Velognome 

rhm - I'm curious too as to how the frame will load. With some degree of comfort, the down wires should load up when there is a rider, if one should snap it would make sense it would be one of those and not the one between your legs..phew!

So your asking if you can plucking ride it right?

Where is this quote from? Please, I want to read more about these bikes!!

Italuminum- & Noglider- Thanks for your post, very encouraging!!
I got the caring down pat...the "knows what he is doing" part I'm a little short on. And that is probably the answer, It may just be a case of diminished return, All the tuning and care may produce a fine ride but it may not be fine enough for all the trouble. BUT IT'LL MAKE A COOL C&V RIDE!!!

Captian- one flaw to the BB/cable plan, the nuts to secure and adjust the rig would be inside the BB. The toggles allow you to adjust the cables prior to or during the ride which seems to be necessary. Cable dia.? I don't even know what the load will be. 2, 1/6" cables have a combine breaking strenght of over 1000lbs with a working load of 220lbs. If it were all cable then that would be close to the limit, but the frame adds strenght too. Maybe 3/32" but 1/8" seems like overkill.

rhm

Relative pitch will help, for sure; especially if you have some fixed reference point, like a tuning fork, pitch pipe, harmonica, &c. You could probably use the spokes of your wheels for this purpose, provided you know what you're doing. But with no fixed reference pitch, you might not notice a constant drop in pitch across all the cables.

noglider 

Maybe others don't know Steve (your LBS mechanic), and I don't know him as well as you do, but he knows a HECK of a lot about bikes. He might know some estimates of how much force is applied during pedaling and riding over bumps. I've heard some numbers like 500 or 1000 pound-feet of torque at the bottom bracket. How that translates to linear force is something I don't know how to do, but it's not rocket surgery, as they say. I think it mostly involves trigonometry.

Velognome 

^^ maybe a spoke tension gauge will suffice, but then you all will miss my solo's " The hills are live with the sound of music.."


Trig. I knew I should been paying attention in class!!!

noglider 

I'm sure you were paying attention in class, though not necessarily to the trig.

Italuminium

@Velognome I don't know... some site in Dutch on weird frame designs and the dutch bicycle industry. Can't seem to find it right now, I read it months ago. But I think you can solve the "know what you're doing part" with a torque wrench and the right attitude to check the cable tension regularely. Keep us posted on the development and how it rides in comparison to your regular bikes!

Velognome 

Yea...funny, I don't even remember her name any more.

Captain Blight

@ Velognome: Yeah, almost all the bikes I work on have cup, cone and spindle BBs-- I see how this wouldn't work with a cartridge BB.

And I am BEGGING you to reconsider cable size. One hard hit on a railroad crossing could easily produce transitory loads in excess of a thousand pounds. Why not try it with the bigger cables and if it feels too stout, drop a size?

Tazio Novolare

Regarding regularly checking the tension - In this modern age of vast computational power & good microphones combined in a pocket-sized device (iPhone, etc) it would seem to be a "simple matter of programming" to devise an app to check the tension either acoustically or via direct conduction. Or maybe use a laptop running a real-time spectrum analyser like TrueRTA.

As for frame dynamics - I recall 20 years ago, Tange distributed a video with an animation of a motion-captured FEA analysis of a diamond-frame being ridden. IIRC, the downtube took the most stress.. It might be worth trying to track down the video just for kicks, even if it's too primitive to tell you much about how a tension-beam frame might ride.

Velognome 

Thanks, sounds like it would work but I don't even own a cell phone! Well, Ok, I got a prepaid job but I never turn it on- I'm stickin' with the spoke tension gauge.

I will be looking for that video though, thanks for the tip.

No RR crossings or pot holes in this frames future. Again, your baseing this on the assumption the wires carry the entire load which they do not. I"ll take your warning under advisment but the final demension will be decided by the guys doing the rigging.

repechage

800 ft/lbs is not out of the ordinary, the duration is not that constant, the high load numbers come at pretty low pedal rpm. And the typical human engine cannot keep it up for long either.

Captain Blight

Okay, just found something out about the original:

Tensegrity wiki

mtnbke

Unless I'm analyzing the picture of the Dutch materials science bike, that's exactly what they did. The cable tension is adjusted at the seat tube. There is one wire from the BB on a pulley at the dropout going all the way up to the seat tube. Same wire acts as chainstay and seat stay.

