How to tell if bottom bracket is broken ?
 

I'm noticing a very small movement in my pedals. It's very slight, but when I press the pedal in, I see the chainrings move a little. Does that mean that absolutely my bottom bracket is broken ?

This bottom bracket is stock from a 2009 FUJI Nevada 1.0 MTB. If it is broken, what should I replace it with that is stronger ? (But not too expensive)

That bike comes stock with Truvative 3.0 crankset meaning it has a Power Spline bottom bracket. They are notoriously short lived in heavy use, so it is possible it is shot.

splined are a bit rubbish, they wear out prettty quickly. if you can, tighten it, it might solve the issue temporarily, if not, your gonna need a new crankset. get isis or square, they are more durable.

How do I tighten it ?

Also, what do you mean replace my crankset ? You mean bottom bracket right ? I don't see why I would have to replace the whole thing...........

If it's a 2009 why not take it back to the LBS or where you bought it and see if they can do a warranty replacement.

it depends what the actaul problem is. it could be the BB is shot, as a guy said, and if you replace the BB with another splined, you likely to get the same problem, also, it may have damaged your cranks, so those would need replacing along with the BB or maybe, if you can, just a new spindle. if i were you, i would check out sci-fi's idea, it should still be under manufacture warranty, go to the place you bought it and see if you can get a replacement fitted for you.

I often wonder the same things when I see a post that starts with the ____ on my 2009 ------- is doing
that is why Bike shops exist service especially your free service

Here's the thing... with THAT crankset, ALL you can get for replacement bottom-brackets are the same crappy ones. That means every 12-18 months, you WILL have to replace that bottom-bracket with a new one. Of the same crappy design.

After doing this 4-5 times, it would've been cheaper, faster and less frustrating to have just picked up a standard square-taper bottom-bracket AND matching crankset. And no, you cannot use a spare-taper bottom-bracket with that crank.

Lol.

We're not even sure if the OP knows how to test properly for play in a BB (e.g worn out). Because from his OP it sure doesn't look like he knows. In which case let's stop talking about replacements before we ascertain that

a) the OP is getting play in the bb
b) it is not the pedals
c) and it's not because he's flexing the crankset

Movement at the chainrings is amgiuous. Pedals have play? BB has play? Crank loose? Normal flexing? Jeeze the list goes on.

I'm with op on this.

The pedals move a little to the side when intentionally pushed. The crank gear rings follow this movement. And no, I don't know about bicycle mechanics, that's why I came here.

Even if you need to replace your cranks... it should be mentioned that you don't necessarily need to replace your chainrings, you may be able attach your existing rings to the new crank 'spider' by way of alen bolts. Thus.. you will need a new square tapered BB, cranks to fit that, and hopefully that will be it. Not a mega expensive job.... your chain rings will detach from the drive side crank from what I can see from the online spec for your bike. Just replace them with a set that will accept your chain rings

The reason I mention this is because new chain rings could mean a new chain... and a new chain could mean a new rear sprocket cluster. I know you are not a bike expert, and sometimes this fact is not mentioned... it is only the crank arms you need (edit: and BB) , not the whole front drive set.

I didnt want to start a new thread on this, but I am having a similar issue. However, I have squared set-up, rather than the splined. Its for the older rincon that I have been using for bad weather commuting. Basically, I need to figure out how to try to tighten this. Do I need to take the crankset off? Sorry for being so lost here, but a point in the right direction would be great.

Otherwise, maybe I need to replace it? What kind of info would help here? The pedals will swing about 1 cm in or out from the frame, so I think that is a lot of play.

You need to replace it. If you remove the chain or drop it to the BB and spin the crank I would guess that it sounds bad, like it has sand in it.

How much is a little: 1mm, 2mm, 5mm? A little play is normal.

Is the crank making any creaking noises under load? Is the crank movement causing any shifting issues? If no to both and if the play is in the 1-2mm range, I'd say just ride it and worry about a replacement later.

In response to the post about just replacing crank arm and swapping chainrings, perhaps if crank arm sets were more commonly sold this would be a viable option. However, unless you are looking for boutique options or buying off Ebay, you'll rarely find just crank arms available. I would recommend saving your original chainrings if you do end up replacing the crankset as they might come in handy some day and should be perfectly usable after only a year of use.

1cm? Really? That's HUGE. You have either experienced a catastrophic failure of a cartridge bearing bottom bracket or the lockring came loose allowing the adjustable cup to back way out on a cup and cone BB. Post some pictures of the bottom bracket perhaps showing the crank at the extremes of it's movement if possible.

Yeah, that 1cm figure is at the extreme ends of the crank arm (where the pedals attach). It went from no noticeable problem to this major amound of play. I probably should have stopped riding it when the problem occurred, but it was raining that day, so I babied it home.

So, when the BB wore out on my road bike, I had the shop do it. I'd like to do this myself, just to understand it.

Is there a place with steps for this job? I'll try to get some pics, but I dont have a ton of time in the evenings lately.

Thanks for the help. This thing has been a pain in the rear lately. Both shift cables broke recently, after fixing that the rear axel snapped, after fixing that, this problem came up.

I'll try that, after the problem started, I got more of a loud click on the rotation of the crank, particularly based on load.

Here's a good site with pictures: http://www.parktool.com/repair/readhowto.asp?id=93

You'll need the following tools at a minimum:

- crankarm extractor (no way around this)
- lockring hook-tool (hammer and big flat-head screwdriver can work)
- adjustable-cup pin-spanner (needle-nose pliers can be used)
- 14mm socket & ratchet-wrench for crankarm bolts, torque-wrench would be better.

Ok, I took it apart, its messed up. Its not really a single unit like I expected (it was on my road bike). It has two bearing cups, plus the middle rod. On it is stamped "CH" and on the other side is "1C". What would I need to order to replace that?

Measure the width of the spindle from end-to-end of the square-taper. If it has threaded bolt ends, leave that out of the measurement. Then find a cartridge BB with similar spindle length.