- Okay, so we're back with another Ask GMBN Tech.
This is where answer all of your
mountain bike tech-related questions every week.
So, please continue fire 'em into the comments below
or the email address on the screen.
And we'll kick you off with Pat Maher.
Hi, guys.
I loved those Pacenti bars
you had on the show last week.
My bike came with Pacenti DL31 Rims
when it was advertised as having WTB I25's.
I can't really find out much about them
as there's no reviews on the website or anything.
Have you got any clues about them?
Have I been ripped off?
Well, first, you know you haven't.
The Pacenti DFM5's and Fin One rims are really, really good.
They are predominantly aimed at Enduro.
They're quite tough, not necessarily the lightest rim.
But that's good because they're durable.
Now the reason you've probably not seen them on this site
is either they're an old model or,
perhaps, they're an OEM-specific rim.
Which mean they're designed for bottom manufacturers
to spec on the bikes rather than the stuff
you would buy after-market sales in the shops.
Now, something really cool about Pacenti.
So, the guys behind it, his name is Kirk Pacenti.
He's actually the reason that most of us
are running 650B wheels or,
as you and I would probably know as,
27 and half inch wheels.
So, 650B.
The actual measurement is done in centimetres
and it's a bit of a French sizing.
The C refers to the width.
The 650 refers to the actual size of the wheel.
The actual size is nearest to the 27 inch
than it is to 27 and a half, but for ease,
to fit in with the 26 and the 29 inch that we already have,
the industry has sort of adopted
the name 27 and a half inch wheels.
Now when 29 came into the scene,
Kirk was quick to sort of realise
that they weren't gonna be for everyone.
They're such a big jump between the 26 and the 29.
He identified that there was actually a size
that would've existed that could be utilised really well
for mountain biking and pretty much the rest is history
because he pursued that to the point
that the industry realised it was such a good idea
and they've undertaken it completely.
So, Pacenti.
So as far as I'm concerned, it is great kit.
So, you're doing no wrong there by having this stuff
and you certainly have not been ripped off.
And next up is a question from Dan Scotney
about this monstrosity on my wrist.
Hi, Doddy.
Got a question for you.
What make is that watch you wear?
Is it custom-made?
I really like and wondering where I can get one for myself.
It's a really, really old Oakley watch.
I don't even know if they still make it.
It's probably about 12 years old.
I got this a long time ago in prior life
when working on Mailbuck in UK Magazine.
And it's kind of ugly, but I love it.
I've always had it.
I did use to wear it on my right wrist
until I broke my wrist pretty badly.
It doesn't actually fit my wrist anymore,
so I ended up wearing it on this one.
And I'm well aware it's not the nicest watch in the world.
It's kind of chunky and just suits me, really.
I am in the market for a new watch, though.
I'm thinking of something black, maybe something sporty.
Perhaps a Kunzite.
Any suggestions, however?
Okay, so next up,
is a pretty in-depth question from Lucas Holecek.
And he's asking because he's found a lot of contradiction,
he says, on various mountain bike forums.
In your opinion, which internal rim width
is ideal for the 2.35 to the 2.5 tyre today
to run basically the common tyre widths.
Shortway, Conties, Maxxis, Maxxis Wide Trail, et cetera.
Everyone is upgrading to 30 plus millimetres.
However, there are some who claim that current tyres
are not designed to work with such a width rim.
How does the terrain affect
the tyres squareness or that sort of stuff?
I have to upgrade my floppy stock Almata rims.
They've got 23 mil internal.
And they surprisingly seem to work quite well
with my 2.35 Schwalbe Magic Marrys.
Should I wait 'til tyre brands catch up or move on?
So, first up, if we look at your wheels,
they are 23 mil internal diameter.
Which is pretty narrow for today's sort of wheels.
And you're running only 2.35 Schwalbe Magic Marrys.
Now the reason you say that feels quite good,
is because that simply is a great tyre
and it's got really great stiff sidewall
in virtually all the different casing options they have.
