(mechanical wooshing)
- Welcome to the GCN Tech Clinic
where I aim to get you riding your bike again problem free.
So if you've got yourself a bike tech related problem,
leave it down there in the comments section,
and I'll do my best to answer it in a future episode.
Let's crack on though, shall we,
with the first question this week.
It comes in from John Potter
who's got themselves some skinwall,
or gumwall tyres on their bike, and they wanna know
are they more susceptible to puncture
than tyres without skinwalls?
Right then John, I love some skinwalled tires.
They do make a bike look good.
But why do they have skinwalls?
Well, traditionally those tires would actually
have the casing made out of cotton, rather than nylon,
meaning that those tires are more lively
than a cheaper tire because cotton
tends to be on the premium tires out there.
What does that mean?
Well, it means better flexibility,
so if you were to encounter a bump or a stone on the road,
that kind of thing, you kind of go over it
more so than with a nylon type tire
where you just hit into it.
Or at least, that's the thinking behind it.
As for are you gonna get more punctures,
well, like I say, those tires are more premium,
so the rubber on them is generally
gonna be little bit softer to aid with grip,
but that doesn't necessarily mean punctures,
although they may cut slightly easier
because you could go out riding on a really tough old tire,
riding along the road and get a puncture,
and you could go along that exact same road
using a track tubular, 18 millimeters,
silk casing, and not puncture.
So puncturing, okay, the tire does play a part in it,
but also bad road surfaces or just riding through a hole,
that could give you a puncture.
So there's no actual science, not that I know of,
that says a skinwall tire
is more likely to give you a puncture.
Next question this week comes from Gabriele Barni
who says they recently installed a new power meter,
with a brand new Rotor 3D crank on their bike.
Since then, despite numerous attempts,
they can't properly tune the front mech.
They always get some very light chain rubbing there.
Any tips?
And they're using a Shimano Ultegra 6800 front derailleur.
Right, now this is a problem which I too have run into,
and I think it's probably most likely happening
when you're on the small chainring
and the smallest sprocket at the rear,
because I can't see why it would be touching
your front derailleur at any other time really,
other than if you're cross chaining on those extremes.
So what you could do is fit an inline cable adjuster,
if you don't already have one.
So that's onto the outer cable of your front gear cable,
and that will allow you to just get really fine tuning
of the actual amount of cable pull that happens.
But in some cases, what it can well be
is that the chainrings are spaced slightly different
to a Shimano setup, which of course that front derailleur
is designed to be working with.
So there's slightly wider space,
meaning that if you're in the little chainring
and the little sprocket, the angle is always gonna be
just a little bit too extreme,
and you're gonna get that rubbing sound.
Something drastic you could do
would be to file away part of
the actual spider off the chainset
so you could get those chainrings a little bit closer.
Personally, I wouldn't do that.
I would rather use that rubbing sound
as a reminder to not be cross chaining.
Next up, got a question from Christopher Melville
who says how do I know
which version of Shimano Ultegra I have?
Good question on this.
Now on all Shimano components,
hidden away on them somewhere, is actually a little number
which denotes which version you have.
So take for example, on this Shimano Dura-Ace chainset.
On this side of the crank I've got FC-7900,
which is etched actually onto it.
So that means it's the 7900 range,
and the FC means front chainwheel.
Then interestingly, on the other side,
I've got FC-7900/7950, because of course,
the left hand crank is a left hand crank.
7950 would mean the compact version of this chainset.
See where I'm going?
Then on the bottom bracket, I've got BB7900.
So again, the 7900 series.
So have a look around, it's probably easiest on your cranks.
So just on the inside of the crank arm like that,
you'll find out which version
of Shimano tech that you've got.
Next is a question from Oliver Schurmann
who says my fulcrum racing zero wheels
suggest running 25mm tyres but I was wondering
if it would be okay to run 23 mils?
Right then, Oliver.
I imagine they recommend 25 millimeters
because they probably work better aerodynamically
with the profile of the rim.
And most rims tend to be getting wider these days.
But don't worry, you can run 23 millimeters,
if you wish to, but it is certainly worth
considering going up to 25 millimeters.
I made the change, and I've not looked back.
The increasing comfort has certainly been worth it.
Next question this week comes from Russell Zeckner
who has to take some time off the bike because of a crash,
and wants to know what can he do to make sure
the bike's ready to ride again?
So Russell want to know should he keep
his Di2 and power meters charged up
during this time off the bike.
Any other tips I can offer
for the safe storage of the pride and joy.
Right then, Russell, sorry to hear about the crash
and the time off the bike.
Let's talk about your pride and joy though.
Fist up, give it a good ol' clean.
So make sure that there's no mud, no dirt on it all,
anything like that, give the chain some oil.
Di2, leave that plugged in, not a problem there whatsoever.
The power meter, it might be worth
just takin' out the battery,
because any knocks of the bike or the cranks,
generally that's gonna give it a little bit of life,
and then it's gonna start searching for a head unit.
So just bear that in mind.
Although, if you don't want to take it out now
and it does drain,
it's only a couple of pounds further down the line.
Other tips is, I always like to keep tires inflated
therefore, to actually just keepin'
the shape of tire on the rim,
so they're not gonna get any awkward kinks in them.
And then, also don't keep it anywhere too hot
because that could dry out your cables,
as well as your bearings, as well as actually
giving your tires cracks in them, from perishing.
And then don't keep it anywhere too cold
because it runs the risk of getting some condensation
and then that forms little puddles of water
inside of bolt heads, that kind of thing, going rusty.
And finally, cover it up with a blanket
so that no UV rays start damaging any paintwork,
as well as protecting it from any scratches
from anyone who's getting a little bit
too close to that pride and joy.