Dynamic tension is cool!

non-fixie 

Found another picture of de De la Haye bike:
According to the book it came from "this model supposedly weighs around 3 kg's". An interesting target, I would think.

rhm

Well, if it's a model, and weighs 3 kg, I'd guess it's around 1:4 scale? Pretty good workmanship, very detailed!

non-fixie 

A little more info on the De la Haye bike: from what I've been able to find on the 'net the design dates back to 1967. The Union prototype was developed in the 70's and shown to the general public on the Amsterdam bike fair in 1980. It didn't make production then.
The design was evidently developed further by De la Haye which resulted in the idea being picked up in the early 90's by the municipality of The Hague, who started production (based on the "university basement design", as far as I can tell - I haven't found any pictures yet) as part of a project for the "occupationally challenged".

The - somewhat optimistic - plan was to build 3.000 bikes, but production ceased after they had made no more than 20 (8 according to another source). It seems the bike was way too flexible. The wrong - stainlesss steel - tubing had been used and the workers weren't really up to the job of building these bicycles either. One newspaper that actually rode one of the bikes mentioned the weight saving compared to a normal 10 kg road bike: 700 grams. A titanium version they had planned was to be another full kilogram lighter.
Another try in the mid 00's, this time with Koga, of Koga-Miyata fame. It seems an aluminium prototype was built, and there was talk of building another in carbon fibre, but it never took off and the whole venture ended in tears in front of a local magistrate.

Velognome 

non-fixie- Thanks for all the reasearch. The photo of the De La Hay Union bike is great, you can see the crossed wires and turnbuckles as in the original Fletcher-Kaim from the '30's. For the frame currently in production, I want to stay as close as possible to the 30's version in that it actually seems to have had some real miles put on it, plus the impulse to build this thing was from a C&V perspective. If it has merit maybe a venture into (gasp) Carbon fiber and Kevlar or Titaniumbut thats for another section of the forum.

Anyway the history of this frame concept is very interesting to me and adds to the novelty of, I pray, a very interesting ride. Keep us posted if you uncover more.

Italuminium

Links please! I'd like to know more, since I'm from The Hague and I like local bike history! I wonder if any of the tooling survived... might start to build one myself!

BlankCrows

Cool project!

I was in a shop a few months ago that had a used (1990's era I think) Slingshot road model for sale. Very interesting to look at with just the one wire replacing the DT. More wires makes for more fascination.

non-fixie 

If you google "spanfiets" you'll find the info, all of it in Dutch, and including the court proceedings from the Koga episode. You will need access to the NRC Handelsblad archives for the newspaper articles. Haege Industrie still exists as far as I can tell, they might be worth a visit.

FlatSix911

Another early wire frame bicycle design ...

Dursley Pedersen ca 1910 bicycle
https://en.wikipedia.org/wiki/File:Du...10_bicycle.jpg

BlankCrows

That Pedersen seating arrangement looks rather uncomfortable.

FlatSix911

Here is another interesting example listed on EBay
https://cgi.ebay.com/Slingshot-29er-S...item2c5b908ddc

Velognome 

Kinda dorta, but both the Dursley Pedersen's and the Slingshots are different in concept. The wires on those are intended to allow flex, this design uses wires to create a rigid frame.

I just picked up the frame from Steve Willis at the Bike Stand, he's the builder. I have to make the patterns for the wire attachment points. (and buy a new camera, since droping it off a moving bike apparently cuases fatal injuries, arghhh!)

I'll post some recent photo's of the progress next week.

aixaix 

Fascinating project! Here are some links to the bike you mentioned:

https://www.delahayedesign.com/bike

The designer's statement, as reported on this site: https://moorebicycles.blogspot.com/20...cle-frame.html

Comment from Frans de la Haye (designer of the "Spanbike");
{Most , if not all, assume that there is a problem with stiffness op the frame (torque). Therefore I had it analyzed by an independent third party. BPO Delft, which company is specialized in making all sorts of strength and material application analysis. After extensive research they reported as follows (in short and in Dutch);

“Uit onze FEM analyses is gebleken dat het ontwerp de krachten volgens de belangrijkste belastingen volgens het EFBe testprotocol weerstaat; "trackholding rigidity", "out of saddle rigidity" en "axial loading" bij een framegewicht met spanstaven van ca. 1,23 [kg]”

In short, the design resists all forces according to the EFBe protocol.**

I find this unconvincing. Wouldn't it be better to hear about how the bike rides, rather than stress analysis?
I'm interested to see how your bike turns out. Good for you for actually putting one together!