(bouncy music)
(horn sounding)
- Fork offset is ever more commonly talked about
but what is it?
And what effect does it have on the overall
feeling of our bikes?
The onset of offset, what is it all about?
So, what is offset?
Well, most mountain bikers are probably very familiar
with talking about the head tube
angle of their bikes, so, we have our steering
access coming down here, offset is how far
the front axle is offset or in front
of that steering axis and changing the amount
of offset on a fork is a way to affect
how much of our weight sits on
the front wheel of our bikes.
To talk about offset, I'm actually going to
talk about our stems but hear me out.
The reason I'm going to talk about stems,
as its something you've most likely experimented with,
and I want you to call upon that experience you have,
whilst I'm talking about offset,
to help quantify what I'm referring to.
So, stems, the longer your stem is,
the more stable your front end is
because the more weight is being exercised
upon the front wheel, conversely,
the shorter your stem is, the more rearward
your weight is in relation to the front wheel.
So, with a short stem, something like 40 or 50 mil,
steering can be more responsive
but it can go too far and come across all twitchy
and unstable, that's because, you guessed it,
there is not enough weight upon the front wheel.
That means that there is only our weight
driving our wheel into the ground to deliver grip.
But isn't that auto correcting sensation you get
with a nice, long stem.
Think of it like dipping your heels,
as you ride through rough terrain,
you're not making yourself heavier
but you are weighting the bike in a certain way,
to make it feel more stable, to achieve grip and drive.
This is what a long stem achieves,
hence why professional road riders,
who achieve warp speed, want that nice,
long stem paired to a relatively short top tube,
to give them that much needed stability.
Another good way to think about offset
is to think of what we know about chain stays.
Now, the longer your chain stay is,
the more it weights the front wheel
and takes weight off the rear wheel.
Now, this might sound slightly ridiculous
but if we take that knowledge
and apply it our forks, if we had an offset
of a thousand, it would actually
be taking pretty much all of the weight off the front
and be putting it upon the real wheel.
So, hopefully that's a good way to quantify
where our weight sits in relation to the bottom bracket.
And our axis.
So, weight on the front wheel is good, viva la long stems.
Stability, boy, oh boy, now we are talking
but is it that simple?
Well, maybe not, we've moved away
from long stems for aggressive riding
for a couple of reasons, if we combine a short stem
with a longer frame, we can get out weight
to sit more centrally plus stubbier stems
tend to play a lot nicer with our nice slack head angles
that are becoming ever more prevalent.
That twitchy feeling that a short stem
can cause is actually quite nice for striking
a balance of stability with out super wide handle bars.
So, the modern mountain bike, perfection, right?
Well, maybe not, there is a term called trail
which is often overlooked but less so recently.
But what does it mean?
And how does it relate to the rest of our bikes?
Trail is the number derived by measuring
the distance between your contact patch,
so, directly below your front axle
and the angle of your fork axis as it dissects the ground.
The larger the trail number, the greater the self
centering stability will feel on the wheel,
the lower the trail figure,
then the more twitchy your steering will be.
Why don't we try reducing that offset
on the forks, a number we landed on many a year ago,
this will help us weight the front wheel,
by increasing the trail number,
giving lots of grip whilst letting
us reap the collective benefits
of all the other changes in progressive geometry.
Its going to mean we can generate
a very stable bike that's nice
and roomy in the cockpit but also
it enables us to weight the front wheel a bit more
by reducing that front center slightly.
So, as you can imagine, as we slacken out head tube angle,
it has a drastic effect on that trail number.
Similarly, when we raise our front axles,
it also has a really big effect.
So, in the last couple of years,
more people are riding big wheeled bikes
and have slacker head angles than their
dizziest day dreams of a few years ago.
So, its no surprise that we've landed on offset
as a cause of conversation because its a
very logical thing to think about changing.
Can this go too far?
Well, absolutely, trail is a number
and there is a sweet spot, we know,
from our long stems, that that stability
inducing feeling is absolutely fantastic at high speed
but it can cause the wheel to bite
and be a cause of instability at low speed.
The theory being that high amounts
of trail give stability, kind of,
goes out the window when we begin to lean the bike.
Like everything, its a compromise.
Think of it like standing up,
as we widen our stance, it can actually
give us a huge amount of stability.
But only in one direction, ala trail.
But if we start leaning forward and back,
it can actually be a cause and generate instability.
This is the conundrum.
Like everything on our bikes, its a balancing act,
literally in this case, namaste.
