(energetic rock music)
- Our mates over at Zipp have just lent us
these rather cool bikes,
so that we can check out their new 303 Disc Tubeless
Firecrest wheels which are available--
- In a smaller size, 650B.
Now if you are a road rider, you probably
haven't ever had to think very much about
wheel size before, if at all.
Because road bikes come with what are called
700C wheels, and that's pretty much that.
- But increasingly, there is an alternative,
this smaller alternative that's called 650B.
They're an interesting proposition.
They potentially help to improve the design
of smaller bikes.
But then there's a new crop of bikes
that utilise this size to increase versatility
whilst maintaining speed and agility.
- By pairing smaller rims with bigger tyres, the promise is
that they can make drop handlebar bikes more fun.
- We can't wait to try them out properly,
on-road, off-road, uphill and down,
and see what all the fuss is about.
Well, let's back up a bit before we start talking about fun.
You can be excused for not knowing
what on earth we're talking about.
So what is it?
Cy?
- A 650B wheel has a rim diameter of 584 millimetres.
A 700C wheel has a rim diameter of 622 millimetres.
Now the concept behind improving bike design
for smaller riders is a simple one.
You see, we don't have to make sacrifices
to the geometry of the bike in order to
squeeze those larger wheels underneath the rider.
But what about the fun thing, then?
Fortunately that, too, is also a simple concept.
By using a smaller diameter 650B rim,
you can therefore fit a larger tyre
and still keep the overall wheel diameter the same
as a standard 700C road wheel.
Now that means you can keep the geometry,
and therefore the handling characteristics,
the same as a normal road bike.
But, the added tyre volume means that you are
not restricted to riding on the road, not by a long shot.
- Or at least that is the theory.
Until Zipp lent us their brand-new
650B 303 Firecrest Disc Tubeless wheel set,
we hadn't had the opportunity to try.
So these are tubeless compatible, disc brake specific,
and they've got that super-aero Firecrest shape.
Now as you can see from the fact that I'm still not
particularly dirty just yet, we still haven't
really tried them properly.
And so, we have planned another GCN epic gravel ride.
And in the process, we're also gonna be taking off
something from our bucket list, by riding
all the way up there.
- Dan, are you serious? - Yep.
- Lord Hereford's Knob? - Yes.
Not for the faint of heart.
- Gonna be quite long.
- Hard as well.
(energetic rock music)
Two bikes, two pairs of wheels.
So that we can put them in context, we've got
one pair of 650B Zipp 303s, with 47 millimetre wide tyres,
and then one pair of 700C 303s, with 35 millimetre tyres.
Same total wheel diameter, same bikes, same ride?
- Or, same bike, different volume tyre, different ride?
- Now, if you wanna go into the real tech and physics
of it all, we'll have a video on the tech channel as well.
But we can talk all about angles of attack
and tyre rollover.
But right here, right now, we are gonna try and
get a feel for just how it rides.
- Most epic gravel rides start with at least some
riding on tarmac, even if that's just to get you
from the coffee shop to where the trail starts.
Let's be honest, if you're riding a bike
with drop handlebars, you're probably going to
spend a reasonable amount of time riding on the road,
which means that the handling traits of 650B wheels
on the road should be an important consideration.
And it's weird.
It feels just like a road bike, really.
We've got different-sized tyres, as you can see,
on the different-sized wheels.
So continental cyclo-cross speed on the 700C wheels,
they're 35 millimetres wide.
And on the smaller wheels the tyres are 47 millimetres wide.
That gives an overall diameter
of 680 and 690 millimetres, respectively.
And that similarity means that the handling traits
are almost identical.
The only real difference is that the wider tyres,
obviously have a larger contact patch on the ground.
So as you begin to turn, you can kind of tell.
In fact, right under your eyes shut, you can
tell a difference.
(energetic rock music)
Right, we've just done a quick wheel swap
so I can get a sense of how these ride before
we leave tarmac for good today.
Now, we did want to also get a feel for
the speed differential between the fatter tyres
on the smaller rims, and the skinnier tyres
on the larger rims, as well.
We know aerodynamically that there's gonna be
a disadvantage to the wider tyres.
Probably now Zipp actually have never thought to test
gravel tyres aerodynamically in a wind tunnel before.
But they very kindly did a bit of maths
on the back of a napkin for us,
and they've worked out that there's a rough
20 watt penalty for using the fatter tyres
at 40k an hour.
- But the Zipp rims are nice and wide anyway.
So 21 millimetres internally and 29 millimetres externally.
That provides great support for these super-wide tyres.
And it could be forgiven, to be honest,
for not really caring too much about all of this
when you are riding on a bike such as this.
What then, about the rolling resistance?
To be perfectly honest, when I was on there I didn't think
you could really feel much of a difference.
- Now we have tried to do a bit of science here,
using a gentle gradient and rolling down it.
We did measure a slight penalty over the wider tyres,
but given the aerodynamics and given the fact
that there's a different tread pattern,
I'm not sure it's going to stand up statistically, Dan.
