- Welcome to Ask GMBN Tech.
This is our weekly Q&A show.
You get to ask questions related to technical stuff
with mountain bikes and hopefully we give you
those answers that you need.
So if you wanna get involved, email us on the email
address on the bottom of the screen there.
Make sure you use that hashtag #AskGMBNTech
or alternatively just get involved
in the conversation below in the comments.
(metallic percussive sound)
A spoke related question from Moejoe33:
Andrew correct me if
that sounds weird if you're saying that.
I'm gonna say it myself.
Doddy, correct me if I'm wrong but aren't straight-pull
spokes harder to tighten once they're assembled
to wheel with tire installed?
Doesn't some of them spin when tightening?
I haven't seen straight pull hubs with grooves
or small notches to prevent this.
It would be better if they were on spokes as well.
It'll catch/bite on both parts to prevent spinning.
Okay Moejoe33 yeah um you're kind of along the right line.
So straight pull spokes there are actually two types.
There's bladed and then there's round.
Now if you've got bladed spokes, you might think
that they're only for road bikes but they are
in fact for mountain bikes as well because they can
add strength at no additional weight.
They're stronger fore and aft
and they offer a bit of flex side to side.
Now if you've got bladed spokes there is a tool
like this one from Park
designed specially to hold, obviously it's different
sizes here, different options for different style spokes.
Hold the spoke still, adjust the nipple, nothing moves.
Job done.
However if you've got a round spoke then
you're not gonna be able to use a tool like that.
So in an ideal world when the wheel is put together
there'll be some sort of assembly compound
which is essentially grease with particles in it
to increase friction and traction, I guess.
At the head of the spoke there that would be used
of course and then cleaned off
so you can't get any near any braking surfaces
but if yours hasn't got that then you need to look
at the other end, so where the nipple screws
onto the thread on the end of the spoke itself.
Get some penetrating oil or some 3-in-1 or even
a decent chain oil and let it drip its way in there
work its way in, and you'll find that you should
hopefully be able to do this because there's way less
torque at this end than there is already on the end
of the spoke that's in the part of the hub itself.
You'll find that they're generally quite wedged in there
and if you can make it easier for yourself
on the threaded end, you should be able to adjust it.
But obviously that doesn't always happen
and sometimes you're gonna get a spinney spoke.
So I had to look this up because I've not actually had this
problem that hasn't been on a bladed spoke in the past.
And you can actually get a tool
this is it on screen now.
It's quite a specialist tool
it looks a bit like a cable tensioning tool
from Park Tools, something like this in fact.
It looks a little bit like this, it has this section on here
in which case it would hold the spoke itself.
Of course you couldn't use this,
it's not designed for that purpose.
But it's quite a specific tool to get and I'm not sure
it's actually the best thing.
In my eyes I would probably just get a pair of pliers
on it and hold it but of course I wasn't too sure
about that because I haven't done it.
So I actually buzzed Calvin from Park Tools
and this is what Calvin said.
He goes yeah, it's a tough one.
Just grab the thing.
If it's stainless steel, straight up use pliers and hold
them tight, you will not mar the spoke.
Again I think he's emphasizing the point that if you
let it slip, then the spoke can twist and get scarred
on the inside there.
He said the special made tools do the same job and
in theory offer better leverage.
Painted spokes will get marred if you grab gently and turn.
Make sure you grab tightly even on painted spokes.
So it goes to show you can use pliers but of course
you gotta make sure that the spoke cannot turn
and then you should be okay.
If that's your problem then hopefully that's the solution.
Good luck.
(bike wheel spinning)
Next question is from Nixobis.
Hi Doddy, can you tell me if having a spare tube
in my backpack for my tubeless makes any sense?
I've often heard that we have to have one in case of
a big tear or if we smash the valve, etc but my tire
is full of bramble thorns, my tube will die instantly
in inflating if I have to use one.
Well really you should always be carrying one
as a spare part when you're going on longer rides.
You could end up using it, your friend could end up using it
or you might bump into fellow mountain biker that needs one.
Given how much they cost and how much they weigh,
it's worth carrying one anyway.
But if your tires have got loads of bramble
and thorns and stuff stuck in them,
then really you should be addressing this
before you go riding because sooner or later your tubeless
they're gonna work into bigger holes and might be a hole
that your tubeless solution is not gonna seal properly.
So it creates a problem in the long run.
So what we always recommend doing here at GMBN Tech is when
you wash your bike or even when you just
return home from a bike,
give it a bit of a once over,
run it around with an Allen key,
make sure everything obvious is tight,
your controls, all the safety related things on there.
