Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 10-18-07, 10:33 AM   #1
balindamood 
Wrench Savant
Thread Starter
 
balindamood's Avatar
 
Join Date: Mar 2006
Location: 61 Degrees North
Bikes: www.2nd-cycles.com
Posts: 2,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Facing?

Time for an expert opinion.

I am familiar with facing head tubes for headset installation. But of late I have noticed tools for facing bottom brackets, disk brakes, seat tubes, and nearly every other attachment point to frames.

Is this REALLY necessary? Does it matter based upon frame material? Is this a nice thing to do to expensive frames, but you would likely skip it on a Huffy?

Just wondering.

Thanks.
__________________
"Where you come from is gone;
where you are headed weren't never there;
and where you are ain't no good unless you can get away from it."
balindamood is offline   Reply With Quote
Old 10-18-07, 01:46 PM   #2
Xhavier_5478
slacker..
 
Xhavier_5478's Avatar
 
Join Date: Mar 2007
Location: Colorado Springs, Colorado
Bikes: '92 Schwinn PDG Series OS 26, '05 Jamis Eclipse set up as TT
Posts: 94
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Why would you face a seat tube? I would say facing a bottom bracket is important if your using new external bearings.
Xhavier_5478 is offline   Reply With Quote
Old 10-18-07, 04:33 PM   #3
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Rans Rockst (Retro rocket) Rans Enduro Sport (Retro racket) Catrike 559, Merin Bear Valley (beater bike).
Posts: 26,743
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 143 Post(s)
I think that the real issue is the paint.

Paint adds a layer onto the bike frame that the other components don't allow for. Sometimes that extra layer isn't nice and even. Powdercoat tends to be thicker than a typical paint job. In this case, thick=bad.

If you have a nice, flat, even paint job, you can get by without faceing anything. If you have a powder coated frame with globs on the headset, bottom bracket, or disc caliper mounting points; you're going to need to face those areas.
Retro Grouch is offline   Reply With Quote
Old 10-18-07, 05:12 PM   #4
Boss Moniker
It's an old photo
 
Boss Moniker's Avatar
 
Join Date: Aug 2006
Location: Entropia
Bikes: Cannondale R500, Specialized Hardrock
Posts: 774
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Cartridge BBs could generally get by without facing because of their continuous design, but external bottom brackets come in two pieces, so their alignment is crucial.

And you're right. Not worth it for Huffys, I don't think anyone really does that. And are you sure you weren't talking about boring out a seat tube? It's a pretty standard operation if you want to switch seatpost sizes or clean out a rusted or chipped, or even bent seat tube. But I haven't heard of facing the top of one.. maybe for a special clamp?
Boss Moniker is offline   Reply With Quote
Old 10-18-07, 05:19 PM   #5
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Bikes: Trek 5500, Colnago C-50
Posts: 9,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
When I built up my C-50 it was necessary to face the fork crown before installing the headset lower race. It would not have gone on otherwise and I could have ruined the fork trying.

Al
Al1943 is offline   Reply With Quote
Old 10-18-07, 05:40 PM   #6
rmfnla
Senior Member
 
rmfnla's Avatar
 
Join Date: May 2005
Location: La La Land (We love it!)
Bikes: Gilmour road, Curtlo road; both steel (of course)
Posts: 6,049
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 156 Post(s)
Old engineering maxim: "A bearing is only as good as it's installation."

Facing yields parallel bearings to eliminate misalignment.

Older better-quality steel frames usually used sand-cast BB shells (cheapos used stamped steel) and there was no way to guarantee perfect surfaces in the molding process, hence facing.

Newer bikes use various manufacturing processes (CNC machining, investment casting, etc.) so they are usually more precise but there are no guarantees.

I face everything.
__________________
Today, I believe my jurisdiction ends here...
rmfnla is offline   Reply With Quote
Old 10-18-07, 07:17 PM   #7
taylor p
Senior Member
 
taylor p's Avatar
 
Join Date: Jul 2006
Location: Brainerd MN
Bikes:
Posts: 999
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
what do you guys use for facing, when I hear facing I think lathe or mill
taylor p is offline   Reply With Quote
Old 10-18-07, 08:04 PM   #8
OneTinSloth
(Grouchy)
 
Join Date: Mar 2003
Bikes:
Posts: 3,643
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
it's like a mill, but hand-operated, and usually with some sort of guide.

i forget who it is ATM, but someone makes a stem facing tool. for the top and bottom of the steerer tube clamp to make headset installations even more precise, and you can use it on cantilever cable hangers that install on the steerer tubes of threadless forks. those things can be VERY imprecise.

this is quite possibly the nicest head tube facing tool anyone will ever see. and i don't think they make it anymore. http://www.chrisking.com/tools/tls_cutting.html i used to sit at the computer late at night and drool over that thing.
OneTinSloth is offline   Reply With Quote
Old 10-18-07, 08:14 PM   #9
JunkYardBike
Since 1938...
 
JunkYardBike's Avatar
 
Join Date: Aug 2006
Location: Northwestern NJ
Bikes:
Posts: 6,208
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Well, to stir the pot a bit, one local LBS proprietor I intrinsically trust, who's been in the business for 30 years, believes facing a BB is really unnecessary, because the cups on an adjustable BB are designed to accommodate 'unparallelism'. I recently had an adjustable cup issue, which most on here suggested indicated a need for facing. He disagreed, but humored me by facing it. It didn't solve the problem.

I asked why he had such a tool, then, to which he responded that every once in a while he'll be presented with a BB shell that is waaay out of square, which the facing tool can at least improve a bit.
JunkYardBike is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 08:52 AM.