Monday, June 08, 2009

36 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.


  1. Chris9:17 AM

    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!

  2. Ron : How did you test it?

  3. Bikeboy,

    I happen to weigh 150 pounds. So I made a 15 foot track and rode my friend's bike into it at 15mph 6-7 times. More times than not, the bike equipped with the modulator stopped well short of 15 feet. It shouldn't go over 15 feet, according to CPSC regulations. We did this by braking with both levers and also one at a time. Regardless, the bike stopped quick. Now the brakes are powerful V-Brakes. If the bike did not have the modulator, and if we repeated the test, it was likely that we could stop short of 15 feet, but now because of the front wheel lockup, the rear wheel would have lifted, causing a potential crash involving the rider (in this case - me)

    My buddy also rode the bike on some singletrack and tried to deliberately push himself over by standing on the pedals and braking. In spite of the shift in center of gravity, the bike did not seem to lockup on braking due to the modulator in place.

    We were not able to validate other claims of the brake that it reduces rim temperature buildup on descents. This was mainly due to lack of time and a suitable terrain (long descent... >10 or 20 mins)

  4. 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?

  5. This desigh would seem to monotonically increase the rear brake cable tension as the front cable tension increases. This is poor; as deceleration increases, the amount of traction available at the rear wheel decreases. This device will lock the rear wheel more readily than using the front brake alone, resulting in increased stopping distance over using the front brake alone.

    Hard application of both brakes generally results in a lock of the rear wheel and, because the front brake still decelerates as the rear wheel loses traction, a 'jackknife' happens where the rear wheel swings around the front. I saw a crash where this happened just the other day. That rider would have stopped safely using the front brake alone, and not a modulator that applies the brakes in a way that promotes jackknifing.

    "If the bike did not have the modulator, and if we repeated the test..." --nice speculation there. Unfortunately a speculation that is wrong, and as you write, you did not do the test to discover that it is wrong, and the shortest stopping distances are achieved using the front brake alone.

  6. ZZ : I see your point. And something like that could happen if the brake shoes for the rear brakes are installed very close to the rims. I myself did not experience rear wheel skid on braking. Now I'm not a huge mountain biker, but knowing the stopping power of the V-brakes, I suspect I would easily go over the handlebars if I applied both brakes hard (without a modulation device). My point about stopping distances without the device, are speculation, I agree. I can still go ahead and test this out. My suspicion is that it would meet the stopping distance criteria but would also place the rider in an unsafe situation if he hit both brakes hard.

  7. 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!?

  8. 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.

  9. Phil : I saw it and it is smaller than my cell phone. Its not too 1.3 oz or something like that.

  10. Ron,

    I know that many fear going over the handlebars when using the front brake. In fact it's fairly difficult to do. I agree with zzyzx that many times the rear wheel locks up and the bike jack knifes or the front tire loses traction on sand or a paint stripe.

    The "modulator" is simply a linked brake system to apply both brakes when either brake is applied. As such the rider loses the feel that direct braking gives. In my opinion it's better to spend a little time learning how to brake fast with both brakes.

    I always enjoy your blog with the diverse range of topics and events you present.


  11. If one cable snaps you lose BOTH brakes...

    There have been devices to address this "issue" in the past, ones which release the front brake if the rear wheel lifts off the ground which seems a more sensible approach than just biassing the brake effort...

  12. Zabel : That was one of my first concerns. While the product is pretty clever, it shouldn't be a substitute for people not learning the actual skill of braking. I think Bud agreed with me as well, but then he posed : what does an experienced rider do in an emergency stopping situation?

    You're right that the modulator is a linked braking system. Infact, this is why our bike shop person here was confused about why the rear brakes activated when he pressed the front brakes. He didn't know what the system was doing.

