Bicycle Mechanics - Bottom Bracket Clicking; Chainring Wobbling
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Onore Baka Sama
06-06-08, 08:18 PM
Okay. I have a 26" NEXT Shocker mountain bike, and it's about two years old (bought December 28, 2006). This has been going on for a year now, off and on, but now it's happening almost nonstop as opposed to just when I pedal hard. And, it's louder. So I'm a bit worried, considering a trip I plan on taking.
When the right pedal goes down, there's a loud click. The chainring wobbles a bit as well, but it's not touching anything when it does so. When I got home to take a look at it, it seems there is no damage. It seems to just be loose, for I can wiggle the entire thing freely in the bottom bracket case.
I checked various sources on the Internet, and it says that this is a very normal thing. But I can't seem to find any instructions on how to tighten it up. Moreover, I don't think I have the tools to get into it.
So, my questions are:
-How do I adjust or tighten the bottom bracket properly?
-Is there a cause for going to the LBS instead, or is this something I can handle myself cheaply?
I can't find the name of the manufacturer of the BB, so... Here is a picture. If it isn't efficient, please tell me and I can try again:
EDIT: Actually, I think I just found the problem. It appears the entire bottom bracket has been bent.
06-06-08, 09:53 PM
That'll happen, w/ those POS Wal-Fart bikes.
You're better off getting another bike rather than spending the $$ to replace what you need to....
Onore Baka Sama
06-06-08, 10:36 PM
Crap, and here I'd thought I'd seen the last of Wal-Mart.
I was planning on getting a new bike that wasn't from Walmart at any rate, anyway. Would replacement parts for the bottom bracket (and for that matter, the freewheel/cassette as well) really be worth more than the bike itself?
06-07-08, 12:48 AM
I don't buy into the department store bike deal - you already have a bike that you've been riding for a couple of years, or at least that's what I gather from your post. I'm by no means an expert, but my dad's old road bike had similar problems. Tightening up the bottom bracket did the trick*. Its silky smooth now and literally cost me $3.85 for a tube of grease which will easily be good for overhauling all of the bearings on all three of my bikes (bottom brackets, headsets, wheel bearings) maybe even multiple times. The bottom bracket on the bike was ridiculously easy though, only needed a flat headed screwdriver and an adjustable wrench. Different styles require different tools but I can't imagine the tools costing all too much. I should look into it, since the other bikes have a different system.
So, sure, it might cost a little bit of money to get your current bike is up and running, and sure, it might be better off putting the few bucks it'd cost into a fund for a new bike, but the way I see it (college student here, with tuition, car payments, etc. to contend with so my opinion is biased) $20-30 put into a bike to keep it operable is a better option than $100+ for a "new" used bike, or even more for a new new bike. YouTube has several videos on disassembling bottom brackets... and pretty much everything for that matter. I found out what style of bottom bracket my bike had from Sheldon Brown's site (http://sheldonbrown.com/gloss_bo-z.html#bottom) Now, if you were considering buying a new bike, perhaps the department store argument stands true, but you already have a bike so no need to buy a new one if a few bucks could get it running again.
* but I disassembled and overhauled it, cleaning and regreasing everything down there.
EDIT: I don't mean to start a flame-war regarding department store bikes, this is just my opinion (however biased).
06-07-08, 05:29 AM
The first thing is to get your crankset off. There is a tool for that:
You'll probaby need a socket wrench with 14mm or 15mm socket to get the crank nut or bolt off first. Go to a LBS and get advice on this process. Here is a helpful web page: http://www.parktool.com/repair/readhowto.asp?id=103.
Then you'll need a lockring tool for your bottom bracket:
I'm not sure what kind of cups you have, but you'll need a cup tool as well. This adjustment is a tricky process, and hard to explain, but once you get the hang of it it is quite simple. I advise getting someone to walk you through it in person the first time. You should really take your entire bottom bracket out and inspect it. All that time riding with a loose bracket probably wore out the cups and spindle, and pitted your bearings. You can get a new cartridge bottom bracket fairly cheaply. Just make sure you get the right threadin and spindle length. 68mm shell by 1.37 is standard, and then you need spindle length. The spindle should be longer on the drive side, to account for the width of the chainrings on the right crank.
For further advice, here are two good article on the procedure:
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