Snapped frame do you trust carbon!
- Thread starter bullcrew
- Start date
Because the opportunity for manufacturing defects is so high with composites all composite parts for aerospace are tested with ultrasound to check for wrinkles, dry spots, voids, debris etc.
On a bike, you are the test.
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I've always assumed pre-preg carbon bike parts are overbuilt to allow for inconsistencies. Otherwise (and without ultrasound checks) most units with inconsistencies wouldn't pass stress tests or would result in warranty claims.
One of the differences between two "grades" of carbon frame (Scott HMF vs HMX, Santa Cruz C vs CC) is more skilled, higher paid workers doing a more consistant job of the layup so they don't have to overbuild as much, saving weight.
All composites need to be overbuilt to a certain extent to compensate for variability in the end product. There is certainly going to more variability compared to metals. You can reduce variable with tighter and more expensive process controls.
There are also different grades of carbon fiber, some go through an extra processing step to strip away non load bearing material so it has better strength to weight ratios, think of it like debarking a tree branch.
Prepreg (weave) and weave (not prepeg) patterns both need to be overbuilt compared to UD. In some cases UD isn't practical, but going in that same direction CF in general is not practical for very small complex structures, like you wont see a CF bolt or threading. In a lot of cases, they cover the UD with a cosmetic weave pattern top later cuz thats what the public's perception of CF is. That's what every auto-person wants to see so they can constantly remind themselves that its CF.
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Which reminds me I have a leyzene CF bottle cage to fix. Last race the bolts to the frame were loose and during the race they got progressively looser to the point where one bolt fell out and my pump and bottle cage went sideways. I got all my mix down and chucked the bottle in a bush and tried to keep riding, but the bottle and pump jammed my cranks, so as fast as possible, I yanked both of them free, breaking the pump mount and cracking the cage, where the bolt goes through. Didn't seem to affect my frame. Chucked those all and the pump on the other side of the trail. All in all probably cost me 10-15s, maybe a few more having to slow down just before. Got going again and finished 6th, was gaining on the rider ahead, but we were spread out enough that I dont think the cage debacle was decisive.
Wen out next day and recovered all the parts.
The cage looks repairable, unlike the bottle mount. I have 3x weave and resin too.
Wen out next day and recovered all the parts.
The cage looks repairable, unlike the bottle mount. I have 3x weave and resin too.
Yeah. Seat tube angle. I've got long legs so I have to get offset seat posts. You know, knees and hips and stuff. Old man syndrome in there too.
But really, Hmm...If I'm going to ride the lift at the bike park and try to hit all the features, proper style, I need a DH bike. A big hit single crown could probably do the job. But, IDK, the nostalgia in me says just get a DH bike. You (I'm talking to myself) already have plenty of other bikes. N+1. DUH.
Realistically I don't really ride DH at a decent level anymore and it's extremely rare I'd travel to either of our two chairlift tracks. Granted if I were to it'd for sure be nicer to be on a modern DH bike but this thing is pretty much as long/slack as any DH bike I'd have and at 170 rear, 180 front with DH tyres. it won't really be holding me back anywhere else.
My dislike of super steep seat tubes is simply because for me too steep gives a horrible position when seated pedalling on flat terrain. and only get's worse if you've sized down in frame size
My dislike of super steep seat tubes is simply because for me too steep gives a horrible position when seated pedalling on flat terrain. and only get's worse if you've sized down in frame size
Yeah I got certified iirp radiation safety with California for open source cobalt and iridium as well as NDT II for ultrasonics, mag particle, dye, Eddy, Vis, radiography...but studies and field was petroleum, nuclear regulatory , aero space, naval and infrastructure......
Ultrasound makes sense I understand it and how it works...just never thought to use it for that composites... radiography and density was considered for fractures and density....
Didn't specialize in composites, don't think I even thought about that region of use...that's cool...
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Nothing wrong with the old man insurance policy the DH bike provides. Just try not to let your brain write cheques your body can no longer cash. That is why I never got rid of mine, bought, paid for and now worth peanuts so why not keep it.
Brain "What you need a million dollars heres a check, oh you need on too sure let me get right on that.." I'm bouncing checks like a b-baller...
Body " WTF you doing man,we so broke we can't pay attention, this is gonna hurt!"
You don't miss a proper DH fork? Even a lowered one?
I am fairly light at 75kg and ride like a conservative wimp but I really appreciate the added stiffness and assurance of the 35mm boxxer on my bikepark Ransom
I always ran my DH fork slightly oversprung with less sag than most and have tons MOAR riding time on old skool 32mm stanchion boxers than the newer 35s. Apart from a couple of years on Monster Ts around 99/00 I didn't ever ride anything stiffer (oo er missus). then managed a couple of seasons on shivers. Possibly the least accurate steering fork evar.
