- Welcome to ask GMBN tech, this is our weekly show where
we get to answer your mountain bike tech-related questions.
You can send your questions in in the comments below
or in the email address
on the bottom of the screen right there.
And kicking off this week the first question
is from Henrik Elle.
"Doddy, do Muc-Off products ever run out of date?"
Do you know what?
I had to go and look at some to see if there was
a sell by date so I wasn't that sure about this myself.
But being chemical products I'm sure at some point
they would so I actually had to ask Muc-Off
and this is what they said.
"They don't have use by dates but we do recommend keeping
in a cool, dry place when you store them.
Also, our athlete performance lines have to be used
within 12 months of opening."
So there you go, there's no real sell by date,
it's all about how you store that stuff.
But I guess you're gonna use this stuff fairly quickly
so I wouldn't worry about that too much
but just take note of the athelete performance lines
which do have a 12 month sell by date on them.
(gear whirs)
Next up is from Tom Roetman.
"Hi Doddy, I recently purchased
a 1993 GT Team Avalanche from another local rider.
I'm thinking of converting the
original triple chainring and 7-speed cassette out
(they work alright but are a bit worn)"
Understandably from 1993.
"I want to swap it out to a more modern one by SRAM setup.
What parts and tools are required to get this done?
Also, will there be a limit on how many gears I can run?
Lovin' the show, cheers!
P.S. looking forward to my bike on rewind."
I'm looking forward to seeing your bike on rewind too.
I'll keep an eye out for it Tom.
Okay, so firstly, very cool you've got nice rotobike
and even cooler that you want to keep it running
but slightly modernizing it.
So, of course, you could just go out and buy a whole
SRAM one by transmission, one by 11, one by 12
and bung it on there, no problem.
But I guessing you want to save yourself a bit of money
so with your triple chainset, in 1993 I don't know
if you were still on the bigger bolt circle diameter
or you're on the smaller one, you'll have to check that.
So there's various different chainrings available
and they all have a slightly different bolt circle
diameter to them so you'll need to know what that is
in order to order the correct chainring.
Now narrow-wide technology is fairly new
in respect to mountain bike technology
so you're not going to be able to get them to fit
all bolt circle diameters for older cranks.
So, if that's the case and you can't find
the right chainring, you might need to upgrade
to a new crank set with a relevant chainring on there,
in which case you'll need to replace
the bottom bracket as well.
So, just based on the fact that you're going to change
all that stuff, what you're gonna need,
here's a list of the things so:
bottom bracket tool, an eight millimeter Allen key,
that's for putting the new cranks on,
cable cutters, basic selection of Allen keys,
a cassette tool for taking the old cassette off
and of course putting the new one on,
a vice to actually hold the cassette tool in
or an adjustable spanner and then a chain whip
to hold the the cassette still,
basically when you undo the old one
and of course, if you're going to be
taking off the old cranks then you might well need
an old style, you just want a bottom bracket tool
and also an old school crank puller.
However, if that's something you don't want to do yourself
you could just go to a bike shop and get that bit done
and then you wouldn't need to buy or use the old tool again
and you can just get the newer tools
which is going to be a bit more future-proof.
Tools obviously are expensive but I do recommend that
every mountain biker has a good basic tool kit.
It's well worth having
and have a look at the park website
they do a really good beginners' home tool kit.
In fact, I gave away some souped up, my sort of choice
versions of that tool kit fairly recently on the channel
and I do recommend, that's the sort of stuff that everyone
should sort of aspire to get to.
You don't necessarily need to have
the top of the range tools but
the style of tools in there is what I'm talking about.
Hopefully you can get on with that because
it's a fun job to turn a bike into a one by transmission.
It's sort of something I'm going to be doing
in a maintenance video soon.
I'm actually going to try and get a hold of some older bikes
and start working on those bikes
to try and reflect what you guys
are actually all asking for.
(gear whirs)
Next up is from Kevin Conaghan.
"Doddy, I've had a creaky headset for some time
and I think it's due to the top cup moving in the frame.
I've reinstalled it a couple of times with grease,
then I've tried threadlock,
then Loctite push fit assembly compound (641)
but it still creaks over bumps and hard braking.
Is it possible to shim out the frame to get a better fit?
P.S. It's a Hope head set and a Titus frame.
Bottom cup goes in tight but I can pull
the top cup out with my fingers."
Mmm. Kevin, I've not heard of an undamaged frame
with those sort of issues.
