Video: Neko Mulally Tests Out Carbon Rear Triangles
 | First ride on the carbon rear triangle of the Frameworks Race Bike. We go through our initial thoughts, some data testing, and what the plan is moving forward with the new material. |
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Spoke tension: I cant say 100% no... but both physics theory and lab testing repeatedly show that spoke tension can not make a difference to wheel compliance unless you are allowing the spokes to go so loose that they fully lose tension and the rim is allowed to flop about in a totally uncontrolled manner. I am 99.9% sure that spoke tension adjustments are pure placebo. Further to that, I'd hazard a reasonably confident guess that a number of catastrophic wheel failures on WCDH race runs in recent years have been the direct result of people messing about with spoke tension, and ending up getting DNF's as a result.
Different thicknesses of butting, and different spoke materials on the other hand are very very interesting.
Spoke tension has no effect on wheel stiffness until a spoke has completely lost tension, and that would be asking for a wheel failure.
Spoke material, thickness, and butting absolutely effect a wheels stiffness.
For some reason the myth of spoke tension effecting stiffness just won't go away.
I couple of WC racers and some test more than others do, some understand the theory better than others too.
Having done my fair share of testing. SD is critical, yes you need a good mean bias, but it's easier to recalibrate to move mean bias than it is to improve SD. Unless you can root case the source of the SD variance and improve it, but generally it's easier to get consistent then improve from there.
Just a guess, I only dig trails just now and never ride my bike these days (snapped my X0 cranks last weekend so am hating my bike just now until it behaves).
why do you think this? honestly asking, becuase I have neither experienced a meaningful difference nor have a read any science based explaination of this. those three parameters definitely affect build quality and weight, but not much else IMO
butting is about weight and being cold forged to attain a higher strength than an extruded straight gauge spoke. I run CX-Ray in all my personal builds and highly recommend them for customers, for a pure longevity reasoning. most Carbon wheel manufactures say you have to run butted and and will deny a warranty for wheels built with straight gauge. why? because a carbon hoop needs a ton more spoke tension to be reliable and straight gauge will fail and stretch, causing massive irregularity in spoke tension, therein killing the wheel in short order.
TLDR: spokes don't stretch enough to be measurable or make a demonstrable difference
Compare the deflection of two wheels: numbers 39 and 47. Wheel 39 is built with 2.0 1.45mm swaged spokes, but wheel 47 is built with 2.0mm straight-gauge spokes. Hub dimensions are effectively identical, spoke count is the same and the rims are the same make and model, so the only structural difference is the spoke gauge.
Result? The wheel with thinner spokes deflected 0.051" (1.30mm) in font and 0.067" (1.70mm) in the rear, but the wheel with thicker spokes deflected less: only 0.046" (1.17mm) and 0.055" (1.40mm) for front and rear, respectively. That's an 11% increase in stiffness for the thicker-spoked wheels."
www.sheldonbrown.com/rinard/wheel_index.html
I vastly prefer building with and riding cx sprint and aero comp over cx rays or aerolites, after experiencing them back to back
bicyclewheel.info/wheel-simulator
Go hamb, make comparisons.
the fact that lacing pattern is not addressed, is a glaring omission! 3 cross v 2 v radial, would have a huge impact on lateral stiffness, simply due to longer spokes. but we don't see that data! why? becuase the lateral stiffness of a built wheel is not spoke thickness or length dependant.
The wheel stiffness test hosted on Sheldon's site was performed by damien rinard.
And wheel 39 and 47 were both 3x
www.sheldonbrown.com/rinard/wheel/data.htm
Measuring stuff is hard when differences get small ;-)
en.wikipedia.org/wiki/Measurement_system_analysis
Obviously they used the same lacing pattern across test wheels. And for lateral stiffness, the difference between lacing patterns is pretty small.
A longer spoke is a softer spring. So is a thinner spoke... And that's how spoke gauge affects wheel stiffness.
"A longer spoke is a softer spring. So is a thinner spoke... And that's how spoke gauge affects wheel stiffness."
this is all kinds of goofy. you claim two absolutes where there aren't any.
also, I still giggle at you brits calling it maths...
A tighter spring is the same spring it always is, with the same stiffness, but with added preload. Tightening the spring changes its starting position, in this case it moves the rim to one side. Doing so on the other side as well will bring the rim back to center. With the springs cancelling themselves out, what's left is their spring rate, which is unchanged with preload. Therefore it takes the same amount of force to move the rim sideways a given amount, regardless of preload.
This has been proven in math, physics, and in real testing. The fact that you don't believe it is on you.
Why tension matters...
youtu.be/7vFlKI_Brts
youtu.be/3jCGmAEUZfA
now...is a butted spoke progressive? answer carefully
if a spoke is a spring, and a thicker gauge is stiffer, than the thinner middle part will stretcher earlier and easier than the thicker ends. so yes, it is inherently progressive, to a degree.
and no, progressive springs don't have soft and stiff sections, and the soft bind before the stiff compress. that wouldn't be progressive, but dual rate(at best. it's actually a silly idea and would just lead to failure from spring bind, in short order).
I think we're done here
what you are saying is that the softer parts of the spring compress fully before any other part compresses at all, and that is just beyond stupid.
now.....jog on.
