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GMBN Tech Essentials Ep. 4 | Adjusting Gears

GMBN Tech Essentials Ep. 4 | Adjusting Gears


– This is the GMBN Tech Essential Series. It’s our easy-to-follow
guide to setting up your bike and maintaining it yourself for home. In this particular video,
we’re gonna be looking at everything to do with
your gears, and that is how they work, how to get
them set up, and what to do if you run into problems.
(booming) Okay, so first up, let’s take
a look at a business end. This is where it all happens
from, this is your shifter. Now, some bikes, you just
have a single shifter, like this particular one,
other bikes you have two. One for the front derailleur and one for the rear derailleur. For the front derailleur, it will allow to be shifting two or three chain rings. For the rear, it’s anything
up to 12 sprockets. The power shifter found
right underneath here sits naturally where your
thumb would actually sit, just below the bars, and that
is responsible for shifting, click at a time or a few at
a time into a lower gear, or your bigger sprockets in the back. Now, the other lever will be responsible for your other shifter, take you back down or into your higher or smaller gear. Now, a Schwinn is designed to be used with your thumb on this side of the bars. On Shimano, you can use
it either with your thumb or with your finger on the other side. Fundamentally, the
shifters do the same thing. You hae your cable spool on the inside that’s responsible for
shifting those gears, and the only adjustment they all have is the barrel adjuster
here, and a barrel adjuster, it’s job is to take up
slack in the cable system. Now, you’ll often hear
the term cable stretch, and what all happens is,
when you put the cable on the bike in the first
place, it needs to sort of bed in, and as you use the gears a bit, you’ll be pushing the
housing into the shifter and into the stops of the
frame, and all those little minute moments, even
half millimeter a time, it will create slack in the system. This is used to counteract
that and take up that slack. You’ll also get some of
this slack over time, and it has a few effects on your shifting, which we’ll go into a bit later. If you wanna know a bit about
the internals of shifters, fear not, we’re gonna be
looking at how to change the whole cable system, and how
to take these shifters apart in order to do so in a future video. Okay, an now let’s look
at the front derailleur. Now unfortunately, none
of our presenter bikes actually have the front
derailleur anymore, they’ve all got one vibe, but I know that lots of people’s bikes
and also your bikes out there, there will still have
front derailleurs on. Now, you get these in orientations to suit two or three chain links on there. Of course, one buys the king these days, and typically that mounts
onto the frame itself here, and there’s just two main adjustments that you can do to the device itself. So, the device is the cage essentially, and then it’s got parallel to the ground that allows it to follow
with the three chain rings. On the top of it are two limit screws. One adjusts the limit
of the inner chain ring, that’s the one nearer to the frame, and the other adjusts limit
on the outside chain ring. The only other two
adjustments you can make are cable tension, the
same as you would with a rear derailleur, and the
height of the derailleur. Now, the way to set the
height up, initially is that when you’re in the outer chain
ring, so your biggest chain, then there should be a gap of between one and three millimeters
between the cage itself and the top of the chain ring teeth, and that enables you to
downshift and upshift as clean as possible, and it
also maximizes on the chance of the cage itself
keeping a chain on there in case there’s rough terrain. Now, the front derailleur
is a little bit different to the rear derailleur in
that the rear derailleur is quite precise, so
remove anything from seven up to 12 speeds really
on them, and of course there’s a tiny amount that
have to move each time, so it’s very precise operation, but when it comes to the
derailleur on the front, if we’re looking at this
one, which is a triple, so there’s three chain links on here, the gaps between the sizes
of those can be quite big, so there’s quite a rough
change of changing experience by comparison to the rear. Now, the aim of the cage
surrounding that chain that’s moved on the
parallelogram is literally to push the chain over one side at a time, depending on which way you’re shifting, until it catches ramps on
the back of this chain ridge, which is designed to hook the chain up onto the next chain ring. It depends on which design
you have, but it can take as much as half of a turn of your pedals from when you operate the
