Brakeforce One bestest ever brakes - geekery

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Brakeforce One bestest ever brakes - geekery

45 posts & 26 voices | Started 8 months ago by clubber | Latest reply from clubber

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clubber - Member

So, following on from this article on the new best ever brakes(TM) from Brakeforce one:

http://www.singletrackworld.com/2011/09/eurobike-2011-brakeforce-one-brakes

and the more technical detail here:
http://www.bikebiz.com/index.php/news/read/schoolboy-designs-most-powerful-brake-ever/011821

"The problem with standard disc brakes is that you have either a fast reaction time, or power, but you can't have both," said Wauhoff.

"This is because of the diameters of the pistons. I thought it should be possible to push the pads to the disc fast with a big piston and then get a small piston to exert a lot of pressure. I built a brake booster to test this theory. It worked."

Anyone have any suggestions how it's actually done - eg how are they getting the variable effective piston size so that they can move lots of fluid early on to get the pads to the rotor and then less once in contact to get more power?

Posted 8 months ago #
berk - Member

On the video there was some plans on his phone (approx 60s in) Seemed like there was a smaller piston within the main piston, which I suspect explains why the calliper looks so chunky

Posted 8 months ago #
uplink - Member

To me it looks like it'll be over complex with too many seals etc. to stick/maintain and generally cause grief when subjected to shitty conditions, day in, day out

Hope I'm wrong

Posted 8 months ago #
aracer - Member

Interesting, but it's not encouraging that he's got it backwards - a small piston moves fast, a big piston exerts lots of pressure. The complete lack of any technical detail doesn't really help in this respect (is he keeping it secret to avoid being copied? does he realise that anybody who wants to copy will just get one and reverse engineer?)

Of course they're not the first brakes with varying mechanical advantage

Posted 8 months ago #
DrP - Member

THe first post is my thoughts - a 'telescopic' piston.
First piston provides the majority of movement to get the pad to the disc, second piston provides the force.
In reality, it would be the smaller of the pistons that would push the pad out quickest (i.e. i expect the inner piston moves first), then the larger piston would come into play (larger piston surface area would provide less movement, but more force)

Clever idea. Of course I had a similar once when I was 4.

DrP

Posted 8 months ago #
clubber - Member

OK, to clear up. A large piston at the lever will move the pads quicker than a small one but with less power. So the system uses the large piston first then transfers to the smaller one.

Oh and the guy is clearly spud from trainspotting

Here's the cross-section pic of the brake lever piston

So it looks like the large outer bit moves first and then the much smaller inner piston moves once the pad contacts the rotor though I'm not sure how the system transfers from one piston to the other as left free, the small piston would move first (less resistance)

I can't listen to the video in which presumably he explains it - anyone care to summarise?

Posted 8 months ago #
slowrider - Member

who cares? its NEW and ANODIZED!!!!!!

Posted 8 months ago #
Davesport - Member

It's old hat. Alloy race jacks for lifting track cars have been using this for a long time. First push on the lever takes up the free space & then the "low gear" takes over.

Fine until the seals gum up & something starts to stick My Hope's have never been short on modulation & have power in spades. What's next ? Triple/quad concentric pistons for more feel. Anyone working on ABS for bicycles ?

Why fix it etc...........Ah...that's better

Ededited to korekt my spellin

Posted 8 months ago #
dirtyrider - Member

999 euros though

Posted 8 months ago #
5lab - Member

can't you just use bite point adjustment to do the same thing? I can see how this is useful on rim brakes, where you need the pad a significant distance from the braking surface when not on the brakes, but on a disk brake I've not seen the issue. Mine start applying braking force approx 25% through the lever travel, which is fine by me.

how do you force the initial bit of fluid to go into the small diameter piston? Wouldn't it go into both pistons equally?

Posted 8 months ago #
uplink - Member

but on a disk brake I've not seen the issue

You should have tried Kielder last week - I would have traded my first born for moving the pads further from the rotor

Posted 8 months ago #
D0NK - Member

I can see how this is useful on rim brakes
Considering at the merest hint of mud my discs get that awful scrr scrr scrr sound of rotor/mud/pad contact I'd quite like disc pads to be further from braking surface too.