However, that is still going to feel better
with a wide internal rim width
because you're going to be running it at a lower pressure
and you know it's subject to much sort of carcass wobble.
Now different tyres are going to feel different
and squarer tyres certainly will be a lot squarer
and roll slower when you put them on a wider rim.
And there is a limit to that.
Now, what I've found is
the best, biggest limit to go for is 30 mil internal.
Now there's various ones, you got 35, 40.
And that's a substantial size, really.
Now really, anything over 30,
I would probably chose to go for plus-size tyre.
So that's a 2.8 or three inch tyre.
For the 30 mil internal width,
I think you'll find from 2.35 up to 2.6.
And it doesn't really change the shape of the tyre too much.
Again, there are going to be some anomalies.
The squarer tyre will get affected by this.
But on the other end of the spectrum,
a rounder tyre you can make for more aggressive
and get a better rider feel.
Now, I think it depends on your riding style
more than the conditions.
Some people like to sort of just have a nice easy turn,
some people love to carve an edge in.
Be more or less snowboarding.
The riders that like to carve are gonna want
that sort of squarer edge, that more pronounced shoulder.
It does affect what you really want out of the tyre.
But something also to mention,
the wider rim width you go,
the stiffer the wheel's gonna be.
Stiff is good, but you also gotta bear in mind
that that stiffness has to go somewhere.
So quite often that shock and the stiffness
gets transmitted through to the bars.
Now, I actually prefer to stay on the slimmer side
of internal 30 mil width for that reason.
Too wide is too stiff for me.
So it's got the best compromise of how the wheel feels
and the tyre size not changing too much.
Next up is over to Scott Smith.
Hey, guys.
Got a question about the crank arms
on my 2017 Giant Trance 4.
That's a good bike, that used to have a Trance.
It seems like the crank arms are too low to the ground
and they catch on anything, slightest bumps, et cetera.
I've had a play around with suspension,
but this doesn't seem to help.
Do you have any suggestions?
Well, I've actually checked out the full spec of this bike
and the bottom bracket is low, but it's not crazy low.
It's actually praised for
the bottom bracket height being low enough
that it gives you good sort of feel on the bike,
but not actually being too low that you clip it.
So, I am wondering if you've got a bit of a problem.
That problem could be with shock,
it could be with the tyres, perhaps your tire's too soft
or is a bit on the small side on the rear.
More than likely, it's going to be a shock problem.
So, firstly, just make sure
that you've got the correct amount of sag on there.
And when you set your sag, make sure you do this
in your full riding kit with any water
and other stuff you like to carry
because it does affect things significantly.
Now what you're looking for is 25-30%
of the available travel sag when you sit on that bike.
If you struggle with this, get a friend to help you
because you can balance up,
they can monitor your air pressure
and the o-ring set for you.
If it's still not that,
then I'm trying to think what other things it could be.
I mean, I did do a feature recently
where I tell you how I use a lock-out on a bike
to help keep the bottom bracket higher
to avoid clipping pedals.
But, bear in mind, the bike was set correctly
for me in the first place.
It was just to help avoid clipping feet
when climbing over things like rocks and roots.
Now it might be helpful for you
if your bike is set up and you're still striking your feet.
So, have a look at that and see if it helps.
Next up, Devon Miller in response to last week
when we were looking at the cassettes.
So, you look at three different cassettes
and how you instal them,
but you forgot one brand that originated in BMX,
but is up and coming in the Mountain Bike World,
that is Box One.
How would Box One differ from the three
in design and instal?
Okay, so they don't actually differ.
The Box One uses the same system as Shimano
and is very similar to some race and other brands,
though, already out there.
So, it uses the lock-ring system
where the whole cassette slides onto the set body
and is secured with that lock-ring.
Very simple system.
Probably, the most original system
there has been in mountain biking.
It's always been there and that's how it works.
Next up is Itzame1.
Can you guys do a video talking about
all the different types of mountain biking.