shifter for that to initiate as the chain grabs and takes
hold as you pedal it around. It’s a little less so
on the way back down. It can be a little bit more punchy, but because of this
jump, it’s really crucial to get those adjustments done
correctly in the first place because sometimes it might not
jump down when you want it to or other times, in case
of this small chain ring, or the granny ring as it’s
known, you actually jump too far and it would jump straight off and onto the bottom bracket shell, and on some bikes you can
become jammed in there, but more than anything,
it’s just an inconvenience, so it’s not actually changing correctly. And now let’s move down
to the back of the bike where you find the rear derailleur. Now, this essentially is
a parallelogram design, and it’s on a pivot, and it
has a sprung lower cage there. On the lower cage, you
see two guide wheels, also known as jockey wheels. The top one, the job
is simply to make sure the chain stays in line
with those sprockets, and the bottom one is simply
there to take up the slack in the chain according
to which gear you’re in. Now, although there’s
different models on the market by various different brands,
fundamentally they work on the same principle,
and they will all have the same adjustments you
need to make to set them up. Now, let’s just take a
look in a bit of detail, and I wanna explain to you what
each of the adjustments does and why it’s so important to make sure that yours is set up correctly. So, on every rear mech, you’ll
have upper limit screws. Now these are based either on the back or on the side of the mech. Now, depending if you
got Schwinn or Shimano, you’re gonna need either a Phillips or a cross head screwdriver or
a three millimeter Allen key. Now, for example, the lower
gearing, or the biggest sprocket you will see at the back, when
I make an adjustment to that, if I get this adjustment
wrong, when I shift the gears, the chain can actually hop over
the top and into the spokes. One of a few things can happen,
so you can damage the spokes or even snap the spokes, being
the chain all gets wrapped up and it can snap your rear
derailleur off or worse, it could snap the derailleur
out of the hanger, so that can be very costly, so that’s why it’s absolutely vital to get
these adjusted correctly. Now quite often, you’ll
find that they are marked low and high, L and H, and
of course the high gear being the smallest, the
low gear being the biggest. Now, if the ones on your
particular derailleur are not marked, you will
usually find that actually they’re opposite to what
you think corresponds. So for example, I’m
currently in my high gear, or my smallest gear at the back here, and you would think, because
there’s the two screws here on the back, that the one on
the right’s been adjusted. It’s actually the one on the left. You can test this out just by
simply looking down the line of the derailleur and making
just subtle adjustments to that screw, whilst keeping your eye on that upper guide wheel. What you’re looking for
is the upper guide wheel in relation to that small sprocket, and now it’s out of alignment, so if I was to pedal the gears now, it
would sound quite noisy, and actually would try
and change gear by itself. What you’re looking for
with your upper and lower limit screws is for the chain
to be completely in line with the guide wheel at that point. The next adjustment you
will see on all derailleurs is the B-tension, or the B-screw. Now, this is directly responsible
for adjusting the height, or the gap, between the upper jockey wheel and the bottom of the biggest sprocket. Why do you need to do that? Well, the reason for that is, of course, there’s different sized cassettes
of different sized sockets on the market, so the
derailleurs have to be adjusted to actually work smoothly
with that, and of course, there’s different ratios of cassette. Sometimes shifting will be
very smooth across the board and other times there’ll be quite a spike up to that biggest gear,
so it’s important to get that B-screw adjusted
correctly with the correct gap. Otherwise, it’ll either, A,
makes it difficult to change into that really big gear
and you’ll find the actual, they guide will foul on it
and the whole derailleur will bounce up and down,
or the other way is you simply won’t ever get
into it, and if you do, it makes it very hard
’cause it won’t be able to drop back down again afterwards. So, another reason to make sure that that is accurately adjusted. And, the final adjustment that
you get on all derailleurs is of course the cable tension there. Now, it’s pointless trying to adjust that until you have your other limited set. If you get those inner and
outer, or upper and lower, limit set, and you get your B-screw set, then is the time to
