear, now what’s the idea?
 

Industrial Designer Jack Russel Working on the Danny MacAskill Bike Testing the Santa Cruz Danny Carbon Bike in the Lab

Process

“We had always wanted to try making a frame using latex bladders” reveals Nic. “Santa Cruz carbon fiber  frame manufacturing starts with an expanded polystyrene (EPS) mandrel wrapped in a nylon bladder. Carbon fiber plies are then wrapped around the bladder/mandrel combo according to the layup schedule, and the bladder is inflated once the frame is inside the tool. For the Danny Bike, we opted to use a latex bladder technique molded to the inside shape of the frame—eliminating the wasted polystyrene and bladder.”

One of our goals at Santa Cruz is to do our bit to develop sustainable practices in manufacturing. A great advantage of the latex bladder technique is that the bladders are reusable. Some bike frames are made using latex-dipped EPS mandrels, but these bladders are still one-time use.

Reusable latex bladders are used in a variety of non-bike manufacturing environments, but they typically require CNC-machining an aluminum mandrel to dip into the liquid latex, and each mandrel can take around 100 hours to machine.

We wanted to develop the best bladder system possible so we relied on 3D printing to create the forms we needed. 3D printing has the advantage of allowing very complex shapes that would take heaps of CNC hours, if even possible. We opened up the design space for the mandrels and made the best possible latex form. It's also much quicker, then allowing more design revisions than would otherwise be possible.

Reusable 3D printed mandrels opened the design space massively and made it possible to turn new, more complex designs around overnight.

Layup & Materials

“Once we had the latex bladders nailed, we needed to understand how precise we could get with layup and materials in order to maximize the new technique” continues Nic.

“Almost every carbon fiber product is made with a wide variety of fiber materials, varying in grades and attributes. Our production bikes are strong as hell, and we feel we have a good handle on our toolbox of materials, but the goal with Danny’s bike was to push that understanding forward, and take advantage of emerging materials technology.”

This is where having a composites facility in Santa Cruz has a serious advantage. Most carbon materials development is done for the aerospace industry, and because of that, there’s reams of paperwork to be done if you want to take it out of the country. But if you’re in the USA, it’s vastly easier to order small quantities for experimentation and prototyping.

One of 11 prototypes that were developed before the finished bike rolled into Danny's hands.

One of the fiber materials used in Danny’s bike is a “braided” carbon, which offers fiber in three orientations in a single material, as opposed to the woven or unidirectional types more commonly found. Braided carbon is an extremely impact-resistant material designed for use in jet engine cowlings. It protects the plane's fuselage (and passengers) in case a turbofan blade breaks loose, and sounded appropriate to crash-proof the exterior of Danny's frame!

Qiso braided carbon fabric layed over the headtube.

Nic McCrae Working on the Danny Mac Carbon Bike CNC Cut Carbon Fabric in the Carbon Lab at Santa Cruz Bicycles

At the same time we were experimenting with layup on Danny’s bike, we were also developing the new Blur and Highball XC frames. Going from one extreme to the other, the learnings shared between the concurrent projects helped accelerate the process all around, and after 18 months of designing, prototyping, and testing it was time for the fun to really start...

And Then There Was a Bike

“We had a frame, we had a spare frame and we had some parts. It was time to go to Scotland” recounts Nic. “I wanted to hand-deliver the frame to Danny. It was the single most expensive thing Santa Cruz has ever made so I needed to handcuff it to my wrist the whole way. Well, that’s not exactly true, but I did want to see firsthand just exactly what Danny might do to it.”

“My new bike is about four pounds (1.8kg) lighter than before” says Danny “And that weight’s primarily come off the fork and front of the bike, so I spent the first hour or just getting used to the new balance point! As soon as I got used to that it was time to start testing.”

“There’s a spot in Glasgow with a series of brutal concrete blocks” says Danny. “It’s where I initially went with the Reserve wheels for some impact testing. Frame number one didn’t quite last like the wheels though and after about a half an hour I’d managed to make a crack in the narrow part of the chainstays.”

Nic had expected to see some kind of damage to the bike and had traveled to Scotland armed with his own repair kit. Instead of vulcanising solution, sandpaper, a patch and a little yellow crayon, think prepreg carbon sheets, shrink wrap and a heat gun! Nic grabbed the spare frame and reinforced the area in need with more carbon, but how could he cure it without access to the Spengler press?  Well, he found some spare British Thermal Units….

For real. Nic sacrificed his impeccable AirBnB rating in order to get the job done. The frame went (half) in the oven. He took the freshly baked results to Danny in the morning and the testing continued. Same spot, no more breaks. 5 star rating.

So back in Santa Cruz we made Danny a fresh version of that first prototype with beefier stays. Gave it a coat of International Orange and left a peek of that braided carbon coming through the lettering on the downtube just because we could.

So that’s it. Testing complete.

Danny will be giving his new bike its first public appearance at the Sea Otter Classic in Monterey, California April 19-22. See you there!

Detail of the Rear Triangle of The Santa Cruz Danny Carbon Bike Logo Details on the Santa Cruz Danny Carbon Trials Bike

Danny's full carbon dream bike with 24-inch Reserve carbon wheels. Not available anywhere.

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