Video: Using a Brake Power Meter to See How & When We Brake

Apr 19, 2019
by Matt Miller  
Views: 6,341    Faves: 2    Comments: 0


After Interbike in 2016, Pinkbike featured a story of the world's first brake power meter. The project was the main part of my doctoral research where I aimed to scratch the surface of one simple question with a super complex answer: what makes one rider faster than the other?

Mountain bike brake power meter

The original prototype was clunky, heavy and not very easy to use (all understatements by every means). It was built with only $3,000 NZD from my postgraduate funding, but was highly accurate and used for several research studies, such as this one on XC racing.

Yes, braking matters in XC, too. Now that my degree is finished I'm now fully focused on helping riders get faster.


I put together the video using the brake power meter on my local trails, and it really makes the data relatable.

Squiggly lines and funny numbers on graphs are good - and super important to understanding braking performance overall - but with the data laid out over the video, the only special training needed is knowing what it feels like to ride down a hill on a mountain bike!

This summer I will venture into the northern hemisphere summer to help riders understand their braking patterns and find ways to gain seconds. And I couldn't be any more pumped to have this out on the race tracks!


86 Comments

  • + 56
 Using Guides..."wow, these are very interesting results! It looks like you don't brake much."
  • + 13
 "It shows that you should of braked before the corner, but then your bike went off the trail and into the woods where we lost the signal and data and the rider"
  • + 3
 You might have something there...Haha. Going to make another video comparing different brakes/rotors/pads
  • + 3
 @Boardlife69: that actually made me lol. And I don't use that word lightly.
  • + 25
 What would really be great is a product that gives me the balls to let go of the f*cking brakes. I don’t need a machine to tell me when I’m grabbing too much brake. I know I’m doing it, I just can’t stop.
  • + 43
 That tech exists. Cable cutters.
  • + 8
 @sino428 A tip that some Aussies shared with me at Whistler once is to stop hovering fingers over the levers, just grab bar. It only takes a short time to grab lever, if needed. Grip the bars and go for it!
  • + 5
 @pdxkid: Yup! I do this, makes me feel like some sort of bad ass too Razz
  • + 13
 Also try slowing your entry speed, so you CAN go brakeless into a turn or feature, just to get the feeling started. Then start increasing your entry speed again. I find this method helpful.
  • + 2
 @pdxkid: this slow down a little let go of the lever and ride as if you don't have brakes.
  • + 1
 @reverend27:

I'm offended that we're in agreement on this one. I dare you to upvote me too.
  • + 4
 @crsimmons: Really surprised no one else is mentioning that. Like this is racing 101. Allows for smoothing cornering as well as traction.
  • + 2
 Meditate on the speed and get woke bro
  • + 1
 @pdxkid: Grip it n' rip it!
  • + 1
 @crsimmons: Seriously underrated comment. This. Corners are for cornering...not braking Smile
  • + 3
 It’s existed for centuries. It comes in 12oz doses in a can...
  • + 1
 Take a medium sized stone and tape it between your lever angle grip
  • + 26
 I've always thought it would be really cool if we could see in real time how DH racers use their front and rear brakes on the course, similar to F1 racing.
  • + 20
 While this data is super interesting, I think from a training and speed perspective, the most helpful thing would be a simple little red light on your handlebars that lights up when you brake. As long as you can see it clearly while riding, it would show you when you are dragging the brakes, and encourage you to let off more in turns, and where you don't really need to be braking, or should be braking harder in a shorter distance. That being said, I friggin love that you made this your post-grad work and that you are continuing to help mountain bikers and the MTB industry learn more about themselves.
  • + 2
 I think this idea with a chest mounted camera that lets you see which brake you're using would be most helpful (coupled with the awesome overlays from his videos). I found it hard to see where he was braking and why because I was either watching the graph, the numbers, or the trail itself. Maybe if the indicators are mounted closer to the stem and either vary their brightness by braking intensity (brighter = more brake applied) or show a number (0-100) so we can get a visual without looking away from the trail riding.
  • + 6
 Cheers, definitely going to try the lights on the next video. Have some new footage from some dope tracks in Rotorua and collecting more this weekend. Appreciate the feedback!
  • + 1
 That's a good idea.
  • + 1
 @mmexperience: great job man! I love the idea. You could have computer game style energy bars at the sides of the screen, left back brake, right front (for those that know ;p). You'd be able to see them moving in your peripheral vision without looking away from the track. They could start at the top of the screen and move down with breaking force, mimicking the direction of your brake lever. I'd still like to see the graph and numbers though, for subsequent viewing.
  • + 1
 @mmexperience:... So it would appear that a number of other people have had the same idea!! Oh well. Great work man, I look forward to seeing your next video. Cheers
  • + 2
 @dicky1080: cheers! I tried going CoD style, but when I started adding the number of rounds left in the clip I realized things had gone too far...