adjust the cable tension. Now, the whole idea is,
you pull the cable taut, but not tight. You don’t wanna be actually
shifting the derailleur just by pulling that
cable out ’cause of course that is the job that the shifter does. You just wanna nip it up,
and then depending on which bolt it has on your particular
one, on this Schwinn, sometimes you get a four,
sometimes you get a five, sometimes you get a 225, and it does vary on different derailleurs
from different years, so you just have to check
that yourself there, but make sure you use the
correct tool, of course, ’cause you don’t wanna round out that bolt on there that pinches the cable. The other thing, of course,
is just to make sure that the cable does line up and
follow the correct route. On some designs of
derailleur, it can be possible for the cable just to
pop out of this groove, and if that’s happening, you
will never get clean shifting. Now, the final thing you’re likely to see on most modern derailleurs
is a clutch mechanism. Now, it differs slightly
on Schwinn and Smimano. Now, the reason Shimano
offer you the opportunity to turn the clutch off is simply for ease of removing the rear wheel. If you have the clutch
on and you try and remove the rear wheel, you’re
fighting that mechanism in order to loosen off the chain so you can drop the wheel
out, that’s all it is. On Scwhinn derailleurs,
you can’t adjust it. The clutch is housed in the same part. It’s the non-adjustable part as standard. The Schwinn has a very
cool getaround for this. They’ve got a cage lock, so
you’d simply move the lower cage all the way forward, press
that cage lock button, and actually hold it
in that slack position so that derailleur is not actually holding nay tension on the chain. Makes it very easy to drop the wheel out. However, it’s very easy to
injure yourself accidentally if you get your fingers trapped in here ’cause it’s a very powerful
cage, as I’ll demonstrate when I let go.
(cage bonging) (cool vibe music) So, once adjusted in the
first place, your front mech will barely ever give you any trouble because it just gets on and does its job, it works under quite a lot of tension, it doesn’t have to do too much. However, there are a few little problems you’re gonna run into
with front derailleurs over time of having one, so
let’s have a look at those and how you get around those problems. Now, the first you might encounter would be the tire rubbing on
the front derailleur itself. Now, this will only ever happen
if you’re on a granny ring, so the small chain ring there, doing an extremely tough climb, really. So, the chain will be
incredibly close to your tire, and also the mech will be
close to the tire as well. So firstly, there’s a few
things that are not anything to do with the derailleur
that can be the cause of this. So, one of them can be
frame flex, so some frames have flex, and you’ll never notice this when you’re in the one bike
system, but it becomes exposed when you have items like front derailleur that are very close to that tire. Likewise, it could be
wheel flex, so wheel flex is far more likely than frame flex, and you’re gonna see it
in somewhere like this. Now at the same time, your
wheel might be out of true, so the wheel might be slightly buckled, and of course your tire
might not be seated, or it might of deleminated itself as well, in which case, the tire might
have a bulge in a casing, or something like that that
is causing the problem. Now, the adjustments to get around this, whatever the reason, is
basically using your limit screw on the inside there, but
beware that if you adjust that limit screw too much, you’re
shifting down into that little chamber, you might suffer slightly. So, double check first
that your entire mech lines up with the chain, so put your bike in the middle-middle sort of
gearing, and what you want is to make sure that the
mech itself in that position is dead straight, so
it’s completely aligned, both sides in the cage are
running parallel with that chain. And as I explained, there’s
really only the one adjustment you can do to that one as your derailleur. If it is rubbing because of
the wheel wobbling around, or there’s some potential damage there, then that’s something
you might wanna address and take it to the body
shop and get those guys to have a look at it.
(pedals whirring) The next up is a classic, and
this will always happen to you if you have three chain rings,
and that will be the chain rubbing on the outer cage
when you’re in the middle chain ring and in the
smallest sprocket of the rear. Now, the middle chain ring is the one that you would use the most, it’s the one you’ll wear out first,
it’s the one that you’ll do the majority of your riding in. Only using the granny