Check your chain is clean and lubed,
make sure you haven't got any frayed cables
that are gonna get worse.
And give your tires an inspect.
Make sure there's no slashes in them and any sort
of brambles and thorns and stuff that are in them
take them out, get them out, erase the problem before it
becomes one because it will become a bit of a nightmare.
But also just on that point,
there's other things you can do with inner tubes.
So let's just say you or your friend's unlucky enough
to break an arm, you can do a make due sling
using an inner tube.
It's a pretty versatile thing.
And if your friend, for example, breaks a chain
you can use an inner tube as a make due tow rope
to get him along or her along a section of trail
without having to walk.
Perhaps if you get down to fire roads you can cover greater
ground to get back to civilization in order to fix that
problem, you can use it as a tow rope.
Now of course you can use it in other repairs as well
like lashing things together.
I know like if your saddle snapped off the rails you can
lash it on with a inner tube, tie it in a knot, job done.
So yeah I think it's always worth carrying one
and I definitely think you should go back to your tires
and get all those thorns out.
Make it easier for yourself in the long run.
(bike wheel spinning)
Okay, next up is from Paul Burn.
Hi Doddy, do you reduce air pressure in your shocks
and tubeless tires when traveling by plane?
I'm off to Rotorua at Christmas and have heard mixed views.
Cheers and hopefully see you guys
in Oz and New Zealand someday soon.
Generally I do but not by much and it's more a fact
of quitting the parts, I've got quite big bikes
and it tends to be to get them in the bags themselves.
Our latest bags actually are big enough, I don't need to do
it anymore but typically with a 29-er like that
Nukeproof Mega in the XL is massive
and when I took it out to Whistler last year I had to
deflate the forks in order to get the whole front end
in the actual bike bag.
And then tires, same thing.
29 inch wheels and my older bike bag
didn't cater for 29 inch wheels so I had to deflate them
slightly in order to put them in
but I'd never deflate too much because that makes it
a bit of a chore if they come unseated
and the tubeless sealant goes everywhere.
Generally, I wouldn't.
And actually, you don't really need to despite what
the airlines will tell you.
I'm not really sure why they tell you to do it
but the plane is pressurized.
Like the storage area, the cargo area is pressurized.
There's no need to actually do this.
But I did have a look online about this
because I did wanna know a little bit more
despite what the airlines say.
And just talking about pressure and atmospheres.
So planes fly at a highest of 12 kilometers
that's about 7 and a half miles
and at sea level air pressure is 14.7 PSI.
And at lowest with elevation I think at ten thousand feet
it's about 10 PSI.
So if I understand in theory your tire pressure can raise
by atmospheric pressure difference.
So let's say it was at 50 PSI at ground zero sort of thing
when you're up top there it can increase by ten thousand
feet by 10 PSI so that would be outside the plane
of course in an unpressurized environment.
So you're talking a nominal amount.
At most it's gonna be 14.7 PSI is the maximum.
Which if my rubbish science is correct,
that's nothing critical, nothing to worry about.
And yeah, I definitely hope to make it over
to your side of the pond at some point
especially New Zealand actually.
Australia, I've been pretty close before,
and I definitely want to visit there,
it's definitely on my places to visit
but I really want to come to Rotorua for when Crankworx
is on I wanna see that gong show, see it.
I've seen Crankworx in Europe,
I've seen Crankworx in Whistler,
I wanna see how it's done in New Zealand.
And if I fly over then I definitely won't be lettin my
shock and fork and tires down,
I'll leave them as they are thank you.
So uh, there you go!
Actually if anyone actually genuinely knows or
are good with mathematics and stuff about what does happen
in pressurized environments with tire pressure,
shock pressures, I would love to know.
I've tried to have a bit a look at this
and it makes no sense to me.
I think my rudimental version kinda makes sense
so if anyone does know, let us know in the comments.
Really interested to know.
Be kind.
(bike wheel spinning)
Next question's from Blake Ashdown.
#AskGMBNTech I've got two questions
hopefully you'll know this lot
but my bottom bracket's creaking.
I've removed it, cleaned it, re-greased it, and replaced it.
It's worked for about one ride
and now it's back to creaking.
Should I just start working on it or
keep going until it stops?
And second question, what does Boost do?
Example, Boost Wheels.
Firstly let's think of the bottom bracket.
So of course with this sort of thing
it's definitely the age old thing of having to do the
process of elimination to work out exactly what it is.
