hello calvin jones here with the park tool company
here for tech tuesday where we're going to take a virtual bike ride
on a wednesday let's go because i think a hill
is coming at us we hop on the bike and we
oh big gear but we grind it out let's shift
because the hill is coming up another lower gear
and another this thing shifts like a dream
goes and goes it's getting steeper it's hill's getting steeper a little steeper
and our dream's gone away it's not shifting so good but we're not
getting off we know what to do you just force it through hey
now it's shifting
great couldn't have been a problem we're at the top of the hill
now we're gonna go back down all right we worked for this this is the fun part
it's getting steeper it's getting steeper
it's getting steeper oh yuck there we are again
down down up we fixed it
all the way down and we're back at the start
what's going on here good shifting it's actually pretty good shifting for
a lot of them two bad ones 12 speed here actually now you got a 10 right but
let's talk about what to do you're on the saddle you're riding along
and things are skipping what can we do you don't want to stop there's an old
adage when in doubt turn it out turn out the barrel adjuster
quarter or a half a turn it's the tendency for our cable systems to
slacken so if it's an index problem let's give
it a try now go a half and see what we get so we shift
on up and we shift and we shift and we get
to what we think might be
i don't think that helped at all this was an index problem no
finding the problem is important so we can have the right solution
it's not indexing so you're pedaling along though
you're up in the saddle you might be thinking ah
chain problem it's a tight link in the chain but that tight link
it's going to be about once every two pedal strokes this skipping
that's like twice per pedal stroke not the chain
not the indexing then hanger ah maybe no all the other gears would have
been off all the other gears are fine sometimes
you got to get off and have a closer look so we have to
dismount we need to get down closer to that cog
and have a look we shift up
oh boy is it ugly we go slow and we see that lift oh
twice we go in one more cog
it sits there but it's more subtle we do have a little bit of
clanking this one horrible what's going on
is a problem with the sprocket the one that we're on so this is where as a
mechanic you got to remember two different points of view so it's
nice to come in and look this way we can see the chain
hopping but we're also going to remember to
change our viewpoint come down on it and another angle and
boy oh boy we can see that one looks bent badly badly bent
right here and again here so what what was going on here i would
have loved to have been a fly on the chain stay
when that went on because i suspect it happened all at once
with a monster power stroke and a bad shift
so just the timing of it unfortunate shift
may have pulled that sprocket over whatever it was
it's pretty much history now so you're on the trail what can we do?
don't use it. right? doctor this hurts! doctor says:
"don't do that." here now we got a 10 speed started with the 12 just don't use it
you get back home can we fix it
not really not a good fix you would have to
bash it back in you're not going to get in here and pry
there's no room if you did you've weakened the metal it's weakened once
you've weakened it twice replacement in this case is really what
we need but diagnosing the issue
that is the important fix so we know what to do
get a new one on a wednesday and that's it from park tool see you
next time thanks for watching if you enjoy tech
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