What is "chain suck"?
Steve Williams
>
> What is chain suck and why has it never bothered me?
>
>Philip Greenspun
To gain a complete understanding of chain suck, simply ask any
owner of a 2-3 year old Klein (mountain bike). They're notorious,
so much so that Klein eventually came out with an add-on device
to prevent it. (Similar to after-market anti-suck devices available
for other bikes.)
Please note that this is NOT a put-down of Kleins. They're good bikes
and my friends who have them are more than willing to put up with things
like a little extra proclivity for chain-suck and, in some cases, finicky
shifting due to internal cable runs and extreme cable angles.
-- Steve Williams
Pat Thompson
>
> 1) Mountain bike ads sometimes show elevated chainstays (that come out
> from the middle of the seat tube instead of the bottom) and claim
> "greater mud clearance" and "no chain suck". How is the mud clearance
> greater when the bottom bracket is still in the same place? What is
> chain suck and why has it never bothered me?
"Chain suck" is when the chain gets stuck between the tire and the
chainstay. It used to be a big problem with chainstay mounted
u-brakes. These brakes were on almost all new mountain bikes
around 87-88. They decreased clearance between the chainstay and
the tire, and when it was muddy - mud would gather around the brake and
make chain suck more probable. Chain suck was most likely to occur when
descending with the chain on one of the smaller chainrings, like if you
had just cleared a climb and forgot to put the chain on the biggest
chainring before descending, as the chain would bounce up into the
chainstay and get caught. The problem was solved when bike manufacturers
returned to cantilever style brakes. Elevated chainstay bikes solved the
problem too, albeit a drastic solution for a simple problem. Today, still,
elevated chainstay bicycle manufacturers differentiate their bikes as
having "greater mud clearance" and "no chain suck", even though they are
solving a problem that no longer exists. I guess they can't think of any
other reason for having an elevated chainstay, nor can I.
> 2) What does STI stand for?
Some Tokyo Idea
-Pat
------------------------------
Patrick Thompson
ntmtv!sco...@ames.arc.nasa.gov
Mark_Donohoe
: From article <PHILG.92J...@zug.ai.mit.edu>, by ph...@zurich.ai.mit.edu (Philip Greenspun):
: >
: > 1) Mountain bike ads sometimes show elevated chainstays (that come out
: > from the middle of the seat tube instead of the bottom) and claim
: > "greater mud clearance" and "no chain suck".
:
: "Chain suck" is when the chain gets stuck between the tire and the
: chainstay. It used to be a big problem with chainstay mounted
: u-brakes. These brakes were on almost all new mountain bikes
: around 87-88. They decreased clearance between the chainstay and
: the tire, and when it was muddy - mud would gather around the brake and
: make chain suck more probable. Chain suck was most likely to occur when
: descending with the chain on one of the smaller chainrings, like if you
: had just cleared a climb and forgot to put the chain on the biggest
: chainring before descending, as the chain would bounce up into the
: chainstay and get caught. The problem was solved when bike manufacturers
: returned to cantilever style brakes.
Not true in my case. I have a fisher montare that had the suntour (I think)
roller cam brake. The real problem was mud stopping the back wheel from
rotating. I fixed that by chucking it and having cantilever style brakes
retro fitted to the bike. But I still get chain suck....It typically happens
when shifting fast from upper/middle chain ring to smallest and the
chain wraps up between the stay the the smallest chain ring....a real
bother at times! I saw a thing in bicycling mag where a small piece of
pvc tie-wrapped under the frame would fix it....sounds good, but I have
yet to try it....
Overall, a good expaination above...
--
Mark Donohoe (ma...@cup.hp.com)
USENET News System
>"Chain suck" is when the chain gets stuck between the tire and the
>chainstay.[...] Chain suck was most likely to occur when
>descending with the chain on one of the smaller chainrings, like if you
>had just cleared a climb and forgot to put the chain on the biggest
>chainring before descending, as the chain would bounce up into the
>chainstay and get caught. The problem was solved when bike manufacturers
>returned to cantilever style brakes.
This phenomenon is not what I understand chain suck to be. Chain suck will
occur with worn chainrings and chain, but causes the most trouble on the small
chainring, where the chain can jam between the chainstay and chainring. When
the teeth on the chainring get hooked, they don't immediately release the chain
onto the next tooth. Add a bit of mud and voila, you have chain suck. The
best way to prevent it happening is to replace the chain before it wears
("stretches") too much, thereby reducing chainring and sprocket wear. I've
also had good service out of stainless steel small chainrings.
>Elevated chainstay bikes solved the
>problem too, albeit a drastic solution for a simple problem.
They might have stopped the chain jamming, but they never prevented chain suck.