At 170mm I still prefer a 35mm Lyrik to a 38mm Zeb. Even on an Ebike. So no. Won't massively miss a dual crown fork. And TBH even at trade price they're all massively too expensive to justify now. (boxxers/40s anyway)
I know it's blasphemy these days, but I wish you could still run Lyriks at 170mm. I've ridden latest & greatest Zeb and Lyrik back to back at 160, and I just prefer the feel of the smaller air spring. The larger diameter one in the Zeb ramps up a lot more strongly deep in the travel, even with zero tokens. For what I ride, I never feel like the Lyrik is flexy, if anything, I feel like the extra stiffness of a 38/Zeb is more tiring. Kinda like running uber stiff wheels.
Wouldn't that be more to do with the balance port location rather than the dia?
And the nut cups and whatnot?
And the nut cups and whatnot?
I went to a Zeb to a Lyrik awhile ago and I'd tend to agree depending on the circumstance. For shorter runs in really chunky terrain I love the Zeb, in some ways its less harsh - I feel like it works better under heavy braking than the Lyrik did, and it performs better suspension wise when it is subjected to cross-rutting etc.
But on long runs it seems to transmit more buzz, or noise to your hands. I did one of the EWS stages during Trans Madeira and had to stop after 8-9 minutes and shake my hands and continue. To be fair, I'm running a 27.5" front still, plus I put the torque caps on to make the wheel easier to locate. I really should chuck the old caps back on and experiment again, because I remember they made more of a difference than I expected.
The Zeb does seem extra progressive compared to the Lyrik, like you said - but i'm not opposed to that personally. I've got a Luftkappe in mine and love it. My mates are running the Secus and that feels awesome but I'm to worried about smashing it on a rock.
Totally agree.
Just run a pre MY24 Lyrik. The old charger dampers are still good despite the whole YUno buttercuppery 3.whatever damper hype train.
I'm running my 29 Lyrik at 180. It's fucking stupid they limited the new ones to 160
Sounds like a candidate for those "reverse volume token" foam things. Was Formula selling those?
My complaint with a 170mm Fox 36 was bushing bind caused by flex on braking bumps. It felt fine until you hit the brake, then it would get MUCH more stiction and be very harsh over braking bumps. A 38 feels much stiffer fore/aft and absorbs bumps much better under braking.
Okay. So can we agree that anything over single crown 160mm fork is not optimal? I mean, if you're really, like REALLY riding? Perhaps racing?
Unless you're on a Marz 66 of course .HA (yes I'm that old school)
But really. I've raced enduro on a Pike. Did pretty darn good. That tells you how long ago it was. And these were old school DH trails.
It's like put a dual crown on an enduro bike. I think Yeti does that for Richie. But seriously. Some dudes need proper forks.
Are you listening industry? This is why I go frame only, and build custom. So please at least do that. (Frame only option)
IDK
Unless you're on a Marz 66 of course .HA (yes I'm that old school)
But really. I've raced enduro on a Pike. Did pretty darn good. That tells you how long ago it was. And these were old school DH trails.
It's like put a dual crown on an enduro bike. I think Yeti does that for Richie. But seriously. Some dudes need proper forks.
Are you listening industry? This is why I go frame only, and build custom. So please at least do that. (Frame only option)
IDK
I know what you're talking about, those funny "carbon air" cartridges. I've looked at them, but I'm very skeptical. They're also expensive as fuck, like $200+ last I looked. And they supposedly wear out / get saturated over time needing to be replaced.
What Fox did with the 38 was put a reduction tube inside the air side to keep the air shaft diameter closer to that of a 36 and make the spring feel similar. It definitely behaves like that when I've ridden 38s - I needed tokens and higher pressure than Fox suggests to keep from hard bottom outs. RS instead tried to balance the pos/neg chamber volumes differently, and I don't think they quite got it right. I've tried a Secus on the Zeb and I feel like it pushed the ramp really deep but then made it a bit sharper, while making small bump and midstroke better.
I really like the Charger 3.1 damper (have it on both my Zebs and Lyrik), so it's not a damper side thing.
Regardless though, I don't think it's unreasonable to want to run a 35/36mm fork at 170mm, especially given the improvements that have been made in bushing overlap, CSU interface, torque caps, etc. EXT's fork goes up to 180 at 36.
I reckon a Secus or one of those activated carbon wundertokens that actually increase the air volume would be the go. FWIW, I think the Zeb's progressivity comes from the lowers as much as from the air spring itself.
Runt has definitely crossed my mind, and even been added to cart more than once. The main reason I haven't is that I haven't is below - even with zero tokens it seems awfully progressive. I'm not sure how the Runt would actually help that - if I run the ramp low enough for it not to spike, I'll have terrible midstroke.
Yeah, that's what I was trying to get at. Maybe I really should get one of those carbon snake oil things in the name of "science."
