Monday, June 8, 2009

Budbrake Modulator : Proportional Brake Control For Safer Bike Stops

Update : Before you read the following article, it may perhaps do you good knowledge wise to read a small analysis of the bicycle "endo", that I wrote recently on this blog. While it is physics driven, it will give you an appreciation for what happens when you apply brakes suddenly.

* * *

Front wheel lockup upon brake lever activation is something that often sends riders (beginners and experienced alike) to pitch-over the handlebars and get injured often seriously. We are all told to feather the front brakes, and apply more braking to the rear wheel especially in a downhill scenario. But what happens in a panic situation? We are all bound to get the shivers and haphazardly slam both levers with full might in the hope that it will stop us quicker. But that's when the front wheel locks up, the bike skids and off you go toppling over the bars.

Now, can a mechanical contraption be made to commit to such braking control automatically for you while you enjoy your ride?

Thats where this nifty little device comes in. I contacted Bud Nilsson from Lodi, CA to explain his patented invention to me and perhaps send me his last sample (incidentally, he had it installed on his bike) so I could take a look at it and see what it was for myself. I have previously introduced the brakes to readers. See here. I always welcome ideas to make cycling a safer experience.

The Budbrake is about the size of your cell phone and is installed close to the levers at the front. Brake cables are routed to this mystery black box before they are connected to both brakes. There is a level of much abstraction to it, so much so that it compels curiosity. With this installed, one immediately observes that no matter which brake lever is pressed (either one or both), the system ensures a safe stop by activating the rear brake slightly before the front.

Budbrake : A brake modulator in a mystery black box

'Mystery black box' didn't come as an understatement. I didn't understand how it worked before I got the sample. The mechanic at The Bike Shop in East Aurora close to where I live had in fact no clue why it worked the way it did. And many others likewise, are confused, says Bud. He told me : "There have been many engineers, technicians and product managers testing my brakes and all are impressed with the performance and agrees that it does work but wonders how does it work and 'why'!"

Here's a small video I made. We had the device installed on my friend Dave's mountain bike.


Instead of muddling readers with my own logic, I'll let Bud himself explain what his design philosophy behind this clever little device is. Why do the rear brakes activate first? What prompts it to do so? What on earth is in this black box?

"Ron. I will explain my reasons for this design. You are an engineer and I hope you will understand my theory. I will also welcome any comments on it.

See, the bicycle frames of today are designed in a way that places more of the rider's weight over the rear wheel for better traction when transferring the power for forward momentum. The saddle is behind the center point between the wheels and the bottom crank is forward of the seat post. You get more power when pushing the pedals around this way and you transfer more weight to the rear wheel. Consequently the rear wheel has more traction than the front.

In the first moments of decelerating speed control (applying brakes), the Budbrake automatically applies the rear brake first when it has most traction for braking. Due to the dynamic forces and forward momentum, the front wheel gets more traction and at that time, much of the momentum has decreased anyway due to the rear brake initiating the speed control.

Therefore, I designed the modulator as a mechanical means of proportional distribution of power to the brakes, just like the proportional valve (hydraulic) in the automotive braking systems to prevent front wheel skidding and maintain traction while turning.

Now do not confuse this with Antilock Brake Systems (in automobiles, there is only one brake pedal for front and rear brakes). The main objective of the Budbrake Modulator is to automatically brake the rear wheel since it has more traction, slightly before the front wheel and with more brake action compared to front, therefore eliminating unwanted skids and mishaps.

There have been a lot of bicycle engineers and technicians that can see that it works but do not understand why and how. The Modulator controls the brakes by changing the cable tensions via alternating the length of the casings, front and rear, not the length of the cable. Again, regardless of which brake handle is activated - front, rear or both simultaneously - the rear brake will apply first and then the front and automatically feather or modulate for balanced speed control. I guess the main difference from conventional braking is that the Budbrake alternate the length of the casings to achieve the goal.

Check out this drawing from my patent :

If you take a look and think about the offset fulcrum point inside the Budbrake, that is what makes the rear brake apply first. When the rear brakes make contact, the system then applies the front brake. The offset pivot point, (fulcrum) and varying the length of the casings produces the automatic modulation action. This is the trick for safer speed control .

The Budbrake has been field tested and lab tested for 650.000 braking actions. It was also tested against the CPSC criteria for bicycle brakes and it resulted in superior performance against their criteria.

