[Closed] So have Health & Safety caught up with steel framed bikes?

I'm not sure what the deal is with this but a mate was enquiring about whether or not Cotic were going to make a Soul that took 140mm forks and was told it had been delayed because of some standards changing.

Its to do with stiffness isn't it? Brant was explaining it some weeks ago.

isnt it to do with a silly CEN test requirement that tests "drop to flat" kind of forces rather oddly instead of "running into things" kind of forces?

[url] http://www.singletrackworld.com/forum/topic/cen-safety-regulations-and-the-demise-of-the-steel-hardtail [/url]

seems sensible to me stoner you expect frames to fail after crashing but not drops (unless you are jey. Are you?)

I am most definitely jey....but more people will ride into something than will land on something.

So surely the test should reflect the use to which the frame will be put (and that's mainly [i]not[/i] landing to flat). If you think that ALL frames should be tested for unreasonable flat landings then in theory all XCJey frames could be used quite "happily" on the Fort Bill DH course, No?

Is there anything to stop small manufacturers building touring/CX/rigid only bikes, that just happen to handle exceptionaly well with 130mm forks?

Here you go - http://shedfire.posterous.com/i-thought-id-publish-the-full-cen-report-on-t

That's the full report with the front page removed so you don't all come around my house for tea and cake.

There is general industry confusion about whether you "need" CEN approval, certification, testing or whatever. I have had one Trading Standard Officer say yes. I've had plenty of people say "no".

I thought a very stringent test would be a good way of seeing how much stick a HARDCORE mountainbike would be, after all, this is just a "mountainbike" test. Not a "long travel hooligan hardtail, jump off things" test - so surely all decent "ride like ****" bikes should pass?
I ride like a **** sometimes, so I wanted my frames to pass, and not just scrape through, so we tested them with solid steel girder "test" forks, to the standards, and the steel one passed. The alloy sample one cracked on the seat tube, so we're fixing that for production with a new tube butting - it's in testing again right now.

I don't disagree entirely with you old chap, it just seems to me the forces that snap frame are often from landings which pretty much any mtb frame will have to endure.

Brant - only 3.1mm of "splay" - so what happened to your theory of "splay" compliance 🙂

al - Id agree that landing forces should be tested, but if you look at the test metrics its 600N riding into something and 1200N of "splay" force (i.e. pulling the front axle away from it's rest position)
Now, Im rubbish at Physics but doesnt 1,200 N in the forward direction only come about after a huge vertical drop of high mass and speed?>

that's permanent splay

I don't know but I don't think that force would only come from a huge landing. 600N is only 60kg which isn't much.

as you say. You're rubbish at physics.

Brant - you measn after one wallop the bike is 3.1mm longer? 🙂 cool!

Al - the 600N is running into stuff - and IMO should be a higher test.

The 1200 N is pushing the fork forward, which would happen when you landed to flat...and at 1200n that would mean quite a ton-sized lad landing at speed wouldnt it?

Someone with the know how can probably calculate what downward forces creates a 1200N forward force with a 26" wheel?

I've read the thread in the link, very interesting

I assume that this legislation is aimed at mass market bikes, rather than small run specialist bikes. Surely these rules cover all imported bikes?!

Regulation is a very double edged sword. Particularly for frames that are currently working OK.

On the other hand I was nearly killed by an a fork failure that was either s*** design or a manafacrturing error. Of course if it was the later then these tests wouldn't have helped at all.

It is an interesting contrast to the sdandard used for climbing gear. I use climbing gear testing when teaching. If a karibiner is rated at 2000kg what does this mean. Usually students say the average of a batch. Average failure load is not much cop is it. Yours failed at 1,600kg but the one sold last week failed at 2,400kg so it all averages out! Not helpful really.

So lots of climbing gear is now batch tested and the stated load calculated so that only 3 in 1000 tests would be lower than the rated value

I'm sure most bikes used by forum members are made to reasonable standards. But 100 pound bikes. Are they really all the same stength?

Finally am I correct in thinking that you can't apply a smaller load testing a bike for smaller people?

Missed my edit time

Scratching on an envelope a splay force of 1,200N would result from a vertival load of about 3 times that (I assumed a head angle of 70 degrees, I think that the horizontal load is tan2o times less than vertical load). A steeper head angle gives more splay force for the same vertical loading

So thats a big bloke landing heavily and hitting 2g (plus his weight) in the landing. I wonder if its hard to simulate a large vertical load and thats why they use a horizotal load

My death forks failed in splay, mainly due to fatigue

I haven't followed this fully, only skim-read it but why are we only referring to steel frames not aluminium?

Early reports from some companies suggested steel frames faired badly under the "horizontal fatigue" test.

cheers ampthill.

ampthill - Member

A steeper head angle gives more splay force for the same vertical loading

Erm surely you have that the wrong way round?

i've just defaced a perfectly good envelope...

'tan theta = (load / splay force)'

'tan 70 = (load / 1200N)'

'2.747 = (load / 1200N)'

'load = (2.747 * 1200N)'

'load = 3297N = 336Kg'

That's 336Kg at the handlebars (down) to create the 1200N splay force.

(which sounds like a lot, but i'm aware that peak loads during a landing will be 'X' times higher than the static load)

(disclaimer; i'm an idiot, and i never was any good at maths)

(at a head angle of 67degrees, you only need a handlebar force of 288Kg to create the 1200N splay force)

If I were ton, Id be worried 🙂

basically 3 times a 14stone person on the bars.

hanging up on a goodly sized jump might get you near that but its still quite a test.

would the fork/steerer withstand that?

