morksmith

When I pedal a bit more aggressively (hills, going fast), I get a knocking noise/sensation from what feels like either the crank or bottom bracket –*any thoughts?


Thanks
mark

RubberLegs

More information is needed. What kind of crankset/BB? Checked the BB for tightnes? Have you checked for lateral (side to side) play? It could also be a loose crank...check for tightness, it could also be a pedal problem...just fixed that on my bike last week, had a little click/thump I felt in my foot on every HARD revolution. Adjusted the bearing and the click went away. So many different things it could be.

rhm

I had that start to happen, rather suddenly, on one of my bikes. I overhauled the BB and found three of the balls had cracked. I replaced them all.

oddjob2

Does the bike have a kickstand?

RubberLegs

Also, carefully check frame around BB for any cracks...a failing frame can make "Funny" noises too. NOISES should NOT be ignored, they tend to cost more the longer you put it off, and can be quite dangerous should a sudden failure occur.

SJX426 

I had the same problem on my 97 RockHopper. Couldn't find th source so I replaced the BB with a Shimano sealed unit UN54 or so. Still had the problem and was not able to find it. It went away and I have no clue why. These can be really difficult to diagnose. Sometimes it isn't the BB but other locations like your seat post, saddle rails, stem or handlebars.

busdriver1959

If you have a cartridge bottom bracket, you may just need to pull it out, wipe it down and put it back in with a thin layer of grease in the cups. Since the cartridge fits in there with a not quite press fit, just a little road grit will cause a light knock that will keep getting louder.

The_Joe

Happened to me and I found that a caged bearing had shed it's cage. I replaced it with the appropriate number of loose bearings and it went away.

jacksbike

Noises from the bottom bracket area can be hard to track down. From my experience, first thing is to take off the original pedals and put on another set. A lot of the time the noise emits from the pedals(perhaps pedal spindle moving around 2 sets of ball bearings). If the noise persists, it could be any one of an assortment of things, as mentioned above: loose bb moving, bb cups not threaded in tightly. If you have square tapered crank arms, perhaps the nuts or bolts are not tight, or the crank arm is no longer square and has worn on the bb spindle.

obrentharris 

Awww! You're making me nostalgic. I had forgotten that during the bike boom, when almost every bike had an Esge kickstand, half of those bikes would go "clunk, clunk, clunk" in a muted steel-on-aluminum chorus from a kickstand that was slightly askew. I'm going to fall asleep tonight thinking about all the different ways we tried to get the angle of the end cut just right on those cut-to-fit kickstands...
Brent

morksmith

It is a Campagnolo crank circa 82 with a shimano BB (I know, I know…) - the first thing I did when I bought my bike (a late 60s lightweight) was to buy vintage Campag crank as it had an ugly modern shimano one – my LBS fitted it without even mentioning compatability issues - but it does work, so maybe they had a point...

The rest of the bike is kitted out with 60s campag Nuovo Record.

Am tempted to ditch the Shimano BB as it sounds like it is the problem and get the Phil Wood BB i've always promised the bike....

morksmith

Checked the frame - thankfully no cracks - think it must be the BB...

morksmith

No - it's a 60s road bike.

RubberLegs

And....change to a different set of pedals first as well....my last "Thump/click" down there was a pedal bearing (every hard stroke at about the same spot)....but the one before WAS a bad BB, I'd get a clunk....or knock....but not on every stroke. Sometimes worse than others...it was a sealed cartridge, and it also was exhibiting a bit of side to side play....so a Velo Orange replaced it....Smooth and quiet ever since.

AAZ

Try tightening the pedal bolts. I've found that to be the cause several times.

John E

I was having a similar problem w/ the mountain bike. Replacing the grease and all of the ball bearings (loose, 11 per side, which replaced the original caged 8/side set a few years ago) fixed the problem nicely. If you do an overhaul of a conventional bottom bracket, be sure to replace the bearings and to use loose instead of caged.

I have also occasionally had pedal problems which mimicked BB issues.

zandoval 

Chased an intermitant clunk in my bottom bracket for almost 3 months then finally found it was from my worn out Free Wheel...

Good luck... Hate those Clunks...

Teon

+1

Had the same trouble with one of my bikes, and thought it might be the bb. But first switched out the pedals, and voila', the sound disappeared. Checked the pedals, and the left one felt like it needed to be regreased. Might be something as simple as that.

SJX426 

So the Shimano BB is JIS taper, I am not sure the Campy cranks are. You should check https://sheldonbrown.com/bbsize.html

jimmuller 

I have a new Shimano freewheel which goes clunk once every wheel rotation. One day I'll take it apart.

Our tandem has recently developed an occasional creak. It comes after we've been riding maybe 35 miles, then will mysteriously go away. I have found no direct cause, repacked both BBs, found no problem. Tried to take the original Lyotard pedals apart, couldn't get the pressed-on dust caps off. But I've found no other reason to worry, have examined the frame carefully, found nothing. Sometimes it doesn't happen at all.

Sometime those things just happen...

peter_d

Mark, you said this happens when you pedal more aggressively. Any chance it could be your pedalling style? The pro's tell us to "pedal circles" that is keep the power on the pedal for the full rotation of the crank. If you're just applying lots of power between the 12.00 o'clock and 6.00 o'clock positions there can be a slight backing off for a millisecond while the other leg powers up, (especially if one leg is a bit stronger than the other), this can cause a knocking noise once or twice a rotation. Try to smooth out your pedal stroke and see if the noise stops. Apologies if you've considered this.
Another possibility could be a slightly frozen link on your chain

RobbieTunes

Campy crankset, Shimano BB. It's going to get worse until you get the right BB.

morksmith

I know in principle it's wrong, but…

It has been fine until now… but I didn't really want to go down the route of getting a used BB so if I go new (phil Wood), I will need JIS thread which is what the Shimano one is anyway isn't it?

from the Phil Wood website:

In brief, most modern cranks will take the JIS (Japanese Industrial Standard) taper, in addition to Campagnolo cranks produced before 1994. After 1994, Campagnolo moved to the ISO (a.k.a. Campy) taper. The less common of the three tapers offered is the JIS low profile, which is used in some specific older-model Dura Ace cranks.

morksmith

Fair point, but it has only started happening recently - so that makes me think it can't be down to my style as I haven't changed... but saying that it doesn't make the noise when i'm pedaling less aggressively, so maybe my uphill pedaling shows up the problem more...

Velognome 

Klunks made under load are bad........... ......could be a loose BB cup, bad bearing or a broken frame even.... I'd find it and fix it before it does damage.