Now Phillip Pitts want to know are 11 speed drivetrains
more sensitive to chain alignment,
making sure the wheels are centered in the dropouts?
The mechanics at the tour seem to have to take
extra special care in changing a rear wheel.
Disc certainly seems to take a few seconds longer.
That's a good question.
It's because yeah, at the rear end there,
there is more sprockets than obviously
with a 10 or a nine speed setup,
but actually for centering the wheel in the dropouts,
it shouldn't make any difference at all,
because the over-locknut distance does remain the same.
But in the heat of a moment with a mechanic,
and the modern rear mechs actually
have quite a strong spring inside of them
that do also have to pull back that mech further
and with a little bit more effort than previously
and then also get the wheel in place.
But again, it does take probably a little bit longer
if you're using a thru axle too.
But as for any alignment, no, nothing at all,
because generally they simply put
the chain into the highest sprocket,
so probably the 11 tooth at the Tour de France,
and then it's easier to actually
line that wheel up and go in place.
Now Jared asks after lowering my stem 10mm,
I noticed there is a slight rubbing noise
when I move my handlebars from left to right.
Is it possible that I removed too much grease
from the bearings in the head tube
on such a small procedure?
I did take everything a part,
but did not apply grease as the bike is brand new
and only had 2 thousand miles on it.
Sounds like a weird one, this one, Jared.
Personally, I would always grease those headset bearings
because a lot of water can actually
come up off the road and get in there.
So put plenty of grease in there,
and then see if it still makes that noise.
Alternatively, maybe you've done up
the headset top cap preload
a little bit too much, and it is giving you
a slightly rough feeling as well as the noise.
So just check that out.
Headset bearings,
they are pretty fragile things, I must say.
So if there is any misalignment or rough abuse on them,
they do wear out really fast.
And finally, just make sure it's not any outer cables
that are rubbing or causing those noises,
possibly in the frame stops too.
Now Jakub 1910 alias Krasty01,
probably one of the weirdest usernames I've ever seen,
wants to know, they're thinking about making an upgrade
for or under 100 euros,
and they were thinking about swapping
the stock 23 millimeter
Continental ultra sports for gp 4000s.
Should they get them in 25mm or 28mm?
Or what else is worthy of an upgrade in that budget?
Nice question, I think tires, really,
are probably the best upgrade
you can make for that kind of money.
So as for going for them, yeah,
those tires, the GP 4000s are absolutely brilliant.
I use them, and I have used them for a long time,
and I've found them flawless.
As for what width to go for,
well, that depends on your frame, because some frames
can't actually accommodate a 28 millimeter tire.
I know one of my bikes at home,
I tried to put some 28s on, and it wouldn't get round.
It wouldn't actually clear the seat tube,
as well as underneath the rear brake stay.
So make sure that they can fit
if you are gonna go down the 28 millimeter route.
Alternatively, just think about going
up to the 25 millimeters first
because the 28s, while they are pretty large,
and it can look quite weird at first
when you're looking down riding,
and you might not really appreciate such a big jump.
5 millimeters doesn't sound a lot,
but it can be quite a lot when you're riding along,
and maybe you'll regret it.
25 millimeters, I am so confident
that you wouldn't regret going up to them.
Now Richard Isaksen wants to know
why are shift cables and brake cables,
both inners and outers, different from one another?
Good question, this.
Firstly let's look at the brake cable, shall we?
So they need to be able to stop both you and your bike,
so they do need to be a little bit thicker
because obviously that a lot more pressure and weight
that is being applied to those cables,
whereas a gear cable, well, it just needs to be able
to move a derailleur one way or the other.
It doesn't really require a lot of strength.
The outer cables though, well outer gear cables,
they have strands of wire that run
in one long line, rather than a coil,
because those long lines can't be compressed,
so that means you're gonna better gear changing,
and then the opposite really for your braking,
because you don't want to have absolute solid brakes.
You want to have a little bit of give there possibly.
So I hope that clears it up for you.
Now Igor Bremec, final question this week
and one of my absolute favorites.
Hi John, can a I get a recommendation for a chain lube?
I've recently degreased a Shimano chain,
which has that nice factory grease on it,
after relubing it with a cheap lube I had lying around
the chain is now noticeably louder.
Is there a chain lube that's similar
to Shimano's factory lube?
I'll gladly sacrifice a watt or two for a quiet drivetrain.
Right Igor, the search for the ultimate chain lubricant.
This is something which I'm currently actually undertaking.
Last night I put a picture up on Instagram
of another product I'm trying,
and while I can't report back yet
as to the exact results,
but the best product I found so far
for as close to factory lubricant as possible
as you get on that Shimano chain
is actually something from a brand called KMC,
who also make chains.
Now this lubricant, I searched so long and wide,
high, low, whatever, for,
and I managed to track down a few bottles
from a bike shop in Italy.
The bad news is I bought those bottles
and as far as I'm aware,
they don't bring those bottles into Europe any longer.
So I don't know where you're from,
but if you can find that KMC lubricant,
I'm pretty sure you won't be disappointed with it.
It does last pretty long time.
It smells just like what come on the chain,
and I found it to be absolutely brilliant.
But there is a whole heap of lubricants out there,
and I'm sure there'd be lots of people commenting down below
with the ultimate chain lubricant that they've found.
So I'm interested to read those answers as much as you are.
So there we are.
That's the end of this week's GCN Tech Clinic.
I hope that I've been able to answer your question.
If not, leave me yours down there
in the comment section down below,
and I'm hoping I can get around to them.
We do get hundreds and hundreds of submissions,
and I really do enjoy tackling your little problems.
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