Viewing 40 posts - 1 through 40 (of 48 total)
  • Wireless electronic gubbins, are brakes next?
  • lovewookie
    Full Member

    now that Di2 and AXS are relatively well established and, for AXS in any case, the desire for cable less declutter has revived itself for those that didn’t wan to go SS…

    What about electrifying our brakes? will that be next?

    I can see a setup where there is a little servo mounted somewhere on one of the stays, bladdered reservoir etc, feeding fluid (think this will still be the preferred method of pushing pistons), which wirelessly connects to the levers at the bars. so lever moves x amount, resultuing in the servo pushing y amount of fluid, all adjustable in quantity and feel (by making the relationship linear or nonlinear for example)

    I guess my concerns at the moment are, how much push do you need from the motor to generate the right amount of pressure and how responsive can we make it? a fraction of delay in fine adjustments at the lever end may make things feel a bit odd and how much pressure does a human put into braking?

    May be a solution waiting for a problem, though this is the bike industry we’re talking about..

    tomhoward
    Full Member

    will that be next?

    No.

    simondbarnes
    Full Member

    Well brake by (electric) wire systems are already out there for motor vehicles so why not?

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    lovewookie
    Full Member

    will that be next?

    No.

    care to elaborate?

    tomhoward
    Full Member

    so why not?

    off the top of my head, extra unsprung weight, over a regular system. Cost, both of development and sale price (though the latter doesn’t seem to be a barrier to anyone). Size of the unit require to perform such a function, over a normal calliper, in a vulnerable spot. In the case of wireless, too high a risk of losing connection (within a week of AXS being released, a couple of folk claimed the mech and controller has lost connection, mid ride) and if you went down the wired, Di2 route, you haven’t gained anything aesthetically. The chance of gremlins in the electronics, you’re feathering the brake and the front locks, so you go over the bars, breaking your spine, and sue.

    pdw
    Free Member

    Well brake by (electric) wire systems are already out there for motor vehicles so why not?

    Are there any production cars that have electric brakes as their primary means of stopping? I know that many cars now have electric “hand” brakes, and that some electric cars have regenerative brakes in additional to hydraulic friction brakes.

    Brakes that stop working when a battery goes flat sound like a terrible idea. Brakes that stop working in the face of wireless interference even more so.

    nixie
    Full Member

    The new leaf and it’s single pedal operation perhaps.

    tomhoward
    Full Member

    Brakes that stop working when a battery goes flat sound like a terrible idea.

    Hadn’t even considered that, but yeah. That. If a cars battery goes flat, it wont start. Even if you had a failsafe on the brakes, would be a PITA to get it home afterwards, or throw you off if it did it while you were moving.

    Then there’s brake feel, don’t BbW systems feel crap, sort of wooden?

    ads678
    Full Member

    How do you apply more pressure in emergency situations with electrically operated brakes?

    pdw
    Free Member

    The new leaf and it’s single pedal operation perhaps.

    Yes, although there’s a “traditional” brake pedal right next to it.

    cookeaa
    Full Member

    I’d love to meet the engineer who can make the SIL rating for electronic only brakes work on a car, let alone a bicycle.

    I think people just have too much faith in “modern magic”…

    thisisnotaspoon
    Free Member

    Well brake by (electric) wire systems are already out there for motor vehicles so why not?

    Are they? Even servo assisted ABS (ok, that’s the basic car brake system now) still has a direct connection between the master and slave cylinders, if you stamp on the pedal with the engine off it still just about brings you to a stop. The servo just doubles your force and the ABS just interrupts each line to the wheels.

    The new leaf and it’s single pedal operation perhaps.

    That’s just regenerative though. You set the level of “engine braking” from freewheeling to whatever level, it’s not a replacement for the brake pedal.

    I’m sure it’s technically feasible with stepper motors etc, but that’s a whole load of complication Vs just a continuous hydraulic hose. Wireless shifting is just replacing one electric wire with a signal, the motors, switches etc are all basically the same as Di2. Di2 was demonstrably an improvement over bowden cables, not sure it would offer the same benefits for brakes?

    Paul-B
    Full Member

    No.

