Frameworks Racing & Cotic Collaborate on a Steel DH Frame
Press Release - Cotic Bikes
Well this is exciting! Neko Mulally's Frameworks Racing is going to be testing and potentially racing a Reynolds 853 steel front triangle designed and developed here at Cotic. I have been working on this for a few months now, and it's great to finally be able to tell you about it.
Fort William
I first met Neko through our mutual friend Chris from Downtime Podcast. Neko is Chris' co-host on the excellent World Cup Post Race Shows, and we got introduced properly at the Fort William World Cup. Neko came over to our stand and we had a good chat about frame design and the details that matter. He was really open, and I am so impressed at how fast he has grasped the detail of suspension design. I gave him a bit of advice about trying to solve the fatigue cracking problems they were suffering from all last season on the aluminium frames. I am just a big fan of World Cup DH racing, so we were all just super excited to have a bona fide World Cup racer chatting to us!
Worlds Les Gets
When we got to Les Gets Worlds last year, we found that there were race teams pitting all over the place. Literally IN town; on driveways, in parking bays, on street corners, everywhere! I rolled down from our chalet to the other apartment we were renting at the bottom of the hill, and I noticed the Frameworks Racing pit just opposite. I was just about to head up to say hello, when Neko rolled out on his training bike, rode straight over, looked me straight in the eye and said "I've been looking for you. We need to talk steel frames!". He had to get going right then, but it still counts as one of the coolest things that happened that week!
The next day Neko and his mechanic Anxo come over to the Cotic stand and we had a long talk about race bike design, and using steel in particular. The plan was hatched that I would design a steel version of the front triangle they were racing - same geo, same pivots, just in steel.
At the time they were still fighting the cracking issues and I could tell Neko was frustrated. I cannot even begin to fathom the mental toughness he has to drop into race runs on frames with cracks in them! A different breed...
Frameworks x Cotic Collab
Although through extensive use of gussets they seem to have gotten on top of the durability issues on the aluminium frames, Neko was still keen to run steel and see if the ride feel or any other attributes would be an improvement for the race bikes.
On the long drive back from Les Gets, I asked Neko to send me the tube specs for the aluminium frame. I set about doing some stiffness and strength comparisons in my notebook using some simple beam theory equations, to get a feel for where we were. Stress = My/I for all you equation fans out there.
As I got further into the design and engineering, Neko's good friend Dan - the Chief Designer and Engineer at RAAW bikes - got involved to design review my work. It was great to work with Dan, having only known him to say hello to at races before. It's fun to bounce ideas around, and having someone as diligent as him checking things is a really great part of the process. Dan's helped Neko out with the carbon design on the rear ends, so it was nice to be able to tie both ends of the frame together in this way.
Ultimately, the Frameworks x Cotic front end uses the exact same down tube as the RocketMAX Gen4, then the same size and spec tube for the seat tube. The top tube isn't Ovalform as it would be on a Cotic. We kept it round because I was a little concerned about dual crown fork stanchions hitting the thin edge of the ovalised tube. It's also two wall thicknesses up on the RocketMAX, because downhill.
After that, it was about getting into the details of the tube junctions and trying to reinforce the frame, whilst nicely managing the stiffness out of the reinforced areas. There are a lot of gussets!
Details
You can see the head tube and seat tube reinforcement. They're pretty obvious. The seat tube gusset design came from my experience with designing rocker link frames for our very first full suspension frame - the Hemlock - way back in 2006.
Neko wanted some adjustability in the frame for trying some different suspension rates, so the shock mount is a shuttle type design that can be flipped to move the shock pivot to reduce or increase the rising rate of the frame. There's also another shuttle for a third configuration. Lots of options!
Our friends at Five Land Bikes built the frames between runs of RocketMAX's, and we had it finished in Stormtrooper White by Cerakote Up North near Preston.
This is such an exciting project to be a part of, and I want to say a massive thank you to Neko and Anxo for putting their faith in me on this. It's been a privilege to get involved, but I'll admit to still being nervous. It's my first full-blown DH bike, and although you can work the numbers and do the maths, it doesn't mean anything until the tyre hits the dirt.
With Neko's unfortunate hip injury, he'll be passing on testing to another rider, but we should hear all about it soon. I'll be on the Frameworks Racing episode where they go over it. There is still the possibility they will prefer the aluminium frame, but even if they do, I still got to design a World Cup DH bike, and that is so cool! Everything crossed it goes well!
Cheers,
Cy
Founder and Director
Cotic Bikes
Follow the project at:
https://www.youtube.com/@NekoMulally
@nekomulally
Follow Cotic at:
http://www.cotic.co.uk
@coticbikes
Author Info:
Member since Dec 12, 2017
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www.vitalmtb.com/community/chunderboy69/cotic-flaremax-gen-4-hubble-purple
Why does the mountainbike-scene seem to bash on people that are trying to move the sport? For instance Paul Aston and Leo Kokkonen both seem to receive quite a bit of harsh feedback in the comments here at Pinkbike. They might not be the smoothest people out there, but they are moving the sport. They are also putting their name out there, and not hiding behind some corporate logo. The sport today would be in a different place if it had not been for their inputs.
