Weight is often the central focus for any discussion around bikes, components and
camping gear. You'll have noticed that I don't emphasise weight very often on this channel,
and that's because it matters so much less than you think. Don't get me wrong, there are some
great reasons to use lightweight gear, and we'll discuss them all later in this video. But if
you're trying to reduce weight to go significantly faster, you're probably barking up the wrong tree.
Today, we'll find out the time penalty of each extra kilogram that you add to your
bike or equipment. We'll then compare these time penalties to other forms of cycling resistance.
Let's start by putting weight into context.
When you ride your bike up a hill, it's not just the bike weight that you are hauling.
You are also pushing your body, clothes, shoes, water, food, pump, spare tube, and any luggage you
might be carrying. Your body weight makes up the majority of this load; it's often more than 80%
of the total. While a bike that's 10% lighter than another feels really impressive when you lift it
up, it often only reduces your total weight by 1%, which is now sounding much less impressive.
Shaving grams off bikes and equipment is often a very expensive pursuit too. One kilogram can be
the difference between a $200 tent and a $600 tent, a $600 steel frame and a $1600 titanium
frame, or a $3100 gravel bike and a $6200 gravel bike. Additionally, lightweight products are
sometimes much less durable. I find this with zips, waterproof fabrics, aluminium cassettes
(and hub bodies), tyres, and rims, in particular. Alright, let's find out how weight affects cycling
speed. My journey to being less obsessed with weight began when I stumbled upon a website called
Bike Calculator, which after filling in all the parameters, could predict my cycling speed using
a mathematical model. I tested it out using my power output, body weight, bike weight and gear
weight. I then created a simple 100km ride profile that went five kilometres up, then five kilometres
down - 10 times - each with a 3.6% gradient. The total elevation gain was around 1800 metres.
I got time predictions on four different luggage weights so that I could work out the time
per extra kilogram on my course. It turned out that a kilogram should add between 76 and 80
seconds over 100 kilometres. And even if I reduced my power output by 30% or set the parameters to a
smaller rider with a lower power output, a kilogram was still only worth two minutes.
Considering that my route had quite a lot of climbing, a minute or two after four to five hours
of riding was significantly less than I expected. So I decided to conduct my own weight experiment.
I rode my bike fitted with a power meter and two large panniers on a 15.4km route which offered 265
metres of climbing. I pedalled along at 200 watts which was a power rate that I knew I could sustain
over a full day of testing. The route was well sheltered, significantly reducing any hindrances
from the wind. It was designed to mimic a day of cycling in the hills whereby around 1800
metres of elevation would be gained over 100km. I conducted two test runs with three different
luggage weights. And here are my results: after around 40 minutes of riding, I saw a two to
three-minute difference per lap as I piled on the weight. As these numbers are a little abstract,
let's extrapolate them to 100km to see how closely they match Bike Calculator's prediction
of 78 seconds per extra kilogram. The added time averaged out to be a touch over a minute,
suggesting that my perception of how weight affected cycling speed was, indeed, a bit off.
Bike Calculator was within just 1.5 and 4.5 minutes of my outdoor testing times which I think
is impressive considering the simple ride profile I created only matched the distance and elevation
gain. I'm sure the accuracy would improve further if I spent the time to make the gradients correct.
I later attempted an outdoor weight test on flat roads. It turned out that whether I carried 5kg or
25kg, I couldn't find any significant difference in speed at 200 watts. Feeling confused,
I fed my parameters into Bike Calculator and it predicted that I should be just 10 seconds slower
per extra kilogram over 100 kilometres. I guess that explains why my speeds were
so similar - weight really doesn't matter on the flat. Alright, so the data and mathematical models
suggest that a kilogram probably won't slow you down that much. But there are a few instances when
focusing on lightweight bikes and equipment is completely justified, in my opinion. Number one:
you do actually race. The difference between winning and losing is sometimes measured in
millimetres. One kilogram less is going to help here, and the benefits of that weight saving
only increase the longer and more mountainous your race. Number two: to improve bike handling
and feel. Heavy bikes don't feel as snappy or responsive when accelerating or cornering,
making them feel a little less inspiring to ride. They are also significantly less agile when you
overload them with all your luggage. Number three: to use a bike that isn't designed to carry heavy
loads. If you've seen my video describing the differences between bikepacking and touring bikes,
you'll know that touring bikes are stiffer, and are built with a slew of overbuilt components
specifically to handle high luggage weights. But here's the deal: if you can keep your luggage
weight to a minimum, you can reliably travel on almost any bike - not just a touring bike.
Number four: to make lifting your bike easier. There are many instances where you might need
to carry your bike. For example, I'm often carrying my bike on hike-a-bike sections of trail,
as well as up and down stairs in apartment blocks, hotels and train stations. And number five:
to make flying cheaper. A few extra kilograms can really add up when you get to the airport.
Make sure to keep your bike light enough so that you don't get caught out with crazy fees.
Ok, let's talk about the factors that are often more important than weight when it
comes to cycling speed. Bike Calculator predicts that five extra kilograms adds 2.5% more time
on my 100km hilly ride profile, and it's just 0.4% more time on a flat profile.
We can compare these time percentages to the two other main forms of cycling resistance:
rolling and aerodynamic resistance. If I fit some of the slowest rolling touring tyres to my bike
instead of the fastest rolling ones, my hilly route would require 12% more time to complete
in this case. Rolling resistance is almost 5X more significant than adding 5kg to my bike,
and it's 17 times more significant on the flat profile! That said, these numbers are particularly
big because I'm comparing the fastest tires with some of the slowest. But even if we compare tyres
closer to the middle of this list, the rolling resistance still works out to be more significant
than the extra 5kg of weight. I'll link my rolling resistance article on CyclingAbout below.
Through my aerodynamic testing on a flat velodrome, I found between 6.4 and 7.9%
extra ride time was required to cover 100km when using panniers instead of bikepacking bags.
This means that a change in luggage set up on a flat ride could be 16 to 20X more significant,
in terms of time, than if I added 5kg of extra luggage to my bike. You can see my list of aero
savings for bike travellers in this video up here. In summary, the data is quite clear bike
weight is not as important as you think. My real-world testing along with the numbers
from the mathematical models suggest that a kilogram of extra weight will likely add one
or two minutes on a hilly 100km bike ride. And on a flat route, a kilogram is likely worth 10
or 20 seconds. This is worth thinking about the next time you find yourself obsessing over bike
and gear weight. Perhaps you could use this information to save $1000 or $2000 by choosing
a steel bike rather than titanium. Or when your ultralight gear wears out, maybe you could replace
it with something more durable. You could even pack a thicker, more comfortable sleeping pad
and get a night of better sleep. If you like my bike-nerd content, please consider supporting
this channel over on Patreon, or alternatively grab one of my books! The Touring and Bikepacking
Bike Buyer's Guides are updated yearly - for free - and will teach you everything you need to know
about the bikes, before allowing you to compare over 220 different bikes at the back of the book.