when you need those real extra sort of low gears for steeps, and likewise, when you’re
spinning out your gears you’ll be using that big chain ring. So, the bread and butter
is that middle ring. Now, you can make limit
adjustments on the outer chain ring and on the inner chain ring
by using your limit screws, but the way to adjust the cage itself on the middle chain ring is
with the barrel adjuster. So, barrel adjuster really
only makes a difference on the front derailleur
in the middle chain ring. That’s what it’s for in this case. So, as you can see here,
the chain is rubbing just on that outward
corner here of that cage. Makes a bit of an annoying noise, and that’s about it
really, so all it will take is a few turns counter-clockwise
on that barrel adjuster on the shifter, and that
alleviates the problem. And the final problem,
which is definitely down to the fact that your limit screws are not adjusted properly
is under or over shifting. Now, under shifting would
mean when you’re shifting down into the smallest chamber,
it jumps straight off and onto the bottom bracket shell, or worse, it gets caught
down there somewhere. That’s the case of just
aligning the derailleur over the inner chain
ring, but the outer one can cause other issues
as well, ’cause the chain will come off completely,
and it can get wedged between that outer chain
ring and the crank, and if that happens, you need to know that that’s something happening straightaway ’cause if you continue to pedal
you’re gonna snap the chain, potentially pull of your rear derailleur. A bit of a nasty thing to
happen, so you need to make sure, with your chain shifted
into that outer chain ring, you then adjust the outer screw there. Just to adjust the limits on
it and make sure it’s centered. Simple as that, make
your adjustment there, and then hopefully your
shifting will be perfect. (cool vibe music) Now like the front mech, the rear mech works very well once it’s been
set up in the first place. However, because there’s a lot
more adjustments to be made on the rear mech, and
the sensitivity of ’em, and the fact that it’s
also in the firing line for rocks and other stuff,
it’s no surprise that here and there you are gonna
have some shifting problems. Now, here’s a bunch of
the very common ones you’re likely to come across
in your time riding a bike, and this is what you
need to do about them. Now, the gear system is
actually fairly simple once you have set where your limit screws and with the adjustment of your mech’s up. Now of course, gears work
on an indexing system, and that refers to one
click of the shifter corresponding to one gear
change at the rear end here. Now, one of the most
common things to happen is, you made a single gear
click change at the shifter and it doesn’t correspond at this end, so it’s a bit of a delay. Now, the simple reason
that doesn’t happen, provided everything’s set up
correctly in the first place, will be cable tension, which means there’s not enough tension
for the mech to move at the same rate as the cable
you’re pulling from that shifter. So, all you need to do to cure this and get it to hop out that
one gear that you need is, get on that barrel adjuster
and turn it counter-clockwise, or anti-clockwise, until,
was pedaling of course, until that actually shifts up one gear. Now, what you wanna do is get this sorted on the first two or three sprockets here, and make sure it shifts up and down. If it’s not shifting back down again, you’ve put too much tension
on, so take some of it off by screwing it back in clockwise
on that barrel adjuster until it shifts smoothly between those first two or three sprockets. There’s no need to do the
rest because the spacing is exactly the same, and
provided your limit screws have been set correctly
in the first place, your gears will be index and they’ll work. Now, the next problem is basically the opposite of that first problem and not shifting into
that smaller sprocket. Now, there’s actually a few
reasons this can happen. Now the first, and normally
the most obvious one, is that your limit screws have not
been adjusted quite right. Now, you can adjust them
and your gears will work, but it’s how well you fine tune them, and in particularly with
the smallest sprocket because basically there’s less
tension on the derailleur. When you’re shifting into
the biggest sprocket, there’s under tension,
so accuracy, especially, will take care of itself, but
when it’s just down to losing that cable tension, it’s
gotta be adjusted correctly for it to drop into that
smallest position there. So, even if it’s like a
quarter of a turn out, it won’t shift correctly,
so check that first, make sure it lines up, and
make sure when you cycle your bike through the
