- Welcome to Ask GMBN Tech.
This is our weekly clinic show
where you guys get to send your questions in
via email to the email address on the screen right now
or in the comments after this very video
using the hashtag askgmbntech.
Hopefully, we get to answer yours next week on the show.
Straight in, the first question is from Velichko Golev.
Hi, Doddy, I'm looking to build up
a new do-it-all hardtail, a steel one.
On one of the weekly shows where you showed
a new hardtail Cotic, you said it was good
they kept the chainstays relatively long
and not overly short because it wasn't good on a hardtail.
Can you please elaborate on that?
On the top of the list for me is a frame
that's got a Stanton Switchback
with a very short chainstay of 415 millimeters.
On that note, have you ridden one?
What are your thoughts?
Let's take this from the beginning.
I wasn't necessarily saying that short chainstays are bad.
I just think that people get carried away
with the obsession that a short chainstay is good.
Now, short chainstays do have positives.
They also have negatives, as do long chainstays.
Let's just go and have a look at some of those now.
Here are just a few points on
the short chainstay and the long chainstay.
Of course, there are other variants
in the bike that do affect these,
but this is just generalizing here.
On a short chainstay bike, your bottom bracket
is nearer to the rear wheel axle,
which means that's your pivot point
when you do things like a manual,
or picking up the front end to do a bunny hop,
or anything like that.
It's gonna feel easier and a lot zippier
to actually pick that front end up
on a short chainstay bike.
On a long chainstay bike, your bottom bracket
is further away from the rear wheel axle,
so unless you raise the front end of the bike,
or your high rise handlebar,
it's gonna feel harder to lift the front end
compared to the short chainstay.
Generally, the bike is gonna feel
a lot more agile and zippier with the short chainstay,
and more reactive to pedal input and what you're doing
with that short chainstay bike
compared to the long chainstay,
which will feel more stable and more planted.
Some people will get on a short chainstay bike,
and they will love that feeling.
Other people might find it's too reactive.
Again, some people will find the stability
of a longer chainstay maybe a bit tame,
and other people will love the fact
they can push it really hard.
Now, when you put it to steep climbing,
the short chainstay, because you're sat
almost on that rear wheel axle
when you're going up the climbs,
you've got an immense amount of traction,
which is a great thing.
However, because that back end is so short,
and you're centered right over
that pivot point of the bike,
unless your front end is really long or really low,
you're gonna find the front end wanders around,
and it's quite hard to control it,
so you're gonna need to either lower those bars,
angle your saddle down, or perch right on the end
to keep the weight on that,
whereas a long chainstay bike balances your weight
nearer to the front of the bike,
so there's a bit more weight on the front end anyway.
It does climb better like that
unless you're talking about
the most ridiculously steep stuff,
in which case, if you're out of the saddle,
then, because of the long chainstay
and the wheel being further away from you,
there is a chance that that could wheelspin.
It goes both ways with all of these things.
The Stanton you mentioned, the Switchback,
that's a very good bike.
They're really nicely made frames,
but I just want to draw your attention,
because you talked about the short chainstay on that.
I have ridden a bike that goes against the way I feel,
and that's the Kona Honzo.
I rode the carbon one.
I think that's got a 415 chainstay out back,
something like that, but that's with 29-inch wheels.
Effectively, it's even shorter,
but the front end is really long
and really low to counter that.
That particular bike, I got one,
and I was like, "I'm not sure,
"it's not gonna suit the way I want to ride."
Actually, it felt amazing.
It's not the sort of bike
I think I would go out there and pick.
I did also find, because the chainstays
were so incredibly short on it,
it's quite a harsh feel on the back end,
such a rigid feel.
Some people are gonna love that,
but I felt, because it was a carbon frame,
it is very stiff anyway,
that I could've done with the chainstays
being a bit longer, but again,
it defeats the purpose of that particular bike.
I wasn't saying they're bad.
I just think they're different,
and I prefer a longer chainstay myself.
Next up's a bit of a wobbly one from Benjy Bro.
Hey, Doddy, what is wrong when I brake
with my front brake, and my front tire moves
to the side with the disc?
Okay, there are a number of things it could be.
The obvious one would suggest that
your wheel is loose within the forks.
That could be the quick release
isn't tightened sufficiently, or your quick release axle,
or your bolt through, depending on
which hub system you have on there.
The first thing to check is that.
When you brake, and that is loose,
basically, your whole wheel will move.
If it's not that, then there's a chance
the bearings of the actual hub could be loose.
If they're cartridge bearings,
that suggests that they're worn out
because the idea of cartridge bearings is,
you don't adjust them, you just take them out,
you put new ones back in.
If it's cup and cone bearings,
then stop riding it now, get them adjusted,
because it sounds like they're loose.
Then you should be okay again.
If you ride with them loose,
you will damage them, and you can pit the bearings,
which means the bearing surface
actually becomes slightly lumpy,
so the bearings will never run smoothly around it.