    Two words. Functional Safety

    Any safety system such as a brake has to have a mechanical interface, that’s certainly the case in terms of motor vehicles.
    I imagine a system to provide the modulation required for a brake system would end up being horrendously complex regardless of the safety aspects.

    tpbiker
    Free Member

    For all the reasons tom has articulated, it’s a terrible idea.

    Reasonably common issue with original etap (that i experienced) was that the rear mech would temporarily stop shifting…then after about 30 seconds of doing nothing suddenly dump all the shifts you had tried to make in one go..

    Can you imagine the end result if that happened with your wireless brake!! Its nor an ‘upgrade’ id be rushing out for..

    philjunior
    Free Member

    No. And if it did go this way, it’d be Ebikes first, as with ABS systems.

    But it all depends, is having a computer controlling your braking a step too far? In a vehicle on an unpredictable road there’s a good argument for having all the help you can get to mash the pedal and stop safely and in control.

    Braking is part of the skillset you need to ride fast/steep stuff, I’m not sure many would want to add ABS let alone this. Especially as adding ABS would stop cool skidz.

    stevious
    Full Member

    That’s just regenerative though. You set the level of “engine braking” from freewheeling to whatever level, it’s not a replacement for the brake pedal.

    Not entirely true. It does use as much engine braking as possible, but you can feel it put on the proper brakes when you’re coming in to stop. That said, even though the e-Pedal (and whatever they call the autopilot setting) are great, I still have to use the actual brake pedal fairly often – I’d hate to have to rely on robobrakes.

    Back to the OP – I can’t really think of a single advantage of electric brakes. If de-cluttering is so much of an issue, why not just route everything through the bars like with road bikes?

    lovewookie
    Full Member

    so I think this:

    wo words. Functional Safety

    pretty much nails the coffin on that.

    proof of concept may be interesting, but in terms of practicalities, no fundamental changes to the braking systems we have?

    epicyclo
    Full Member

    ads678
    How do you apply more pressure in emergency situations with electrically operated brakes?

    Use old tech known only to the generation brought up on rod-brake bikes.

    In case you’re unaware, the main function of rod-brakes was to maintain a fine polished appearance on the rim.

    Retardation was a secondary function.

    When stopping became a priority the rider would put the toe of his shoe behind the seat tube at BB height, and then lever the sole backwards onto the tyre. This worked quite well and was a skill most people acquired.

    In panic braking the rider often missed the down tube, and simply stabbed his foot into the spokes. At which point his entire leg would be drawn into the wheel and jammed against the chainstays.*

    As an automatic reaction, it was a remarkably effective way of maximising retardation.

    I’m looking forward to see these lost skills revived… 🙂

    .
    *Guess how I know this. 🙂

    BadlyWiredDog
    Full Member

    If you’re riding so fast that you can’t stop if your electrical brakes fail then you are simply riding too fast. I honestly can’t see why people are objecting on safety grounds. I mean, what’s the worst that can happen?

    molgrips
    Free Member

    When stopping became a priority the rider would put the toe of his shoe behind the seat tube at BB height

    I can’t imagine doing that! When I had a bike with chromed rims and leather brake pads, and it was raining, the place for my foot was behind the fork crown. This worked reasonably well and seemed to be favoured by most kids who happily rode their bikes around without any brakes at all.

    tomhoward
    Full Member

    When stopping became a priority the rider would put the toe of his shoe behind the seat tube at BB height

    Was on the tyre just behind the seat stays for us on bmxes

    petercook80
    Free Member

    Why worry about something that does not yet exist – If wireless (or wired electronic) brakes for mountain bikes come on the market lets see how they function first , then have a worry fit….

    lovewookie
    Full Member

    I think, if electric brakes were to be on the horizon, it’d be interesting to see how each manufacturer addressed the problems raised here.

    ndthornton
    Free Member

    Any conceivable implementation no matter how much it costs would be a lot worse than standard hydraulic brakes in terms of both functionality and safety. The only advantage to this sort of setup is to provide power assist from the servo…but for something as light as a push bike and with decent size rotors your index finger can provide way more power than you actually need or can use.

    ta11pau1
    Full Member

    As above, won’t happen.

    Wireless shifting, droppers, brilliant – give it to me!

    Wireless brakes? Hell no.