Not my personal taste in geometry, but still a great company in my eyes.
What do you think I am biased towards?
I am definitely biased toward bikes that are reliable, well-made, interesting, forward-thinking and that handle extremely well and safely for their desired purpose.
I am biased against bikes that are unreliable and break, brands with bad after-sales service and warranty, carbon wheels that explode, expensive suspension that has issues out of the box or within a few days of riding, and outdated difficult and dangerous geometry.
If that's what you mean by bias then I am probably the most biased 'journalist' in the industry and proud of it.
Thanks.
For what its worth my flare max hasn't snapped but then I'm not exactly riding like Neko
How bad is Bobbins, on a scale from fully dodgy to dog's bullocks?
How heavy would a steel frame be, if you tried to make it fatigue resistant?
I think strain gauges on a frame used by Neko might give an idea on the real world load cases?
The better the inputs, the more precise the design can be. If we could somehow know precisely all material properties, stresses, environmental factors, and desired service life, a factor of precisely one would be sufficient. Safety factors are a reflection of the uncertainty of the inputs.
It's also a matter of what the factor is applied to. It could be applied to a static load case to cover dynamic loads, or a dynamic load case to cover environmental conditions, or maybe the applied stresses are poorly known.
For example, a bridge may have a factor of ten, but that may refer to ten times the load case for the bridge when new, with the additional strength requirement due to weathering / corrosion. If we want it to last, say, fifty years, that factor of ten may barely cover the full lifespan. Or maybe a bike could be designed perfectly for the 99th percentile user, yet still given a seemingly excessive safety factor to cover the possibility the bike will be purchased by Brage Vestavik.
Stresses in bikes are nowhere near as well understood as stresses in airplanes - let alone the disparity among potential buyers. Being involved in the engineering side of the bike industry, I've seen several approaches:
1. Design for the lab tests (ex. ISO or EFBE) and apply a - somewhat arbitrary - industry-standard safety factor. The tests are an imperfect simulation of actual use, hence many bikes breaking in similar locations, despite passing the tests.
2. Attempt to record actual stresses from company staff or sponsored riders and assume these are a good model for customers' use. Few companies do this to any extent, let alone sufficiently for me to trust the results without applying a hefty safety factor.
3. Iterate until the bikes stop failing. While this may feel unscientific, it often produces the best results.
Sounds to me like the Cotic-Frameworks collaboration is using method 3. They already have a product with fairly well understood properties (the aluminum frames) and the outcomes are fairly well known, so it's reasonable to add a small safety factor over the last generation of the aluminum frames. It also helps that these frames will be inspected more frequently than could be expected of customers' frames, allowing Cy and the team to cut it a little closer than would be the case if they were going straight to production.
My own areas of specialization are geometry, kinematics, and chassis dynamics*, and I also appreciate the usefulness of observation, rather than clean-sheet calculations. For every dodgy, what-were-they-thinking design, someone calculated that to be the ultimate bike! Better to rely on lots of observation and a little innovation than the inverse.
* Particularly for front linkages - yes, we've chatted before
@R-M-R: Thank you for your thorough insights. Yes, you are totally right. Safety factors are not straight forward in practice, especially if you do not know enough about the real world stresses the bike experiences. I was trying to get a little more insight whether there are some well accepted models for dh bike load cases so running a simulation and using a good safety factor could cut down the number of prototype iterations.
The 3rd approach seems legitimate if you go through a lot of iterations especially if you have a lot of experience and failures are most likely not of catastrophic nature.
@zoobab2 I'm not sure about the correct english term. I was trying to describe the term "dauerfest", which means that the stresses in the material are so low that the material could go through infinite cycles without failing. For some steels, that behaviour is theoretically achievable and I wondered how heavy a frame would be if one made it fully fatigue resistant.
There are no industry standard load cases. There are common tests, such as ISO and EFBE, that provide a good starting point, but simply designing to these standards is an incomplete picture. The closest thing to an industry standard is to apply a safety factor within an established range to the ISO test protocol. It's lazy and incomplete, but it (usually) works.
A few companies have used strain gauges under actual riding conditions - and even fewer have done a good job of it.
While it may be possible to create a predictive model of stresses, I favour observing past designs. There have been hundreds - maybe thousands - of DH / freeride / superenduro frames and there's so much to learn from designs that have failed or survived.
With carbon, where few companies do their own lay-up design, factories are the best resources: they have the greatest knowledge base of what's worked and what hasn't. As one design firm I worked with told me: "we just draw whatever looks good and let the factory fix it in lay-up". I quickly dismissed them from the project, but it shows how things are often done in this industry - at least at the low-effort end of spectrum.
*for avoidance of doubt, I am being sarcastic and very happy with my 16kg rig
Getting the lower bend in the thin wall 38.1 must have been a tricky bend for the Fiveland guys.
When you say up two wall thicknesses on the top tube would that be a 1.0/7/1.0 (vs an .8/.5/.
www.mtbr.com/threads/anti-corrosion-product-shootout.1073581
If the link doesn’t work just google “anti corrosion mtbr” and it will pop up