(futuristic flying and landing sounds)
- Welcome to Ask GMBN Tech.
This, of course, is our weekly Q&A show.
You ask the questions, and hopefully,
I get to answer some of them for you.
Get your questions in to the email address
on the bottom of the screen there,
and you can add them in the comments
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especially if you're emailing in,
put it in the subject header.
Makes it nice and easy
to spot your emails.
Okay, so first up, this
week is from MTB/ST.
"Doddy, I've recently decided
to build a dirt jump bike.
Can you explain the rear axles
on them for horizontal dropouts?
Thanks.
Well, firstly, assuming
that most dirt jump bikes
these days have a one-three-five
millimeter spacing
between the back of your frame,
you don't really need anything special.
So the more important bit is
actually part of the bike.
So you can, with a
standard, quick-release,
run a horizontal drop
out on a single speed.
Now, you an also, in an ideal situation,
have a bolt-through set up,
but that does involve
a slightly heavier hub
with a threaded axle, or
alternatively have one
that's got a hollow axle
that's threaded at the ends,
and you can screw in bolts.
Now, the Canyon Stitched that
you can see on screen now,
Blake has this bike and he
has this exact set-up on it.
So, that's nice and reliable,
because you haven't got
a quick-release lever, you
can crank those bolts up tight
to stop things moving.
But the real key with
the horizontal drop out
is to making sure that nothing moves,
and of course so you can get
that correct chain tension,
is a chain tensioner.
Now, not as a chain guide
or a chain tensioner that
you might see on a downhill
bike or an Enduro bike,
these are very different.
Their job, very simply, in
the horizontal drop out,
is to move the wheel axle to position
that tightens the chain just enough.
And it holds them there,
then you secure your wheel,
and they can't actually
move in any further.
So they're very stiff and
at times you get ones
built into the frame,
like this one on the Canyon Stitched,
but then you get old-school
ones known as chain tugs.
Now, chain tugs go on the
other side of the frame
and they actually pull the axle,
as opposed to pushing the axle away,
so the effect is basically the same
they're just a little more fiddly,
and they used to be really
common in the BMX world.
Although, most manufacturers
now, when they spec
a dirt-jump frame, they'll
be using integrated ones,
so they're known as chain tensioners.
Nice, simple set up.
Of course, if you have got
a bolt set, it does make it
a lot more secure and less likely to slip,
but slightly more of a
pain if things do slip,
'cause you need to get
the Allen keys out to
get it back up in the right place.
That's about it, I think.
Alright, next up is from Crayrenee.
"Hi Doddy, I've just purchased
a 2019 Trek Remedy 8"
Very nice bike, that.
And it comes stock with
800 millimeter bars.
I am a female rider standing around 5'7".
I've had it for two weeks,
but I'm wondering if
they are too wide for me?
What would be a good length?
Also, can you please explain sweep
and other terminology in
regards to handlebars?
Love the videos, keep them coming.
Thank you. Yeah, and we will.
Right, so let's start off with this.
Well firstly, let's it's a nice bike.
Secondly, it's really cool that
it comes with full length bars.
The reason I say that is,
there is no sort of
consistency in manufacturing
with the types of bar specs on bikes.
In an ideal world,
to save those who produce all these bikes,
it would be better if
they produced them at,
in my eyes at least, at 800 mil
and then you could chop them
down to your preference.
Because really there is no right and wrong
as far as bar width goes.
It is down to preference.
Unlike in the road world,
where it is based on your frontal position
and comfort and all that sort of stuff.
In the mountain bike world,
there are a whole bunch
of different reasons
why you'd want different height,
different sweeps, different width bars.
Now typically a smaller
rider may have a narrow bar,
and a taller rider might have a wider bar,
but it's not always the case.
I know plenty of shorter riders
that love full width bars.
But if you're unsure, what
you really want to do,
is experiment first
before you trim them down,
to get you preferred sort of width.
Now I would take a wild
guess, that your height
if you're unsure, try
anywhere from 720 to 740,
that might be a good place to start.
And what you just simply want to do
is just move all of your controls in.
So don't chop your bars down
and move all your controls in.
Measure it. You could even
go a millimeter at a time,
until you get to a place that
feels about right when you're riding.
Now it's not quite the same as
actually chopping the bars down
because you'll find when you
got your bars at full width
and they are chopped down
you'll move your hands
around on those bars.
And when you do this and
the bars aren't chopped
and the grips are just in,
it doesn't quite feel the same,
but it does give you a good
indication of the area.
And now something else worth trying,
is just asking loads of other
riders similar heights to you.
