A Note On Chainsuck - ibis Mojo Sl-R Notes On Tuning And Maintenance

A Note on Chainsuck

The Dark Art of Shifting in Mud: the chain during a ride.
Another cause of sticking is a worn
How to Avoid Chainsuck.
"Chainsuck" is when your chain does drive train, particularly if your
not detach correctly from the bottom chainrings are more or less worn than
of your chainring, and instead wraps your chain. Drivetrains work best when
around the ring until something jams. they wear together as a unit. If it's time
Chainsuck happens when the force for a new chain, then be sure to care-
provided by the rear derailleur is less fully check your rings. Another thing
than the force causing the chain to that causes chains to stick is mud.
stick to your chainring. There are many It all depends on what type of mud
ways to reduce chainsuck, but they can you have, but if the drivetrain gets too
be broken down into two categories: dirty, the chain is going to start sticking
1. Preventing the chain from sticking to and it will take careful chain manage-
the ring. ment to keep it from sticking.
2. Maintaining chain tension while That brings us nicely to the next part;
riding. maintaining chain tension. Let's as-
Let's start with the chain sticking to ring sume that your chain is the minimum
past the correct departure point. length needed to go around the big
The most important thing you can do is chainring and large cog at bottom out
to keep your drivetrain clean and your (standard full suspension chain length
chain lubed. Even if you do nothing spec.) The more tension you have pull-
else to your bike, you should at least ing the chain off the chainring, the less
wipe the chain down with a rag and likely the chain will become stuck to
put some lube on either before or after the teeth. The component that provides
almost every ride. If it's wet out then this chain tension is the rear derailleur.
use a wet lube, like Finish Line Wet However, the derailleur's pulling force
Lube or Pedros Synlube. Sometimes it's is not always the same. It pulls less in
necessary to actually clean and lube smaller gears and more in larger ones.
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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
few things that can cause a sudden suspension frames are not completely
decrease in tension. One is shifting innocent. Most modern suspension
from a larger to a smaller chainring. designs use chain growth to create
Because the ring diameter is decreas- anti-squat and keep your bike from
ing, the derailleur has more slack to bobbing. The rebound part of the sus-
take up and it can't do that instantly, pension motion shortens the distance
so while the rear derailleur is mov- from BB to rear axle and creates slack
ing to the new position the chain is in the chain, thus reducing tension.
momentarily de-tensioned. There's no real way around this but if
Another factor that influences the you do everything mentioned above
chain sticking to the chainring is to it's not usually an issue. It's all about
suddenly pedal harder as the higher managing the combination of factors,
chain force against the chainring so if you're riding in the mud, stay
teeth can wedge the chain in place. out of your granny gear if possible. If
This works both ways, if you ease you do have to shift down try to plan
up a bit you can actually reduce the ahead so that your suspension is not
chain/chainring stick. If you put the rebounding at the same time as you
last two concepts together and ease suddenly put down full power.
up a bit right as you shift then you'll Sometimes the mud is just so bad
probably have better results. Since that nothing is going to help. In that
you usually can't ease up like this case, a single speed is the best tool
in the middle of a steep climb, you for the job!
should plan ahead to get front shifts Before we finish let's stop to clear up
done before you need them. Your some misconceptions:
drivetrain will thank you. 1. Low chainstays do not cause chain
Most of what causes chainsuck is suck. They can make it more difficult
covered in the sticky ring and chain to extract the chain if it gets caught
tension part above. Unfortunately above or against the chainstay but it
A Note on Chainsuck
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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