  13. Gsport : Pardon me (and I'm still learning how it works) but how do both brakes not work when one brake's cable snaps? It is true that it is linked through the seesaw pivot, but when one snaps, the other should work like an unlinked brake? Or am I wrong? If, say in the picture, brake cable for lever 3 snaps, then due to tension imbalance, the distance between point 1b to 2b will be higher, and the brakes will also recede from the rim by that much distance. The rider may have to apply more torque to the functional brake to get it to touch with the rim. I'm not sure if that's what you meant.

  14. Personally, I am skeptical, although it could perhaps be of use for an inexperienced rider who is very much afraid of going over the bars.
    I'm not sure that the argument of traction in back being greater before braking (because that's where the weight is) is correct for this application. You go over the bars not because you lock up the front wheel and lose traction; you go over the bars because you lock up the front wheel and DON'T lose traction. In other words, either wheel was turning, wheel can't, so whole bike turns around wheel instead; or bike decelerates very quickly but rider hasn't braced against the sudden deceleration with his arms and keeps going forward, over the bars, possibly helped by the back wheel popping up a bit. I suspect this second scenario is actually the more common, although to the person flying through the air they probably feel pretty similar. When the front wheel locks up and loses traction, you wipe out. Yes, both are bad, but this is an important distinction because your argument for this device is that the front wheel has better traction once you've started decelerating, so you should start decelerating first with the back brake. If going over the bars is possible, sufficient traction in the front wheel at the start of braking is not the problem.

    However, wipe-outs are a problem because while it is possible to maintain some control with a locked and skidding rear wheel, even with the tendency to fish-tail, it isn't possible if the front wheel is locked. However, it's also much easier to skid the rear wheel when you slam on both brakes as hard as you can (actually, if your brakes are any good and you slam them both on, you will always skid the rear wheel) because it is unweighted during hard deceleration. So then the question is really whether a possible small decrease in the probability of skidding the front wheel is worth an increase in the already high probability of skidding the rear wheel. If it means that the rear brake is always on harder than the front, rear wheel skids will be much more common, even outside of panic stops.

    While many beginning riders are terrified of going over the handlebars, that is of course not the only way they can crash. Beginning riders are also less able to maintain control of their bikes in the event of a rear skid. This device may provide them some peace of mind knowing that the back brake will always be used more, but I'm not sure it actually makes them safer.

    Personally, I would not want to couple the usage of my front and rear brakes; I use them differently at different times and under different conditions and wouldn't want to relinquish that capability.

  15. Emily : My sincere apologies. Perhaps the sentences you quoted weren't worded with more clarity. Anyway, this seems to be a minor physics problem.

    Due to the 40-60% (or something like that) static weight ratio between front and rear wheels in most modern bicycles, the rear wheel does have most traction. When braking occurs, there is a load transfer from the rear axle to the front (like in any road vehicle). Now experienced riders know that they must shift their weight rearwards in a situation like this, but novice riders may do the opposite. The sudden death-grip braking, the load transfer along with a possible shift in center of gravity forward is likely to induce a pitch-over of the rider. Or if not pitchover, a fair amount of stability or control maybe lost that it may be inevitable that the bicycle with the rider topples.

    The maximum braking force that the tire-road interface can support is determined by :

    1) Normal load
    2) Co-efficient of road adhesion

    There is a critical braking force that could be withstood before the tires are at the point of sliding or lock up. But take note, because of the static weight distribution in modern bicycles, the rider has to manually distribute the braking force to each lever in such a way that proportion of braking forces matches with the proportion of static load on each wheel (or axle). Only then will it be satisfied that the maximum braking force (or critical braking force) on each wheel and tire are reached at the same time.

    Beginning riders hardly think about those kind of issues and are likely to see one wheel-tire exceed their maximum braking force capacity before the other wheel-tire system. In most cases, this wheel is likely to be the front simply because of unneeded center of gravity shift, and the inevitable load transfer to the front that happens on braking.

    I believe Bud's whole idea is to brake the rear wheel first BEFORE the load transfer takes place to the front wheel, when it has most traction available. When this happens, some of the momentum in kinetic energy is absorbed by the rear brakes and then the front brake can be activated, ensuring the completion of a safe braking protocol...which beginning riders are very less likely to understand unless they are taught to and practice that skill.