I don't see how my arms could carry 288kg even momentarily

I don't see how my arms could carry 288kg even momentarily

thats what your testicles are for.

alot of that force will be generated through the pedals and seat as well

i guess its quite easy to land pretty heavy. but you wouldnt be putting xc bikes through that sort of abuse.

maybe dirt jumpers/slopestylorz only.

"I haven't followed this fully, only skim-read it but why are we only referring to steel frames not aluminium?"

it's to do with the flexibility designed into steel frames and fatigue limits - different materials affected in different ways by the test. the test appears to be designed to fatigue alu frames to failure fast, the result of this is that many current-design steel frames failed where their alu frames pass. our alu 2008 and 2009 frames passed without modification on a steel girder rig with full speed hydraulics (ie a harsh test!) but that same jig tore cr-mo steel top and down tubes in a way i've never seen before.
When the mode of failure of a fatigued alu frame can be dramatic and happen after 3-4 years in some cases, wheras steel rarely fails and when it does it's usually a 'less dramatic' fail after a longer time, this was puzzling for a test that is primarily about the safety of the rider.

Thinner tube walls and diameters of steel frames, ie built-in flex, also mean the peak loads or stress concentrations are higher than on a common Alu frame where large tubes and gussets create an almost monocoque front end. i'd back this up by saying that there are a few brands as well as tube manufacturers that have seen failures from EN HF tests that were never seen before from riding streses, but we've since had EN HF passes on steel frames that were designed pre-EN by looking at the test method more closely - so if that can be done it's not all too dramatic.

tbh the test method is the important part as test results vary wildly across different testers and methods. the CEN doc doesn't help really as it gives a fair amount of scope for adjustment of the method and hence the results. it's down to the designer to ensure the test is relevant, representative, repeatable and demonstrates a safe bike - well actully it would be down to a court to agree if it came to it, but basically it's a self-certification due-diligence test that helps show safe products.

however there are other ways to do this if required, ie light steel frames may be be sold without EN marking if it had an 80mm fork max / no jumps + drops decal if you were sure you were clearly marking out the use limits. however CEN is good back up and it's better to have it than not.

The Road and MTB HF tests are the only one anyone has had any issues with, the pedal fatigue and vertical drop / fatigue tests are something that almost any half-decent pre EN designed bike would pass.

James / Genesis

Cheers James, very interesting

ahwiles same result as I got. Maybe we're correct..

cy-nical Bigger head angle more splay for sure. If you're really interested I'll try and explain

The idea that these loads are part of a fatgue test seems amazing. How many flat landings are we allowing for? Or if its the same for road bikes is this sort of force generated briefly bay say a road tyre well pumped up hitting a raised drain edge.

please explain.I can't see how a vertical head tube would create any splay.

Are cycnicl my idiot mistake

You are correct vertical head tube no splay

In my stupid mind a 60 degree head angle is bigger than a 70 degree head angle. Which it is sort of , but not numerically

with my calculations; for a slacker head angle, i need LESS handlbar load to create the 1200N splay force.

(someone might spot that it's a bit of a simplification)

will i die on my old steel kona hahanna now? :s

yes the slacker the angle and longer the fork the higher the splay force on the frame on landing, but the EN test appplies a horizontal force not a vertical / handlebar force, applied at the front axle. it's to simulate hard braking forces, hitting bumps at speed and splay forces from landings and compressions.

the EN test has a set load for any MTB type, the only variation between a DH bike and XC is the fork length, plus frequency of cycles if you choose to vary it. A DH bike could take faster cycles to simulate higher speeds and impacts, i don't know if that's how they test them tho, we don't make DH bikes.

i'd carry on riding old steel frames quite happily - an old style kona like a thin wall kilauea wouldn't last half of the HF test but how many break prematurely in use? that's the whole issue with the EN test, but we are working with Reynolds on ways to add the durability needed in the HT/DT area without adding any weight. until then we'll carry on with gusseting as it's hard to beat as an EN-effective reinforcement in this area. I expect you may see more top-to-down tube front end gussets like Brant's new bike and some steel dirt jump bikes. effectively it creates a HT area more like an alu bike in that it's closer to a monocoque, rigid structure - the removal of flex in that area solves much of the problem created by the EN test method.

the EN test has a set load for any MTB type, the only variation between a DH bike and XC is the fork length, plus frequency of cycles if you choose to vary it. A DH bike could take faster cycles to simulate higher speeds and impacts, i don't know if that's how they test them tho, we don't make DH bikes.

DH bikes, to my mind, should exceed the minimum EN test by a large factor.

with reference to the soul with 140mm forks:

I'm a bit worried that you wont be able to get any nice whippy trail bikes anymore, just loads of really long forked stuff!

but more choice is always good!

whippy and long forked don't often go that well together though, you just can't get the best out of a long fork if the front end is a bit twangy. don't get me wrong, twang and whip is what i love about steel, but there's a limit to how much you can have. a soul would be so much nicer at 100-120 i'd expect.

for 140mm you need a more rigid front end for the speeds and impacts it can handle - and at these speeds it will feel like a lighter / zingier 100-120mm forked bike does at a slightly lower speed on less rocky ground. it's all relative.