You’ll be hard pressed to find a form of racing that isn’t somewhat concerned with the weight of their equipment. From Motorsport to cycling, every discipline has it’s own dedicated group of ‘weight wenies’ searching for marginal gains through weight reduction.
The vast majority of BMX consumers are looking for the lightest and stiffest because that’s the fastest! But in reality, is bike weight directly correlated to improved performance? Does lighter equipment really make you faster? And how light should your equipment be?
These are all questions we look to answer as we explore the world of weight reduction.
Static Vs. Rotational Weight
First, we need to identify the two different types of weight on a bike before we discuss the performance benefits of lighter equipment. This may all seem complicated at first, but as you continue to read the picture will get clearer.
Static weight is motionless, meaning it’s bolted to the bike and doesn’t spin freely as you ride. Static weight represents just about everything except for the wheels (think frame, handlebars, forks, etc.)
Reducing Static weight makes the bike lighter.
The second is Rotational weight which is free sprung, meaning it moves or rotates as the bike is put into motion. On a bike, Rotational weight is mainly associated with wheels.
Reducing Rotational weight makes the bike lighter similar to Static weight, but it also dictates how much inertia or force is required to put that component into motion.
For Rotational weight, think of a pebble vs. a boulder rolling down a hill. You can push the pebble down the hill with almost no effort and it’s just as easy to catch at the bottom of the hill (stopping its motion). The boulder is heavier and requires more force to push down the hill. Once it’s rolling, it’s much harder to stop at the bottom of the hill!
The pebble and bolder is an extreme example of light wheels vs. heavy wheels. The weight of the wheels dictates how much force is required to put the wheel in motion. Also, decelerating (braking) is easier with a lighter wheel.
A lighter wheel is capable of accelerating at the same speed of heavy wheel but with less force needed to produce motion. Because of the difference in weight, the lighter wheel is more willing to start spinning than the heavy wheel. Remember the pebble vs. boulder example (the lighter rock is more inviting to motion) the same thing goes for the wheel set you have.
Keep in mind that the difference in force needed to produce motion is comparative to the difference in weight. So a wheel set weight only a few grams more will only be marginally harder to move. But a wheel set weighing 1/2lbs or even a few pounds more is noticeably harder to move! The difference in weight is just as important if not more important than the weight itself! (More on this later)
*For more information about Rotational weight, check out our article on carbon rim right here. To learn more about braking and disc brakes, click here!
Light = Fast
Nowadays, you don’t see many frame manufactures advertising how heavy or bulky their latest frame is. If they did, no one would buy it. We want light and stiff, but why do we want this?
It’s really all about efficiency. A lighter bike (in terms of Static weight) takes less effort to maneuver around the track. A lighter bike takes less force to position over each jump which equals energy saved!
Think of a barbell in the gym. The less weight on the bar, the less physical energy is required to move the bar from one position to another.
BMX Racing is already extremely taxing on the body. A full race lap takes virtually everything out of you! While you’ll still be struggling for air after a full lap regardless of what bike you have. A lighter bike should make the effort marginally easier since it won’t take as much effort to position the bike.
In terms of Rotational Weight, lighter wheels help acceleration. Thinking back to the pebble vs. boulder example, It requires less leg power to get a lighter wheel spinning out of the gate then it would for a much heavier wheel set.
So is lighter faster?
I’d would agree but it’s really more about providing increased efficiency. I wouldn’t say that lightness is directly tied to being faster. Explosive leg power and proper pedaling technique are things that make you faster. Pairing those two with a lighter bike means less energy used on each pedal stroke and maneuver. So while a light bike won’t instantly make you faster, it makes the job of going faster a bit easier through increased efficiency and energy savings.
Saving Pounds Vs. Saving Grams
So lightness can aid in becoming faster, But does saving a few grams equal 2-3 seconds off your lap time? Not quite.
A bike that’s a few grams lighter than another IS better on paper. But it’s not a difference you can feel or notice on-track. With saving weight we have to look at how significant the savings is. Our bodies can only feel a certain threshold of weight difference. Add a few grams to your bike and you wont notice a thing. Add a few pounds or even a 1/4 pound and then you’ll feel something!
If you swap out a singular chromoly bolt stem bolt (roughly 25 grams) for a ti bolt (roughly 15 grams), your bike IS lighter but it isn’t enough of a difference to impact performance. Now, swap out every chromoly bolt on your bike in favor of ti bolts, then you have multiple marginal weight savings combing to produce a significant weight savings for the whole bike (nearly 1/4 pound!)
Basically, don’t stress about a few grams. It isn’t going to make a huge difference. But on the same note, we should be aware of how saving a few grams in multiple places can compound into a noticeable weight change.
Key takeaway: Don’t stress weight savings, but don’t entirely ignore it.
(confusing, I know)
So Does Bike weight Matter?
Yes!… But also no
Over time your body will adapt to the weight of any bike and it will start feel normal. Weight savings is important, but it’s importance decreases as the amount of weight you save decreases. Going from a 30lbs Walmart bike to a sub 20lbs race bike is a game changer! But saving a few grams on a new stem won’t get you too far.
As long as you’re within a few pounds of the other competitive bikes, I wouldn’t stress.
Also remember that if you aren’t doing your sprints or training on a weekly basis, a light bike won’t make up for your lack of training. Think of bike weight as a method for maximizing your performance rather than being the determining factor of performance.
Reducing weight provides a more effective platform to go faster, but it won’t magically make you faster!
Below is a list of recommended weights for all sizes. Of course you can get your bike lighter than what we are presenting here. But let this serve as a goal or ball park of where you should be. As long as your bike is within a few pounds of the recommendation, then you have a competitive bike in terms of weight.
Total Bike Weight
Micro - 14 - 15lbs
Mini - 15 - 16lbs
Junior - 17lbs
Expert - 17.5 - 18lbs
Pro - 19 - 20lbs
Cruiser - 22lbs
As mentioned before, a pound or two difference won’t keep you from winning races. But the lighter you can get your bike the more efficient it will become. As long as your build is somewhat close to these ranges then you can make the choice for how important saving more weight is to you.
Other Weight Considerations
Remember that your bike isn’t the only thing you’re lugging around the track. You also have various protective gear and your own body weight as well.
While it’s crucial for every racer to have a safe helmet, you could look at helmets that provide the same protection of your current model, but also weigh a few pounds less. Same thing with your pads and jersey. Maybe you could get a tighter jersey, some lighter pants, or slimmer protective pads. these are all things that won’t make your bike lighter, but can still provide you with benefits similar to a lighter bike.
You could also view your body weight as a method for weight savings. At a certain point, your limited by technology as for how much more weight you can save. But in terms of body mass, there are various things you can do to save a couple pounds. I typically weight about 5-10lbs more during the winter as I’m building strength which will then be turned into lean explosive power. As the spring months approach, I shave that weight and get back into peak race form. We could write a whole other article about power-to-weight ratios, but becoming lighter and more explosive as a rider can help make you faster too.
Wrapping it up!
So yes, a lighter bike can make you faster. But so can lighter equipment, or reducing body mass. While bike weight is important for maximizing performance; There’s still other things we can look at in terms of weight for becoming faster. Bike weight matters, but it isn’t the end all be all of racing.
- Written By, Jonnie Vance
This piece contains the findings and sole opinions of the author (Jonnie Vance). This article is intended for entertainment purposes only and is not reflective of the thoughts or opinions of SUPERCROSS BMX or it’s partners.
Sprints are an essential training tool within every racer’s prep kit. But with so many variations, what sprints should you actually do? In this article we tell you all about it and even provide a free sample workout for you to try!