BIKE: Creaking bottom bracket

[Michael Zakes]

2 common things to check for:

1) loose LH crank arm, ck by holding bike stationary and pushing down on LH
pedal, or while riding if you get more noise on the LH downstroke. if so
tighten and possibly spray some lightweight lube (TriFlow/WD-40) in between
the axle and crank arm, especially if the bike's been out in the wet
2) Aluminum frame/steel BB mix will often times creak, wrapping teflon tape
(find at your local hardware store in the plumbing section) on the threads
before re-installing the BB.

----- Original Message ----- 
From: "Fred Meredith" <bikin-fred>
To: "Robert M Farr" <bobfarr>
Cc: "Bike Forum" <forum>
Sent: Friday, June 03, 2005 9:31 AM
Subject: Re: BIKE: Creaking bottom bracket


I would have started with additional questions such as:

How new is the bike and what is the frame material?

Newer bikes often have cartridge bottom brackets not designed to be
serviced by the owner. Also, historically, on some aluminum or titanium
bikes with steel components, mysterious creaking noises resulted from
the contact points of dissimilar metals. I never really believed that,
but ...

A quick way to check for serious problems in the bottom bracket begins
with holding the ends of the crankarms (next to the pedals) and
attempting to rock them side to side. Hold both crankarms and try to
rock them as if they were a single long piece. Any side to side
movement is not good. One of two possible things is wrong then. If only
one crankarm moves or clicks sideways, you have a loose crankarm. If
both wiggle in unison when you try to move them, you have a loose
bottom bracket.

Second test before taking anything apart is to shift the chain to the
smallest chainring and carefully lift the chain off of the chainring
(gee, I hope you have been keeping your chain clean) and place it on
the bottom bracket. Make sure it is clear of all chainrings and not
touching them. Now turn the cranks by hand and feel for any resistance
(bumps or sticky places) or grittiness in the feel of the rotation. If
there are broken bearings, a lack of lubrication, or other serious
problem, you may be able to feel it as you use your soft touch during
spinning of the cranks. This is like holding a wheel in your hand by
the axle and spinning it. If the adjustment of the cones is wrong or
there is inadequate lubrication or other problem, you will feel it
through your hands as the wheel spins.

The next step would be to remove both crankarms and turn the spindle by
hand to "feel" for any problems. This is also about the last thing you
would do with a cartridge bottom bracket. At this point it is pull the
old one and put in the new one, but make sure it is the proper one.
Spindle lengths vary depending on such things as number of chainrings
and resulting chain line. As Bob said, the whole thing is easier with
the proper tools, including the cartridge tool.

With an older cups and bearings BB, just to be on the safe side, you
can go ahead and call it a tune up by taking apart the old bottom
bracket, cleaning all of the parts and inspecting them for unusual or
uneven wear and replacing the bearings (at a minimum) and lubricating
it well with WATERPROOF grease as you reassemble it. If you do a proper
job of installing the fixed cup and making the final adjustments, you
should not need any kind of locktite. Just make the check for BB
looseness part of your frequent check list.

Of course you can take the bike to your friendly bike shop and describe
when and how it creaks.

Does it creak just when you are pedaling or also when you are coasting?
Only on bumpy roads or all the time?

Does it creak only when you are climbing out-of-saddle? Or does it stop
creaking when you stand to pedal?

Does it seem to be related to how hard you are pedaling?

Different answers to these questions will lead a mechanic to check
different things.

Ignoring the noise and just riding on could lead to sudden failure. I
keep, as a visual aid when talking about maintenance, a bottom bracket
cup that was given to me by a shop mechanic. When the owner of the bike
finally brought the bike in, it was because he was finding it hard to
pedal.

It had been ridden so long with a loose bottom bracket that some of the
bearings had failed and the resulting uneven wear and lack of
load-bearing surfaces had worn clear through the side of the bearing
cup and into the cup threads. When the mechanic finally got the cup
out, you could see through a hole in the side. THAT'S a total lack of
maintenance and an ignoring of the symptoms.

And yes, the fixed cup (the one that comes out last and is hard to
break loose) is of the "left-handed" variety and often has to be
encouraged with the correct application of the proper tools. A large
"Crescent" (adjustable) wrench is not such a tool.

Good luck with your creak.

Fred Meredith

On Jun 3, 2005, at 8:10 AM, Robert M Farr wrote:

> The bottom bracket bearing cups (the threaded parts) moving around in
> the bottom bracket housing (the frame) can be a source of creaking.
> The creaking may also be coming from your seat post, either at the
> seat or the seat clamp at the seat tube of the frame.
>
> Because it's not something the typical prospective buyer looks for,
> bottom brackets are typically some of the most marginal quality parts
> on a bike. And the threads on bottom brackets aren't always machined
> to the tightest tolerances either. That means they're often sort of a
> loose fit that refuses to stay tightened after assembly.
>
> If you don't already have them, get the appropriate tools necessary
> for disassembling your crankset and bottom bracket. (NOTE: sometimes,
> not everything is righty-tighty/lefty-loosey -- be prepared to
> encounter left-hand threads) Then remove your cranks and get at the
> bottom bracket bearing cups on both sides. You'll probably find that
> at least one side is already loose. That's probably where your
> creaking is coming from. Clean out any spooge in the threads and
> reassemble using threadlock compound like Locktite TM which comes in
> blue, red and green "flavors."
>
> I'd only use the blue low-strength variety on a bike application
> although I've seen the green very-high-strength variety recommended
> for problem bottom brackets. Be warned: the green variety requires
> lots of heat and muscle to bust loose. In other words: It's best
> thought of as an alternative to epoxy or superglue.
>
> If the creaking is coming from elsewhere -- like your seat post -- 
> grease or anti-seize compound may help.
>
> Robert Farr
> Austin, TX
> bobfarr
>
> Kevin Winert wrote:
>> I have a very loud, creaking bottom bracket (although
>> the creaking could be my knee). I read on line that
>> usually this means it needs to be tightened or
>> adjusted, perhaps greased.
>> Does anyone have experience with this?
>> Thanks,
>> Kevin Winert
>> kwinert1
>>
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When in doubt, ride your bike … or at least write about it!

Fred Meredith
P.O. Box 100
Manchaca, TX 78652
512/282-1987 (voice)
512/282-7413 (fax)
512/636-7480 (wireless)
visit <http://2merediths.com> for writings and photos


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