Author Topic: ABS for bikes  (Read 995 times)

Andre Jute

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ABS for bikes
« on: March 18, 2012, 04:52:36 AM »



Budbrake ABS "Anti-lock" Brake System Modulator for Bicycles
http://budbrake.com/

SEEN ON THE NET, NOT TESTED

I have a form of ABS on one of my bikes, a disc brake at the front with a particularly limp early roller brake on the back. Wasn't enough to prevent a face plant one day when I was distracted at a busy T-junction by a pretty girl in a translucent skirt. Now, on my fave bike, I use Magura HS11 which is the most progressive brakes I know though most of the other cyclists who've tried them on my bike dislike the lack of positive feel in the handle. I don't care: they stop my bike as fast or faster than the sudden-death brakes they prefer. (Admittedly, I'm one of only a handful of people I know who liked Citroen's orange bulb brake system, to the extent that I had a couple of DS and several SM, and the Maserati-engined SM is still my favourite fast touring car of all time.)

Whether these Budbrakes will be useful for adults depends on how fast and consistently they work. I'm a snob; I tend to wait for even a good idea until a German firm takes it up and engineers it properly. Hey, Andreas, aren't you guys at Schmidt Maschinenbau (makers of the SON hub dynamo) looking for something related to do just about now?

Andre Jute

Danneaux

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Re: ABS for bikes
« Reply #1 on: March 18, 2012, 08:36:19 AM »
Quote
...a form of ABS...Wasn't enough to prevent a face plant one day when I was distracted at a busy T-junction by a pretty girl in a translucent skirt...

Understandably!  ;D

Andre,

This is surely an interesting development, and may well benefit some riders. I saw a number of attempts at producing anti-skid devices on Dutch city bikes when I rode through Europe, particularly on the lucrative "Oma" (grandma) and "Moeder" (mother) bikes, where a fall really can't be tolerated, especially if carrying a child in a carrier. I was amazed at the advanced development of many of these bikes and in many ways, they represent the apogee of bike-as-car-substitute, with the details fully realized, as on Gentleman's Bikes. Some of the bicycles in your stable are among the most advanced in this regard; I could look at and appreciate them for these reasons alone, though they are also very pretty and beautifully turned-out.

However, I have to offer a dissenting vote purely on personal and sporting terms. Given my roadie origins it wouldn't be for me: I prefer unattenuated, non-modulated front braking on my bicycles, and I do the majority of my braking when touring or unladen on pavement using the front brake alone, or by apportioning the lion's share of braking to the front and using the rear brake only for trail braking as appropriate for road surface and weather conditions. Weight transfer allows the front wheel to provide the greater stopping power and traction under braking. Weight transfer also limits the braking forces possible from the rear wheel due to loss of traction. Weight transfer under braking explains why a rear brake applied with maximum force will produce a skid, and why a front brake applied with maximum force will lock the front wheel, causing the rider to rotate around it and do a face plant onto the pavement. A photo of a MotoGP rider at the point of maximum braking appears here: http://commons.wikimedia.org/wiki/File:Loris_Capirossi_MotoGP_China_2007.jpg

I think it is horses for courses, Andre, and down to personal preference and riding style. While this wouldn't be for me, it might suit others. I love reading about and playing with the very latest gadgets to automate cycling to some degree -- and have even adopted some.  :D

The BudBrake is certainly intriguing. The plastic box adds mystery, but I figured it must contain an offset balance-bar arrangement. A quick look at the patent application and drawings confirms my hunch. See:
http://www.google.com/url?sa=t&rct=j&q=bud+nilsson+lodi+patent&source=web&cd=3&ved=0CC8QFjAC&url=http%3A%2F%2Fwww.google.com%2Fpatents%2FUS20040079186.pdf&ei=EoRlT9rQLcTOiALs3r22Dw&usg=AFQjCNGLIXER1C3X20IgybMBoPK0BuBGNA&cad=rja

It isn't immediately apparent from the drawing, but the balance-bar pivot is offset in a manner that assures the front brake is operating at a relative mechanical disadvantage to prevent lockup. A product review and interview with the inventor appear here, along with reader comments:
http://cozybeehive.blogspot.com/2009/06/budbrake-modulator-proportional-brake.html

I'm a bit concerned by some of the inventor's comments in the interview. I don't buy his explanation of how braking forces act on a bicycle, and housing-actuated brakes are not unusual; the cross-top interrupter levers on Sherpa work the same way, by pushing on the casings rather than pulling the cable. I think this particular iteration of attenuated and proportioned braking will not ultimately be accepted by accomplished sporting cyclists, but may find a market among those whose main concern is avoiding front wheel lockup. This it will prevent, though I believe it will be at the loss of ultimate braking power and increased stopping distance compared to skilled modulation of the front brake alone. I cannot understand how this brake proportioner will in any way reduce rim heat buildup.

