Knocking sound and vibration from left crank arm area

[withiniswithout]

I'm getting a knocking sound, sort of a tock, tock, tock once per revolution on the left side. I can feel the vibration in the pedal under my foot. The pedal moves freely with no sound so it doesn't seem to be that. There's also a notchy feeling, a hitch in the motion with each noise. Could this be the bearings? I've been using it awfully hard lately on very steep hills and some rough terrain. The crank arm doesn't have any play in it.

UPDATE: Took it to the shop and the problem was the goddamn pedal. They tightened it, and it's good. No charge. I just got a set of Crank Brothers Stamp One pedals, bright yellow that matches an accent stripe on the bike. They're size large. Will have the shop put them on as I don't have the proper tools or grease. Looking forward to a ride with these to see how they feel.

 

[indianajo]

Yes.
Turn the bike upside down, add some oil in the hole in the bottom of the crank tube. Let it sit 5 hours to flow out to the bearings at the edge. If there is no hole, drill one in the middle.
Can also be loose crank arm which can wiggle rotationally even if it doesn't wiggle in and out. I've had a plastic crank arm on a Pacific Quantum (a $200 kid MTB) wear out in 5000 miles.

 

[withiniswithout]

Yes.
Turn the bike upside down, add some oil in the hole in the bottom of the crank tube. Let it sit 5 hours to flow out to the bearings at the edge. If there is no hole, drill one in the middle.
Can also be loose crank arm which can wiggle rotationally even if it doesn't wiggle in and out. I've had a plastic crank arm on a Pacific Quantum (a $200 kid MTB) wear out in 5000 miles.

Thanks. I'll bring it into the shop. The bike has close to 8K kilometers on it, and lots of hills and some rough terrain, and it's supposed to be a city bike. The crankset is an FSA CK-745. Is this something that can freeze up, or more likely simply be present for many miles?

 

[fooferdoggie]

Thanks. I'll take a look. The bike has close to 8K kilometers on it, and lots of hills and some rough terrain, and it's supposed to be a city bike. The crankset is an FSA CK-745. Is this something that can freeze up, or more likely simply be present for many miles?

if you have not serviced the bearings then its time for that. you need the right tools for the bottom bracket you have so it may be a shop job.

 

[indianajo]

I've never replaced a crank bearing. I have oiled them. My current bike has ~8000 miles.

 

[fooferdoggie]

I've never replaced a crank bearing. I have oiled them. My current bike has ~8000 miles.

they should have grease not oil. it depends on if they are sealed or not.

 

[indianajo]

they should have grease not oil. it depends on if they are sealed or not.

I can't hear the knocking sound of the 8000 mile bearing. Maybe I'm deaf? Funny I hear the radio okay.
No grease fitting on any of my bikes, and I parked the last one (Pacific Quantum) when I couldn't get the worn out plastic crank arm off. I had 6 auto/industrial pullers and a tie rod wedge fork; none of them would work.