(powerful music)
- Welcome back to another episode of the GCN Tech Clinic
where we solve and fix your bike problems in a virtual way.
So if you've got one make sure you leave it for me
down there in the comment section below
or on all forms of social media
using the hashtag #ASKGCNTECH.
Right let's crack on as ever
with the first question this week
and it comes in from Vishwa Dev
whose converted their time trial bike to a 1x drivetrain
using a narrow wide chainring.
Now, Vishwa says that they have a rubbing kind of noise
when the chain is on the last three cogs,
so the 11, the 12 and the 13.
But it becomes really smooth and silent
when the chain in is between the fifth
and the eight sprockets.
"Any reason why this is happening?
"Should I be concerned about anything
"or is it just the sound of possible slight cross chaining?"
Right, okay, could well be Vishwa
because you're using a narrow wide chainring.
Obviously you do have some wider teeth on there
which means that the chain
doesn't have the option or ability
to move just a fraction of a millimeter
so the chain can just flex slightly
and get a better running chainline
which you've already mentioned.
So if you're really keen to still use quite a big gear
so 54, 11, 12 or 13 is pretty big,
consider getting an even bigger chainring
and then you can still use the sprockets
in the fifth to eighth positions
so you get that perfectly straight chainline.
Something else to consider,
you may well be able to get some spaces
on the actual spider and push the chainring out
or inwards slightly so you get a better running chainline.
But that's quite drastic and it could well affect
the actual drivetrain performance there too
in terms of power efficiency.
But I reckon it's probably because of the narrow wide
chainring you're just getting increased friction
like you've already said.
Okay next up is Henry Kennaway
who says, "Love the show I have an 11-speed Campagnolo
"Potenza groupset and I would like to install Campagnolo
"Chorus carbon shifters for the added ability
"to shift down more than one sprocket per shift.
"Would these components be compatible?"
Henry, good to hear from you.
I've not actually tried this myself
so I can't give you a real life example
but the official line from Campagnolo is that it won't.
They do actually list that on the help section
of their own website.
The reason being I imagine it's something to do with
the actual spring return mechanism
inside of the rear derailleur
and it's just not compatible with the power shift function
within the Ergopower levers.
Now the reason your shifters
don't actually allow that shifting mode that you desire
is because the shift hood style
replicates more the EPS shape
rather than the traditional Ergopower one.
So it's probably slightly more comfortable in my opinion
anyway from using the two different types
and the actual shape and way it's been molded
just doesn't allow the ratchets to work in such a way.
So I'm afraid, if you want those extra shifts
you are gonna have to change the rear derailleur as well.
Okay Joe Pavlik is next or TheJoePavlik even,
"Speaking of jockey wheels,
"when do you know it is time to replace them and how?"
Right then Joe.
Well firstly if the teeth on them are really sharp
and look like shark's teeth then
it's definitely time to replace them.
Also if the bearings or bushes within them are really stiff
so the easiest way of finding that out
is to try and take the chain away from them slightly
and try and turn them.
If they're really difficult to turn
they definitely need replacing.
Bushes you can revitalize and get them running good again
if they're the ones with sealed bearings though to be honest
it's not worth the hassle or the time to actually bother
trying to revitalize them
because they're relatively low cost
and well are consumable I guess.
Now, do consider though, if they are moving around
the upper pulley wheel on virtually all systems
is designed to have a little bit of float there.
'Cause that takes up any differences and tolerances
in indexing so between the actual chainline
and the indexing of the rear derailleur.
The bottom one though,
generally they are in a fixed position
and don't have very much flex at all.
But if they're really really flexy and sloppy
definitely replace them
and if the teeth are jagged like shark teeth
replace them too.
Right next up is Jose Mangini who says,
"Can I use Campagnolo wheels and cassette
"with the remaining parts being Shimano,
"everything 11-speed?
"I used this combination 20 years ago with 9-speed
"and they worked fine.
"If not any suggestion on how to make
"Italians and Japanese speak the same language?
"Thanks and keep up the wonderful job."
Jose, yes.
All 11-speed cassettes work fine
across all 11-speed groupsets from my experience.
It's not 110% perfect but well it's 100% perfect.
I've never had any problems there
so it's gonna be totally fine.
Yet the manufacturers will say it won't work
but it will.
Now the reason being,
the actual sprocket spacings, Shimano and SRAM is identical
and the difference in distance
between Shimano and Campagnolo or SRAM and Campagnolo
is just 0.1 of a millimeter.
Pretty minute.
And the actual thickness of the sprockets
is the same across all
so it's gonna work absolutely fine.
Italians and Japanese they speak the same language
for what you need to do.
Okay next up Kevin Aguilar who says,
"Great content as always."