Runt made that FUCKTARD of a fox 38 fork I had worth a shit...
interesting...i have zero issues with my 38...but maybe i'd be even moar happy if i runted it nao???
This is my experience is well. Haven't done a Zeb/Lyrik comparison though.
I'll preface this with less ignorant prejudice...everyone has a different style, size, weight, torso and so on ..some come from my others from BMX...so we all rise different and I don't think there is one perfect item for everyone for riding besides just having a bike and build it to you..
I got another Zeb the other day to play with some more also ordered a new rfx38 for the slashs rebuild after breaking...I want to play with the Zeb a bit next couple weeks more than I did, some different terrain and really take a day to dial it and see...the 3.1 is good the 3 had some issues with lighter riders again I think it's stuff chasis matched with too stiff of a platform on charger 3...(Burnish fork .14, drop oil to 5wt 19 CST and it comes to life)
That's said..
I like the way a coil rides I like a linear consistent feel ..why I prefer Ohlins as well . But the runt made the 38 more consistent and predictable than it was...also not a fan of a 34mm air chamber versus a 36 is bigger ...should have gone the way of the 40 on air chamber but for 38....I didn't get a long with it real well...tried I was digging fox but after an injury and riding different stuff it fell short on the list down...even my fox 40 is avalanche spring and open bath...rest of bikes are now all ohlins...
I think it's too (chasis) stiff, too progressive and it fights itself...matches with a damper and limited comp it never felt right...I can see where it would work for a different style rider for sure though....
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i do wish mine was a bit more supple. don't mind progressive...i'm a 170# hack...on the dh i'm more plow than air...
did go back to my 11-6 coil on the rear after i couldn't get the kitsuma air to not bottom/squawk without giving up small bump compliance...but i'm also shit and knowing much about suspension/setup. i generally find something that feels about right and forget it....
This is exactly what it's about..this is a crap ton more fun then my ritual...
I find a baseline and adjust a little bit, if I find some inconsistent behavior or areas that would make me faster by taking out the terrains input and dumming it down down then dial it in...
I'll ride a few times and get close then I adjusty style to the behavior a bit..tune a little and get a good baseline...I just want to ride..
I do have motion industries telemetry system coming and I'm going to balance mine and dial it in.. once I know it fits me as well as it will then I'll adjust my style to it to ride synergistic with it...
Once I have a baseline for primary I'll do a decal on top tube that has everything, tire pressure, shock fork settings and psi..
I have 1 for Rocky technical and one for jump line park and senders..
Then I lose sticker, screw up settings and just ride it to ride lol..
Yeah, different strokes for different folks. I really like the air spring in the 38; it's the main reason I keep using them. The tube-in-tube design allows them to have proportionately larger negative air spring volume. I find it does a better job with mid-stroke than any other non-dual positive design. So much so that I didn't wind up running a Secus in it. The weak compression damping isn't great, but I compensate with more spring. In general I prefer more spring support to compression damping support - it keeps the ride lively and I don't need to push through a wall of low-speed compression - that said both versions of the Grip 2 could use more.
I think this gets overstated a bit when it comes to bike manufacturing. Aluminum alloy frames have a lot of areas to have manufacturing defects as well, there's probably more recalled aluminum frames than carbon out there. It turns out to be "easy" to forget to weld all the way around the headtube (the way the downtube, headtube and top tube come together and are welded turns out to be important), or drilled some extra vent holes, or "forgot" to heat treat the frames again after a thermal event that would weaken them. As price for aluminum frames went down, some of the fine art/attention to detail/process control gets lost in the higher volume facilities.
is that a result of there simply being much, much higher volumes of aluminum frames being manufactured, or is the incident rate of defects/failures actually higher? (or both?)
This looks like a pretty common failure mode, one I used to see a lot. Seatstays don't need to be super strong compared to every other tube on the bike, but they get whacked in a crash or tip over pretty easily and thats enough to break em. If you still have the piece, cut open those rectangular stays and look at the cross section. What I found after some investigation was that the corners get thin, must be some dynamics in the mold with the bladder inflation into the corners and ply migration or some such. We designed an impact test that hit the seatstays on the side, and then experimented with different ways to make it more fracture resistant to impact like that. We ended up using a tow fiber method in the corner. Imagine taking a piece of UD prepreg thats 18" x 1". Roll it up so you end up with a fat piece of spaghetti thats 18" long, and place one on each corner of the rectangular tube. It reinforced the corners so the tube would resist fracture when hit. That reduced failures significantly.
i don't know the answer to that - probably some of both. Could be that you can often identify what the defect actually is on the aluminum when you examine it so "the remedy" to fix it is more cut-and-dry. The number of variables is fewer, but that also means screwing up one thing, like using the wrong welding rod, etc. can have a big impact