You don't want to do that because
that means new hub time.
There's also, when you're down there,
you may as well do a safety check.
Check your disc rotor bolts are all tight,
because sometimes, when you hold that front brake on,
you rock it backwards and forwards,
and there can be a little bit of movement.
It can be from a loose disc rotor.
Make sure that they're all tight.
Ideally, use a bit of thread-locking compound
on each one of those six bolts.
While you're at it, check the front brake caliper
is tight as well.
Hopefully, that should solve your problem,
but also, just to make you aware
that your brake pads themselves can move a tiny bit.
We're talking two or three millimeters
within the brake caliper.
Even when they're held on, there is some movement there,
so just check all of those things.
Of course, the important ones,
check your axle is tight and safe,
and see if there's any play in the actual wheel hub itself.
Next up is from Remco Vlaminckx.
Hi, first of all, great video.
I've got a question now.
I'm trying to find the Mountain and Trail King,
but it seems I can't order the 2.6 ones
you have in your video.
I need some new tires for my mountain bike holidays
in the north of Italy, so can you tell me
where I can order them?
Firstly, when I made that video last week,
they literally had just landed in the office.
They're hot off the press, they're brand new tires,
so they're only just going into shops now.
I think, if you go back to shops you've checked,
you might find that some of the tires
have started getting there.
We are aware that, the Trail King,
there is a slight delay in shipping,
so they're gonna be a little bit later getting there,
but the Cross Kings, the Mountain Kings,
and the Baron Projekts, they should all
be on their way to European shops
any time around now, so hopefully,
you can get that sorted for your holiday.
Next up, from Crysonix.
Hi, Doddy, I've got a three-by-nine groupset,
but want to change it to a one-by system.
Do you think I can swap the crankset to a one-by-nine,
or would I have to change the whole groupset itself?
Am I okay with gearing for the trails I ride?
Firstly, you haven't listed the type of trails you ride,
so going one-by, you obviously lose out
on your higher and your lower end of the gear,
so if you think you don't use those enough,
you spend most of the time in the middle,
then yes, you can get away with that.
For the other part of the question,
which the three-by to one-by,
yes, you can ditch off all those chain rings
and get yourself a one-by specific chain ring
to go in the middle there.
There are two things to bear in mind.
Firstly, you need to bear in mind
the clearance you have between
where that middle chain ring is,
and where your chainstay is.
There will be a limit on the size
of middle chain ring you can have
on your particular bike.
Now, I can't imagine you're gonna want to go
bigger than a 34, and I think a 34
will fit on most bikes these days,
but you will need to check that.
If you're unsure, take your bike
to your local bike shop, and at least
they can have a look for you.
Now, when you're buying a one-by specific chain ring,
you need to buy something that uses
that narrow wide profile, or the alternative profile
used by MRP and Praxis, which is the Wave ring style
so the teeth are actually slightly offset
to actually hold against
the in and outer links of the chain.
The reason for that is because,
by losing the front derailleur off there,
you need some sort of chain retention to keep it on there,
and they do the job perfectly well.
You can save yourself the money
on buying all new stuff by just buying
a single chain ring, and that should work fine for you.
Sort of a road-based question here from Andrew Frink.
As a roadie, it always surprises me
that you mountain bike guys
haven't figured out deep section wheels.
It seems like Nino would be going fast enough
to get some advantage out of them.
Is there a UCI rule that limits the allowed wheel depth?
No, I don't think there is a UCI rule
that does stipulate anything to do with that.
I know that, in downhill racing,
one of the rules is the wheels must be same size,
so they can't have a 29 and a 27-and-a-half, for example,
but I don't think there's anything on wheel depth.
Now, deep section rims were something
that were toyed with in the early to mid '90s.
If you look on screen now,
you can see a Yeti here with
some Hed carbon fiber deep section rims.
Whilst these things were really good,
and unquestionably, they can be
slightly more aerodynamic, you gotta look at
the way that most riders are riding.
I do agree that, in some places,
some of those cross country guys
might be able to get an aero advantage,
and I do think that's something
that we can probably look into later on,
but the issue with the deep section wheels
fundamentally comes down to how stiff that wheel is.
Now, if you take a look at some modern carbon fiber wheels,
some of them are so stiff,
they're almost unbearable to ride.
Because of that, you imagine how much stiffer
the wheel would be with a deep section rim.
It's just gonna be incredibly stiff.
Now, people want stiff wheels,
but they gotta be stiff in different ways.
They have to have some level of compliance.
A little bit of vertical compliance is something
that some carbon fiber wheels do very well.
If you do that with a deep section rim,
I just don't think you're gonna be able
to get the same thing.
I might be completely wrong here,
but I can't see why no one
has pushed that design further since,
and really, the deepest section ones you tend to see
are the ENVEs, I reckon.
They're quite a high profile,
but I don't think you're gonna get much higher than that
on mountain bikes, but perhaps
that's something to look into.
They are a dynamic thing,
'cause the skin suit thing's definitely coming up again.
