I can tell you now that it is a square taper bottom bracket. You'll need a crank puller to get the arms off.

The bottom bracket is a cup and cone type. Removing the 15mm pedal bolts alone won't be enough to remove the pedals, a crank extractor is needed to push the pedal arms off the square tape spindle ends.

You could replace all the individual parts that make it up with a sealed cartridge bb as they are fairly inexpensive.

This video shows how to do that.

Actually, it isn't cup and cone. It's got a locknut on the non-drive side.

It sure looks like a cup-and-cone bottom bracket to me:

http://www.bikeforums.net/attachment...1&d=1502596289

http://www.bikeforums.net/attachment...1&d=1502596289
http://www.bikeforums.net/19788327-post22.html

And regardless, the OP will still need a crank puller to get the arms off of the spindle.

I stand corrected. I understood that the video attached was what you all were saying he had, whereas it is what is being suggested that he replace it with. My mistake.

I ordered that one as well, will post it here in few days if I'm not sure which BB is inside.

Alright guys, I opened that crank up and here is what I have. I suppose it's a regular Square Taper Bottom Bracket. But correct me if I'm wrong. So now I think I need to get a bracket opener and clean it all inside.
I'm just thinking, maybe I should get rid of biopace crank alltogether and replace it with some regular round $30 Shimano crank off Amazon. I think BB should be included in those sets. I'm just not sure if this oval shape is of any use to me as I'm not doing any trails, I'm just using my Giant as a hybrid for casual riding at the evening.

You might be able to open the lock ring with a large flat screw driver and some light taping with a hammer (forward to loosen). Putting it back on you'd want to use the correct tool. The bearings inside might be loose or caged.

If you decide to just get a cartridge BB which is better sealed for riding in poor weather you could get just that tool.

I'm sorry I missed it. So to get that lock ring off I don't need any additional tools? I can just hit it with screwdriver/hammer and unlock BB. But I think I still need a BB removal tool to get it out, just unlocking it is not enough.
And if I buy a new BB, will it have a new lock ring? And what tool would I need to lock it again.

I managed to open it using just big wrench.
So I have a screw sticking out inside of the bracket socket. It's from the plastic cable holder on the bottom. I guess I will have to remove it if I install a new cartridge sealed bracket.
I think I understand it now, so in order to install a cartridge BB I would need a special tool for that one. But no more lock rings.
There are so many of these BBs out there, different sizes, with or without bolt, I would need to figure out which one I need at all. At least for that bolt thing.

I have 68x118 bracket size, just need to figure out what interface and what threading it uses. Probably English. It looks like JIS but also a bit like ISO, I'm not sure.
I think any should fit those crank arms anyway.
I think this one should work well:

https://www.amazon.com/Shimano-Squar...ket&th=1&psc=1

For that type of BB the only special tool needed is for the lockring. The cups can be removed with an adjustable wrench.

Shimano cartridge bottom brackets are installed with this tool: BBT-22 Bottom Bracket Tool | Park Tool

No lockring needed, the bottom bracket comes as a single unit that threads in from the drive side and a plastic cap for the non-drive side. That tool has a propensity to slip out of the bottom bracket so I've taken to using a metric m8 bolt about twice as long as the pedal bolts and a washer to hold the tool in place. Though slippage is a little less of an issue during installation than removal.

The video I posted earlier shows how to select a bottom bracket that will fit. Important measurements are the bottom bracket shell width and the spindle width.

edit: Part of the reason there are so many choices is because in addition to multiple sizes there are multiple product levels. The UN55 is a step up from the basic UN26. Not sure what the differences are, could be size / number of bearings, seals, weight. UN55 is still pretty cheap.

Ok, I ordered those and let's see if that clicking goes away once I install the new BB.
I can say for sure though, the old one spins super noisy and not smooth at all. I just tried it - it feels like there is gravel and sand inside or something.

That looks identical to the set up on the Chinese Schwinn's that Wal-mart sells. And yes, they are prone to clicking.
If find a bb cartridge that fit, you'll need to back out the bolt that holds you cable guide.

Ok I'm trying to install a new bracket and it goes very slowly and super tight for some reason. I had to apply extensive physical force just to get to the point you see on the image. It went smooth first but at some point became super tight. I can still finish the process, but at the other side it doesn't look even. See the pic. I can still put a cap in and screw it in, but I don't know if that uneven position of the bracket might become an issue.
I was afraid I damaged threading first, but that's the only way it screw in - super tight and uneven.
What do you think? Should I undo it or just finish the process and see how it works? Again, it goes in SUPER tight.

Make sure the threads are greased. The other cup should be partially threaded in before you start (it will act to guide the BB straight). Is the cable guide contacting the BB inside the BB shell? It may be forcing the BB to skew as you thread it in.

Ok I undid the whole thing and checked it out. Apparently I was idiot enough to leave that cable holder screw in. It was in the way pushing the bracket. It's a miracle, but it looks like threading survived my efforts. I was able to put everything in, guide the bracket as you mentioned above and easily tighten it full way. Damn, I almost broke it I think. Shish.

Ok, grand finale. With a new BB it was still clicking. I've decided not to push it any further and visit a bikeshop. 5 min and my pedals were tightened. No more clicking. Apparently pedals were the only part I didn't really check.

oops. my bad. my answer found above after posting.

From your description, you needed a new BB anyway. I think you did OK. I bet it feels a lot better riding your bike now. Congrats.