It can still occur and has the potential to damage the rear derailleur or
hanger on these bikes.
>Today, still,
>elevated chainstay bicycle manufacturers differentiate their bikes as
>having "greater mud clearance" and "no chain suck", even though they are
>solving a problem that no longer exists. I guess they can't think of any
>other reason for having an elevated chainstay, nor can I.
I was a skeptic until a really muddy ride when my compainion's e-stay bike's
rear wheel kept turning when mine was hopelessly clogged with mud.
Unfortunately for him, the bridge for the brake cable on his suspension forks
caused his front wheel to jam up, while my standard forks remained clear. The
mud clearing ability isn't enough to make me a convert to an e-stay bike,
though, as I have found standard chainstays sufficient for all but the most
extreme conditions.
Phil Etheridge Internet: P.Eth...@massey.ac.nz
Macintosh Consultant Phone: +64+6-356 9099 ext 8689
SMIS, Massey University Fax: +64+6-350 5611
Palmerston North, NZ 40*23'S, 175*37'E ; GMT+12
zaphod beeblebrox
tire and the chainstay. . . Well, what is it called when the chain
gets stuck between the chainwheels and the chainstay? I had a
Schwinn Cimarron that had this problem (it is no more; the frame
cracked near the headtube :-( The first time it happened was in my
only mtn. bike race (so far :-). I was climbing and shifted and
_crunch_ and the pedals stopped. I didn't have the tools to remove
the chainrings (it would have also taken too long in a race) so I
gave a few _good_ kicks on the pedal and unjammed the chain. It
happened many times since in similar situations.
If there is no term for what I described, then I Christen it the
"chain wedgie."
BTW I like Schwinn's warranty. The frame cracked in January of this
year. The Cimarron was an '87 model with Deore XT parts. $38 for
bike shop fees got me a new Paramount Series 30 with a vastly better
frame and lesser (Deore LX) parts. Getting the Hyperglide was worth
losing the great feel of the XT brakes. All this less than a month
after another Schwinn frame of mine cracked. '85 model BMX bike.
They gave me the full original retail price of the bike as credit at
the shop I bought it at. Don't think Schwinn bikes aren't good.
They are great, though overpriced, bikes. I might be just a bit
rough on them at times, thats all (raced the BMX bike for years and
never had any probs, and they still made good on the warranty :-).
___
/ APHOD
/__________
R. Scott Truesdell
> from the middle of the seat tube instead of the bottom) and claim
> greater when the bottom bracket is still in the same place?
Mud clearance has no relation to ground clearance, per se.
The mud clearance they are referring to is between the bicycle frame
(specifically the chain stays) and the tire. In muddy conditions mud
can build up in the area where the chain stays are welded to the
bottom bracket to the extent that it impedes the tire.
> What is chain suck and why has it never bothered me?
Chain suck is when the chain doesn't release cleanly from the chain-
rings and "sucks" up the back side of the chainring. It then usually
jams between a chainring and the chainstay, scratching the paint and
even metal of the frame. Chain suck can bend chainrings, break or
seriously weaken chains, and in extreme cases cause serious damage to
the bicycle frame. It occurs when shifting the front gears which
forces the chain against burred gear teeth.
As chainrings wear they can develope burrs on the teeth that can cause
the chain to "stick" in place instead of releasing easily and heading
back to the rear derailleur. Mountain bike gears are often abused and
people shift in desperation (heck, I sure do!) which causes the
aluminum chainring teeth to develope these burrs.
Another part of the chain suck equation is short chainstays. Shorter
chainstays can contribute to increased climbing traction to a certain
extent.
The third part of the equation is fat tires.
The fourth part of the equation is mud clearance between the frame and
the rear tire.
Put it all together and it spells trouble. The chainstay snakes between
the tire and the chainrings, which happen to be overlapped, and both
need plenty of clearance. Since the width of bottom brackets varies by
only a few millimeters and since the front chainrings need to align with
the rear gear cluster, there isn't anyplace for the chainrings to go.
So when, during hard shifts, the chain "sucks" up on burred gear teeth,
it jams between the chainstay and the chain rings. This usually causes
pedaling to come to a grinding (literally) halt. Often it is difficult
to get the chain back on the correct side of the chainstay.
Elevated chainstays remove the chainstay from between the tire and
the chainrings so (a) there can be almost infinite mud clearance and
(b) when the chain does suck up, there is no place for it to jam.
Generally the burred teeth will release the sucked chain before any
damage can be done to the derailleur cage.
Disadvantages of elevated chainstays are (a) more weight (there is
generally more metal involved and it needs to be stronger because of...)
