(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
at the bottom of the page.
Don't forget to use our hashtag, #askGMBNTech,
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.