Like, downhill, cross country, Enduro, et cetera.
What they are and what bikes are suitable for them?
Kind regards and curious customer.
Yeah, we can, of course we can do that and we will do that.
You've got to bear in mind that most mountain bikes
are good for most things you want to do.
You don't need a specific mountain bike to do stuff.
So, it's not one of those things
that you feel like have to keep buying bikes
in order to ride them different ways.
So, if we just go back to the beginning for a minute,
so mountain biking actually started in the 70's,
with a bunch of hippies using converted
or beach cruiser bikes and putting motorcycle brake levers
and some tougher bits in them.
And they were basically just racing them unofficially
down Mount Taberei in Marin County, California.
And that was really the fundamental start
in mountain biking.
Bunch of guys having fun
just racing each other down the hill.
Best man wins sort of thing.
And then off the back of that,
mountain bike actually took a few leads from road racing
and XC sort of side of it was born.
The bikes became very light-weight, short geometry,
with high saddles and long stems.
Aero-dynamic sort of position.
But then, as riding disciplines grew
and sort of changed a bit,
bikes kind of evolved to sort of work with that.
So you start having downhill bikes
which has lower saddles and more aggressive angles,
and suspension, and bigger tyres and stuff.
But, really, if you go back to where we are now,
we've gone full circle and the average trail bike
is good for most things
you're ever likely to do on a mountain bike.
What I mean by that,
is you could go ride cross country on it,
you can do any sort of trail centres
or official trails out there.
You could race an Enduro on it.
You might want to put some tougher tyres
and things like that, but it will be good to go.
And also, you can do a lot of downhill stuff.
Now I don't necessarily mean take it
on the World Cup down hill, but the downhills
that most people are likely to ride
you can amount to do that on your regular mountain bike.
So, don't get too focused on the type of mountain bike
you need for what you want to do.
Any bike, really, is going to be good for you
to get out there and learn the basics
on any of those disciplines.
Next up, question from Axel.
Hey, guys.
Is it possible for you to test the Sunrace MX 80 cassette?
Well, firstly, no, we don't really do product reviews.
But I have ridden that before,
so I'm very familiar with it.
I don't know if it fits to my bike.
I've got a Canyon Strive AL 7 Race from 2015.
What do you think about a cassette?
Is it worth buying it or should I stick to Sram?
Well, I don't the spec of your bike, exactly.
Basically, if your bike has Schimano cassette on there,
the Sunrace will fit
because it uses the same fitting system.
So, some racing cassette has 11-50 range.
It's massive.
It's a really, really nice big kit
and it's a quite alternative to Sram and Schimano.
But, like I've said,
if you've already got Schimano on there,
it would work and it would be a good hop-up.
If you've got Sram on there,
I'd be more inclined to stick to Sram
or even things on E13.
Because you don't have to change the driver body.
If you want to fit the Sunrace one,
basically you're gonna have to upgrade your hub
to fit the driver body that fits the Sram cassette,
as well as the price of getting the Sram cassette.
Just think about the amount of money
you want to spend in the long-term there.
Some races, the easy option is
if you've already got a Schimano in there,
if not, stick with Sram, I think.
Okay, next up, from Ric Jorge.
Hey guys.
As with most people, I'm trying to get the biggest bang
for my buck when upgrading my bike.
Assuming that used components are in good condition,
is it better to buy three to five year old XT/XTR Drivetrain
or buy new Deore or SLX?
Are three to five year old XT/XTR components
still better than the latest offerings?
Thanks a lot.
Personally, I don't have any issue buying secondhand stuff.
I've bought a lot of camera stuff secondhand,
and I buy secondhand bike stuff here and there.
But I do tend to buy stuff
that can be fixed and maintained easily.
And things like that include things like a chain set,
for example.
So if the chain needs a walnut,
you can replace those chain rings.
That's no issue.
The bottom bracket's worn out,
it's a future replacement part.
The same if you buy suspension forks or a shock of somewhat.
