[Closed] FAO doubters

Looks great. What could possibly go wrong 🙄

just needs a jubilee clip and duc tape

Jeez you lot would piss on anyone's chips would you not? 🙄

So the rack is structural now is it? 😉

That's horrible, looks like [i]I[/i] welded it 😆

Well OK maybe not quite that bad.

Nope, never was, CBA removing it for pic.

Just imagine it's not there 😛

please can you explain what you have done?

please can you explain what you have done?

sure looks like it....why has he done that....and to a Ti frame no less?

Nope, never was, CBA removing it for pic.

Just imagine it's not there

We can but dream...

To be fair - I'm liking his style on this one

hope he lives 😐

That is so awful; Its does not even appear to be one plate but two straps of alloy with no triangulation. Even if the lower mount stays rigid the calliper will rotate around lower mounting bolt, clash on the disc and just push the glued on top mount straight off. Its laughable its so cruddy. And you claim to be a mechanic and have good physics knowledge? thats one of the worst bodges have ever seen.

Any credibility you ever had as a mechanic is just gone.

harsh but essentially fair by TJ

it really does look like a spoon.

it's an entertaining bodge.

certainly worth doing/taking a photo of/testing.

just, er, don't test it under circumstances where you'll be hurt if it doesn't work very well, ok?

Fortune favours the brave, but remember "there is no spoon" 😉

Please let me be there with a video camera when you first try that brake in anger 😆

Sorry to repeat, but what could possibly go wrong?

A clear example of someone's ambition outstripping their talent.

Magnificent.

Have one of these for effort and entertainment value

[img] [/img]

Why even go to the effort to do all that for a cable disc?

I don't understand.

And you claim to be a mechanic and have good physics knowledge?
Any credibility you ever had as a mechanic is just gone.

Teej, and you claim Al makes ad hominen attacks on you? That was a bit mean.

It's hard to tell from the pics, but at first glance it looks risky..
It seems that any resistance to rotation is reliant on the frictional force in the bolts, and the stiffness of the glue joint? Which are both, ummm not good. Is the spoon connected to anything else in any way other than the single bolt and the glue? (I'm hoping there is something we have missed which isn't obvious?)

Good on ya mate.10/10 for effort. 😀

TandemJeremy - Member
That is so awful; Its does not even appear to be one plate but two straps of alloy with no triangulation. Even if the lower mount stays rigid the calliper will rotate around lower mounting bolt, clash on the disc and just push the glued on top mount straight off. Its laughable its so cruddy. And you claim to be a mechanic and have good physics knowledge? thats one of the worst bodges have ever seen.

Any credibility you ever had as a mechanic is just gone.

I truly am sorry that I appear to have sufficiently upset you to make you act like a crying schoolboy and type without thinking.

Here's a clearer pic, have a think about what you see and see if you want to revisit any of the above before I destroy it. Oh and how is my ability as a mechanic (proven in various lbs over decades) related to my ability as a designer/fabricator? A mere moment's thought establishes the 2 are quite different.

[url= http://farm6.static.flickr.com/5249/5686353032_c83f014d2b_z.jp g" target="_blank">http://farm6.static.flickr.com/5249/5686353032_c83f014d2b_z.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/7693620@N05/5686353032/ ]IMAG0479[/url] by [url= http://www.flickr.com/people/7693620@N05/ ]alan cole[/url], on Flickr

toys19 - Member
It seems that any resistance to rotation is reliant on the frictional force in the bolts, and the stiffness of the glue joint?...Is the spoon connected to anything else in any way other than the single bolt and the glue?

It's not a spoon, it's 4mm plate steel 🙄 the lower mount is bolted on by 2 M5 bolts to the frame, the upper mount is glue/CF wrap, under the wrap the arm is about 2" long where if mates to the stay.

Robz - Member
Why even go to the effort to do all that for a cable disc?

I don't understand.

(1) You can't get hydraulic discs for drop bar brake levers and (ii) they work as well as hydraulics.

trailertrash - Member
sure looks like it....why has he done that....and to a Ti frame no less?

ti frame - ideal for the bike's purpose, easy to remove the mount & revert if it doesn't work out - would be a lot more tricky if the frame was painted.

[u][b]You lot really haven't thought your flaming through at all have you?[/u][/b]

🙄

I think TJ meant the triangulation on the top mount, I hate to say this but I probably agree with him on this sole point.

I would just quickly add a piece so the top mount was a triangle, then you will be ok. Other then that good bodge.

