ibis Mojo Hd 160, Notes On Tuning And Maintenance

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few things that can cause a sudden
decrease in tension. One is shifting
from a larger to a smaller chainring.
Because the ring diameter is decreas-
ing, the derailleur has more slack to
take up and it can’t do that instantly,
so while the rear derailleur is mov-
ing to the new position the chain is
momentarily de-tensioned.
Another factor that influences the
chain sticking to the chainring is to
suddenly pedal harder as the higher
chain force against the chainring
teeth can wedge the chain in place.
This works both ways, if you ease
up a bit you can actually reduce the
chain/chainring stick. If you put the
last two concepts together and ease
up a bit right as you shift then you’ll
probably have better results. Since
you usually can’t ease up like this
in the middle of a steep climb, you
should plan ahead to get front shifts
done before you need them. Your
drivetrain will thank you.
Most of what causes chainsuck is
covered in the sticky ring and chain
tension part above. Unfortunately
suspension frames are not completely
innocent. Most modern suspension
designs use chain growth to create
anti-squat and keep your bike from
bobbing. The rebound part of the sus-
pension motion shortens the distance
from BB to rear axle and creates slack
in the chain, thus reducing tension.
There’s no real way around this but if
you do everything mentioned above
it’s not usually an issue. It’s all about
managing the combination of factors,
so if you’re riding in the mud, stay
out of your granny gear if possible. If
you do have to shift down try to plan
ahead so that your suspension is not
rebounding at the same time as you
suddenly put down full power.
Sometimes the mud is just so bad
that nothing is going to help. In that
case, a single speed is the best tool
for the job!
Before we finish let’s stop to clear up
some misconceptions:
1. Low chainstays do not cause chain
suck. They can make it more difficult
to extract the chain if it gets caught
above or against the chainstay but it
is not the cause of the chainsuck.
2. Aftermarket / new parts are not a
guarantee that chainsuck will be
solved. In addition to the factors
discussed above, some chainrings
are better than others at releasing
the chain, even when new.
We have had the best luck with
Shimano and SRAM chainrings.
3. The lower roller of a dual ring chain-
guide does not help chainsuck.
It doesn’t provide any additional
spring tension and in fact is there
to keep your chain on your ring
past where it normally detaches.
Depending on the roller design,
it can increase chain suck because
the chain is forced to go through a
step on the roller at the same time
it’s being forced the other direction
on the rings. To do that the chain
has to twist in a small space and
that increases the chance of the
chain sticking to the ring.
OK, that’s it! If you don’t master the
techniques explained above on the
first ride, don’t worry, it will come
with a little practice!
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The Dark Art of Shifting in Mud:
How to Avoid Chainsuck.
“Chainsuck” is when your chain does
not detach correctly from the bottom
of your chainring, and instead wraps
around the ring until something jams.
Chainsuck happens when the force
provided by the rear derailleur is less
than the force causing the chain to
stick to your chainring. There are many
ways to reduce chainsuck, but they can
be broken down into two categories:
1. Preventing the chain from sticking to
the ring.
2. Maintaining chain tension while
riding.
Let’s start with the chain sticking to ring
past the correct departure point.
The most important thing you can do is
to keep your drivetrain clean and your
chain lubed. Even if you do nothing
else to your bike, you should at least
wipe the chain down with a rag and
put some lube on either before or after
almost every ride. If it’s wet out then
use a wet lube, like Finish Line Wet
Lube or Pedros Synlube. Sometimes it’s
necessary to actually clean and lube
the chain during a ride.
Another cause of sticking is a worn
drive train, particularly if your
chainrings are more or less worn than
your chain. Drivetrains work best when
they wear together as a unit. If it’s time
for a new chain, then be sure to care-
fully check your rings. Another thing
that causes chains to stick is mud.
It all depends on what type of mud
you have, but if the drivetrain gets too
dirty, the chain is going to start sticking
and it will take careful chain manage-
ment to keep it from sticking.
That brings us nicely to the next part;
maintaining chain tension. Let’s as-
sume that your chain is the minimum
length needed to go around the big
chainring and large cog at bottom out
(standard full suspension chain length
spec.) The more tension you have pull-
ing the chain off the chainring, the less
likely the chain will become stuck to
the teeth. The component that provides
this chain tension is the rear derailleur.
However, the derailleur’s pulling force
is not always the same. It pulls less in
smaller gears and more in larger ones.
That means you should use your small
chainring as little as possible. If you’re
in the small ring and more than three
or four gears down from the top of the
cassette then it is time to shift back into
the middle ring for a larger diameter
gear combination. For example,
instead of running a 22 front 24 rear,
run the 32 front 34 rear for the same
ratio but much higher tension.
Another way to increase your average
chain tension and still use the small
ring is to remove the big chainring and
shorten the chain accordingly. This
will provide significantly more chain
tension. If you’re trudging though sticky
mud you probably don’t need that
high of a gear.
A final trick is to tighten your rear
derailleur’s B tension screw a few
more turns than normal to increase
your derailleur’s spring force. This nice
write up from Park Tool tells how to do
that: http://www.parktool.com/blog/
repair-help/rear-derailler-adjustments-
derailleur
Now that you’ve got your average
tension up a few notches, there are a
A Note on Chainsuck A Note on Chainsuck