Generally, if a headset doesn't, you know,
if it fits in quite loose it suggests to me the frame
might be slightly stretched and what happens is the frame
could be ovalized or belled out slightly.
There's a few reasons this can happen.
It could happen for manufacturing reasons
but more than likely it's happened from an impact,
in which case the frame literally, the metal is softer
than the cups of the headset that are pushed into it
and it can just stretch, even fractionally, is enough to
make it loose in there and of course the other one is if
it's being ridden with a loose headset in the first place.
Think how long a fork is; all that leverage going through
a tiny little head tube with a couple of bearings on.
If one of those is loose and it's enabled
to play around at all you're actually going
to stretch the head tube of the bike.
And I really hope for your sake
you haven't done that to your frame
because if that's the case you will be
looking at a new frame down the line.
So what I would suggest is take that headset out
and see if you've got a friend with a similar cup
they can take out their bike to see you can try it.
Process of elimination.
If their headset does fit your bike
but it's still loose in there then your frame
is knackered, I'm afraid,
and you're going to need to consider other options.
You say it's a Titus frame but
you haven't said what it's made of.
If it's made of steel you can get that fixed.
If it's aluminum sometimes you can get the head tube
taken off and have another one welded back on and get it
really treated but it could be an expensive process.
So, I hope for your sake it's just a dodgy headset
and it's not the frame but process of elimination my friend,
you're going to have to try and figure that one out.
(gear whirs)
Next up is from Daniel Silva.
"Doddy, I'm doing a bikepacking trip next month
and I need to install a bag in the stem/bar area
to carry my stuff, but the cable
of the fork lock-out system is in the way.
I'm just wondering, is it possible to easily change from
a remote lockout to a crown lockout
or am I better off just taking the locking cable off
and riding the fork fully open?"
Depends what you want, of course that's a lot of cables
on the bar so you can reduce that
by getting a conversion kit from whoever
your suspension fork it by whether it's Fox or RockShox.
Now it will cost you to get those parts
but it is worth doing, it does mean you forks got
the same adjustment but built onto it
rather than at the bars.
Now, you're going to need to look this up yourself
because you haven't actually told me which it is.
So, I did ask Fox UK about this because I have a Fox fork
on my bike with an adjustable lockout from the bars.
Now, I can get the internal bits for that particular fork
and it's not that expensive to do that process
and you can do this the other way around as well
if you wanted to have lockout at the bars
but it might be more expensive
depending on what your particular fork is.
I mean, you say the other option is you could just
take it off for that trip and run the fork for the open.
I don't see a problem with that.
You're gonna have to probably run slightly
more air pressure in your fork anyway
to compensate for the weight of stuff
so you might get away with that.
I would definitely try that first
it's probably a cheaper option and it does mean,
after your bikepacking trip, you can put the cable
back on again and make the most of that handlebar lockout.
However, if the handlebar lockout is not something
you like to use that much then
I would do the upgrade and go for the fork look.
Nice and clean, it's all there, the same adjustment,
you don't lose any performance from your fork
and more importantly the cable is not in your way.
Good luck with that.
Next up is from Mikey Ponsford.
"Doddy, loving the show,
I've got a Scott Genius LT700 tuned 2016 model
and as you probably know it came with a front hub
Syncros TR15 plus CL/Boost, yeah yeah,
made by DT Swiss and a rear hub as well.
What I'd like to ask you is can you please do a show
showing how to service the bearings
on both front and rear hubs.
I can do most things when it comes to bikes
but I don't know everything and
these through axles are very new to me.
The reason why I'm asking is because I asked
my local bike shop how much a full service would cost
and to do the whole bike, including forks and shock,
it would cost me 450 quid.
Thanks for your help,
anything you can give me would be appreciated."
Yeah, actually a few people have asked about
hub bearing over also we are gonna do that.
I'm gonna try and do it with a couple of different wheels.
We tend to have DC wheels on most of our bikes here
so very similar to your particular wheels but
to remove the bearings on the inside of DT wheels
you need a special tool and that is a dedicated tool from DT
so I've ordered one of those and as soon as it comes in
I'll show you how to whip those bearings out
and put the new ones back in.
However, you might decide that it's not worth your while
getting that tool for yourself.
Some hubs you can, with a punch,
take the bearing straight out but with the DT ones
you certainly have to have that specific tool.
And when we're doing the video like a hub overhaul
we can only be quite general with it
because it's impossible to actually make a video like that
for every single hub, I'd be there all year
just making those videos so I'll try and be as general
as I can and I'll try to include any recommendations
for specific hubs that do have unique tooling for them
because we do know of quite a few out there.