    I think that if the bicycling industry can come up with modern conveniences such as nose-less saddles and belt drives, why not a simple system like this? You can prevent someone from getting hurt.

    Ofcourse, this whole idea of braking philosophy can be critiqued which is why I leave the table open!


  16. Anonymous3:21 PM

    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.

  17. 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.


  18. Anon at 3:21 : Yes, and I feel automatic braking modulation is something that can be explored. In these days when people are talking so much about efficiency, I realize that cyclists dont tend to use their brakes very efficiently. Atleast for beginning riders, perhaps they could be taught to use their equipment better or have a device retrofitted into their bikes that makes this happen. The latter situation is where the Budbrakes come in, I guess.

  19. 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.

  20. Spirit : My grandma used those. I would perhaps say the same as you..but think for a minute. Suppose the person was old (maybe in her 60's), her eyesight is not so sharp as she had in her prime, and she is cutting onions. What then? Is it better to cut the finger or wear a cheap protection to cushion for clumsiness? :)

  21. 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

  22. If one cable snaps then both brakes are out of action because when you pull the good lever you will just open up the other side of the scissor mechanism against no resistance and run out of travel at the lever.

    Similarly if one brake looses a pad both will be effectively disabled.

    All the mechanism does is bleed off some of the front brake levers effort to the back by using the compression in the outer housings like kids on an uneven see-saw. On a steep downhill the amount of brake you want to divert to the back will be different to on a level road so which do you "gear" for? If you gear for a hill then on flat you give up a lot of the effectiveness of your brakes.

    The previous design I saw used a rear caliper that could move and in doing so apply the front brake. So you pulled the rear brake, which moved forward under braking load and applied the front brake very hard, at the point of the rear wheel lifting the wheel would cease to be carried forward and so stop applying the front brake, once the rear wheel dropped it would re-apply, so it would act rather like ABS..

    However, most cyclists learn to use two independent brakes pretty fast and although "inventors" keep devising these things there just isnt a demand for them...

  23. 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.

  24. Zabel51 : Perhaps it is a difficult thing to do a pitch over. However, it seems likely to happen in smaller bikes with short wheel bases such as folders. I showed a video in a past post where the anchors of The Gadget Show tested the disc brakes that came on the Strida. A small application of the brakes lifted the rear wheel off the ground slightly. The problem however is when the bike falls back on its wheels again. That backward motion can unseat you and even throw your valuables attached to the bike off it. In a traffic situation, an awkward movement like that could endanger others behind you.

    See video at the end of this post.

  25. @ Gsport 7:03PM : Thank you. That was what I thought then. But how often do you hear of a steel cable snapping? Pleas clarify. Did you feel there is more potential for the rear cable to snap as it is being used more regardless of which brake is applied?

    About "gearing" for the type of terrain, I think it may be sufficient to do a small adjustment before you get on the bike(?)

  26. 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.

  27. M.Eng7:56 PM

    What you and some other commentators forget to consider is possibility of bicycle fork damage from sudden slamming of front brakes, regardless of how effective they can be to stop someone. A poorly designed bicycle fork combined with rapid wheel jamming due to excessive brake application can bend the fork backwards because the available frictional force exceeds the strength of the fork. See a good analysis done here -

  28. Gsport : There are probably mutiple devices like this in the market. Bud pointed out to me the One Hand Braking System from Brake Director which uses a variable ratio cam force multiplier to increase the force output of a single hand (interesting). Cost around 130 dollars plus additional 60 dollars if you want installation help it seems.

    Also check out the Double Stop Braking System from Zone Darshan Enterprises. Somewhat same concept, activates both brakes at the same time...but Bud tells me it costs about 5 times more than his design and weighs 6 times as much.

  29. Sorry but this seems pretty pointless for anyone who even has a tiny amount of ability on their bike.

    Once you have mastered basic bike control skills - especially if you have ridden off-road - you quickly learn that in practice it never happens that you go over the bars just from braking too much.