Al you cheeky bugger I was trying to be constructive not flame you. Unless the top mount is connected to the caliper by some method other than the single bolt then it looks to be a risky design.

toys19 - Member
Al you cheeky bugger I was trying to be constructive not flame you. Unless the top mount is connected to the caliper by some method other than the single bolt then it looks to be a risky design.

It's more to do with the single mount of the bolt onto the frame (if you know what I mean) I think we are essentially saying the same thing. This will cause big bending moments in your frame which are not a good idea.

I love it. Build me one. I'm not afraid of death.

It's more to do with the single mount of the bolt onto the frame (if you know what I mean) I think we are essentially saying the same thing. This will cause big bending moments in your frame which are not a good idea.

TBH I think they are both equally likely to fail for the same reason.

I think Al is trolling, winding us up or carrying out some kind of social experiment..

You really pought to dust your server/comms room occasionally.

I would just quickly add a piece so the top mount was a triangle, then you will be ok.

2 spoons then 😉

The bottom mount looks very nifty though.

And yes bb7's are truly ace and a match for many hydraulic brakes.

Is that a 140mm rotor Al? If so, good. If not, would it mitigate against or hasten premature failure?

Sorry toys I wasn't intending to include you among the lame-flamers.

Look at the line of force into the top arm - what would adding a strut to it achieve? Remember the two bolts are connected by the solid brake mount, and the rear bolt is rigidly mounted by a triangulated strut.

It may of course break! 😀 Truth is I made it that way as I'd kind of ****ed up the mount first time round and CBA making a whole new one 😎 and my plate of steel is getting small 🙁 if it does break a beefier one will follow

Test riding shortly.

I had expected the whole mount to be one-piece - i.e. the "spoon handle" would be joined to the lower triangle. Is there a reason for [i]not[/i] doing this?

You are living the dream Al, most of us can only imagine it.

If that's the dream, at least it explains why I've had such a dreadful might's sleep.

[img] [/img]

I wonder why this hasn't been marketed yet.... 😉

Do yourself a favour, sort out a triangular spoon for the top mount then the caliper won't be able to rotate (well not without bending the stay anyway) and you'll be a lot less reliant on that black scab holding the whole thing together.

You know that blue nylon string you find tied to the corner of old palets...well where's that then? I can't see any.

Does this mean you can't lend your bike to Uri Geller?

Probably a good thing, to be honest.

that should be buried at sea

kleenex "mansize", really??

That DVD player seems a bit dusty, tut tut. 🙂

Looks good.
Take out some [url= http://www.tescofinance.com/personal/finance/insurance/dentalins/index.jsp ]dental insurance[/url] first.

[img] [/img]

ah, is that AV stuff, I thought it was a forgotten corner of some cupboard at cynica-al's work place.

Al I stand by what I say.

No triangluation at all on the upper mount. Relying on the friction of bolts and glue to hold a brake calliper on is stupid.

If the mount was all one piece so had some rigidity then it might work - as it is?

Teej I think you will find an awful lot of railway bridges are held together by friction (admittedly when the friction fails then there is a second line of defence), and lots of CF bikes are essentially held together with glue. I have a Giant CAAD aluminium frame which is held together with glue. Lotus Elan, and I think Elise are glued together?

Its true the mount looks iffy, but lets try and solve this and not just use it as an excuse to lay into someone you have a personal vendetta against? Your behaviour here is unedifying.

That looks like a shocking bodge.

You may be a skilled mechanic, but frame modification is not your forte...

Toys - Looks iffy? 🙄 OK maybe I was a bit harsh but we can all see the flaws in it apart from Al who simply attacks the folk who point this out.

He claims to be right about everything to do with bikes based on his extensive education and experience and comes up with that? Its laughable

He claims to be right about everything to do with bikes based on his extensive education

i'd have liked to do that course, is it avaliable on the OU?

Toys, do you think your chassis or railway bridges are cobbled together by an amateur in a shed with zero engineering?

The problem here is not the materials it's the execution (maybe CA's execution if it fails).

The mount is relying on CF/epoxy holding in shear where it's been splatted against the smooth Ti stay. How was the Ti prepped? How was the epoxy cured? Is it pukka fit for purpose stuff or Araldite from the shed? We know the answers to these questions BTW.

If the top mount is replaced by a triangular mount it can be jubilee clipped to the stay and will 'only' then have to resist the frictional forces of being pushed up the stay. It should resist this pretty well as stays typically get fatter towards the top and the jubilees will efectively tighten the more they are pushed (if that makes sense). The only other thing to watch then is that the jubilees are man enough for the job.

CA, cut yourself a big triangle and fix it to the stay with clips. The black scab will probably just peel off unless you keyed the Ti really well (i.e. f*cked up your stay good and proper), the epoxy won't have taken well.