gears, so you can even try this by pedaling backwards, there shouldn’t be any
clicking or anything. It should be like just nice and smooth. The only noise you will hear
will be like the cassette freewheeling and all that sort of stuff, so just pay attention to that. The next up is you’ve basically
got too much cable tension, so it’s just not allowing
it to drop back down into that smaller sprocket
there, in which case the option there is to remove
some of that cable tension by screwing it in clockwise,
and it might only need a quarter or half a turn
on the barrel adjuster in your shifter, but that should
hopefully take care of it. The final option, which
is something that happens when you’ve been riding
your bike for a little while and perhaps you’ve not been maintaining it as much as you should’ve
done, is that the cable is actually sticking inside the housing. Now, if that’s happening,
basically there’s a good chance it won’t ever drop back down
because the cable is sticking and it’s not allowing it to. If that is the case and
it’s happening to your bike, fear not, we are making a dedicated video on how to change flush-outs,
put a new inner cable in, and how to set it back up again, so that one is coming
very soon on GMBN Tech. So, the next one is something
that’s actually plagued myself in the past on some bikes, and of course, I know that Blake’s
done this several times. So, picture this, you’re out on the trail, you go up a nice steep
section, you grab a handful of nice low gears, get ready
to tackle a knuckle in there, and your chain goes all
the way over the top into the spokes and it
all gets mangled up, and of course the only way
to do anything about it is to stop pedaling and
grab a handful of brakes, so it doesn’t continue
pulling everything around. Now, that is a really, really
expensive problem to have ’cause not only does it damage spokes, it can damage your
derailleur, snap your chain, snap the hanger, and in
some cases, even bend past your frame if you’ve
got a very lightweight frame. So, to get around this, you
absolutely have to make sure your upper limit screw, the
one that controls its railure on the upper sprocket there,
is crucially adjusted. Now, just wanna make sure
you do pay attention to that because on some wheel designs,
the spokes will be closer to the cassette than the
others, and of course, if they’re close to the cassette
that means they’re closer to your rear derailleur, in
particular, the top of the cage by the upper guide rail,
and if you’ve only got a couple of millimeters to play
with, common sense dictates that you not got much
room for error there, so just make sure that it’s
always adjusted correctly and it won’t cost you any money. And the final problem
you’re likely to have is one that makes you
scratch your head, really. So, your limit screws
are adjusted correctly, the cable tension is correct, your B-screw is adjusted correctly, everything
should be working, right? But somehow, your gears
are a little bit erratic, nothing’s quite right, but
you can’t place what it is. Now, that basically tells me that something is loose on your bike. Now, of course, everything
is subject to vibration on a mountain bike, and
the common things that can rattle loose on derail is
the jockey wheel bolts, those two bolts there, in this
case they’re three millimeter Allen key heads on there, and
the actual main hanger bolt that attaches it to the frame. If that has unwound itself
even like an eighth of a turn, that’s enough to just
take all the spacing out and your gears will never shift correctly, and I’ve seen people before
that have had this bolt a tiny bit loose, and
they endlessly play with their limit screws to try
and compensate, not realizing that this is loose, and they
mess up all their shifting. So, just be sure to check those bolts. And actually, the same
goes for all of your bikes, just be on top of that. Every now and then,
periodically, get an Allen key, run around the bike, make
sure all of the obvious bolts are tight, there’s
nothing loose, gives you the good opportunity just to
look after your investment. (pedals whirring)
So there we go, like I said, nothing to be afraid of. Your fundamental really
some a very simple things, and as long as you know
what the adjustments do. All based on those initial adjustments, and then just cable tension, so hopefully you’re gonna be able to
cure any small issues you might have with yours at home. For the rest of our Essentials videos, click over here, so there’s
loads of videos there already, and we’re gonna be making loads more. If there’s any particular
Essentials videos you want us to tackle for you to help
you work on your bikes, let us know in those comments
below, and of course, make sure you subscribe
and give us a thumbs up.