Posted 8 months ago #
5lab - Member

fair enough, looks liek some folk do want a pad thats further from the rotor, but doesn't servo wave (which puts variable pad movement into the lever) do that for you? if you mess about with the angle of the cylinder in the lever you should be able to get the fluid-sent-per-mm-of-lever-travel to ramp down significantly through the lever travel?

Posted 8 months ago #
D0NK - Member

but doesn't servo wave...do that for you?
not significantly (at all?) no

Edit Servowave does adjust leverage* vs lever travel which is nice, the screw in thing (freestroke?) I think was supposed to alter the pad distance but I can't tell any difference.

*or atleast lever feel, I know I can get my XT brakes setup to feel just right

Posted 8 months ago #
clubber - Member

I think you're missing the point. With a dual piston setup you can have LOADs more power than current designs because you don't have to worry about clearance or actually moving the pads to the rotor. Several of you say that pad clearance isn't an issue but that's because pads retract enough to stop that. You could make current brakes loads more powerful by reducing the clearance and making the master cylinder smaller but they'd always rub which would be annoying.

The dual system allows you to have a very small working piston (eg lots of power) without clearance issues.

but doesn't servo wave (which puts variable pad movement into the lever) do that for you?

Yes, that's another way of doing the same sort of thing (changing linear distance the piston travels instead of the area.

Posted 8 months ago #
5lab - Member

actually, reading a bit further, it sounds like there are 2 pistons in the lever, not in the caliper. This is why the small piston exerts the pressure and the large one does the distance, and also why you can change the balance between the two using a dial on the lever. I guess its the same as servowave, but actuated hydrolically, not mechanically

Posted 8 months ago #
thisisnotaspoon - Member

I'm sure this has been done before at the calliper end though?

Even hope made simlar claims about the m4 and m6 having different sized pistons to maintain some modulation.

Posted 8 months ago #
alfabus - Member

Pointing to a knob on one of the levers, Wauhoff said: "Space between the pads and the disc can be regulated with this wheel, so if you hear 'bling, bling, bling' you make a few turns and the rubbing noise disappears."

like hope c2's ??

Why won't he have the same issues that all closed systems used to have - expanding hot fluid eventually locks the brake out?

Dave

Posted 8 months ago #
jackthedog - Member

Why won't he have the same issues that all closed systems used to have - expanding hot fluid eventually locks the brake out?

Due to the volume of the piston/s?

Nay sayers perhaps just need to hold fire on their dismissals until they're heard some reviews. This system has had investment and industry interest, so let's just see how it goes.

Everything new, different or interesting tends to be dismissed until it's had a chance to prove itself. If everyone had always dismissed new directions like they tend to get dismissed on here, technology wouldn't have progressed much beyond fire.

Posted 8 months ago #
alfabus - Member

but for any given volume of piston, if the fluid fills it completely, then if that fluid expands, it will push the pistons out. If this happens enough, there will no longer be room for him to adjust with his little wheel.

Or are we saying that the lever piston is so massive that even if the fluid expands A LOT, there is still room to wind the lever and adjust? - a brute force technique, if you like.

Dave

Posted 8 months ago #
jackthedog - Member

but for any given volume of piston, if the fluid fills it completely, then if that fluid expands, it will push the pistons out. If this happens enough, there will no longer be room for him to adjust with his little wheel.

Or are we saying that the lever piston is so massive that even if the fluid expands A LOT, there is still room to wind the lever and adjust? - a brute force technique, if you like.

I suggested it as more volume takes longer to boil than less volume. I don't really know, hence the question mark. My knowledge of the finer point of hydraulics is limited to pulling the lever or pressing the pedal and hoping I stop.

Posted 8 months ago #
alfabus - Member

for the record, I wasn't dismissing it... just interested in how it works, and how he has got around some of the problems of a closed system.