I actually hadn't thought of adding something to the side, but that's probably worth doing!
  • + 3
 @mmexperience: lol!! one thing that could be super cool would be to record a pro on the same track, then break the track into segments and watch your run superimposed onto theirs. You could see the difference for each feature on the track and maybe learn a lot in the process???
  • + 2
 shock therapy braking system
  • + 2
 @dicky1080: heck yeah, in the works! Smile
  • + 1
 I just watched the GMBN's "brakeless challenge part 2" last night and it's surprising to think how much over braking is holding me back from going faster.

I wouldn't want the light to show me when I'm braking so much as when I SHOULD be braking. It would be cool if when the light came on I should be braking. If I'm on the brakes at any other time when the light is not on, it's because I'm over doing it. You'd have to learn to trust the light and only brake when it comes on.

This seems like the next frontier for advancing the sport for all riders and racers. It's an area of riding where to go the fastest there is only one way of braking properly and that's at the very last minute for the exact duration needed to scrub the unwanted speed.

This kind of assistance I would think requires a lot more data on a track to calculate a theoretical maximum speed for a corner given the so many factors including weather, soil conditions, bike setup, and rider strength. Then calculate how much entrance speed needs to be scrubbed to get through the corner. Showing current speed and desired speed for the corner to a rider in a google display with the addition of the light could help greatly.

It's a complicated of a calculation with so many factors at play, but ya never know. Some factors one might think would be important might be negligible in the end too.

The future is an amazing place.
  • + 2
 @Patsplit: how about smart goggles with a head up display that shows lines, breaking points, dangers etc superimposed onto your real time view of the trail? You could see in advance where you need to be and what you need to be doing
  • + 1
 @dicky1080: that's the future I see. Wearables with mixed reality is going to be cool stuff.
  • + 9
 if this becomes popular, in the future people will get fined by bikeparks for causing brakebumps.
  • + 8
 YES PLEASE for more squiggly line, peer reviewed content on PB.
  • + 3
 Could a simpler metric be measuring hydraulic preasure?

@Shockwiz just pm me and i'll give you an address to send licensing checks to Smile
  • + 2
 If it were just to register when the brakes are pulled then yeah for e-bikes this is common (using a HAL sensor) to disengage the motor when braking. But I'm not sure if there is some threshold. Especially in DH type riding I see people pull the levers close to the bite point without actually braking yet. And different brakes increase differently in brake force per increase of pressure, especially those with different sized pistons. So you'll need to calibrate that, to then find out that it works very different once the first splash of mud landed on your discs. Measuring the forces on the brake mount seems like a good idea. Maybe those power meters that go in the hub could also measure brake force? That would give you even more interesting data.
  • + 2
 @vinay: Well I mean, yeah.. but..

I think for a product to be marketable it would need to be simple and light. Measuring hydraulic pressure is by no means perfect but would give pretty good data on how much power the rider is actually applying.

Don't get me wrong the posters device does a much better job of measuring how much braking power is being transferred to the ground, I just think it would be much more complex to make into a product that you or I could use, and perhaps more importantly want to purchase.
  • + 1
 @vinay: ..That said there could also be simpler ways to measure braking at the caliper as well.

agree to disagree.. and agree Razz
  • + 1
 @ripcraft: Thinking from Instrument design here, but to get a full reading you could possibly need many sensors to achieve all the required data. Simplest 2 would be a motion sensor to see if the wheel/caliper is spinning and also a pressure sensor (analogue output style so 4-20mA).
If you're going slower then you'll possibly need less pressure to stop the wheel spinning than that of a higher rotational speed with more momentum.
But then there are all the other factors such as friction of the surface which really speaking, could very widely vary, just depends on how in depth you want your data to reflect the overall scenario.

We did at work one time a test of how much pressure goes into hydraulic brakes when you grab them hard as we were adapting them to work via air for a hose reel application. Was close to 3000kpa or so on for a full lock, so there are some considerable amounts of force being applied.
  • + 0
 You really want to be measuring power due to other things that will change wheel speed, such as bumps and surface friction transition. Brake effectiveness at a given hose pressure will also change as the temperature in the rotor/pads change.
  • + 1
 it would be easier to watch if the breaking power was indicated by a BIG display, so that we can watch the center of the vidéo, AND see the breaking power at the same time, without having to look at a tinyurl.c om/lzxp6sk red dot ON a red line !
  • + 1
 Cheers mate, I'll try making it a bit bigger next time. One of the things I was trying to accomplish by using video plus graphs (instead of just graphs) was to make the video the focal point, with the braking as a side dish of tech. Still always the option of just looking at graph plus gps, too.
  • + 1
 Cool research! Do you have a link to your thesis, or a summary of it you can link to? Also, watching the video for the first time, you can't really watch the trail and see braking data at the same time. Maybe light up a sequence of bars on each side of the screen, like a race car's gear change lights?
  • + 1
 Thanks! Yeah definitely needs a few times watching until you know what you're looking at. Like anything I guess. I'll try the light up bars next time, and probably a dial to show left/right balance. Also I have all my research linked up on a page on my site- mtbphd.com/research
  • + 1
 @mmexperience I’ve been following your awesome work out of Massey for a few years now and have always wondered if there’ll be a wide commercial use for the BPM? Outside of a coaching clinic, and the same with other Power Meters, I personally don’t worry about the data.