    You can go over the bars from a) hitting something solid, b) having your weight too far forward when you are going down a very steep hill, or c) if you have a combination of a and b and lock your elbows. But just from braking? Come on.

    Ok I'll add to that: it is possible to go over the bars if your brakes are faulty and they jam on the rims (or fall into the spokes!). However, this device isn't going to help either of those.

    Maybe I didn't read closely enough, but I assume you also lose your ability to intentionally lock the back wheel (don't try to tell me you never do that!).

    For the people who really can't or wont learn to modulate their brakes with their hands - because they are just using the bike for transport, or are old or young etc - then the solution is to make a bike with the centre of gravity very far back and low. This is what they will prefer anyway. Look in any Asian city and you'll see millions of bikes like that, and you wont see millions of people with scabs on the faces from going over the bars.

    In short: this is a great solution to a problem that doesn't exist. Learn to ride instead.

  30. b said :In short: this is a great solution to a problem that doesn't exist. Learn to ride instead.

    B, the invention was not some figment of imagination but one that was prompted by a serious bicycle injury which happened to a friend of the inventor who went head-over-handlebar as the result of a front wheel lock-up. So its a solution that came from a need which I admire.

    Plenty of videos on the internet show that this can happen. Skill and learning how to ride is all good, but not everyone does drills to keep their eyes, ears and hands sharp in emergency braking situations whenever they come by. Perhaps you can get more people on bikes by making bikes safer to use. You and me might not want such conveniences on our bikes but there may be others who dont want to deal with dirty chains or repair things or learn umpteen rules by which to ride a bike. Its just another side of the world.

  31. Gsport said : If one cable snaps then both brakes are out of action because when you pull the good lever you will just open up the other side of the scissor mechanism against no resistance and run out of travel at the lever.

    Gsport, I added the following statements from Bud to the post. This is in direct reply to your point about snapping cables. Please let me know if its a sufficient answer.

    "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 to about 75%. 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."

  32. Anders10:48 AM

    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

  33. This is a nice engineering exercise, driven by a sincere desire to prevent rider caused endos.

    The device adds cost and complexity to a system designed for simplicity both to reduce manufacturing costs and demand minimal upkeep from owners.

    Adding cost and complexity to address a problem resolved by gaining experience or being trained doesn't make sense cost wise.

    I doubt any manufacture will adopt this device unless someone can build a fear campaign around braking. Really do we need another campaign about how dangerous cycling is, just to sell an accessory?

  34. As far as I can make out...

    The mechanism sits in a gap in both outer cables and would need to be set with a gap at both sides (or at least on the front brake side) in order to work to limit the force to the front brake. But there is also talk of either brake lever operating both brakes so there would need to be a gap at both sides.

    IF a cable snaps (which I admit is rare with well set up and maintained bikes, but common with badly setup and maintained low end department store bikes (which is where this device MIGHT find some small market)) then pulling the brake will first have to move the mechanism to it's end stop (ie one end of the scissor closed) before any of the cable travel could get through to the brake itself. Similarly if a brake block slips then the effort will be diverted down the line of least resistance until the "slack" is taken up.

    Complete bikes are built down to a very very very tight budget, specifiers are chasing not just dollars but cents, so persuading them to ADD any cost at all is a very very hard sell. In the consumers eye a "safety" device like this is not exactly appealing either IMO.

    As I mentioned before there have been NUMEROUS other devices that aim to address this "problem" and some I would suggest are much more likely to optimise stopping distance while still preventing OTBing, yet NONE of them has caught on. This could be because they havent been pushed hard enough, but my feeling is that people dont want them...

  35. Thank you all for your comments. Hopefully, Bud will take note of some of them and try and think about them and how it affects his design and marketing proposals. I always like to be safe on the bike and will always promote ideas and inventions that aim to make it so.

  36. Rein Gortemaker10:59 AM

    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.


Thank you. I read every single comment.