Forks are available in many different offsets now,
be it Fox, RockShox, Suntour, Formula, whatever.
You just have to choose your flavor.
Today, we're using this system from Mojo Rising,
as opposed to anyone else's forks
just because the adjustment is all in the same fork
and it saves us trying three individual set ups.
We can just change the offset and ride back to back
different settings in this comparison.
Now a small caveat, is offset important?
Absolutely but it is just one piece
in the larger puzzle of our bikes.
Its just as important as something like stem length,
as if people still talk about that,
when it is so 2013, what I'm tryna say is,
there are no golden tickets in bike design
and everything we change has a ramification
within the larger picture of our bike.
So, what fiendish plan have we come up with
to try out this system?
Well, its undoubtedly very cunning
and highly sophisticated, for weeks,
I have been scouring roots and rain
with various algorithms and formulas
to find out my perfect candidate
and I am very confident I have done so.
We've got our very own Top Gear Stig,
an anonymous racer to push this fork
to its absolute limits, to hopefully give some
feedback about how the different settings feel.
And, of course, I'm not going to tell him
what offset he's running.
So, who is our mystery rider?
Well, they've won national downhill and endurer racer,
they've top 10'd at world cups
and if you feed him a few stiff shandies,
they'll tell you all about the time
they won rear of the year in 2007.
Who is this mystery rider, well--
- All right, Henry?
- Its, Neil, its mean to be anonymous.
Can we pixellate his face?
I'm sorry mate, I told you to wear
a full face and tints.
- Yeah, I missed that man, I'm sorry.
- Can you just put this on,
so we can disguise your appearance?
- What is that?
- Its a bloody, its a highly sophisticated--
That's straight from MI5, that.
That's what they use in the field.
- Should have had a shave.
- So, its (bleep) first run, he hasn't ridden
these forks at all yet, he's in the 46 mil offset
but he doesn't know that and away we go.
Be really interesting to hear his thoughts.
(intense electronic music)
So, we've changed the fork settings a bit
to reduce his offset but don't tell him.
Lets see how this anonymous rider
goes on for a second run.
(casual bouncy music)
So, we've had two tests, now, I'm not going to tell
you which one was which but one of them
was slightly longer than the stock set up
on the strive, one was slightly shorter
and now we have this which is obviously very different.
- Oh, its much shorter, I mean,
it looks crazy, doesn't it?
From the side, from up here, birds eye view,
it looks all right.
- I had a little wander around the carpark
'cause what we've done, if its not immediately obvious,
is swapped round the crowns, now,
this isn't advisable to do at home
but its going to make an interesting experiment.
So, we've swapped around the crowns
and put that flip chip in its most extreme position.
So, I think it gives an offset of almost, like, zero.
Its really, really, if you drew a line
through the head tube to the axle.
- It doesn't feel as crazy as it looks,
just riding along on the flat,
it feels like you are putting a lot of input into the bike,
the whole time it feels like you're turning a lot,
sort of just keep to keep your balance, so.
- It felt to me like, when we just rode around there,
if I closed my eyes, it felt like I was riding
a road bike with a really short stop tube
and a really long stem.
- Yeah, true.
- Just that, kind of, oh my god.
- Yeah.
- The way it arced but anyway, we're going to go for
a bit of a potter, well, you are.
I always potter, yeah, we're going to see how we go
and we'll end the day in the pub, I guess.
- All right, lets do it.
(slow electronic music)
I don't feel bad but that's went, for me, like wheel base.
Like, that feels like the biggest difference
but if you're going straight through rough stuff,
wheel base, to me, doesn't make that much difference.
Whereas if you change the head angle,
I would really notice it,
this doesn't feel like a huge difference.
Its only when you add it all together, for me,
I've always been really sensitive about
front wheel weight and being able to drift a bike.
Rather than just slide on the front
and that's been everything together.
Stackers under you stem, bar rise, head angle.
- [Henry] But do you feel that--
You know, offset is obviously something we can change
with a system like that and that's great
but you can't view any one part of a bike
in isolation.
No fork set, where it sits in the travel,
that effects head angle, which then effects this--
- Exactly, how aggressive your fork is,
actually dynamically effects where your weight is
not just, like, when I was riding around on this,
you can really feel the difference, I think,
in when you're going slow and you want to
just turn along the far road, it feels different
but when you're riding hard down this,
you're only changing one thing
and I don't that huge amount of difference.
- So, there is our day wrapped up
of trying out different offsets, back to back.