Obviously, all the cross country guys use skin suits,
although skin suits, hilariously,
are banned in downhill racing,
which is a race against the clock.
The riders, in the moment, are wearing stuff
that is getting closer and closer to skin suits.
If you look at Loris Vergier's Fox Racing kit,
that is so tight, it's getting there.
Troy Brosnan's racing pants, check those out.
They're so tight.
These guys are pushing the limits
of what they can get away with because,
obviously, it's gonna be more comfortable to ride in.
You haven't got stuff flapping around.
It definitely is gonna save them time.
Perhaps we need to look at
some sort of speed advantages feature.
A noise-related one from Ali Helmy.
Hi, Doddy, thanks for the vids, as always.
I have a very consistent ticking noise
when I'm pedaling any harder than a casual cruise,
but only while pedaling.
I heard it might be related to loose drive chain parts,
so I went around with a torque wrench,
re-tightened by pedals, cranks,
front and rear gears, and it's still there.
Please help, it's driving me mad.
Okay, so creaks and clicks, they literally,
they can drive you mad.
I do sympathize with you.
There's a number of things it could be.
Obviously, make sure you check all the little things
like the chain ring bolts.
Even inspect your chain.
If there's any links that are bent,
twisted, or even perhaps open,
it could snap, so it could be something like that.
Also look to see if there's a stiff link.
Of course, it's only gonna show up when you're pedaling.
If it's not your drive train,
not anything you can immediately see,
the next thing you want to do is
start sitting down and standing up,
see if you can make the noise
happen in different situations.
If it's only happening when you're sitting down,
then it could be something saddle-related
because you put a lot of strain
through that saddle when you're pedaling,
so check the saddle rails, check the saddle clamp,
check the seat post clamp itself,
check all those sort of things.
Next up, of course, is where that torque
goes through on the bike.
Check there's no play in your pedals.
Check that your cleats on your shoes,
where they engage with the pedals,
check that they're on properly,
they're not moving around.
Check the jaws on the pedals,
if you're using clipless pedals, are okay.
Check the cranks don't have play.
Check the bottom bracket doesn't have play.
Check the bottom bracket, it isn't loose, it doesn't creak.
It's literally, you're gonna have to be systematic
in the way that you work these things out.
A good way to start often is to clean your bike.
Clean it head to toe, and then you might
be able to start spotting these small problems.
With other torque-related things
that you might not consider,
check the rear derailleur is tight in the hanger,
and check the hanger is tight on the frame.
Any movement as you're pedaling
is gonna pull, and twist, and creates a clicking.
Check those jockey wheels.
Check your cassette is tight on the rear hub.
Check that the cassette, there's no play in it
which would suggest the free hub body is loose.
That might need tightening.
Literally, I'm sorry that I can't be more specific,
but it is literally, you're gonna have to work
your way around these things until you find it.
I really do hope you find it,
'cause it can drive you mad.
If you do manage to do that,
and you sort your problem, if you fancy playing
a little mean joke on a friend of yours,
get a ball bearing and a little blob of grease,
and put it on the inside of his handlebars,
and put his bar in plug in.
When he's riding, every now and then,
the ball bearing will come out of the grease,
roll around in the handlebars,
drive your friend mad, and then when he puts his bike down,
it'll stick back in the grease again.
Vicious little trick.
I had that one done to me,
and it drove me mad for about three weeks
until I found out what it was,
but it's pretty funny, I think.
A shocking question from Jeremy Olson here.
Have shock manufacturers tried
using nitrogen instead of air in the shocks?
Pressure chambers filled with nitrogen
don't fluctuate their pressures nearly as much
as air when they warm up or cool down.
Yeah, and they do.
In the main air chamber that you inflate yourself,
your body weight is the main spring,
that's not, so I'm not sure if you mean that or not,
but that's just conventional air.
That's not subject to the same heat up
and cooling down in the same way
as the pressurized chamber that's behind the IFP.
That one is often nitrogen on a lot of shocks.
You can alter the boost pressure in there
additionally with a regular shock pump,
but it has to be charged up initially,
which, I mean, I haven't got the tools
to do that sort of stuff.
If we have to mess around with shocks like that,
then we generally take them to the specialists
that have the pressurized nitrogen tools to do that,
but yeah, they do do that, and it's very cool.
There we go, another Ask GMBN Tech show in the bag.
Again, any questions, fire them in to the usual address,
and add them in the comments below.
For a couple more great videos, click down here
for Fat Versus Plus.
That's a geek edition.
That will tell you everything you need to know
about fat bike tires, how they feel,
how they ride, should you even ride them,
what they're good for, what they're not good for,
against plus tires.
Of course, plus tires are somewhere between
a regular fat bike tire
and a regular mountain bike tire,
so you gotta decide which one suits you,
or maybe they don't.
Click down there for that one.
For hydraulic disc brake setup hacks, click down here.
There are little handy tips
just to get your brakes feeling absolutely primo.
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