The McNamara Fallacy and bikes

Making the rounds this last week was a photo of a 4.5kg “mountain bicycle”. It can’t possibly function, but I’m sure few realize that. Last week someone I know was bragging to me about how amazingly light their bike was (although, they get a pass, being pro AF). I’ve been planning to get around to this post for a while and now I’ll get to it….

Back in the day, there was a guy named Robert S. McNamara. You should know who he was but if you don’t, watch The Fog of War right now, it’s worth it. McNamara was the Secretary of Defense during the war that the United States prosecuted against the people of Vietnam. That was, and is, known as a great disaster, primarily for the people of Vietnam but also for US foreign policy. Spoiler, we were the assholes. We’ve learned many lessons from that war. Most forgotten. Some we remember, most from McNamara’s specific policies.

Because it was difficult to know if the US was winning the war against the people of Vietnam, McNamara, a numbers guy, would use the body count of perceived enemy killed in action (KIA) to approximate our success. The law of unintended consequences immediately went to work. Within a short period of time, US troops were entering villages and killing every Vietnamese person they saw without discretion. It was a genocide….a slow moving, accountant driven horror. Driving KIA numbers up meant soldiers were “succeeding”. Commanders got medals. High fives abound. They didn’t have to make hard choices. They didn’t even know why they were there but they were #winning.

The US was losing that war even as KIA numbers were climbing to ever more impressive levels. In April of 1975, the US ran off, leaving a broken people behind and a pox upon our house.

This way of measuring success is the heart of the matter I’m discussing in this post. The history of this era left it’s mark on all of us and today there is something in the logical world called The McNamara Fallacy. Most simply stated:

“If you can’t measure what’s important, make important what you can measure.”

That’s some pretty profound stuff. When are we measuring data that isn’t very important and placing priority on it like it is? When is the easiest property to measure magically one of the most important? Pretty often.

Bike Weight.

This is the most important tool that the entire bicycle industry relies on to up-sell bikes. It up-sells new bikes and parts using this tool more than almost any other tool. Lighter!

The weight of a bicycle is important. Don’t get me wrong. I do pay attention to it when I’m putting a bike together. All things being equal, I’d love a lighter bike. Things are very rarely equal though and often the cost of a lighter bike isn’t just lots of money but real performance. Weight is just not the most important thing about a bike. Actually, it’s not even close to the importance of good fit, good gearing, quality tires, a holistic build that makes sense, a chassis that doesn’t cause concern or bad feel. Weight is pretty far down the list of what you need for equipment to have a good experience on a bicycle. So, when I’m choosing my parts, I will end up with quite a few parts that aren’t “super light”. Their durability, specific performance areas, cost, serviceability, and systematization are most often the reason for the choice with weight being factored in later in the process. It takes a lot of knowledge, experience, and planning to be able to make these choices well. It’s not easy.

Here’s the thing about the weight of bicycles, frames, and parts; It’s easy for anyone with a scale to weigh a bike or a component. It’s easy to list that weight in an ad. It’s easy to put that weight next to the component price in an online shopping cart. None of this is hard. None of this takes any knowledge of bicycle mechanics, bicycle riding, engineering, or simply what it is about riding that we love. It is simply the most accessible and simplest metric that can be applied to something. Moreover, a company is motivated to make a component lighter as they will be rewarded by the market over their competitors. This is why weight has become so important in the bicycle business.

It’s industrial heroin.

Nothing is said in an ad or magazine that tells me that one part is better than another or if it is the right one for me, just that it’s lighter. Look again at the last few bike articles you read or last few parts you bought. Did weight get discussed the most?

I’ve been riding fancy bikes for almost 30 years. Shit bikes since before that. I’ve had light bikes. I’ve had heavy bikes. When I think back, the actual mass of the bike was one of the least important factors of the bike. When I rode my full on DH bikes on trail rides, it wasn’t the massive weight that caused much issue, it was the ergonomics and gearing. When I had a light bike on big mountain rides, it wasn’t the weight that made the ride great, it was all the flat tires and lousy shifting (etc) that made it suck. Think about your last ride. Would it really have been different if your bike weighed another 3 pounds? Are you putting together a better bicycle or just a lighter bicycle? Is the bike really serving you and helping you or are you just serving it?

Fabien Barel showing what bikes need to hold up to.

Not using a dropper post on your bike because it will add a pound? You are stupid. Period.

Really. I use Onyx hubs on my bikes. They are simply the most amazing and profoundly good bicycle part I’ve used on my bike since SPD pedals over 25 years ago. Why? They make my ride better, more fun, I put more power into it, in a more controlled way. They are awesome. You know why you don’t see a lot of them on high end bikes? The weight. They weigh a bit more than other hubs that do nothing for the bike other than drive down the overall weight. I’d choose the heavy Onyx hubs any day of the week over another hub while people who only look at weight have never even tried them. This really is a glaring example of a simple choice, driven by weight, can make a bike less of a bike.