48 comments on “GMBN Tech Essentials Ep. 4 | Adjusting Gears

  1. Top tip. Always do a pre-ride safety check ( check tension on all bolts, check chain wear and tire condition/pressure), keep the "dork disk" on (even if your mech is perfectly adjusted a stray stick can throw your chain over the cassette and into your spokes.

  2. Hi doddy
    I bought some crank brothers stamp 2 flat pedals and the Allen key bolt used to tighten them into the crank does not turn the thread. The bolt it’s self turns however it doesn’t engage the pedal thread turning. Is this a fault In the pedal or am I doing something wrong. Would appreciate any thoughts.

  3. Hi,
    I usually strugle with the indexing doesn't match the gears. It is like 10-9-8 will work then 2-3-4 will not, like it will be jumping, and if adjusting then the problem just change to the opposite end of the casette.

    I do not understand this issue when in when ever video I watch it is like if it works in one end i must also in the other.

    This is not a problem I have had only once I have had it several times on different setups.

    Can anyone explain?

    Thank you

  4. forgot one thing to mention and explain, mech hanger bend, i work in a bike shop, that is the most common issue people happen to have

  5. What's up if on one gear in the middle I can shift to the smaller cog perfect but shifting back to the big one it doesn't switch (but gets noisy) and if I shift again it goes two gears bigger? Everything else on every other gear is perfect.

  6. Very practical tips, thanks doddy. I would like to see how’s the correct way to Align disc rotors. See you around.

  7. Ahhhh… just got done messing with my shifting today. Shifting seemed a little off since I got the bike a month ago. Well, she finally fell off into the spokes. Luckily I was riding my home trail as I had to pull the cassette to get the chain out it was so bad. Well, 5 minutes of fine tuning and she shifts sooo much better and won't drop off into the spokes anymore. That'll teach me to ignore issues.

  8. I had the erratic shifting problem on my new bike, when I replaced the cassette from a 11-42 to a Boxone 11.46. I finally checked the mech mounting screws, and sure enough they just loose enough to cause the problem. Once tightened up, the bike shifted perfect..

    @Doddy, can you do a video on how to remove, and replace a the rear wheel on a hardtail, where the tire is fairly close to the seat post..? I have a devil of a time getting my wheel on, even with the clutch disengaged..Great show, as usual.

  9. Hi , I have a question.
    I have a 12 speed gx eagle transmission and I have trouble with it. The top 4-5 gears work fine , but the harder gears just shift up and down uncontrollably when shifted onto. I have gotten my hanger checked and it is perfectly straight. Any ideas why that might be happening ? The transmission is quite new the first chain isn’t even worn yet.

  10. when i go backwards or fakie on my montainbike, the chain on the front derailleur jumps from the 2nd gear to the 1rst gear
    i dont realy know what is the reson for this

  11. Thanks for the series so far! I've been watching your videos since I started mountain biking and even now as a competent home mechanic still watch them and learn new things here and there!

  12. I'm perplexed why there is blue duct tape on the non chain side of the lower chain stay… can't be for chain slap protection.

  13. How about hard shifting? Sram Eagle XO1. Brand new, adjustments correct, hanger isn't bent. Shifts timely and smoothly, all the way through, in both directions, but when shifting to a lighter gear, under slight load, it is very loud, clanky, and kind of a grinding sound. The example would be, when transitioning into a climb from a downhill, finding yourself in too tough of a gear, and trying to get into a lighter gear quickly during the pedal stroke. Thanks!

  14. thanks for the help, i was having serious issues on my last ride, only being able to use gear 8 and 10 whilst climbing. turns out, my cable just needed a little more tension.
    i love to work on my own bike but get a bit fearful cause i don’t want to make a little problem bigger, specially with a $4k bike. Your channel gives me the confidence and knowledge i need. thank you

  15. Concerning the issue with 2nd chainring getting noisy when the highest gear is selected in combination… don't do that! The concept that you have an "X"-speed transmission calculated by taking the number of chainrings X the number of gears in the rear mech is (generally) a fallacy. 3-5 gears is typically what you should expect to use for each chainring. The chain design is a controlling factor since each rear mech progression (8 to 9… 9 to 10, etc.) uses a more flexible (and weaker) chain to accomplish the side-to-side requirements of the rear mech. I'm generalizing and there will be exceptions… also, you might just have to tolerate a little noisiness… there's no significant wear (I'm told) caused by such slight interference considering how little time we mountain bikers can reasonably spend in a single gear selection.

  16. Ghost shifting when pedalling? Whenever I put the power down it slips gears all over the place on its own, both up and down the cassette. Driving me mental.

  17. 2 other causes of erratic shifting: 1) chain stretched and needs replacement and 2) cable incorrectly routed through derailleur body

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