(cinematic music)
- I hope you're ready for some serious tech,
because in this video, we're gonna be looking at dynamos
and we're gonna explain what they are,
how they work, and why you should be using one.
For this video, we've luckily been sent
a nice new pair of HUNT SuperDura Dynamo wheels,
which, I have to say, I'm genuinely impressed
and surprised at how normal-looking the front hub is.
Granted it is bigger when you look at it front on,
anda bit more bulbous than a normal hub,
but especially once it's on a bike,
it's hard to tell the difference.
(cool jazz music)
There are two main types of dynamo, hub and bottle.
Now, bottle dynamos attach either on your seat stay
or your fork, and they're designed to
contact your tire, and as the tire moves,
it moves the dynamo.
Now, these aren't great.
They're not the most efficient.
They're quite hard to set up.
They can move, and they can also wear out your tires.
So in this video, we're gonna focus
on hub-based dynamos because they're the most common
type of dynamo you generally get today
and they're also far more efficient
and this particular model we have here is called a SONdelux
and it's got some pretty cool tech in it.
First of all, how do dynamos actually work?
Well, it's quite simple.
There are a series of magnets inside the hub
that move around a copper coil.
Now, the action of the magnets moving around the copper coil
actually induces an electrical current in the copper coil,
which can then be used to charge and power your devices.
And this process is electro-magnetic induction,
and it's essentially the same process
that occurs in any electrical motor, albeit in reverse.
(smooth jazz music)
What can you actually use dynamos for?
Well, fortunately, we have some top tips
from the 2015 trans-continental winner, Josh Ibbett,
who certainly knows a thing or two about endurance cycling.
So, according to Josh,
you can charge most things from a dynamo,
including phones, laptops, electric blankets, whatever,
but if you are gonna be charging your phone from a dynamo,
Josh suggests not to use the dynamo
directly into your phone, but instead,
charge a USB battery pack first
and then charge your phone from the battery park.
The reason for this is that the DC current
coming directly from the dynamo
can damage your phone's battery.
Why would you need a dynamo?
Well, there are several reasons.
The first reason is that they're great for people like me,
who constantly forget to charge batteries,
but if you've got a dynamo, you can simply plug it in
and you can still ride and you've got power
and you can charge your devices.
That brings me on to the second great use for dynamos,
commuting.
Now, I like to commute on bike whenever possible,
including in the winter, when it's often dark,
and my commute is typically around an hour,
maybe even sometimes longer
if I'm doing a bit more training.
Now, this means that I have to charge my lights daily
and you don't wanna be stuck at work
because you forgot to charge your lights,
so having to wait for them to get some charge.
And having a dynamo means you'll never have to do that
because you can simply run your lights off the dynamo.
Finally, dynamos are loved by ultra-endurance cyclists
and the bike-packing community.
And the reason for this is that
if you're riding for days on end
with no civilization in sight,
if you want to keep your computers, your GPS,
and your lights, and other devices charged,
then you either have to use a dynamo
or carry loads of additional battery packs,
which not just add loads of bulk and weight
but also is just another thing to worry about
once you invariably ready civilization again.
It really is rare to see an ultra-endurance cyclist
leave the house without a modern dynamo these days.
What are the drawbacks to a dynamo hub?
Well, there are two main disadvantages.
Weight and drag.
So firstly, weight.
A SON 28 dynamo hub weighs 440 grams.
We put this into context.
A DT Swiss 240 hub,
which is a really common and good quality road hub
that's fairly standard across a lot of wheels
weighs just 96 grams.
So nearly four times more for a dynamo hub.
In terms of drag, hub dynamos produce more drag
than a standard hub.
A SON 28 hub dynamo produces one watt
of additional drag at 25 kilometers an hour
when it's not turned on.
And admittedly, this doesn't sound like much,
but once it's turned on at that same speed,
it actually increases to six watts of drag.
Now, this, again doesn't sound like a huge amount
but over a huge ride, this adds up significantly
to a huge amount especially if, like me,
you don't have many watts in the first place.
However, with modern road-specific dynamos,
the penalties are somewhat diminished.
So with the SONdelux hub we have here,
it's actually 50 grams lighter than the SON 28
we mentioned previously.
And actually, when it's built up into
this HUNT SuperDura Dynamo wheel set,
it actually comes in at less than two kilograms
for a complete wheel set, which,
for a, with a dynamo and disc, very specific,
it's pretty impressive.
In terms of the drag, well,
six watts is quite a lot if you're doing a time trial
or road racing, but you're not really gonna use
this kind of hub for those applications.
If you're bike-packing or doing something
like the trans-continental,
then that six watts isn't gonna
make a huge amount of difference
once you're riding a fully laden bike
and also, the advantage of being able to charge
all your gadgets on the fly vastly outweighs
having to stop all the time to recharge them.
If we're being technically correct,
then most dynamos actually aren't dynamos.
Confusing, I know,
but they're actually what we call magnetos
which come to think of it is a much cooler name.
(smooth jazz music)
What's the difference between a proper dynamo
and a magneto, then?
Well, those of you who are fans of rock music
may be familiar with ACDC.
Now, proper dynamos produce DC or direct current,
whereas magnets produce AC or alternating current.
The different is, is that a proper dynamo
requires a piece of kit called a commutator.
Now, this is a bit techy, but a commutator
reverses the polarity periodically
to create the DC current.
This sort of power generator
wouldn't really work in the way that
a bicycle dynamo functions
and it's really easy for lights to have
AC to DC converters, so it's not really an issue.
As to why bicycle dynamos are called dynamos
and not called magnetos, I don't really know,
I have to be honest to say. Maybe one of you knows.
You can let us know in the comments section below.
Well, I hope you've enjoyed this deep dive
into the world of dynamos.
And if you have, why not give the video a thumbs up?
And also, check out the GCN shop.
If like me you demand the finest T-shirts
available to humanity and you demand them now,
then the GCN shop is the place to go.
And if you wanna watch another video,
why not check out our video on the trans-continental race,
where you'll see loads of people using dynamos?
See ya later.