Each individual part is replaceable.
So, if there any problems with it in the future,
you can get those things repaired.
But stuff like a transmission,
you got to bear in mind how much abuse that gets on a bike.
Mainly because of the torque that goes through it
and also the conditions that mountain bikers ride in.
Now, things like a rear mech.
It may look good, a secondhand one,
and it may be a great price.
But you're never gonna know how baggy it is,
if it's lost it's spring, or even if it's bent.
I mean, it's very much down to the good faith of the person
that's selling it and advertising it to be sold.
So, personally, I would actually go
for a brand new Deore or a SLX.
So, rather than buying a secondhand XT or XTR,
because you really know what you're gonna get
with the secondhand stuff.
Again, don't let it put you off
buying other secondhand components.
Like I said, wheels, forks,
there's plenty of things you can buy you can upgrade.
But if you do buy secondhand rear derailleur
and it is bent or is wobbly,
there's not really much you can do about it.
So, you can replace the jockey wheels on it
and that's about it.
You might just be stuck with something
that's already worn out.
Next up is a question from Jasper
in relation to the clips and flats video I did recently.
Kind of like how to pick a pedal for your bike.
One question.
Why is concave important?
Almost every brand brings this up,
but don't really understand the benefit of this.
I've always set my flats up well and have no problems.
Can you shed some light?
Okay, so basically a concave pedal enables your foot
to sit into the pedal a bit more
so you've got a bit more feel, a bit more control
than you have with a flat pedal,
as in completely flat surface.
Now the easiest analogy
to talk about this is with skateboards.
So if you've ever skated on a completely flat skateboard,
you know it's a lot harder to ollie
and control the board than it is with a concave skateboard.
You have a better feel and purchase on that.
That is the feeling we're talking about with concave pedals.
And if pedal doesn't actually have that,
you can still achieve this
by using shorter pins on the middle
and bigger pins on the outside
just to help your foot sit into that.
It's basically all about feel.
But, of course, don't sort of dictate
to you what you should have.
It is a personal preference thing.
Most riders that want flat pedals do prefer a concave feel,
but that's not to say that you have to.
Colin S. has a bit of different question from Bike Stuff.
And this is directly to me.
Doddy, what type of rider are you?
Are you cross country racer, an Enduro rider,
or a downhill rider?
To be honest, I just class myself as a mountain biker.
Because when I started in sort of the late 80's, early 90's
there wasn't really any disciplines.
There was just mountain biking.
And if you raced, it was cross country racing.
But it wasn't called cross country back then,
it was racing because that's what it was.
As the sport developed, other things came into it.
Street riding, trails, downhill, slidon.
And I kind of, sort of chose to do
bits and pieces of all of those.
And to be honest, I love all forms of mountain biking.
I'm quite happy going out for cross country,
uphill, down Down Tucker Ride.
Because I am going to local woods,
pushing up and doing some downhill runs.
Or equally, go for bit of an urban ride with Blake.
Doing some stuff and a little bit of jibbing.
Literally, I love all of it.
What I am going to say,
I'm not massively keen on racing these days.
I am competitive and I do like racing.
Probably just to the fact that I need to spend
a lot more time on the bike to do that.
And when it comes to the weekend,
I'm quite happy to just ride, to be honest.
Okay, next up is a techy questions from Cameron Prentice.
Hey guys.
Is there a way to adjust the B screw on Eagle
without the adjustment tool that measures it for you?
Well, yeah, there is.
Let me just explain to people what that is first.
So the B tension adjusts the height of the upper guard rail
on your rear mech from the biggest sprocket of the cassette.
Now this is especially important
on the 11 and 12 speed to get that gap right,
because otherwise you'll never be able to change gear well.
The top guard rail actually found
on the top of the cassette there
will never work correctly unless you get it right.
Now Schram developed this little plastic clipping tool
just to aid the setup of that.
Just a visual reference, basically.
And yes it makes it a lot easier, but you don't need it.