- Yeah, fun day.
- Yeah, now I've, kind of, experimented with this,
actually, just last week, wanted to,
kind of, get my head around it
and really understand the nuanced world of this--
- I mean, something that I don't--
'Cause, in the past, its something that,
you know, you couldn't really change your offset,
you had what you were given and that was it,
so, for me, I was more dial then on,
head angles, bar height, all these,
sort of, different things, whereas,
this offset is a new one to me.
- Yeah.
- And its a difficult one to get your head around.
- Yes, could you tell, what do you feel
you were trying, you know, for the first one,
second one set ups, could you tell the difference?
- I mean, yeah, visually, for me,
you can see, when I get on a bike,
I look down, you can sort of a gauge
from the head angle and all these sorts of things
like reach, just by sitting on your bike,
so, it did feel like it was coming further towards me.
- Yeah.
- Obviously, the last one, it was very obvious,
it was right back.
- Yeah, yeah.
- And, again, its, sort of, only when I'm riding
around a carpark where I can really notice the difference.
Like you say, a bit more agile, bit more twitchy.
When I'm bombing down a straight bit of track,
I really, it starts going down into the minute differences,
where its not a big enough difference for me,
it has to work with other things together,
for it to really make a difference.
Yeah, I found, for me, I really noticed
shorter offsets when, if you're kind of,
you know, we should always brake in a straight line
with our bike, you know, perpendicular to the ground.
- [Neil] It doesn't happen.
- It doesn't happen, and ever I was dragging my brake,
it felt the grip was more, maybe, binary.
- Yeah.
- Do you know what I mean?
I felt like, as a mountain biker,
I've conditioned myself to realize
where the locking point and modulations on the front wheel.
And it was, kind of, flying in the face of that.
I think, for short offset forks,
whether they have their place or not,
well, they obviously do but I think, for me,
I would have to commit to riding them.
- Yeah.
- And it would have to be the system I used
'cause I think it is quite a difference.
- Yeah, for me, I've always been
really sensitive to get in
the weight balance of front to back wheel.
And now there's just an extra thing to try and dial in
to get that right, so.
Yeah, I think for a lot of people
it can get confusing tryna find all these things
to make their bike ride how they would like.
Its funny, when we had Martin's tandem,
that's one thing, when I re-noticed the offset on that,
with it flopping side to side
but then changing it and making it feel more direct
and feeling like you're not just going to go thwak
and, sort of, just flop over and lose your balance.
- Because, originally, on Martin's bike,
although he's currently running
the set up that we are today, he actually just has
swapped around--
Reversed his low end, sorry.
- He did try that, yeah, yeah.
- Yeah and that was a thing that opened
up that big conversation and then, for me,
well, I think actually there are
some really important things to take away from this.
The offset will be more effective
when you've got a really slack head tube angle.
- [Neil] Yep.
- If, Doug's in on it as well, if you've got a steeple on,
then actually it moves it on that plane, almost,
so, I think in terms of the effect
in the amount of trail, I think we should do
a second video but we do it with a downhill bike.
- With a slacker angle?
- With a slack angle.
- Yeah.
- I mean, the Strive's such a fun bike to ride
but I don't think, its not, you know,
some bikes have 63 degree angles on them,
its a few degrees off that.
And I think, yeah, I think it'd
be really interesting to try.
But thank you for your time.
- Its been good.
- Thank you for, you know, riding the bikes,
you poor sod, having to spend all day, you know,
mountain biking, the final say, does offset matter?
Yes or no.
- To me, not much.
- Cool, well, there we have it, its personal choice,
part of a big equation and, like I said,
there are no golden tickets in mountain biking.
And, well, that's it, I want to make a joke about
fork offset except with these bad boys.
I really am racking my brain
and I just can't get it done.
- You're starting to bore me now, Henry,
with your fork offset.
(crickets cheeping)
- Fine, well, lets end it there.
Now, actually, the last time I came to the
Forest of Dean, was when I decided to do the laps--
Enough laps for a lifetime.
- Yep.
- And I Everest'd this very hill.
So, I'm going to throw to that video.
- You pedaled up that hill twice today,
that must have been easy.
- I can't get my head around it,
I was in a really weird mental space
but 82 didn't seem like that much
but hey, ho.
- Its a lot.
And if you want to JMBN throw their hats in the tech ring,
two pot versus four pot, check my new video, over there.
- Don't forget to like and subscribe
and we'll see you next time.
- See ya.