And no I didn't say one part fully compresses before any other part compresses at all. I'm not sure how you managed to get that from what I wrote. But I am understanding better how you ended up confused about the springs on your truck.
In the case of a wire, at no point will the thinner section quit stretching and transition to the higher rate of the butted sections, the wire would instead yield, stretch, and fail.
I do know that pinging my spokes with my little plastic spoke key before setting off on a race run is neither calibrated or scientific, but it gets my wobbly wheels down a race track.
Run them too tight and uneven and they go click click, ping ping and settle down, if they didn't care about tension they wouldn't stop making a noise.
The pesky things come loose again when hammered and you can feel it on track, feels wrong and doesn't hold a line through a higher g force corner as well.
Do I go any slower, no, that's not possible but it doesn't take a rocket scientist to realise a very highly tensioned wheel feels different to one that's loosely tensioned, through corners.
My guess... The park tools guys talking about loads and where that force has to go have a point and more force means less sideways displacement (not that you can see this on some videos of riders with different preferences).
What does the maths say about elasticy metal stuff... Dunno and don't really care what a science thing says. Only really care about noticing stuff on a track, the maths dude telling me I didn't notice when my spokes were loose can do one with his jotters and abacus.
Slight jest but you guys have gotten way too serious about something that pretty much every half decent rider can feel.
you think having 2 rates of spring is somehow progressive, wherein actual progressitvity has an infinite amount of rates, as every .0000000000001mm of compression has a different rate at which it compresses. when we talk about a progressive spring, the best example of this is an air spring. you understand air springs right?
Also, you won't find a tt or class 1 in the top 20 or perhaps even in the field with a progressively wound coil, variable pitch or tapered wire coil, all will have dual rate setups.
I know some incredible giraffe readers that I wouldn't let put a nut and bolt together (maybe I work with them)...
The best thing about science and numbers.... you can prove 10 different outcomes from 1 experiment to fit your narrative.
Re: the above ongoing noise about springs. Any and all multi rate (2 stage/3 stage/2758 stage/infinite stage) metal springs work as I described above. The more coils that get blocked (either by going coilbound or by being mechanically stopped prior to binding by some external force), the more the springrate increases. There isnt a progressive rate coil spring in the world that doesnt work in this way, if all the coils stop at the same time, then the spring is not progressive. Air springs are a different matter entirely. And yes I understand how they work too.
G'night
I have worked with scientists for over 25 years.
Amazing multiple PhD graduates, best in class, hand picked by JnJ Flex engineering, HCL, phenomenal at what they do but... Don't get them to see adjacencies or understand what is common sense to an engineer, it just won't happen. Their brains explode and they have a melt down, going into repeat mode (see your posts above). xxx
Spoke tension, butting, and material make a difference for a very simple reason. It effects the elasticity.
Watch the park tools video for an education.
Then watch plenty of world cup racers on "properly tensioned" wheels and the wheel flex.
Then remember. Text book boy is on about a force acting in a single plane, whereas the wheel under load whilst riding is under stresses from different directions at varying frequencies due to the terrain and rider input forces.
Engineering... The world that proves school text book science wrong.
Just a guess.
If you don't get it, then stick to the science book, real and imaginary numbers would baffle you and control theory and laplace would just blow your mind.
I have been an R&D engineer for a while (yeh, qualified and have a couple of decades of experience).
One thing you learn in R&D (large companies, not the small design houses wich are fun to work for), multiple PhDs doesn't mean you are the most effective in the real world!
If it's precision is good enough then a demo is fine for a relative type test.
Actually thats not entirely true. My preferred method is to use a better tension meter, haha.
If every part is off the self and using non custom geometry aluminum bikes can be made cheap. Standard aluminum tubes are cheap. It's easy to machine, and it's pretty easy to weld.
Doing one off anything adds huge cost in design, sourcing parts, machining time, fitting, fabrication, and welding. One offs are also often less reliable and within tolerance.
As a welder and fabricator the first one of anything is time consuming and tedious the second one and beyond are pretty straightforward.
Building prototypes is a much more costly exercise, the first one is especially expensive as you have to include the design time and creating one off parts. Though each iteration that Neko does should get a little cheaper each time as some of the parts and processes are repeated.
By the time he is ready to sell any, if he decides to do that, he would sit down and work out how many his target is and spread the costs out over that number. If it's a small number then the frames will be a higher amount each. If it's a big number then the frames can be priced cheaper and still make some money out of it.
He is fortunate that he doesn't have to make any money out of it at teh moment so can be quite competetive if he sells some. If he decides he wants to continue on and make it a fully fledged business then he has to price then so they can sustain the business and all the expenses involved. It's never just the bit standing at the bench. That is a small part of it and something a lot of people seem to forget. That $3k materials and build costs quickly blow out once you add admin, insurance, storage and then making a profit to make it worthwhile. Otherwise you are working for free and nobody does that.
Custom bikes are cool, but some random horst link bike with custom Geo is not gonna be better than even a stock V10 or Commencal Supreme, sorry.
UCI rules do say road bikes have to be available for sale and UCI approved. They do give them a grace period from when riders start riding them and they are for sale to the public.
Nice touch. Awesome video!
At which point along a chain stay does it morph from sprung - to un-sprung mass?