- No, basically then monster wide tyres like this
will slow you down ever so slightly when you're
riding on the road.
But nevertheless, due to the geometry,
it stills feels lively and responsive.
As accomplished as they are on the road,
you're not going to want to use these
as your go-to wheels, for that purpose alone.
No, you're going to want to take them off-road.
- Yeah, because here they really come into their own.
Because if you're using a normal 700C wheel
with a cyclo-cross or a gravel tyre on there,
if the trail gets too rocky and too rough,
you lose some of the fun factor.
Because the puncture risk goes up,
therefore your tyre pressure needs to go up,
and that makes things a little bit uncomfortable.
- Well not to mention sketchy.
- Not to mention sketchy.
- But, with the 650B wheels you get to take
your nimble, agile road bike off-road with abandon.
And these are running just 30 PSI while Cy has got 45 PSI.
That's 50% more. - It is.
Now, that 650B wheel and tyre combo therefore
makes things an awful lot smoother.
You can hit things harder and faster,
and you still have way more control.
- Or at least you would do, if they weren't
completely slick down the middle.
- No, no, that's true.
Now there is also one last string to the bow
of the 650B wheel, and that is that they're lighter.
Quite significantly, in fact.
So the Zipp 303 650B wheel is just 1450 grammes for the pair,
whereas the larger 700C wheel is an extra 195 grammes.
Now in this case, there is a significant weight
penalty with the tyre, so this continental cyclo-cross tyre
is actually 170 grammes lighter.
So although they still come out slightly lighter,
with different tyre choices they could be
significantly lighter.
Now that may not matter all that much on the road,
but off-road, where your speed is lower
and you're also changing speed more frequently,
that is a big advantage.
(energetic rock music)
- Well here we are, we have made it.
Nice one, mate.
- Yeah, check out the view.
That is amazing.
- I must admit, I'm not sure I've ever seen
fog up close quite like this.
- Really impressive, isn't it?
Really impressive.
Anyway, some of you at home might be there
quite disconcerted about the fact that we're using
these carbon rims off-road.
And you might be questioning whether that's sensible or not.
However, don't be worried because Zipp have informed us
that these very rims stand up just as well
to that kind of terrain as their mountain bike equivalent.
- Yeah, on a personal note, these very 700C wheels
have been through the mill this season with me.
And the only scars I can find on it, Dan,
are from the sealant
that I haven't cleaned off properly yet.
- Oh well, that's not too bad, is it?
Right, shall we descend Lord Hereford's Knob?
- Yeah, go steady mate.
- I will. - It's quite hard.
- Well I think it's going to be quite exciting.
Probably over far too quickly.
Always the way.
(energetic rock music)
Okay, we have descended Lord Hereford's Knob now,
Cy, haven't we?
We've gone from the clouds up there
back down into the woods.
Now at the start of this video, we made the suggestion
that 650B wheels could make drop bar bikes more fun.
And completely subjectively I think we can both say
we can see the appeal. - Oh yeah.
- However, is there a way
of scientifically measuring the fun?
- Well, we are going to try, using some pretty pioneering
science involving advanced facial recognition software.
We're gonna try and quantify smiles.
That's right.
Now you can probably see the difficulty here,
particularly because Dan rarely smiles himself.
We're going to have to use
some seriously sensitive equipment.
But can we effectively measure the size of a grin,
off this super-cool bit of trail?
(energetic rock music)
- Processing. (phone beeping)
42-year old man with a moustache wearing a hat
looking neutral.
- 42? This is not right.
It's got my age wrong to start with.
- Yes, sorry damn it, the science appears to have
failed us there.
Maybe it will work better with Matt.
- Hm, well that thing quite let the fun factor out today,
if I'm perfectly honest.
42?
- (laughs) Well just tell us how they feel then.
- Well, today is kind of reminding me of that first
GCN epic gravel ride that we did a couple of years ago,
where I was insistent on using my normal road bike
because I'd been successful on that in the past on gravel.
However, it was clear that you didn't puncture like I did
and that you had a lot more fun and you were
more comfortable off-road.
This is like an extension of that, isn't it?
The 650B wheels, with those wide tyres,
are super-comfortable over roots and rocks off-road.
It also reminds me of what we both started out as
as cyclists, mountain bikers, cross-country.
Because at the time, mountain bikes were kind of
race-ready, weren't they?
They were low at the front end, they only had 1.9 tyres,
but on 26 inch wheels which are very similar indeed.
I think it's very similar to that.
- Yeah, you know what?
I wonder actually where the whole 650B phenomenon
on drop handlebar bikes, actually stems from the
fact that mountain bikes have gravitated more towards
long travel trail bikes that don't really want to be
ridden very far, dare I say.
So now, people like us that were on 26 inch of cross-country
bikes, back in the day, are now loving these.
And I absolutely do love them, because
although you can get faster bikes off-road,
of course you can, you'd get a 29er hardtail
and you will absolutely fly,
it's not necessarily more fun.
This, because it's a little bit harder when you're
going properly off-road, you don't go as fast
but it feels faster.