Well I've had a good think about this and had a chat with some of the other engineers here and we don't think its as bad as it looks. The funny thing is everyone in the room (2 x phds, me an MSC and a recent grad) are trying to find how it works, not piss all over it.

If the line from the centre of the piston goes directly through the bolt and along the "spoon" then the spoon is in compression only, so it just relying on the glue and cf. But that assumes there is no eccentricity, which might be harder (read impossible) to achieve.

The glue and CF is the most likely failure..

If there is eccentricity then you get into bending moments about both single bolted joints on the mount. Defo bad news..

Either way we all agreed it's not ready yet and is definitely not advisable to ride or use the bike in its current condition.

Toys, do you think your chassis or railway bridges are cobbled together by an amateur in a shed with zero engineering?

The problem here is not the materials it's the execution (maybe CA's execution if it fails).

The mount is relying on CF/epoxy holding in shear where it's been splatted against the smooth Ti stay. How was the Ti prepped? How was the epoxy cured? Is it pukka fit for purpose stuff or Araldite from the shed? We know the answers to these questions BTW.

If the top mount is replaced by a triangular mount it can be jubilee clipped to the stay and will 'only' then have to resist the frictional forces of being pushed up the stay. It should resist this pretty well as stays typically get fatter towards the top and the jubilees will efectively tighten the more they are pushed (if that makes sense). The only other thing to watch then is that the jubilees are man enough for the job.

CA, cut yourself a big triangle and fix it to the stay with clips. The black scab will probably just peel off unless you keyed the Ti really well (i.e. f*cked up your stay good and proper), the epoxy won't have taken well.

Boblo this is all true, just trying to be constructive/positive. I love a tryer/doer. There is a lot of talk on this forum, I personally admire Al for having a go. If he is daft enough to try and use this then Darwin will be proven right, but I like his heath robinson style..

Also it's amusing watching TJ lay into him..

I love you Al

Toys - think about what happens as the calliper attempts to rotate around the lower mount - it will push the lower end of the top mount towards the seatstay. Teh force is parallel to the direction of travel of the disc in the centre of the pad - IE horizontally forwards

Teh top mount will not be in compression only - it will be pushed towards the seatstay with a great deal of force - remember you need to consider the bolted mounts as pivots not rigid.

Remember the magnitude of the forces here - thousands of newtons

Toys - remeber Al asked for advice - was given a load of good advoice which he has ignored completely.

This

Teh top mount will not be in compression only

Contradicts this

it will be pushed towards the seatstay with a great deal of force

I said the [b]spoon[/b] (not the top mount) will be in compression only if it is in line with the bolt and centre of the pad/piston.

Toys - remeber Al asked for advice - was given a load of good advice which he has ignored completely.

Not all advice is good advice.

Anyway just trying to be constructive

I think we've finally found a use for [url= http://bikelean.webs.com/photos/The-Bike-Lean-Stability-Tool/Bike-Lean.jp g" target="_blank">http://bikelean.webs.com/photos/The-Bike-Lean-Stability-Tool/Bike-Lean.jp g"/> [/img]

Its the direction of teh force - the force will be applied to that "spoon" horizontally at its lower end So there will be a huge bending moment.

Its always hard to describe these things in words - diagrammes are really needed.

[i]advice which he has ignored completely[/i]

Am I the only one not surprised?

Screw all of you.

Al - rack it up to warp factor 10. I've just got a cover-teacher in to do my next three lessons in order to see how this develops...

Think you'd have been better off with a decent sized P-clip (without the rubber). You've basically made a torque arm - standard on shimano roller hub brakes and rohloff hubs, with a poor frame attachment. I'd revisit the design and look at [url= http://forums.mtbr.com/showthread.php?t=314985 ]this [/url] solution
[img] [/img]

Notice the fixing point is something rigid!

Hey Toys, in the interests of being constructive/positive, why not get one of your boffin colleagues to do the calcs on this? Empirical data will at least stop TJ speculating about 'thousands of Newtons' and might actually go some way to prove the errrm, 'design'. 🙂

Well it has been done by me this morning and reviewed by the others but we all have worries about liability insurance etc so no can do.

The only sure answer is that it will fail.

Al, you will forever be associated with cutlery now. Chapeau.

Well I for one want to see the test run!

Pics or it didn't happen.

Boo hiss 🙂 All you need to do is 'estimate' the shear force on that scab (assuming it's not asymetriacally loaded - tee hee). That's what he needs to deal with. The rest is academic as it won't get that far 🙂

"darwin will be proven right" Now that brightened up my morning 🙂

Turn it up to 11 and go for broke ... literally.

