we're going to look at what threads are they're the one
the most important things on your bike whatever that was
oh a valve cap you know what we do with valve caps here right there there's your valve cap
so i was thinking about this this this session today it's gonna be the most important one here
it's what keeps bikes together what keeps bikes together this could be your bike this could be
your friend's bike this could be anybody's bike we're going to talk about what keeps it together
it's an important thing sometimes it's a welding torch sometimes it's wire feed uh tig and mig
sometimes just plain old walk do i have a pot of people some volunteers that are kind of together
over here yes we have a pod come on up here stand here here and here and we'll tell you what they
are so three parts of the thread you need to know we have around here you stand here you stand here
and you stand here here's our welcome to your threads spread your feet touch feet touching
feet touching feet touching that's that's good now hands up so we have hands up straight up
straight up you got to squat down you're the tallest a little bit okay now what do we have look
at the little valleys this is called the crest the very top that's the crest of the threads right
so down here the root down at the root down in the bottom of the valley that's the root the pitch
diameter it's not exactly halfway but it's through the middle here that's the important part because
that's when you stress it that's what happens now what keeps it together is stretching everybody
stretch it's all stretch stretch you know what metal does when we tighten it what does it do
stretch when you tighten it these actually flex all right so i want you to lean to the
left it's flexing the nut the other threads going the other way in the nut
but now you've over tightened and you've stripped the thread so go like this
oh we've stripped the threads notice we're not the same height when you strip a thread and we
had several yesterday little pieces of metal are gone can we restore these threats can we
put these threads these guys back the way they were no these things are ruined we throw them
out boom they're gone guys go back the material is gone a tap cannot restore the material here
it's a nice hydra here's the neck warmer thank you ride your fat bike this winter so the threads
flex over tighten they strip what holds things together is that tension that tension
when we have metal it stretches it literally stretches and that that holds things tight
so let's talk about the type of piece joints we have on our bike right where we join things
we've got hard joints and we've got soft joints and clamps what's a hard joint typically a pedal
bam right into the crank it's not an adjustment it just goes straight into the crank let's talk
about who's strong here he's strong you're his mechanic when you tighten down that thread there's
actually an equation okay who's good with math here forget it there's an equation of the preload
equal to the torque divided by the diameter thread times the coefficient of friction
and it turns out when you tighten the nut and bolt it is a lot of pressure even even a pedal thread
will be at least easily 2 000 pounds of pressure in there so when you tighten
the pedal down it's as if you're running beside him and holding that pedal on with your torque
now if the effort he's able to generate riding is greater than the stress you put on
you two are arm wrestling right we didn't have koba to have you two arm wrestle
so if your thread is weaker than his effort whoa what's gonna happen to the pedal
loose and fall out when something falls off on the bike what is the common reason it fell off
it wasn't tightening to begin with it's not his mighty effort it's not the vibrations
it's not mars traveling next to pluto and venus no you didn't tighten it it's that simple
okay so a hard joint those are easy they're going to be a certain torque manufacturers
give them now let's talk about different joints clamping is this a good place for a torque wrench
well you should buy a toy wrench buy a park tool torque wrench available retailers near you
this is actually one of the places that a torque wrench is not so great not so great
simple this is a bianchi bike this bolt is a campagnolo binder bolt this is a avenir seat post
tell me all those engineers talk to each other right so what does what does the bolt do that's
your question to yourself what does the mold do this bolt keeps it from rotating so this
is a good example of a minimal torque minimal pedal and hard joints are more maximal torques
you if if you get away with four newton meters here and it says six newton meters four is good
now if it's carbon fiber especially carbon fiber hates to be clamped
let's go to the step typical stem here has these four bolts that are clamping
right so you tighten them enough so it doesn't rotate this bolt here this is an m5 bolt
remember our crest here five millimeters apart that's our crest m5 this bolt easily can take gosh
120 120 inch pounds you know 10 12 newton meters before failing why don't we tighten this thing to
12 newton meters the bolt's happy what it's not going to strip what's it holding it's going to
crush you out it's going to crush the handlebar that's exactly right so sometimes it's a minimal
torque to get by with what you're doing this is a pretty straight bar where's our roadies
any roadies here right behind you let me we have a talk we brought a token ready with us
so out of roadie what's i'm saying about it rhodey you've got these bars sticking out there
you have a much longer arm and a pivot they their lever arms a lot greater typically more
is needed on them so that's a minimal torque maximum torque how about these nuts and bolts here
32 nuts and bolts what are they spokes you don't want them the spokes will handle far
far more tension than their rim so we are not setting these at maximal the rim the weak
the weak length of your system determines the torque so in a handlebar what's the weak link
the carbon fiber is the weak part here not the bolt not the clamp so on a wheel the weak part
is the rim typically the rim all right so we we set our our tension by by the rim okay so what's
a torque wrench torque wrenches measure the effort of turning it is not a magic wand okay you ready
oh it's good i touched it no what happens on a torque wrench we're back to that wrestling
contest inside there's a spring i have to hold the handle i'm measuring the effort here but it's
funny this is called the click type this pivot my spring is is only concerned with this pivot
there's another lever here from your bolt head to the pivot so that's how it's measuring these two
so here i want to go on a bolt here let's go something mild if i go like this oh that click see
that move right away is this bolt greater torque than the wrench no no no it is the bolt's greater
i see the bolt is greater than the wrench do i need to keep going it clicked should i keep going
no these are polite midwestern wrenches they say please stop but i'm asking you would you just
please stop oh you want to keep going you just go right ahead this ranch ah this is more west
coast this is pushy no it's not it's a helicopter edge let's see what happens here so on this range
okay it clicks when i when i turn it it just ticks and goes right over it it stops
all right this is the uh the uh the mama's ranch all right i'm gonna look out for you
i'm looking out for you you're trying to turn in more but we're not we're gonna stop
all right so you can set it for different torques so it's a torque limiter torque limiter
so that's there's a difference there what's another important very very important thing
musician do they they play music right they hear the music do they always use a scale in computers
no they hear it same with the mechanic you need feel is still a very important thing the feel so
i recommend when you use a torque wrench also get in there with a hand wrench and just oh man you
know that's tight or whoa that wasn't so tight put it in your head right musician we play what scales
no no no no no no your whole stick of life scales you get stuck up but that's what mechanics need
to do learn the feel of the note right what the 40 newton meters is learn it all put it in your
head then the torque wrench is going to make sense right does that replace the torque range
why why say it cook the great chef will also have a good sense tablespoon right
three centimeters 50 cubic centimeters they'll have a good sense of that for the recipe and a
mechanic needs to have that feel as well so let's summarize what holds the bike together what is it
tension in the threads it's the tension in the threads right you have a nut and
a bolt and you put it put it on the bike if you didn't tighten it it's meaningless
really quick we're going to finish with thread preparation thread locker is fun
grease is good we like to grease these because it helps you pull them tighter
thread locker is good too now when it's wet it provides lubrication but understand
thread locker does not mean you get to back off the tension all right if i put
thread locker in here and put it in finger tight and you go the right ride the bike
tears in the end it's not good so tread locker helps seal it helps prevent corrosion
it's a backup to your tension but it doesn't replace tension okay so without with that go about
sea otter wherever you look look for attention okay get out there and stretch thanks for coming
you