- [Instructor] Now that we've created the front triangle,
we can have a look at playing around with our geometry
and seeing how this affects the frame.
So from within the assembly, let's have a look at it.
It's looking pretty good.
But one thing I can immediately say is if we zoom in here,
this down tube is a little bit too low down
where it joins the head tube.
Ideally, we want a bit more clearance
for the head tube cups that go in here.
So we need to move this down tube upwards a little bit.
And luckily this is quite an easy fix.
All we have to do is edit the layout sketch,
so click on it and press edit sketch.
And then I'm just going to go to a side view.
And all we have to do is double-click on this 30,
and then let's adjust it to maybe 50.
And as I do, you can see that line moves,
but the model doesn't update.
Let's accept that 50 and then exit the sketch.
Now to update the model, we need to rebuild it.
So you can click rebuild here, or press Ctrl + B.
And as I do, you see the entire model updates.
So now we've got a lot more space there.
If we look at it in 3D,
you can see that notch angle has updated as well.
And then down at this end,
where we've got that compound notch that was more complex,
that's all automatically updated as well.
So this is really the beauty of working in CAD.
We can literally just make a few clicks,
it takes about 10 seconds,
and then all of these angles are automatically worked out.
So there's much less potential for us to mess up our maths
and the model just updates straight away
because of the way we've modeled it.
So that was a fairly simple change,
but what if we want something more complex?
Let's edit that layout sketch again and go to a side view.
What if we wanted to change maybe the head angle here.
This angle generally determines
how fast the steering of the bike is.
So 71 degrees here is actually quite slow.
This means it takes more effort to change
where the bike's heading.
So this would probably be useful
on something like a touring bike
where you've got a lot of weight.
So actually you want the steering to be quite slow.
If you're making something lightweight
like a road bike or a racing bike,
then maybe you want to increase this angle
to maybe 73 degrees.
So let's try that.
Let's just double-click on it,
and then try changing it to 73.
And as I do, you can see it's changing these other lines.
So you can make certain changes.
So I can go up to 73 here,
but then if I go to 74,
you see we get some errors in the sketch.
That's because 74 degrees here won't work
with all of these other dimensions that we've got here.
So when you make certain changes,
you might have to temporarily delete
other dimensions in the model.
So if we wanted 74 here,
maybe we'd have to delete these two top tube dimensions
and then add them in afterwards,
or maybe even make the wheel base here smaller.
So try having a play around with the geometry
at this stage if you like.
You can also do this later on
after we've made the rear triangle
or any point in the modeling.
For me, I'm going to go back to that 71.
And I'm going to keep that 50 there and exit the sketch.
Now I'm just going to save my assembly.
And if you want to check your own assembly
against the exercise files at this point,
then the starting point of the next chapter, chapter three,
is the same as this ending point that we're at now.