So what you're looking for is a 15 millimetre gap
between the upper wheel,
so you want 15 millimetres of daylight
between the upper wheel
and the top of the biggest wheel of your cassette there.
But, it's important, you need that measurement
to be done when the bike is sagged.
So when you're sat on that bike.
So you don't need to have the tool for this,
but you will need a friend to help you.
So the easiest thing to do is,
is to either sit on the bike and balance
and get your friend to make the adjustment for you
to allow the 15 millimetres when you're on it
or, alternatively, you can let the air pressure down,
the shock can hold your bike at that point
and I've used a tow strap or something
to compress the back end for you then set it.
Or, even just get someone to hold it
and do it yourself so you can see where it is.
So, you don't need the tool.
It does make it easier.
But just look for that 15 millimetre gap
and don't forget to do it when the bike is sagged.
Okay, a maintenance-related question
from Benjamin Billingsley here.
After seeing your teardown of the headset a few days ago,
I'm curious if there's other maintenance
that should be done at certain intervals.
I'd love to see a list of things to check every ride,
or perhaps time-based.
Every three hours, 10 hours, et cetera.
Then maybe maintenance I should be doing in the off-season.
Checking brake pivots,
how often to check chain tension, brake fluid.
I know there are a lot of variables,
such a riding conditions, et cetera.
But it's good to have a starting point,
especially for your average rider.
Do you know what, that's a really good point.
We do talk about regular maintenance
and it is very hard because of those variables
to tell you exactly when to do it.
So if you start with a chain.
So if you have a little chain checker tool,
it's a really good idea to have one of these,
especially if you ride a lot
or if you ride in really demanding conditions.
So when I say demanding,
I mean muddy or dry and gritty.
So anything that can give premature wear to the chain.
The more often you check your chain,
the least likely you are to have to replace it.
In the same form, the cassette and the chain rings.
You at least better get two chains to one cassette
if you worn it to that use.
Of course it does vary on the amount you do ride.
With forks and shocks,
generally most manufacturers will recommend
a 50 or 100 hour intervals for servicing.
So, 50 hours for shock is a basic air current service.
That means, removing the air current,
re-greasing the seals, putting a bit of lubricant in there,
putting it back together again.
And for fork, that's a lower leg service.
So, again, it's a fairly simple procedure
that you can follow at home if you're comfortable.
And just requires sometimes changing the seals,
but usually just inspecting them, greasing them,
and putting some fresh lubricant inside.
The 100 hours, that's a full damper overhaul of service.
That's the same for forks and shocks.
Again, this does vary.
This is a typical sort of usage
that a manufacturer will recommend.
You might find out that what you're riding
might be 200 hours you need to do this.
That's just a guideline just to make sure
that everyone's covered.
Now with brakes, it does vary
because some brakes are minimal fluid
which need slightly less maintenance on them
and some brakes are dot fluid.
So the dot fluid brakes, Shram for example,
recommend annually you should replace the fluid
and give your brakes a full overhaul.
Now again, brakes are something
that we all use constantly,
so I tend find any regular maintenance, you know,
every few months one of them might need a bleed
or you might've split a hose in a crash, things like that.
You stand to pay attention to how much you ride,
but I do love your idea of that having some regulars charts
and stuff with some recommendations.
So, I am going to work on something like this
for all of you guys.
So, hopefully, today's Ask GMBN Tech's
been helpful for you guys.
Please continue to keep those questions coming in
on the Facebook page, even via Instagram, as well.
Use the email link on the screen
and add them in the comments below.
Of course, there's so many of them,
we can't always get them all on,
but we always try to answer them as best as we can.
If you want to find out a couple more really cool videos
to get you going, there's five riders to watch for 2018
up at the top here.
And if you want to see the pedals video
where I recommend how you choose a set of pedals
that suit your sort of riding, click down here.
As always, click on the globe to subscribe
and if the video was good for you
and you like it, give us a thumbs up.