They used to be the norm, and gave you the advantage of being able to dial out pad rub, but the boiling and locking issue killed them off. If he's found a way out of that then good luck to him.

Will he try to make a go of it, or sell out to SRAM or Shimano?? High risk going against those guys. SRAM seem more likely to hoover him up for a big payout, just like they did with Avid.

Dave

Posted 8 months ago #
glenh - Member

Or are we saying that the lever piston is so massive that even if the fluid expands A LOT, there is still room to wind the lever and adjust? - a brute force technique, if you like

The reservoir on a open brake has a limited size too, so it can only cope with so much fluid expansion before the pads can no longer retract properly. It's just that the available volume is generally large enough to cope with pretty much any normal use.

It's perfectly possible for a closed system to have sufficient volume adjustment, although it may need a lot of adjusting.....

Posted 8 months ago #
peterwp - Member

Davesport +1............

ABS for bikes surely within the next 5 years? They said it would never happen on motorbikes but surely not on humble 'pushbikes'????

Posted 8 months ago #
alfabus - Member

I don't think I'd want ABS... sometime you want to lock your wheels!

skids are for kids, but what about endos and stoppies?

Dave

Posted 8 months ago #
glenh - Member

ABS would be useless on a mountain bike.

Posted 8 months ago #
jackthedog - Member

Yes, ABS and loose surfaces are incompatible.

Wouldn't bet against seeing it being made available on commuting and city bikes at some point in the future mind.

Posted 8 months ago #
Omar Little - Member

I've never felt that i've had a slow reaction time with disk brakes, is this really a problem that needs solving and its because i'm a shit rider that i've never suffered from it?

Posted 8 months ago #
alfabus - Member

I think the point is that you would have a slow reaction time if the pads were far away from the rotors.

His system lets you have the pads a long way away (so they don't rub), and still get them across that distance to the rotor with enough power to stop you properly.

If it works, it sounds good.

Dave

Posted 8 months ago #
clubber - Member

It's nothing to do with reaction time. The theoretical benefit of the design is that you can have much more power without the drawback of rotor rubbing or a lever that has to pull to the bars before doing any braking.

As to the expansion thing, yes, he basically said that the oil volume is sufficient that heat expansion will not significantly affect clearance. I'm slightly sceptical that the volume will be that much bigger than say Hope C2s were but then again, my Hope C2s never had any issue with pumping up either. I know that the DHers of the time though did have issues - they'd start races with loads of pad clearance so that as they pumped, the wheels could still turn

Posted 8 months ago #
woody74 - Member

For someone that has Avid Elixer's that rub constantly as the pads have to be so close to the disc to work I would be certainly interested. Even the Avid race tech's couldn't make the brakes work without rubbing. Like most things the technology is out there and it is the bringing together of ideas and actually getting them to work. Good on the fella, competition is always good as too many of the big firms hold back improvements so they can slowly trickle them out over the years, bolt through hubs a fine example.

Posted 8 months ago #
ir_bandito - Member

Why won't he have the same issues that all closed systems used to have - expanding hot fluid eventually locks the brake out?

I presume the acres of clearance it sounds like they've got, means this won't happen. A small amount of expansion at the pad will barely be noticed at the lever. If you really do hammer it, you wind them out, c2 style

Posted 8 months ago #
jameso - Member

999 Euros? Really?

i hope that's front and rear!

Posted 8 months ago #
5lab - Member

I presume the acres of clearance it sounds like they've got, means this won't happen. A small amount of expansion at the pad will barely be noticed at the lever. If you really do hammer it, you wind them out, c2 style

they may have acres of clearance, but it sounds like the 'crossover' point between big movement and big pressure is manually set. if you set that up right (so it kicks in just as the pads touch the disk), it only takes a tiny bit of expansion for the pads to hit the disk in 'high movement' mode, and you'll never get into the 'high power' part of the lever stroke..

Posted 8 months ago #
steve_b77 - Member

999 euros you say. Don't worry, when the euro zone crashes and takes all of their economies with it you'll pick them up for peanuts

Posted 8 months ago #