    Brake ‘feel’ is a very important thing, it’s not just modulation, it’s the ability to tell what the tyres are doing and how close to the limit of traction you are – your fingers are doing this constantly when braking. An electronic system would never be able to give this, seeing that there’s no direct connection between finger and ground as there is with a hydraulic brake.

    And of course there’s the slight issue of safety. One instance of someone going off a cliff due to a monetary loss of connection between brake levers and calipers, and it would be the literal death of them.

    leffeboy
    Full Member

    On mountain bikes probably not but on general issue ebikes maybe.  As long as the extra power is supplemental over regular braking power just like with pedaling then it  might be a nice think to have.  We aren’t the real market. A powerful brake that wouldn’t lock up might be ideal for people already going faster than they can safely handle.</span>

    ta11pau1
    Full Member

    Double discs, bigger calipers etc will come before any other systems, for ebikes anyway.

    Let’s not forget that mtb brakes are just miniature versions of motorbike brakes.

    My 1000cc, 140mph, 180kg motorbike has 4 piston front calipers with 320mm discs and a handlebar mounted master cylinder.

    The only real difference is they run much closer to the disc, when pushing the bike they rub slightly (as designed) and when up to speed the pistons are pushed back slightly. 2 finger braking is plenty from 150+mph down to zero. There is a bit more power though so no need to worry about drag 😁

    There’s plenty you can do very easily to gain huge amounts of power on an mtb with little effort. 220mm discs, dual front discs, etc etc.

    pdw
    Free Member

    Brake ‘feel’ is a very important thing, it’s not just modulation, it’s the ability to tell what the tyres are doing and how close to the limit of traction you are – your fingers are doing this constantly when braking.

    Really? What information is your finger getting apart from how hard you’re pulling the lever?

    If you did make an electronic system, you could still make pad force proportional to lever force, as it is in a hydraulic system.

    It’s still a terrible idea, but I don’t think feel would be an issue.

    ta11pau1
    Full Member

    Really? What information is your finger getting apart from how hard you’re pulling the lever?

    Masses of feedback from the tyre, the ground, giving information about grip, fade, and so on.

    Brake ‘feel’ is very much a thing.

    Whether that’s on a motorbike or bicycle, or car in fact. I’ve had motorbikes with both ends of the spectrum, brakes with great feel and brakes that are ‘wooden’ in feel. There’s a huge amount of difference when using them.

    Pretty much all mtb brakes have decent feel, take that away and they’d be horrible.

    pdw
    Free Member

    Masses of feedback from the tyre, the ground, giving information about grip, fade, and so on.

    Brake ‘feel’ is very much a thing.

    So what exactly are you feeling? The force on the lever doesn’t change as the grip changes. All you can feel is the reaction force of the disc on the pads.

    I’d don’t deny that you can feel changes in the bike’s handling and grip due to braking but that’s not coming through the brake lever itself.

    ta11pau1
    Full Member

    It is coming through the brake lever, but it’s hard to explain unless you’ve used a variety of braking systems.

    Having used motorbike brakes, some ‘wooden’ feeling and others not, there’s a big difference. Both do their job, but it’s very hard to modulate the power as you can’t feel the tyre grip/lock up on the wooden feeling brakes. It’s a ‘numb’ or a disconnected feeling.

    Exactly what an electronic brake system would feel like. Disconnected.

    philjunior
    Free Member

    I can believe what people are saying about brake feel, I had a disc I Fitted that had a bit of a wobble or change in thickness, it was totally intolerable, but you wouldn’t feel it if a servo was applying a constant force to the pads based on your lever input.

    You get slight clues through the lever (as well as through the rest of the bike) as to what the wheel is doing and what the pads are doing on the disc.

    For a market like mountain bikes where it’s all about fun and feel, it would be a hard sell even if there were performance benefits. And if there were performance benefits, would you still have all the control, would it let you endo/skid when you wanted to? etc.