It makes it more fun.
Then there's the fact that it still feels
like your road bike off-road,
which adds another dimension of fun to me as well.
I think they're great!
- Yeah, we should probably add that these aren't just
for people that are apparently 42 year olds
that are reminiscent of a bygone era.
- It's a lovely moustache as well, though.
- What I particularly liked was the transition between
off-road and on-road and vice versa.
Because you don't feel like you're at
a disadvantage either way.
When you get there, you're confident the bike is
going to be able to do what you want it to do.
- Yeah, now there is one burning issue that we
haven't addressed yet this video.
And that is, why on earth it is called
650B in the first place?
And why, in fact, are they called 700C wheels?
Let's put you out of your misery.
In France, many moons ago, total wheel diameter,
so rim and tyre together, was all-important.
There were two key sizes,
650 millimetres and 700 millimetres.
The letter on the end then referred to the width
of the tyre, A being the thinnest tyre,
C being the widest tyre, and B somewhere in the middle.
Now in order to keep that overall wheel diameter the same,
you had to have a different rim diameter
for each of A, B, or C.
C, giving the smallest rim because the tyre was widest,
and A having the largest rim because the tyre
was the thinnest.
Now as you can imagine, producing six different rim sizes
for two different wheels was pretty complex,
and blooming expensive.
So in the end, market pressures prevailed,
and 700C ended up being the most common rim choice,
with an arbitrary diameter of 622 millimetres.
The same is true of 650B.
It has an arbitrary rim diameter of 584 millimetres,
but now with the super-fat tyres on,
the overall wheel diameter measures 684 millimetres.
Interestingly, or perhaps not, if you truly
wanted to ride a 700C wheel, you'd need to run
a tyre size of 40 millimetres on that larger rim.
Because that then adds up to a diameter in total
of 700 millimetres.
It's for this reason that when you're buying
a new tyre, the diameter is shown as 700C,
but the width is measured in millimetres,
not the common mistake of C,
which as we've just seen, isn't a measurement of anything
at all.
Nice, mate.
- That was good.
Well I personally don't think we should break
with tradition, Cy, like the last gravel ride.
Yeah, pick one.
Let's end it in the pub.
- Sounds like a plan.
- You still there?
Oh good. - Excellent.
650B wheels then.
I think you can probably tell that we're really
rather taken with them.
- We are, but inevitably, Cy, there is a down side.
That is, that currently there aren't many frame sets
out there that will accommodate these 650B wheels
with the max volume tyres.
Reason being that although you don't need longer
fork blades, or longer chain stays, or longer seat stays,
what you do need is extra tyre clearance.
The flip side to that, though, is that when you're
next wanting to purchase a bike, you might decide
to go for one of these, because it is a one bike
that does it all.
- That's right.
So you could have your 700C road wheels on
for fast road riding on a bike that feels
like a fast road bike.
But then you stick your 650B wheels in, with your
fat tyres on, for when you want to venture off-road.
And we really mean venture off-road.
As you can probably have guessed.
- Yeah, that was gnarly trail today, dude.
- Oh yeah.
- One question you could inevitably ask yourself
now, though, is why don't you just put those
max volume wider tyres on the normal 700C wheels?
Then, in effect, you'd be creating some kind of
drop handlebar 29er mountain bike, wouldn't you?
We all know how fast those things go.
- That's right.
It's a tough question to answer, that.
I think it kind of comes down to geometry,
and then also a little bit of philosophy, really.
The difference in wheel size will be quite significant,
so 680 millimeters-ish for 650B,
and then 720 millimetres for a 29er.
And that extra size means they feel a little bit
less agile, and the bike also has to be longer,
it has to be tauter.
It's going to make it feel more stable,
and of course it will also roll over anything.
- Hm, they sound like some great characteristics,
don't they? - Well ...
- For many people out there they will be.
Others might be slightly less excited about them.
You see the way that a road bike feels and responds,
the way it feels when you're cold, the way it feels
when you sprint or when you climb,
is down to the size of the wheels, but also
the angles and numbers which hang off them.
These wheels allow you to maintain those,
but giving the extra versatility to venture off-road.
- Yeah, are they more versatile?
Oh yeah.
Are they more fun?
I don't know, mate.
I mean they are super-fun, but are they more fun?
It's just like different fun, isn't it?
It's not in any way the same as riding a
super-fast aerobike super-fast,
but then they are great fun.
- Yeah, that was a very concise and accurate summary
right there, Cy.
I have to agree to agree right there.
- Make sure you let us know what you think
in the comment section down below.
Really, really interested to hear your thoughts,
actually, on this new trend, this new phenomenon.
Are you tempted?
Have you got some already?
- Yeah, we look forward to reading your thoughts.
Don't forget to give this video a like,
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- That's right.
Back in the early days, what can a gravel bike do
that a road bike can't?
That one is just down there.
Or, if you want to make every ride epic,
irrespective of whether you're off-road and you're
on gravel up in the mountains, we've got
some great tips just down there.