- Welcome back to another ask GMBN Tech.
This is our weekly Q&A show, so you guys
get to ask questions, and we try and
answer them for you.
If you wanna ask any
tech related questions
there's a link at the
bottom of the screen there,
you can contact us, and
of course you can add
your questions in the comments below.
Don't for get to use that #askGMBNtech,
it makes it nice and
easy to see which ones
are questions and which ones are comments.
So first of this week is from Alfie Green:
"Hi Doddy, I've got a Boardman MTR 8.8",
nice bike actually, "and it comes with an
FSA Gamma Pro Crankset.
I wanna change the chaining on
it to a raceface narrow wide,
but would I have to
change my cranks as well?"
Blah, blah blah.
"Also how to I find out my bolt circle
on a chainring?"
Hi Alfie, okay so I've had a quick look
at that crankset.
It's not a lot of information online,
but it's a four bolt system on there.
So if you want to measure
the bolt circle yourself
you just take the cranks off, actually you
could do all this on the bike,
base your measuring
just between opposites.
So literally you're looking
for 104, for example,
bolt circle diameter,
and that's the fairly
common one you see these days.
And if so, yours is, that
means you will able to put
raceface chaining on there.
In order to do that, you
obviously need to remove
the crank from the bike, and then
on the back side of
the crank there will be
access to those bolts holding
the chainring onto it.
You'll need to remove those, they might
5 millimeter allen key head bolts,
or they might be torque T25.
It's quite likely that there will be some
threadlock of some kind holding them on,
so make sure you use a good fitting tool.
And be careful just when you're undoing
in case you slip and skin your knuckles
on the actual chainring.
So just take care with that,
take the chainring off,
get that new one, just
confirm that the boltcircle
is the same as obviously
various different ones,
and you should be good to go.
Alright, next stop.
"Hi, my name is Hugo
Oliveira, a bike enthusiast
from Portugal. I see all of GMBN videos,
keep doin it, I love it."
Cool, thanks for that.
Right so your question.
"I have a Cannondale Trail 5 29er and I'm
upgrading as I go along, but obviously
on a tight budget, as you can see
by my current hardtail.
I've upgraded my fork from a SR Suntour
XCM
- RL 100mm
to a budget air fork from
Manitou, also 100 mm."
So, yeah that's a great upgrade to do.
"the grips to SRAM lock-on, etc.
bit by bit improving my ride."
That is exactly how you do it.
"The biggest change I
believe is to upgrade
my bottom bracket, which is a square taper
and crank to a better one.
Can you tell me can I go 1X8
just by changing the crank,
or is this a stupid idea?
Does it mean that I need to switch
the entire group set, to like say SRAM GX?
That's the cheapest I could find online."
No you can't go straight to a 1X8, Hugo.
But you have to bear in
mind a couple of things:
So your typical 1X8
transmission as you see
at the moment, there are two major factors
that make them work.
One of them is the narrow
wide chainring upfront.
Your idea with a narrow wide chainring is
those narrow wide teeth profiles
match the narrow wide
profiles on the inside
of the chainlinks on the male and females.
So the idea is the chain can't move around
too much on that chainring
and therefore it's much,
much harder to derail.
So that is part of it, but also the
clutch on the deraillieur.
SRAM and Shimano both have their own
individual systems for a clutch,
and the reason you need this is basically
to increase the tension on the chain.
And basically that works hand in hand
with the narrow wide.
So your mech won't be a clutch mech,
so it does mean you have
a couple of options upfront.
So when you change to a single crank
and a new bottom bracket,
which will as you point out,
be a very good upgrade to do,
I wouldn't focus too much on getting a
narrow wide chainring, okay.
So it will definitely
help, but you're gonna
need to have some kind
of compact chain guide.
Just a minimal upper one.
Now MRP make one
that's it right there on the screen.
Now it's various different 15's, but this
going up to the front
mech round the seat tube
on to IOCG mounts.
So even the bottom bracket shell there.
And also e-thirteen make one as well,
and they're both very good for the money,
they do the job excellently.