Shockwiz (from a layman’s perspective) achieved this when they made it all about set up and not data driven performance improvement.

Also Arapuke has to be one of the country’s most underrated parks!
  • + 1
 Sweet! Yeah, I think this will find its place nicely. 15 years ago, power meters didn't really have much of a place in the pro peloton. But now anyone training for bike sports has one.

MTB will advance eventually with some new tool, and the shockwiz shows that we are ready. But while I definitely love the data, I also like riding with no gizmos. And really I think that balance has been really fun for me over the last 6 years

+10 for Arapuke!
  • + 1
 Lol. I tried to take the MTB PhD YouTube name with half a mind of quitting the science world and creating some technical MTB channel.

Guess you beat me to it and I have to admit: your dissertation also seems much more relevant than synthesis and optoelectronic properties of metastable 2D chalcogenides...
  • + 1
 Funny enough mtbphd as a pinkbike username was taken by someone in 2012... haha
  • + 4
 Will the BPM make me have more fun on the bike or just more technology that is going frustrate me more?
  • + 1
 I had @mmexperience (Dr Matt) on my podcast talking about the Brake Power Meter if anyone is keen to hear it. Here's the link bit.ly/2KMPrB8 otherwise look up 'Performance Advantage Podcast' on your podcast app, and it's episode 9. The podcast video is here youtu.be/pxTwhMcveLY
  • + 2
 "I brake when i see the white of god's eyes " Kevin Schwantz. Well, he said something prety close to that and i certainly don't doubt him.
  • + 0
 Go out and ride/ train.
Train more you’ll get faster.
Now the mechanics of this simple machine ( bicycles) and you’ll never get stuck.

Electronics and scientific analysis with nice graphical presentation is very attractive but will wast a dear riding time.

I like technology. But it should be simple and solve painful issues.
Like SRAM AXS - no cables & minimizing the shifting settings frequency. Same gos to DI2 but didn’t save the cabling.
FOX Racing with the live valve, taking the inertia valve a step feather to be ready for the trail coming instead of reacting to the trail.
  • + 3
 The less you use your brakes the faster you go. All I need to know.
  • + 2
 Not true. If you use the brakes in a clever way you go faster. If you enter a corner too fast an you loose traction you will loose more time than braking more.
  • + 2
 @Cheyax: totally. Plus I always say that if you're picking your bike out of a bush you're not riding very fast.
  • + 4
 Hard and late. Next!!
  • + 1
 I think about this concept ALL THE TIME. would love to see live power, breaking, and Gforce data from World Cup racing tied to live video.
  • - 1
 Could you please now do studies on when dropper post is engaged when approaching a drop? And gyroscopic measurements on when one typically starts to lean when approaching a curve? Or the exact moment when we need to flip the burger?? Or how much time I have before I take a dump in my pants? ???? just kidding and great work!!
  • + 1
 Danny Hart seems to already be doing something similar to this with his mechanical Dave.

www.youtube.com/watch?v=nVJZ3ag8gLU
  • + 3
 Already know why I brake....because I'm scared.
  • + 1
 This is neat! I wonder if you can sell it off for a couple million bucks like Shock Wiz??? tup
  • + 1
 Fun project and sweet trails! I like this idea of tracking my brake usage just for plain curiosity's sake.
  • + 2
 $3000 and a post graduate.....pfffft,I use skid marks
  • + 2
 And yes,that includes the ones in my pants..
  • + 1
 I'll have to watch that again. I'm from the NE US, I was mesmerized by all the beautiful dirt the first time through.
  • + 1
 That's where I grew up riding. Definitely miss my home trails but NZ goes pretty good Smile
  • + 2
 How you gonna ride that bike? You got no legs!

*In my best Forest accent
  • + 2
 Brake less and ride more...done
  • + 0
 Not quite bit nice try
  • + 1
 Cool, thanks for the info.
  • + 1
 Wow. Brake less go faster. That is riveting stuff
  • + 1
 I have codes. I know when I'm using the brakes cause they howl like a MF
  • + 1
 Interesting. I'm still running XO trails and was looking at upgrading to Codes. Stay away you reckon?
  • + 1
 @danlovesbikes: I love my codes. Reason they're loud is because of the metallic pads I'm running. More often than not I'm riding in the rain.
  • + 1
 @ThunderChunk: thanks for the info.
  • + 1
 Holy hell that trail looks fun!
  • + 1
 I need to take a Brake from Pinkbike.
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