Even the frames that I make, could they be lighter? I guess they could…but I’ve been putting most of my efforts into making them better frames rather than lighter frames. Better for mountain biking. Better for having fun. Better for going super fucking fast on. About the only thing they don’t do well is impress the scales. It’s just not a real factor in what makes them so good.

I often offer others to give my bike a try. For them to get on and pedal it around or take it down a trail section. Very few people take me up on the offer BUT, they will pick the bike up to see if it is light. Like that alone is some kind of real measure of the bike. It is literally insane especially as you see it happen over and over.

Still, most average bikes of today are much lighter, cheaper, and work better than dream bikes of just a few years ago. Don’t confuse “lighter than something else” with “quite light already”.

Tracy Moseley is a legend in mountain bike racing with rainbows from several disciples of racing and over many years. The guys at GMBN were doing a piece on her bike during the 2016 EWS season. They ask how much her bike weighs. Listen to how a legend responds (4:39). Notice how much she cares.

Carbon vs Aluminum & Whistler.

Let’s do some math. A 2018 Transition Sentenal XO1 Carbon retails for $5999 and weighs 29.7 lbs. The same bike, but made from aluminum and with some cheaper parts, GX Alloy, retails for $3999 and weighs 32.6 lbs.. That’s $2000 for less than a 3 pound weight reduction. Yes, there are many specific differences that will make the X01 Carbon version a little bit nicer than the GX Alloy version but anyone with a brain would be happy to ride the GX Alloy bike. Will you be faster or better or have more fun on the more expensive “lighter” bike? Probably not. If that is your real goal, you could take that $2000 and go with your bros on a road trip to Whistler for a week. Would that make you a faster, better rider who is having more fun? I absolutely guarantee it (if you don’t get broke off). There’s no question that money you spend on chairlift tickets, road trips to rad spots, or just having a little cash on hand to take your lady (or man) out on a Friday night will do more for your riding and experience than 3 pounds on a bike will ever make. Build the heavy bike and buy a couple season passes. Be smart. At the very least, all that money that you spend making the rider and bike system 1.25% lighter is far better served investing in riding and learning to ride rather than impressing friends with some silly number.

When does weight really matter? Weight really matters when you are a competitive rider, racing in advanced categories, among otherwise equal athletes, and points are on the line. Weight matters then…as long as your bike functions flawlessly, brings out your maximum abilities, and won’t fail you in a race even after crashes. That’s when weight really matters. Weight doesn’t matter if you aren’t in this place.

This isn’t really about weight. It’s about any parameter that you have that you use to establish value that doesn’t actually produce what you like. A bike’s fancy paint job doesn’t make it a better bike to ride. A companies pro riders don’t tell you anything about the bikes you can buy. Cool parties or flowed parts don’t really make a part worth considering. Check your metrics.

Fat Fuckers.

I’m not a light guy. I never have been. Now, as I’m 48 years old and it’s getting harder and harder to stay light, I’ve got the added problem of weight that is all about me, not the bike. Let’s say I weigh 205 pounds. With a decent muscle to fat ratio given my structure, I should weigh about 178 pounds. I’m 27 pounds heavier than I should be for optimal performance on my bike. 13% weight penalty on the GX bike above. That’s significant. That’s weight that can really change the power to weight dynamic on the bike and make my riding far more reactive at the same time. Three pounds off the bike is really insignificant when looking at this changeable reality. I just need to make my whole life miserable and give in to the diet gods.

“If you can’t measure what’s important, make important what you can measure.”

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Want some more sage words? Here’s something that Dan Kyle (two time AMA tuner of the year) told me while I was in his shop learning from him that burned into my brain the second I heard it:

“All the math and science won’t tell you what will work at the racetrack, BUT, it will tell you what won’t.”

Fuck wow! So often, when arguing about performance equipment, the discussion devolves into empiricists vs theorists. Some folks say, “It just works, so we do it”. The other side says “This is why it works so we do it” Do we know what we know from experience or from science? Really, it’s most often both. Dan’s expression seems to solve the dilemma between the two factions of argument.

I do a lot of math, calculations, and research to derive what I want to try. I study so hard and make sure. Then, with some idea of where I’m going and several paths ruled out by the physics, I start testing. Then I can figure out the real answer. It helps to not have to test 10 or 20 ideas that (in theory) can’t work. I want to test plausible answers not all answers. This is how it really works. Like Wernher von Braun said, “One test launch is worth a thousand expert opinions.” But Wernher wasn’t a stupid guy and brought real potential to the launch pad, not imaginary concepts.

I thank Dan so much for that as it has guided me in many endeavors.

“All the math and science won’t tell you what will work at the racetrack, BUT, it will tell you what won’t.”