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.