The reviewer/interviewer in the above link states...
Quote
A big question in Bud's mind is how he can get his invention accepted. Having seen and tested it, I think it has potential for beginner riders and anyone who wants that extra margin of safety...
...I think this summation is spot-on. Again, not a product with universal appeal or application, but likely ideal for the needs of a smaller number of riders, skewed toward those particularly keen to avoid a face-plant at the expense of maximum braking in the majority of conditions.

For those interested in a fuller discussion of the physics of bicycle braking, see:
http://www.physicsforums.com/showthread.php?t=205437
...and...
http://sheldonbrown.com/brakturn.html
...and...
http://sheldonbrown.com/brandt/over-the-bars.html
...and...
http://www.faqs.org/faqs/bicycles-faq/part5/section-6.html
...and...
http://www.bikexprt.com/streetsmarts/usa/chapter6a.htm
...and...
http://cozybeehive.blogspot.com/2009/10/analysis-of-bicycle-endo.html

Andre wrote...
Quote
...the Maserati-engined SM is still my favourite fast touring car of all time...
Among my favorites, too; SMs rule. They may really have been the product of an alien civilization advanced far beyond ours. So much so, few people truly understood or appreciated them!

All the best,

Dan.
« Last Edit: March 18, 2012, 05:52:23 PM by Danneaux »

Andre Jute

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Re: ABS for bikes
« Reply #2 on: March 19, 2012, 12:18:44 AM »
Thanks for the extensive additional information, Dan. I thought the roadies might take that background, and in fact the makers seem to agree, aiming their product more towards bikes for children and shopping bikes than the sporting segment of cycling.

All the same, if this idea were properly developed, ABS would offer even an experienced roadie on sporting bike a faster, shorter stop than a human can. Whether it can be done with a crude mechanical balance, as in the Budbrake under discussion, is another matter altogether. But made electronic and possibly adjustable to allow for rider parameters and their interface with the bike, and perhaps also for rider daring, I expect it could be made to work. It would not take much to integrate it with the gear changing electronics, which already contains some of the necessary sensors.

I had the first car ever fitted with ABS, taken off a Boeing. It was a Jensen Interceptor, an Anglo-Italo-American crossbreed GT car. I could beat that crude ABS, no hassle, and so could half a dozen young men I knew, all of us experienced racing drivers, but your average driver of cars in that class (middle-aged men with experience of really fast cars) couldn't, and no women could, including one racing driver of quite substantial achievements. But that wasn't the point. You didn't always want to drive a car like that as if your were competing in a thousand mile race, you often wanted to come out of a thousand mile journey relaxed, and for that it was good that the mechanics took care of shortening your brake distances no matter how carelessly you put your foot on the pedal. As an aside, a version (FF) of the Interceptor had 4-wheel drive developed by Fergusson for Grand Prix cars but banned by the FIA, and, compared to a Range Rover today, it was unbelievably crude, yet I set a time in one from Rome to Vienna over passes technically snowed in that stood for over twenty years.

We need to look at the concept of ABS for bicycles and visualise what it could be if developed without reference to this first crude execution in the Budbrake. Today electronics rule, and the humble push bike is just at the start of its electronics revolution, of which ABS could and should be a part. As you point out, whether you and I think it necessary, there are parts of the cycling community for which every extra increment of security is valuable.

Who would have forecast that Shimano's semi-sporting and sporting multi-ratio hub gearboxes would be such a success?

Andre Jute

Danneaux

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Re: ABS for bikes
« Reply #3 on: March 19, 2012, 12:50:03 AM »
Andre, my friend...

We're in complete agreement!  :D

You have made a beautiful summation of where we are and will likely need to go in further developing the bicycle for a mass market, given present trends.

All the best,

Dan.