Throw it out on a Facebook group;
there's lots of riding groups
and there'll be some in your area.
And just say "hey guys & girls, I'm 5'7"
and currently I'm riding 800mm bars.
I'm not sure if they're right for me.
What length is everyone else riding?"
And just see and you'll get
a good indication of riders
in a similar ball park to
yourself what they're running.
But I do reckon somewhere
720, 740 might be about right.
But of course, it is down to you decision,
so hopefully you'll get
that sorted fairly quickly.
Okay, so as for terminology
with handlebars,
so let's look at these bars on screen.
And the first thing we're going talk about
is the diameter of the bars.
Now the clamp area is
where they're talking about
and typically come in two sizes,
so 31.8 millimeters
and 35 millimeters.
Now 35 obviously is quite a lot fatter,
and you might think a lot heavier,
and a lot stiffer, and the rest of it.
But actually they are fairly close,
and a lot of manufacturers I've spoken to
say there's not that much
difference between them.
But there's such demand
for people wanting those
two different feeling bar setups,
so they offer 31.8mm and 35mm.
Now the rise, this is the next one.
This is where the rise is measured from,
simply put is where
the clamp is on the bar
upwards to where your hand position is.
So you get various
different rises available,
and that can tune your riding position.
So the typical ones you tend
to get are zero degrees,
so that would be like a
cross-country flat handle bar.
Now, I say cross-country,
it tends to be on cross-country
bikes you see them
but it isn't necessarily a thing
that makes it a cross-country bike.
It just happens to be a flat bar.
Then you'll get a 10 degree
option, sometimes a 15, a 20.
You don't tend to get 25,
you'll go straight up to 30.
And then strangely, it goes
up to 38, rather than 40.
Not quite sure why it
is 38 and not 40 or 35.
A question I'm going to
have to find out for myself.
But 38 seems to be the upper end of that.
Now you'll get upsweep and
then you'll get back sweep.
Upsweep is literally just
the angle the bars can
basically angle up at
towards the end there.
And back sweep is the same with
the bars curving backwards.
Now the reason, especially for back sweep,
is think about your hands
and the position they
actually are on your wrists.
If you hold them out,
they're not straight.
So holding a straight
handlebar is quite unnatural
and will put your elbows in
quite an awkward position.
Now some riders, like a really
aggressive position on bike,
and they'll want less back sweep.
And the reason for that is
it puts your elbows out in that
aggressive riding position.
But it's not as comfortable
for all around riding,
so the more back sweep you have,
the comfier the bar is going to be
for long durations in the saddle
and the less it has the more
aggressive it's going to feel.
But again, it's down to what
you like and what you feel.
There is no right and wrong.
Now of course you can also,
especially with the higher bars,
you can roll them backwards or forwards,
to get a similar effect
basically, and different effects.
I quite like rolling
my bars quite forward,
because I like that position
of having my elbows out,
but that is a total
personal preference thing.
I often get people saying
"oh, is your bike too small
so you have to roll your bars forwards?"
No, I just like rolling my bars forwards.
Always have, probably always will.
It's a preference thing.
If you look at Gee Atherton's bike,
his are almost the other way around.
You know, so, you could argue
that if you go for a cruise,
it can make your elbows go down,
but he certain doesn't
ride a bike like that,
so it's just a personal
preference thing, that is it.
And hopefully that answers some
of those questions for you.
Okay, next up is from Zouler CRO.
Can I wash around bearings
with normal water?
Yeah, absolutely.
In fact, just using water is probably
the safest way you can
wash just around bearings.
It's not going to get
all of the muck and stuff
away from around the area as
using a dedicated cleaner,
but it's definitely a lot
safer because cleaners,
although they're not degreasers,
do have agents in them that
can break down those greases.
So you have an inner and outer race.
Then the seals on either side.
And on the inside, although
different to these,
you'll have a set of bearings,
basically that spin around.
The idea of these is the
fact that the bearings sit
inside in their own sealed
microclimate of grease,
basically, so they're nice and sealed
and do their own thing.
Now this works very well,
until you get degreaser or
any other sort of cleaners
into that, that can break it down.
Then it's a matter of time before
they just start rattling around loose,
and then they'll start wearing.
The bearing surfaces will pit
and become very grindy.
In fact, that one is an old
grindy one, I've got there.
And then at that point,
they'll start rattling
and they'll get loose.
Then you'll get play in your hub.
Then it's time for new bearings.
So it's really important to make sure
you do keep them maintained
and you clean around them.
Now a little hack that you can do
to increase the life of your bearings,
is by carefully taking off the seal,
using something very fine
like this pick I'm using here,
and then you can see the
bearings on the inside there.