You're welcome.
"How do you plug the holes in a carbon frame
"where mechanical groupset cables enter
"when you switch to Di2?"
Right Kevin, a few options here.
Easiest one, get some electrical tape and just go over them.
Not that elegant though.
Alternatively, contact the frame manufacturer
and ask them for some rubber bungs to go in there
they normally have some specialist ones.
Also Shimano, they've get a Di2 grommets set
that you could pop in there.
Something a bit more well hack or bodge if you like
is to get some soux grouse
that's like a moldable type material
you put in there and that will block it off,
you can smooth it off nicely.
Or alternatively some silicone sealant
so the sort of thing you might use in a bathroom
or a kitchen, around a sink or some windows
that kind of thing.
You can put a dab of that in there and smooth it off nicely
and it's easy to pick out if you ever go back to mechanical
but I don't reckon you will.
Right next up rr8299,
that is a very weird name.
I would like to see your birth certificate
actually I would send it in.
Right anyway, rr8299 says,
"When I'm not pedaling the chain suddenly taps the frame
"and even falls of the big chainring.
"If I pedal backwards it falls off for sure.
"It's as though it gets caught or stuck in the cassette.
"Di2 Ultegra on a giant advanced Defy."
Right then rr8299
this seems to me like your freehub body is jammed up.
So the actual pulls or the ratchets within the freehub body
and where it joins onto the hub shell,
they've got too much grease in there or for some reason
the little springs or clips they're not releasing
and it's making your bike well almost like a fixed wheel.
So as you're trying to freewheel it's not allowing it
and therefore it's trying to kick you forward
and that's what the slamming is,
likewise when you're trying to pedal it backwards,
it's not doing so and it's just dislodging
from the chainring.
So if you're a competent mechanic,
take apart the freehub, clean up all the grease and the gunk
inside of it, take out the pulls and the springs,
make sure they're sparkling and then apply
a very small amount of quite thin grease in there
before reassembling and it will be okay.
Otherwise take it down to your local shop
and tell them that's what Jonny Tech has recommended.
Right next one is Gem Lacson who says,
"Hi Jon, is there a way to have a 10 tooth sprocket
"on the current 11-speed groupsets?"
No, not that I know of.
I know years ago there was a 10 tooth sprocket
or even a 9 tooth perhaps that threaded
into where your lock ring would go
and acted as both a lock ring as well as a sprocket.
I think it was for downhill mountain bikes or something
but then you had to change the axle
and do all sorts of jiggery-pokery
likewise I think Moulton, the fold-up bikes
that are pretty bling from Bradford on Avon
not that far away from here,
they also had a 9 tooth sprocket as well
but that was a specialist bit of kit.
And Shimano, pretty sure they've got a groupset
or they certainly did called Capreo or something like that
that was designed for fold-up bikes.
And the freehub body was normal width
but sort of the last third of it was really really small
so you could put the smallest sprocket on there.
Of course you've got smaller sized wheels
so having a smaller sprocket means you can
get a bigger amount of wheel revolutions per turn
of the crank and everything.
But yeah, what you're searching for isn't available
to my knowledge.
I'm sure someone out there has probably hacked or bodged one
but certainly as an after-market component,
no it's not possible.
Final one, Tim Hughes, now Tim says,
"I have a question, is it possible
"to attach a front derailleur to a frame
"that previously did not have one?
"I've seen band on adapters is that all I would need?
"I'm in the process of attempting to convert
"a cheap Chinese bicycle into a modern day road bike
"with a 105 groupset."
Tim, yes sir.
A front band on adapter is all you need really
to actually put that front derailleur on.
What you need to consider though
is that you've got a adequate frame to actually allow
the routing of a front derailleur cable there too.
Now if you've got a under-the-bottom bracket shell
cable guide then make sure its got two slots
basically for your cables.
If not you can probably buy one that would bolt on there
or screw in there absolutely fine you'd be able to use that
but you do need to make sure obviously
you've got a cable stop at the front of the bike
to allow the outer cable to stop
in order to get tension on the front derailleur cable
running backwards.
Likewise if you don't have a cable guide underneath there,
then maybe you've got one on the seat tube
like a cyclo-cross bike or old school mountain bike
and you can run it into there
and do some magic with that too.
But the other thing you need to consider,
you need to have a cable stop
in order to allow the cable to have some tension
before fitting that front derailleur.
But I'm interested to see this,
I do like sort of a cheap bicycle conversions
so make sure you send some pictures of that in to me.
Right, there we are.
I hope I've been able to help answer and solve
your bike problem.
If not make sure you leave it down there
in the comment section below or on all forms of social media
using that hashtag #ASKGCNTECH.
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