    What could perhaps be interesting would be allowing lighter weight rotors and discs and more durable brake linings by using a servo with variable assistance, e.g. if it could detect when the rotor was wet, what the temperature was etc. and just give totally consistent performance. Some cars do this (well the temperature part, wet brakes don’t really matter so much on performance cars) although I get a bit worried that it’s then masking the fact that you’re reaching the edge of the performance envelope of the brakes, a bit of fade might let you know it was a good idea to give the brakes a break.

    hols2
    Free Member

    As above, can’t see any benefits at all, safety issues would make it a non-starter, and it would be expensive.

    funkynick
    Full Member

    I believe that Audi are using brake-by-wire in their E-tron car, as it allows on the fly adjustment of brake operation based on the amount of regenerative braking from the motors. Also, I think F1 cars use it at least partially.

    Both of those are effectively electro-hydraulic as the actual braking is still done using a master cylinder and caliper.

    As for it’s use on a MTB? At present it requires more ‘gubbins’ (technical term!) than the simple brakes found on our bikes, and they still require a master cylinder so there is no real benefit to them.

    There are different methods for doing this either electro-mechanically, or all electronically, but both would require significant reservoirs of power to be able to operate, which on an e-bike might be possible, but would likely impact range etc, and neither will work with no battery attached!

    Now, and ABS unit for bikes might be interesting… :o)

    ta11pau1
    Full Member

    Regenerative braking (with a hybrid hydraulic/electric system) might appear on ebikes, as that’s the main function it provides in cars – probably only on commuter ebikes though rather than mtbs which skid and slide at the time. Would make for much smaller batteries if you can recharge them when braking.

    wobbliscott
    Free Member

    Electric brakes would be a good idea. Forget the claptrap above…that is all solvable, but the prize would be no brake fade…you can jack up the temperatures in the brakes to get more efficient and effective braking, not to mention smaller components which will be lighter. You can get better modulation and customise the brake feel according to the individual rider – you can programme whatever brake lever movement to caliper pressure relationship you want to achieve whatever feel you want.

    It’s all possible and technology is here …just depends what cost you want to pay. The only reason why it’s not here is because it would be too costly.

    mlltt
    Full Member

    After loosing the charge cover of my magura seatpost and not being able to get a replacement, I’d already think twice before buying anything electric for my bike again!!

    hot_fiat
    Full Member

    @thisisnotaspoon

    Well brake by (electric) wire systems are already out there for motor vehicles so why not?

    Are they? Even servo assisted ABS (ok, that’s the basic car brake system now) still has a direct connection between the master and slave cylinders, if you stamp on the pedal with the engine off it still just about brings you to a stop. The servo just doubles your force and the ABS just interrupts each line to the wheels.

    Brakes on my Giulia are electric over hydraulic. The brake pedal, like the throttle pedal, just drives a Motor-Potentiometer. ABS computer interprets this signal and applies force to the hydraulic circuits as appropriate. You can have different pedal feels depending on which mode the car is in with feedback provided through the motor. You cannot change the brake pads without first instructing the car to retract all the pistons. Once changed you tell it to apply pressure until all the slack has gone out of the system. There’s 20 pistons in the main brake system, with a further 4 running the electric-over-hydraulic handbrake. The brakes are superb: initial pedal feel is very sensitive, but you just learn to be really, really gentle. Allegedly it’ll stop from 60mph in under 40 metres and from 125mph in under 140m, pulling a straight 1g.

    thisisnotaspoon
    Free Member

    Brakes on my Giulia are electric over hydraulic. The brake pedal, like the throttle pedal, just drives a Motor-Potentiometer

    I did google that after I posted what I did. And we’re both kinda right. There is a “brake by wire” system, but it’s replacing the ‘traditional’ vacuum operated servo (and separate ABS, stability control systems etc).

    The brake booster/servo in the Giulia is controlled electronically, but there’s still a master cylinder connected to the pedal.

    So more like an E-bike’s motor, or power steering than true ‘brake by wire’.

    F1 (I didn’t know this) does have brake by wire for the rear of the car to modulate between downshifting/engine braking and the brakes themselves. The drivers foot pedal is only hydraulically connected to the front brakes.

    hot_fiat
    Full Member

    That makes more sense. There’s a bit in my (admittedly 25 year old) Bosch blue book which explicitly forbids no direct connection between control input & outputs*, otherwise they’d have dispensed with the inconvenience of steering racks years ago.

    *unless you’re making a tractor or fork lift.

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