Now if you take both sides off,
you can purge grease through.
Make sure it's nice and clean in there
and there's no grit in there.
I can actually see that there's
nasty stuff inside there.
Apply fresh grease and then
get those seals back in place.
Then your bearings, provided
they were just a bit lacking
in the grease department,
should feel a lot smoother,
and will fend off water
and all the horrible stuff a lot longer.
Okay, next up compression related,
or lock out related in
fact, from Tobias Fasth.
My son has Rockshox
Sektor RL Solo Air Fork
with remote lockout on
his Rock Machine Blizzard.
The problem is the lockout doesn't work.
The remote turns the blue
disc on the actual fork,
but there's no different in the travel
or damping no matter if
the lockout is on or off.
I've tried searching
for possible solutions,
but without any luck.
I've done a lower leg service
but never anything to
the damper or upper legs.
Alright, Tobias, I think this a bit
of a process of elimination here,
so if you remove the cable from that dial
and just see by turning the
dial if it does anything,
cause you could find it's not
being pulled around quite enough.
If that's the case, then you
might need a new inner cable
because it might be gunked
up inside that housing,
and it's not able to pull it through
enough to turn that
dial all the way around.
If it is turning all
the way until it stops,
and it's not having any
affect on the compression,
then it's likely to be
something to do with
either the oil level in there,
like perhaps there's not
enough oil in that damper.
It could have leaked. A seal
could have burst at some point.
But you would notice that
when doing a lower leg service
cause some of the oil would have
purged it's way through into those lowers.
Or perhaps when you did
a lower leg service,
it could have already been in there
when you emptied the oil
out and you didn't notice.
So that is a possibility,
and worth checking on.
But I did hear, I looked on
a few forums a while back,
and I remember from theRebaFork,
where she uses exactly the
same style lockout dialer,
and other sectors from a few years back,
some people having problems with
the spring on the inside,
basically, that activates that,
just popping out of its seat.
Now if you're unsure
about taking them apart,
I can't actually tell you
because I haven't taken one apart myself,
but I can just imagine
how that actually works.
If that has happened to you,
and you're not comfortable
taking it apart,
pop to your local bike shop and
explain what I've just said,
and it might be a known problem
that suspension tuners are aware of.
If not, if you're not sure
about it, take some photos of it
and then you need to
let your local Schwaben
or Rockshox center to help
you sort this problem out.
And it is a problem that can be sorted,
and generally it's something quite simple,
so hopefully you're lockout
will be sorted soon,
and your son will be back on his bike.
Okay, next up from Zero Grandark.
Hi Doddy, I had a crash
recently from a jump.
And I didn't disalign
my rims but my tire has.
Okay, so you mean you didn't
buckle or damage your wheels,
but your tire is, so I guess,
it's wobbly on the rim.
What can I do to fix the tire?
Well hopefully, your tire has just come
unseated from the rim.
So the rim will have a profile like this,
and at the end of the rim
it has a kind of mild hook
and the tire basically hooks into that.
If it's popped out of that,
part of the tire will bulge,
and it will move around.
So the first thing you need
to do is deflate your tire.
Give it a good sort of work it around,
and make sure it is in
place and reinflate it.
And hopefully it will pop into place
and everything will be fine.
If doesn't and there is the problem that
it isn't quite popping into place,
get some warm soapy water,
put it on a soft brush,
and brush it all the way
around the bead of the tire,
obviously with it soft,
and then try it again.
And it might be that
there is a bit of friction
between the tire bead and the rim itself
and it couldn't quite pop into place.
Obviously by jumping
funny or landing badly,
you could have just
pulled it out of place.
And that will sometimes cure that problem.
It's definitely a problem that occurs
when you're setting up tires tubeless,
so that's something I
often recommend with that.
If it's not, then quite likely
the things that's happened
is that your tire has become delaminated.
So the tire build itself is made up of
seven different layers
which are bonded together.
Now if any of that is torn or
rips apart, you get bulges,
kind of like you can
in motor vehicle tires,
but generally if you get
delamination on a car tire
that's a pretty big bad thing.
On a bike tire, it's not quite as bad,
but you get those annoying wobbles.
And if that's the case, unless
you're happy riding with it,
which I probably wouldn't,
probably time for new a tire.
So hopefully that's not your problem
but good luck with that.
So there we go, there's
another Q&A session in the bag.
If you've got any
questions or any comments,
leave them in those comments below.
Let us know what you think.
Let us know what you want to know.
For a couple more tech related videos,
get them up right down there
at the bottom of the screen.
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Cheers, guys.
