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Recently my 2008 Devinci mountain bike sounds like it's ticking when I push down on my left pedal on a usual rotation.

When I turn the bike over and go through rotations, I can't get it to tick.

When I put my left crank all the way down & jump a little on the left pedal, I don't get the ticking. Only when I'm spinning.

The ticking isn't 100% consistent, but probably about 80-90% of the rotations have this tick.

I took it to my LBS, but they just said it was a bent chainring tooth - which it wasn't.

Does this sound like this is definitely the bottom bracket?

Thanks.

Update: I took it into my LBS to get the BB taken out & cleaned. The tech said he couldn't find anything wrong with it, but did hear the ticking. He greased & lubed anything that moved, and the sound lessened quite a bit. I haven't had a good long ride on the bike since, so I haven't verified if the sound has gone away.

Final update: Went for a good ride & didn't hear the ticking, so it was likely the BB.

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Call the bomb squad!! –  Daniel R Hicks May 30 '12 at 0:52
    
On Tri and Road bikes, I would rule out that it's not the front derailleur cable. These can cause a tick when shoe or crank arm rolls by if it's sticking out. Not sure about MTB, but suspect the cabling is similar. Something easy to check before you start taking the BB apart. –  Ken Hiatt May 30 '12 at 6:51

3 Answers 3

up vote 3 down vote accepted

If it's happening on every revolution, I would say it's not a frozen link in the chain as that would take a few revolutions to get back around. Does it also happen when you stand up out of the saddle? that would rule out any noises related to your saddle/seat post which can often be mistaken for BB noises.

More than likely it's your bottom bracket, the crank arm is loose, or perhaps the pedal is loose. Especially on a MTB you can get dirt and grime in the interfaces where these parts join to one another and they will work themselves loose a little bit through normal wear and tear. The reason it's not making the noise when you flip the bike over is because you need some torque to make it happen go out of alignment and cause the tick.

I'd either remove, clean and regrease your BB, crank arms and pedals yourself if you are comfortable with that or take it to a shop and let them know you need your BB removed, cleaned and reinstalled.

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Bottom bracket noise is a frequent problem, and often hard to diagnose.

First and foremost, check the tightness of the crank bolts. (Your LBS should have done this when they checked out the bike.) A loose crank bolt can be the cause of BB noise, and failure to tend to the problem immediately (if not sooner) can result in irreparable damage to the crank arm.

After that there are a number of possible causes. On a non-derailleur bike the chain may simply be too tight. On a derailleur bike the chain may have a frozen link. There may be a bent chainring tooth, or a deformed chain link.

Rarely, the problem can be due to bearing problems within the BB, but much more often with BB cartridges the cups have worked slightly loose and the cartridge is sliding back and forth in the housing (harmless and easily fixed).

On bikes with loose bearings (vs a cartridge) in the bottom bracket a loose cup can allow the crank to actually tilt slightly, such that the chain hangs up on the sprocket. (This is easily diagnosed by simply grabbing the crank and shaking it -- there should be no bearing play detected.)

And pedal bearings seem (to me) to go out with aggravating frequency.

Then, of course, there's the "trick" knee or ankle that clicks sometimes.

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I'll add that this summer, before my annual bike trip, I had my bike virtually overhauled by a very competent mechanic. He replaced two front rings, repacked everything, tuned up everything. I've no doubt that everything was properly torqued. Got on the ride and, after the first day, there was an annoying BB "tick" that came and went. The mechanic on the ride tightened the pedals and crank bolts each maybe 10-15 degrees, and then the ticking went away. –  Daniel R Hicks Aug 28 '12 at 16:08

Believe it or not I thought I was having crank issues on a new bike with Ultegra 6700 turns out my mavic front wheel had loosey goosey front spokes...once that was tightened up the sound went away...it took me a while to get to the bottom of it because it only made the noise when I pedalled medium strength. I figure that with the side to side torque it made the noise? All I know is it is gone!

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