Now long before all this
1X phase everyone in now,
the 1X11 and 1X12, I
used to run 1X8 and 1X9
in those days way before clutch mechs and
way before narrow wide chainrings,
by using one of those MRP 1X guides.
Loved it, I loved the
simplicity, and of course
it doesn't cost you anything.
Because you don't really have to buy
the new derailleur, new shifter,
all that stuff, you can just do it by
literally get a 1X and just getting that
compact chain guide on the top.
So, a little bit more money to spend,
but you can do it without having to do
a whole new transmission.
So get it done.
In my opinion, I think it
will make your bike quieter,
and you will love it.
A help related question now from
Arron J Hall.
"I currently have a 2011 Kona Hei Hei 29er
with a broken chain stay."
Unlucky.
"The current chain stay is a quick release
with a 2011 Easton XC 29er wheelset.
I can only replace the chain
stay with a newer model,
which Kona has told me will fit
but does require a thru axle hub."
So that's a 142X12.
"Is there a new way to replace or convert
to the hub given the age of the wheel,
or do I need to purchase
a new wheel instead?
Thanks for any advice."
Okay well first up, I don't know if
the back of that bike is 135 or 142.
You might be in luck
because those Easton hubs
on those wheels, I think they're EA70s,
so they're very similar to the Havens,
which I had in that era.
And it's very much just
a plug and play system,
so you get different caps for 135, 142,
thru axle, and quick release.
Now if you're in luck,
which I think you are,
yours would just have the quick release
caps on the end,
you can check this by
trying to pull them out.
They should be push fit on there,
but quite a tough fit.
So see if you can pull those out,
and if that does come out
successfully like that
there will be a spare part from Easton.
They do carry a lot of parts, so
I don't know where you're
based, if it's in the UK
the distributor is Silverfish.
They will be able to help
you, or at least advise
if they haven't got the part,
which part you need to order.
Failing that, Easton do tend to have
pretty good customer service.
It's definitely worth
dropping them a line.
So hopefully you can get that sorted
and just get the adapters,
which I think you can,
and continue riding your
bike with a new chain stay.
Good luck.
Got a great one here from Andrew Dobbins.
"I've been looking at the
Schlumpf Mountain Drive,
which allows you to convert a 1X into a 2X
by lowering the gear ration by 2.5
simply by pressing the side of the crank.
I haven't seen anyone review this
or even discuss it in any detail.
I guess there must be some downsides
other than the price,
but would of though mountain
bikes would have been
all over it.
Be interested in your thoughts."
Andrew from Chipstone.
I have heard of this before
to be honest, Andrew,
but I have to check it out, so I wasn't
too sure of it.
And the reason I heard
of it before was actually
the users on Moulton
bikes and a few others
of alternative branded bikes.
So it's basically a
planetary gearing system,
so it's got a set of
gears, and may engage.
And on this particular setup by Schlump,
there's a little leaver that you just
kick with your ankle in
the center of the crank.
Basically that engages the overdrive
or the second shift gear.
So I think it's kind of a good concept,
but I think there are some issues with it,
which is why you probably
haven't seen this.
So it's potentially quite
heavy, the star system.
It involves having quite a large chainring
because of the way the system works,
And that chainring is
in a central position.
And most mountain bikes are designed,
even 1X bikes, are designed around a
smaller chainring in that middle position.
So you're very limited on the bikes
that might be able to accept it.
You could of course space
out the whole crank set,
but it would put your chain line off.
So you don't really wanna do that.
So I'm sure it would work on some bikes,
but not on all of them.
Now also the way they're designed is
they're supposed to have minimal friction,
because of course gear boxes add friction.
Planetary gears like
those again add friction,
so these particular ones
have minimal sealing on them.
Basically, so they're not
really good in wet weather,
they're not good with mud and actually
it's just gonna get into those gears,
and they're not really
designed for the conditions.
However, they would cope with the torque
that we're gonna put through
them, and that sort of stuff.
So definitely be keen
to have a look at one.
But just while we're talking about this,
you've actually reminded me of a product
that was really cool
and quite revolutionary
at the time, made by TruVativ,
called the HammerSchmidt.
And this was basically
the mountain bike version
of one of these.
Now I know the slove drive one they do say
is a mountain friendly one.