The product managers at Giant looked at this and told me that if one cable broke, the brakes would completely fail. I did not want to cut or brake the cables so I disconnected one at the time and tested. The stopping distance decreased (as it would without the Budbrake) but the brake, front and/or rear worked. It is a fail safe product as any other. Now if both cables snapped, then the system is trash of course.

I also took one unit and drove over it with my motor home front wheel. The unit broke somewhat but actually it still would work. The black plastic material I use in the injection molding is not ABS like most people are used to. I am using the toughest composition that I can find available and it has a Teflon in it for lubrication of the pivot. If I used ABS in production the price would be at least less than half, but I want to produce the "very best" product for cyclist's safety.

I am thinking that the reason I have a hard time to get the Budbrake accepted and on the market is that the bicycle engineers , product managers and marketing people do not understand " why" it works. I'm not much of a writer but I hope I explained this to you and your readers in a simple form. "

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. So this is to you readers : Would you rather bike with the Budbrake or without it? What are your thoughts and feelings? Think about it and let us know by dropping your comments.

* * *

An example of a crash caused by excessive front wheel braking and moment about the same caused by high forward center of gravity. Notice that a rider's vertical fall drop is much more on downhill that if it were a flat section. Possible injury could be a wrist or collarbone fracture, or the possibility of planting your entire face into the rocks and dirt.


Chris said...

This just send some thought waves in my head. We're in the age of electronic shifting tech. Why not make the brakes electronic too? No more cables!

Ron said...

Chris : Neat! The bike wouldn't need brake levers that way, would it? We could have buttons somewhere on the hoods that when depressed, activate the brakes. For the same reason, I think the handlebar itself would have to be redesigned to integrate the new functionality and for better ergonomics. But the challenge to creating something like this is how to mimic the analog braking of conventional systems in the new, discrete digital domain?

eigersa said...

Personally I don't care how the magic box works, if it stops my bike from practicing judo throw on me... I'm all for it! I think it's awesome that people keep innovating like this; I am keen on the electronic brake idea though!?

Phil said...

Super post today Ron! Whats this whole modulation thingy? How much does it weigh? I'm all for safety but its going to stick out like a rock in front of the bike, I can see how people can shy away from it.

Anonymous said...

Front wheel lockup causes inability to steer off obstacles. It can be dangerous in tight situations. Not a bad idea but I likely won't use it, but may recommend it to another rider.

pm said...

This device would seem to distribute front and rear tension in the same ratio no matter which lever is actuating, and if you tried to use both brake levers you just get one hand fighting the other and not increased braking force. So there's not much point to having two brake levers on a bike using this.

Second, there is no effective braking here until both the front and rear brake pads are brought to the rim, so you have to have the brake pads set much closer to the rim to avoid running out of brake lever travel.

In any case it's questionable policy to actuate the front and rear brakes proportionally as this device does. The harder you are stopping the greater proportion of the braking should be done with the front.


Spirit of the Season said...

They make little guards that you can put over the tips of your fingers so that you don't slice down into your fingernails when you are cutting veggies. A better approach is to learn how to use a knife.

Seems to me like it would be better for folks to learn how to brake, rather than relying on gadgets.

Neil said...

Alas... a swiftly moving body continues to move in a straight line. Sometimes I think if we didn't have Newton's laws, the world would be a safer place

Yokota Fritz said...

Seems interesting and I can see the utility of something like that, though I'm with zzyx that your shortest braking distance will come with use of the front brake over the rear.

In the video it looks like the dude was intentionally trying a reverse wheelie when he lost control.

raam said...

where kids are concerned avoiding traffic is paramount, I don't want
to confuse a kid needing to emergency stop having him try to remember to modulate his braking to avoid an endo.

Anders said...

For a mountainbiker like me I suspect that the Budbrake Modulator would slow me down considerably. I sure want to control my brakes individually.

On my road bike I have experienced a couple of close calls with cars but managed to slow down (or come to a complete stop) with my rear wheel spinning in the air, a couple of centimeters off the ground. When you use the front brake to that extent the rear brake doesn't have much say, it's pointless to use it in a panic-brake situation.

I fail to see why the Budbrake would make anything better for riders who have the slam-the-front-brake-and-release-if-necessary reflex.

For those who don't know how to brake efficiently and are not biking enough to learn how to brake efficiently this seems to be a very good product though. Good luck to the guy who invented it!

Anders in Sweden

Rein Gortemaker said...

The working principle is easy to explain: the pivot point is 40/60% positioned between the cables;this results in 40% front en 60% action to rear wheel. not a big invention. I am not convinced this device will work in all critical conditions.