But we'll try and help you as best we can
but it will be coming quite soon on GMBN tech.
In the meantime, good luck with your bike
and keep an eye out for that video.
Next up is from Super Specky4eyes.
"I was just wondering if riding drop offs whilst
the fork locked out is bad for your forks or shock.
I can't be the only one who's forgotten
to set them open after a long climb, cheers.
No, generally speaking when you have the fork
or a shock and lockout it has a blowoff feature.
If it was just to stay locked out then it would damage
the internals of that and I have heard about it before
in the past especially with shocks where people have been
riding with them locked out too often
and you can actually bend the shims on the inside.
It's not biggie because you can replace that stuff
but it is at your expense because
you're going to have to pay for
getting your shock taken apart
and rebuilt with those new parts inside.
Now I wouldn't worry about it too much
you're quite happy to run them locked out
and do the old jump here and there
just don't too much of a habit of it.
The blow off feature is there for a reason,
it allows the oil to not blow straight past there
so your fork will actuate and it won't damage
but just don't worry about it but just
try and pay a bit more attention and should be alright.
Alright, this one's from Dan San.
"Doddy, I'm sure you'll know the difference between
the 11 speed SRAM cassette 1195 and 1199.
They're close in price and weight.
They talk about coating, thanks."
So with the coating there's the silver edition
and there's a black one I think they're color-coding jet.
On that, basically it's like an anti-corrosion
or at least a corrosion-resistant coating
that's supposed to make the cassette last a bit longer.
Isn't going to last any longer to physical wear
because it's essentially the same thing
but it's the resistance against corrosion
and it definitely does do that.
So, technically your cassette will last a bit longer.
However, because it's got that black coating on it
you do notice it when it starts wearing
more than you would on a silver cassette
and for that reason some people prefer
to stick to silver cassettes.
I don't worry about that sort of thing too much.
I like the fact that it's a bit more corrosion-resistant
and I don't mind it when it looks a bit worn.
That's cool, it's like a bit of patina.
I'd go for the black one myself.
I don't think there's any strict advantage to either of them
perhaps if you're riding dry conditions more often
you don't need to go for that corrosion one.
If you're riding in wet conditions, might be a better idea.
But I'd go for the black one all day long
I think that looks cool.
And the last one this week is in relation to rear shocks.
This is from Andy J.
"Lovin' the channel,
it's been really helpful for me so far."
Thank you for that Andy.
"I'm curious about position of rear shocks.
Does the positioning and
fixing point of the rear shocks affect ride handling?
E.g. a rear shock that's vertical compared to one
that's angled, as well as being fixed to the top tube
or the down tube like the Yeti ASR-5
or the Whyte T130 compared to Canyon Neuron, thanks."
This is a bit of a tricky one because there's a lot of...
Lot of different things to talk about here.
If you're just literally talking about the physicality
of where the shock is, the shock will be functioning exactly
the same as any other shock but of course they're
going to perform differently because it's down
to the characteristics of that suspension system.
Now ideally, a shock, you want it as low on the bike
as possible just for weight distribution
and all of those heavier components
in a rear suspension design like
the big aluminum rockers and stuff.
If you can keep that nice and low,
like that Santa Cruz Nomad for example,
everything's quite low down on that bike.
Gives you a good sense of gravity down there;
tucks everything away.
But, of course, it's not the same with all bikes.
Some bikes they clean the lines like that new Canyon,
lacks the top tube mounted shock that goes right
in line with that top tube, super clean-looking.
The actual physicality of the shock work
is going to be no different but they will feel
completely different just because of the suspension design.
Now we're going to be doing a bit
of a suspension 101 feature soon because a lot of people
have been asking for this video but we are actually
getting some motion graphics made for this
so you can actually understand a bit what's going on.
So just be patient and we'll explain things
in a bit more detail.
Okay, this is another weekly ask of GMBN tech in the back.
For a couple more great videos, click up here and down there
and of course, if you've got any questions fire them in
we love answering your questions.
Get me into the email address that was on the screen
in the beginning of the show and of course
in the comments below this.
Use that hashtag ask GMBN tech just so we know
which ones are questions and which ones
are actually comments on this show.
Love having you guys interact, we love having you here.
Of course, please subscribe to the channel by clicking
on that globe, tell everyone about us and if you
like asking questions about mountain bikes
give us a thumbs up.