I'm sure it could work, you know,
I'm still on the fence on that one
because I've not tried it.
HammerSchmidt was incredible.
Now HammerSchmidt was developed by
SRAM in conjunction with TruVativ,
and it's got a planetary gear system.
But it's fully enclosed so you use a tiny
chainring and it had an equivalent of
two gearing on there, and
a tiny, and what felt like
quite significantly bigger chainring.
So that's just by flicking the gear.
It had a gear lever, just not the
traditional gears we
use, so it's not quite as
convenient as the system
you've just told us
if we kick it.
But add a chain guide built into it,
a bash guard built into it, and it was
designed to cope with the worst conditions
because it's fully sealed.
It's a really, really cool product,
quite ahead of it's time to be honest.
And a lot of people still
talk about HammerSchmidt,
but i think really the
reason it's not used much
on mountain bikes was simply
it had too much friction.
Now I forget in which mode, whether the
standard or the overdrive mode,
but you definitely notice
you change that gear.
You can feel the friction
as you're turning
all those extra planetary gears
around on the inside.
So once it was a fantastic
idea, and it was made
a phenomenal piece of kit, it just
wasn't that successful, unfortunately.
I wanna try and get a hold of one
for TruVativ to show you on another show
because it's such a cool bit of kit.
I just want to show you how they work,
they're really cool when
you take them apart.
But there you go, now
I think that's a reason
why we've not seen them.
Okay, another one, a
simple one actually from
Gregor Calkovsky:
"Hi, I have a problem.
When I move my wheel
from left to right and holding the frame
I hear a sort of knocking.
I think that could be
something from the rear hub.
Can you tell me how to fix it?
Thanks a lot."
Well first you do need identify
specifically what it is.
There's a whole bunch of
things that it could be,
but of course it does suggest that
it might be the hub being loose.
Now your hub will be one of two options,
it will either have
traditional cup and cone
style bearings, or it will
have cartridge bearings.
If it's traditional cup and cone ones
you can adjust those, it's basically
you can adjust the cone
and then have a lock nut
that adjusts against the cone to stop it
basically coming loose.
And it sounds like if
it is, it has come loose
so you'll need to readjust those
and re-lock that.
It normally takes a 15-17
millimeter cone spanners,
which are the really thin options,
especially with a job that you can often
get away with doing this
with adjustable spanners
or just regular spanners.
If yours is a cartridge bearing,
it is one of two things.
Either the bearing itself is worn out,
and that's why its
knocking and moving around,
in which case they'll need replacing.
It's a fairly easy job to do,
it does vary on hubs how
you get those bearings out
and you punch them back in again.
If you're unsure about that your bike shop
will be able to help you.
But also it could be that those
bearings aren't preloaded.
Now, there's often confusion with
preloading cartridge
bearings, because you know
once you load in the bearing because it's
a sealed unit.
But what the term preloading it means
is making sure all the hardware
is snug up against it
so there is no movement.
And if any of that is loose, then you will
have that movement, which translates to
a wobbly wheel.
So there's a few options of
things it could be there.
You really have to try
and identify it yourself
before we can figure out any more,
but I think that's gonna
help you on your way.
So good luck with that.
Now this one, I can't tell if this is
a real name or if Blake
is playing a prank on me,
but this is from Dick Splatts007:
"Where did you get the 10 mm reach stem
from in the cut scene from GMBN?
I've searched everywhere, Mondraker
don't even do them anymore."
I got it with my Mondraker.
Basically.
Yeah they don't do them in 10 anymore.
I've got the 10, I've got the 20
and then of course I've
got a regular 30s, 35s
with the other ones.
And I've got a few
different options of those.
I've ridden a lot of
their bikes in the past,
I was an early adopter
of that 10 mm system
when other people thought it looked a bit
strange and even ugly.
You should still be able to find them
and track them down.
I'll tell you what, drop me an email
I might be able to help you on that one.
So drop an email to hellotech@gmbn.com,
and in the subject line do
the Mondrake 10 mm stem,
and hopefully I'll get to see that email
and I'll see if I can hook you up.
So there it goes, another GMBN
Tech Q&A session in the bag.
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