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carlinojoevideo Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 4:00pm
For sure, I agree with you. I love this type of content. I am running OneUp Aluminum bar, Ochain. I have mass dampers on my current frame, but I didn't run them on Fury. To onto PacoJo question, I have been using SynBike data acquisition to measure frame movements with the 6axis IMU's. I've only had it on 2 frames now, but would interesting to hear how the baseline of compliance is chosen, FEA or ride tested on dirt?
This forum topic has 135 replies.
carlinojoevideo Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 4:00pm
Photos here of Danny's modified rear end from PB for people who haven't seen it.
This forum topic has 135 replies.
Ryan Burney Added a reply to MTB Frame Compliance Analysis & Discussion
11/11/2024 4:00pm First off, thank you! And that’s a solid question. You can FEA full frames and estimate deflections, but you’re making a lot of assumptions, and they start to stack on each other, so things can stray from reality quickly. And speed to reality is crucial. Using FEA is useful but only for very basic analysis and often you can guess...
pacojo Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 3:27pm
to expand on rhodefab's original question a bit, I'm curious how stiffness is analyzed for geometrically complex systems like full suspension bikes. how do you find yourself estimating total stiffness in a given direction (like roll or wag) most often? I can see a springs-in-series approach being useful for quick iterations, but I'd assume that FEA tools are necessary at some point to get more accurate values, assuming that you aren't yet ready to test it on a load rig. also, awesome writeup in your initial post. it really helped piece together some of the intuitions I had about what...
This forum topic has 135 replies.
Ryan Burney Added a reply to MTB Frame Compliance Analysis & Discussion
11/11/2024 2:39pm Imagine a bike with just a chain stay, like a dirt bike with no seat stay. This design mainly allows roll. Now add a seat stay about the same size as the chain stay, and you should get way more wag and way less roll. How much? It depends, but Dak’s bike has smaller seat stays and larger chain stays...
rhodefab Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 1:55pm
That's a good point about short link 4 bar. Does adding the corresponding upper link (and it's additional bearings) help or hinder the desired compliance in flex or roll? To bring you back to Dak's bike
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Ryan Burney Added a reply to MTB Frame Compliance Analysis & Discussion
11/11/2024 1:34pm Haha, fair! I think going to extremes in examples helps illustrate points, so you'll see me slipping into that mode a lot so my apologies in advance. Let's compare a single pivot to a short link 4 bar and just look at the chain stay and its stiffness: A typical single pivot has a set of main pivot bearings between...
rhodefab Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 1:23pm
Let's not use a hardtail as an example, we're working with full suspension bikes 😉
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Ryan Burney Added a reply to MTB Frame Compliance Analysis & Discussion
11/11/2024 1:02pm Good points! The more pivots/joints you add to a bike, the less stiff it becomes. For example, a hardtail will always be stiffer and lighter than a short link 4 bar bike. Adding pivots reduces structural efficiency, meaning you have to add more material (and weight) to maintain stiffness. More pivots = less stiffness and more weight. But suspension is...
rhodefab Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 12:38pm
I think various links used to connect the rear axle to the main frame need to be accounted for. Horst links, short link 4 bar and direct single pivot designs all have different loadings at the joint. Is it common practice to consider them rigid but articulating joints?
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Ryan Burney Added a reply to MTB Frame Compliance Analysis & Discussion
11/12/2024 5:48pm Great questions, Carlino! Luis is the man and a pleasure to work with, his kinematic knowledge is the best. Bikes like the Commencal and Ari, with removable seat stay bridges to tune stiffness, show where the industry could head. It’s a great way to dial in feel based on rider preference and terrain. Danny’s mods are an example of getting...
carlinojoevideo Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 12:03pm
Hey Ryan, appreciate this Post! I had a chance to ride the new fury for a few days and I think you and Luis did a great job on the new version compared to the 2023 model. It’s interesting to hear your philosophy on stiffness and Compliance because I felt exactly what you mentioned above on the fury. In my opinion, I think the front end was a little too rigid for me, at my speed and riding level. The rear end to me was much more to my liking of how I like a bike to ride and feel...
This forum topic has 135 replies.
pedalpedalpedal Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/11/2024 11:01am
Mmm, al dente tubes for crab links
This forum topic has 135 replies.
Ryan Burney Started a new thread MTB Frame Compliance Analysis & Discussion
11/11/2024 9:29am Hey, I’m Ryan Burney. I’ve spent eight years as an engineer for full-suspension bikes, working on some fun projects, like developing the flex Horst link for the Cannondale Scalpel and being lead engineer for the latest GT Fury downhill bike. With over a decade of downhill racing under my belt (even made it to one World Cup—though I didn’t qualify...
This forum thread has 135 replies.
sspomer Liked a reply to forum topic MTB Tech Rumors and Innovation
11/6/2024 6:16pm
the only brand engineer to make a finals at the world cup - According to Kirk, Episode 2 from Norco (Kirk McDowall)
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