[Closed] FAO doubters

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.

Can I ask what was wrong with well set up 'non-spoon' v-brakes?

Reminds me a bit of the badger thread. Just need bez to do a few photo-shopped pics, and Al to threaten to take take TJ to court.

Can I ask what was wrong with well set up 'non-spoon' v-brakes?

They don't work with sti levers

The forces that go through a disc brake can crack/snap welded even casted mounts and yet you thought some what looks like badly applied epoxy would hold it? Also did you allow enough time for the epoxy to cure fully before trying it?

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 is not only the bonding that is the weak point, the design places all the stress onto the bonding in a way that will guarantee it will fail.

Listen to everyone, they are right.

You need a brace coming straight down 90 degrees from the top nut to stop it being pushed toward the seatstay. Ideally, this would be in the form of a triangular piece welded to the seatstay (look at any other brake mounts on seatstays for ideas).

Unless it is welded on, I wouldn't trust it as far as I could throw it.

The thing is with this, if you manage to bodge it so it can resist a 5mph stop on a flat road, what is going to happen is it'll break when you are doing 30mph down a hill, and a car / person / hedge appears in front of you.

A bike is a very minimalist structure that needs properly designed and built to resist the forces applied to it. If it is not properly designed and built, it will fail and you will crash and hurt yourself.

So have a flippin word wi yersel, and drop this stupid idea.

You did video it! What a sport 🙂

Don't let TJ piss you off btw. There's no need for agro even if your bodge isn't trailworthy. You wouldn't want to spend your last hours alive (you weren't wearing a helmet 😉 ) arguing with TJ, that'd be a shame.

I still think Toys is right, you just need to make the bit triangular (the short side will stop it rotating) and then attach it to the frame. Jubilee clips will work because they'll provide friction, but you'd be better off using the V brake mount. Which means you might as well just buy or copy one of the existing designs.

Can you give the lawyer crap a rest guys? It's really really boring.

Keep going al - I don't reckon it will take much to get it to work.

Though I do think you need something better than glue, and another (spoon) brace...

Can I ask what was wrong with well set up 'non-spoon' v-brakes?
They don't work with sti levers

isnt there something called a 'travel agent' or some such thing?

Kuco - 48 hours or so?

iDave - discs offer real advantages over rims brakes for me.

TandemJeremy - Member
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.

Of course I understand it. If the friction is insufficient to stop the part moving, as you seem to suggest, it will move, and then the shear strength of the bolt omes into play.
In any event I made sure the plate was rotated as far as possible in teh direction it wants to rotate under braking forces before I tightened the bolts up - or I should say nyloc nuts.

I meant to imply that I accepted the OED - I have no idea how you mis-interpreted that.

Sorry but your statement was bollocks - many private practice solicitors appear in employment tribunals for both sides.

thebunk - Member
Can you give the lawyer crap a rest guys? It's really really boring.

molgrips - Member
Don't let TJ piss you off btw.

It's 100% fun here 😛