"darwin will be proven right" Now that brightened up my morning

Well you know I am a creationist and just need Al to carry out this experiment to prove that there is/isn't a god.

If Al lives, there is.
If he dies there isnt.

lol @ Cutlery-al

Ok - this is what I am seeing. Vastly oversimplified of course.
As the brake is applied it will attempt to move in the direction of the green arrow. The lower mount is triangulated and rigid (ish) so the caliper will rotate around the lower mounting bolt marked with the red cross. as it rotates it will push the top mount is (aprroximatly) the direction of the top arrow. there is nothing much to resist this load.

[url= http://farm6.static.flickr.com/5253/5686208299_3d76fc3bd7_b.jp g" target="_blank">http://farm6.static.flickr.com/5253/5686208299_3d76fc3bd7_b.jp g"/> [/img][/url]
[url= http://www.flickr.com/photos/25846484@N04/5686208299/ ]Image1[/url] by [url= http://www.flickr.com/people/25846484@N04/ ]TandemJeremy[/url], on Flickr

According to toys ... God will hold it (assuming Al lives)

Is that a spiders nest at the end of the spoon?

Now you have your angles correct (i found this the hard bit when I built mine) you can make a template to make a proper 4 hole mount . 2 for the caliper and 2 for the mudguard mounts on the frame

I did this and connected a tie- rod (threaded bar with some rod-ends ) to the V Brake mount. worked really well.

As TJ has pointed out, your devcon is just going to peel off in the end, surely?

Cynical spoon

Won't the back of the brake stop the red arrow movement going too far and add extra stopping force to the disc. Brilliant design I think.

Hmmm, where to start ❓

TandemJeremy - Member
Al I stand by what I say.

No triangluation at all on the upper mount. Relying on the friction of bolts and glue to hold a brake calliper on is stupid.

Indeed and a point I have conceded. Oh it's "caliper" BTW. I'm relying on shear strength of the bolts not their friction.

we can all see the flaws in it apart from Al who simply attacks the folk who point this out.

wwaswas - Member
advice which he has ignored completely

Am I the only one not surprised?

toys19 - Member
Well I've had a good think about this and had a chat with some of the other engineers here and we don't think its as bad as it looks. The funny thing is everyone in the room (2 x phds, me an MSC and a recent grad) are trying to find how it works, not piss all over it.

Thanks.

If the top mount is replaced by a triangular mount it can be jubilee clipped to the stay and will 'only' then have to resist the frictional forces of being pushed up the stay.

I've already kind of done it that way. My concern is the forces into the seatstay may crack it. Jubilee and P-clips are you having a giraffe?

Anyway, the coup de grace. It broke very quickly, coming to a brief stop. As Bloblo guess the cf parted from the ti so it was the gluing that was the weak point. I'm gonna try it again with proper glue, just to see, it would be great to be right on this, but I'll live if I'm not. You can hear me chuckle at the end.

At least I tried, discussed it and even posted a video of the outcome -more than anyone slagging me off has done, but do keep going, all of you.

I would have loved a Middle Finger up to the camera then

I'd best get myself along to a church ... 🙂

Drop bars.... Ah!

Didn't realise it wasn't going on a mountain bike. Sorry.

We must be doing a very different type of riding if you think a BB7 is even remotely in the same league as a decent hydro brake.

mightymarmite - Member
I'd best get myself along to a church ...

Come and join me..

Al - you are relying on the friction of the bolts to stop rotation. waht else is preventing them from rotating as in my diagramme?

Edit - do you understand how bolts work? The tension on the bolts creates friction between the two parts bolted together and thats what resists movement.

calliper. two ls in calliper single l is a variant according to the OED

I was correct about the solicitors 'but of course I did not say what you claim - I said you cannot claim costs for a solicitor at a tribunal which is correct.

he he, quality thread Al

Keep it real :love:

1. shear strength.

2. Wowsers, never seen that - bet it was a typo though 😉

3. Here's the quote from the thread:

http://www.singletrackworld.com/forum/topic/employment-tribunal-a-very-seriously-nervous-question

TandemJeremy - Member
You would be.

You cannot claim expenses in a tribunal so [u]lawyers won't do them except CAB / law centre types. [/u]

Oh dear...

really al.

Do you not understand the basics of how a bolt works? clearly not. Yo put tension on a bolt. This clamps the two pieces together and creates friction between the two pieces. Its the friction that resist movement not the strength of the bolt. If it was merely the bolt it would always fret as there is a clearance in the hole

Your setup you have rotational loadings on the bolts

That statement about lawyers is correct in the context of the thread.

You know better that the OED do you.