But suggesting by saying that you've taken your bottom
bracket out and put it back in,
in that process it has been temporarily cured.
So that tells me that it's probably not
the bottom bracket itself that was creaking.
I suspect it's something else like the crank
or some other part that you tightened
or adjusted in putting it back on.
Now you haven't said exactly what sort
of bottom bracket it is.
If it was a press fit bottom bracket there's
a good chance those cups could be creaking
in the frame in which case you'll wanna use
a press fit retaining compound.
That with the shim and everything is cleaned
and there's nothing damaged, that will cure the problem.
At least until the bottom bracket is dead.
If you've got a bottom bracket for example
with a tapered axle on there then it's probably the crank
that is at fault because the soft aluminum crank
against the steel axle, if it's really loose it can
stretch and you'll never tighten properly and of course
any metal to metal movement you're gonna get translates
into creaking at some point so that could be it.
But also, check your pedals, check your chainring bolts,
check the chainring direct down to the crank
if it's direct mount, check every single part.
And then of course there can be other parts of the bike
that creak under torque that you can confuse
with the bottom bracket.
I mean it does sound like you do know your way around a bike
so not trying to patronize you but there's a lot of parts
on a bike that can creak and you would never realize.
It can even be saddle rails that you don't notice
if you stood up but you notice when you sat down.
And you might not be thinking about that because
you concentrate so hard on one part of the bike.
It could be your seat collar.
It could be the freehub body on your rear hub.
And it can even be, and I've had this before,
a rear derailleur where it's been the tiniest bit loose
on the hanger bolt into the frame and that creaks
but it only creaks under a certain amount
of crank tension and torque.
And it's confused the hell out of me in the past.
So just make sure you've checked everything
because there definitely will be a cure for it.
And of course the final one is if your actual bottom bracket
is knackered and somehow is just massed by grease
or something you put it in.
It might just be your bottom bracket that's knackered.
So good luck with that one.
It's a horrible thing to have to work around and try.
In a kinda weird way I actually really like trying
to find those creaks 'cause it bugs the hell
out of me and I really wanna stop them.
As for your question about Boost, Boost essentially is
a slightly wider platform.
So upfront, hubs used to be 100 millimeters, Boost is 110.
And that basically compensates,
gives you a bit more clearance.
But it doesn't really do too much upfront.
It's out back it makes the big difference.
So conventional rear hubs were 135 millimeters or 142.
Boost is 148 so although it's only a nominal amount
at the back of the bike, it enables the cranks to be
very slightly further apart.
You get that better chain on, you get more clearance
around the bottom bracket.
Arguably your frame could be stiffer because it's got
a wider stance there and of course wheel manufacturers
can build stronger wheels because they can put the flanges
on the wheels further apart which means the spokes
have a better bracing angle so it's more of a pyramid.
So there's lots of benefits to have Boost
but don't worry if your bike hasn't got Boost,
it's not gonna suddenly not ride well.
There's nothing wrong with non-Boost stuff,
it's just Boost is a logical progression to have
on any bikes you have moving forward down the line.
(bike wheel spinning)
And last question this week's from Phillip Au
GMBNTech, the problem that I have that wasn't addressed
in the video, the video by the way is
"Looking after your riding kit", is how to
dry out the hydration packs properly post-washing.
There always seems to be a bit of water left behind.
There's a couple of ways you can do this.
Personally, I roll mine out and then when I put it in the
fridge it kinda doesn't really matter if there's a few drops
in there but of course having it completely dry is the best
way for no bacteria to grow in the first place.
So have a look on screen, this is a specific dryer.
It's basically like a coat hanger for your hydration pack.
You put it inside, it springs out, opens it all out
and you can hang it upside down and it enables all
of the water to evaporate and then of course
you wanna make sure it's treated with either some
sort of sterilizing fluid like a Milton baby bottle cleaner
or bang it in a fridge or freezer to make sure any
of that is killed or stays nice and cold.
(bike wheel spinning)
So there we go.
There's another Ask GMBNTech session in the bag.
Hopefully I've answered some of your questions.
If you've got any questions, let us know in those comments
below and if you're an expert on altitude and air pressure
I'd definitely love to know your response
to the earlier question as well.
For a couple more great tech related videos,
click down here on repairing a tubeless tire puncture
and click down here on everything you need to know
about selecting and replacing a chain and cassette.
As always, don't forget to click on GMBNTech to subscribe
and of course if you love mountain bikes and tech
give us a thumbs up.