Bicycle Mechanics - BB help plz!

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View Full Version : BB help plz!


Tober1
06-10-09, 01:51 PM
I'm pretty sure the bottom bracket on my commuter is toast. A lot of grinding and clanking when I pedal at any speed. I've isolated it to the BB so no question there. Started after a pretty bad ride home in heavy rain. Sounds like something is loose/broken.

I do pretty much everything else, but headset and BB are out of my league. If I want to get a new BB for this bike what kind would I look for? Can I order one and have the LBS put it on? Worth doing myself? It's a 'biopace' crank if that makes a difference.
Do I need to replace the crank as well as the BB or can I just get an old BB and that'll work?

It's an old Fiori road bike. It was a Norco house brand up in Cananda. I love the bike apart from the racket I make when I roll down the street See pictures.

Thanks in advance.


stausty
06-10-09, 02:45 PM
To do this fix you need a few specialized tools that'll end up costing around $50 total. I'm all for fixing things on your own, but if you don't plan to do a lot of wrenching then passing this off to the LBS is forgivable. Most likely they'll want to sell you a cartridge BB, which is a reasonable upgrade and shouldn't be too expensive. You can consult Sheldon Brown's page for the length BB spindle you need. I'm almost certain that you need a spindle for a 68 mm English threaded BB shell, which is overwhelmingly more common than anything else. And make sure you get a square tapered spindle, not anything with splines.
http://www.airbomb.com/ItemMatrix.asp?ic=19693&GroupCode=PG-817&MatrixType=2&agent=Froogle&utm_source=Feeds&utm_medium=GoogleProduct&utm_campaign=Froogle

That's what you're looking for. The 68 is the width of the BB shell in the frame (almost certainly that number) and the 113 the length of the spindle (may or may not be right). Other members will hopefully chime in with the spindle length that you need.

Chances are you could restore a good bit of the effectiveness of your current parts by disassembling, cleaning, regreasing, and reassembling, but you'd need to do that yourself to make it cost-effective since there's a bit of labor involved.

The 'Biopace' name refers to the chainrings, which are not perfectly round, not the cranks themselves, so it will not affect this repair.

johnknappcc
06-10-09, 03:06 PM
I vote overhaul, its easy. You will need a crank puller (15$), lockring wrench (15$), and a spanner (8-15$)

New bearings (grade 25) for 5 bucks.

Its fun, but yeah, cartridge is the easier route to go, unless you enjoy the maintenance.

It will most likely look like this inside:

http://gallery.a-symmetric.com/main.php?g2_view=core.DownloadItem&g2_itemId=165&g2_serialNumber=2

With these parts

http://gallery.a-symmetric.com/main.php?g2_view=core.DownloadItem&g2_itemId=169&g2_serialNumber=2

Check out the overhaul on bicycletutor

Ditch the cages though.


Tober1
06-10-09, 03:08 PM
Stausty,
People like you make this world go round.
Appreciate the help!

I'll definitely try and fix it myself. Guess I'll start with a dis-assemble and lube and work from there.

J

Tober1
06-10-09, 03:10 PM
Perfect!
Many thanks.

I'll let you know how it goes :)

Tober1
06-10-09, 03:44 PM
Ditch the cages though.

Why ditch the cages? Do they tend to wear faster?
Will any LBS have the bearings?

Would there be a benefit to going cartridge BB? Once the cartridge is done, it's done right?

Which system wears better?

Many thanks!

stausty
06-10-09, 04:56 PM
The cages don't allow the bearings to roll quite as smoothly. For what you're doing I wouldn't worry about it too much - they do make assembly and disassembly easier and the difference wouldn't be noticeable, really.

The advantage of a cartridge is what you pointed out - once it's in, it's in. Cup-and-cone BB's, which is what you have now, do require some maintaining. If you overhaul what you have now then you'll get to practice that. The other advantage to a cartridge is that you don't have to worry about getting the adjustable cup adjusted correctly, just thread it on in. I personally prefer the older style because you can see all the parts and when something does go bad, you don't have to throw it all away, and from what I've heard they last longer on average. But a good cartridge will last plenty long for your purposes, will be easier to deal with, and the small difference in performance won't be an issue - it's not like you're going to be taking this bike out with Lance any time soon.

Tober1
06-10-09, 07:17 PM
What do you mean? Lance and I are doing a century early next week :)

Thanks for the help.

operator
06-10-09, 07:34 PM
The cages don't allow the bearings to roll quite as smoothly.

Wrong.

The advantage of ditching the cages is that you can possibly fit more bearings into the bottom bracket. This increase longevity. Frequently the cage itself blows up and prevents proper rotation of the axle. Another reason to ditch it.

johnknappcc
06-10-09, 08:08 PM
Wrong.

The advantage of ditching the cages is that you can possibly fit more bearings into the bottom bracket. This increase longevity. Frequently the cage itself blows up and prevents proper rotation of the axle. Another reason to ditch it.

Yep, when I still had the cage it actually bent a little on the cone. I was noticing a little friction, opened it up and had a bent cage. Removed the cage, and added two bearings, and was good to go.

I don't think the assembly is any harder with cageless, I found it to be a quicker overhaul. Pedros, Phil Wood, and some teflon stuff, all have enough viscosity to hold the bearings in place during the reinstallation.

Panthers007
06-10-09, 09:38 PM
A properly adjusted BB with loose, or balls in the retainer, bearing rolls much smoother than a cartridge such as Octalink. Or a newer external - BB. This is assuming your bottom-bracket isn't damaged or the races badly pitted.

Here's Park Tool's take on them:

http://www.parktool.com/repair/readhowto.asp?id=93

operator
06-10-09, 09:45 PM
A properly adjusted BB with loose, or balls in the retainer, bearing rolls much smoother than a cartridge such as Octalink. Or a newer external - BB. This is assuming your bottom-bracket isn't damaged or the races badly pitted.

Here's Park Tool's take on them:

http://www.parktool.com/repair/readhowto.asp?id=93

And wrong again.

The only advantage races have before loose is that it speeds assembly. If you're on the clock for a repair and shop rate is $1/min then by all means **** around with ****ing around with the cages and saving some time.