(b) less strength in the rear triangle. By decreasing the angle between
the seatstay and the chainstay the structure surrenders some vertical
rigidity. The better designs (Cunningham always does this) incorporate
an additional compression strut between the seatstay and chainstay to
beef up that shear web. Cunninham puts it right at the cantilever bosses,
which is the absolutely most logical place for it to be. Most people I
know prefer the traditional chainstay for weight and strength reasons.
> 2) What does STI stand for?
"Shimano Total Integration". It's marketing b.s. It means that Shimano
wants you to THINK that if you use ANY parts of this grupo on your bike
you MUST use the entire grupo. This, of course, is false and many people
successfully mix and match parts of various grupos. Basically, all the STI
components (brakes, shifters, derailleurs, etc.) are designed to work
together in an "integrated" fashion. Like I say... marketing b.s.
--scott
Art LaValle
>
> "greater mud clearance" and "no chain suck". How is the mud clearance
> chain suck and why has it never bothered me?
It's my guess that since the distance between the elevated chainstays is not limited
by standardized bottom bracket width (which normal chainstays are) then the "mud clearance"
between the chainstays and the tires is much better. This also allows the use of the widest
tires available, not always true with bikes with chainstays that are joined at the bottom bracket.
To me, chainsuck is what happens when I jam my chain in between the granny gear and the chain
stay. This ususally happens because I'm trying to maintain contact with the group I'm riding with
and an unexpected severe vertical change in topography (big mother of a hill) suddenly appears
and catches me in the wrong gear. Naturally I panic and try to downshift ASAP, and naturally
making the transition from a larger chainring to a tiny whirring one tends to *whip* the chain
up under the bottom bracket in between the small ring and chainstay - thus it appears there
is some sort of vacuum under there that "sucked up" my chain.
> 2) What does STI stand for?
Strategic Technology Initiative - It's Shimano's plan for zapping all other Bicycle component
manufacturers and becoming the Bike Component Superpower - it seems to be working :-)
Art LaValle
> From article <PHILG.92J...@zug.ai.mit.edu>, by ph...@zurich.ai.mit.edu (Philip Greenspun):
>
> chainstay. It used to be a big problem with chainstay mounted
> u-brakes. These brakes were on almost all new mountain bikes
> returned to cantilever style brakes. Elevated chainstay bikes solved the
> problem too, albeit a drastic solution for a simple problem. Today, still,
> elevated chainstay bicycle manufacturers differentiate their bikes as
> having "greater mud clearance" and "no chain suck", even though they are
> solving a problem that no longer exists. I guess they can't think of any
This may be your definition of "chain suck" but it's not the only one. Unfortunately
"chain suck" still exists and the problem isn't limited to u-brake bikes only. The
"elevated chainstay" bike may be a solution to the problem, but it's a pretty drastic one.
If you haven't heard there is a company reknown for it's superlight parts D.B.A Ringle and
they sell a nifty little widget called of all things "A Chain Suck Thing". This piece mounts
under the chainstays just behind the Bottom Bracket - it's reputed to solve the chain suck
problem. If you've read the recent MBA test of the Klien Attitude (I think) you'll notice
that this bike came equipped with a chain suck thing. I've also noticed some of the carbon/alum
tubed TREK's around here on display with these widgets on them. Apparently two of the more
respected Mountain Bike Manufacturers still think it's a problem otherwise why would these
things show up on their bikes ?
c922...@wombat.newcastle.edu.au
Shimano Total Integration (RapidFire MTB shifters, Dual control Road shifters)
In my three years of mountain bike experiance, chainsuck has been one of my
greatest problems, often during racing.
My chain has never been caught between the tyre and the chainstay of my
Raliegh technium.
The chain has been caught between the chainstay and the chainrings!
This totally jams the transmission and usally ocurrs when changing gear
during a jaring downhill run.
I have found the cause of chainsuck is due to the lack of space between the
smallest chainring and the chainstay.
The elevated chainstay eliminates this problem.
As the chainstays are elevated above the transmission.
As a result I will soon be the proud owner of a
Cannondale Elevated Suspension Technology (EST) frame !
If any one is having similar problems I believe an American company:
R I N G L E now produces a chain deflector that I have heard eliminates the
problem completely, (once installed correctly).
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diagram: ||
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=| |=||| x= jammed chain
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/ \ X||
/ \X |
/ \X
/ \
Australian MTBiker,
Tim McCallum.
Christopher L. Morrow
anti-chain-suck-thingy, I did and it works great!! PLus it is custom
fit to my bike, not like the ringle thing, also since it was constructed
of scrap, it was totally free!! Saved myself 34 dollars!
Next on the builders list is a new headset with a high-density
polyethylene bushing instead of ball bearings!