I have built several bikes over the years and never bothered to get the BB faced. I have just got a new road bike frame to build up and I am wondering if I ought to take it to the LBS to have this done or just shove the BB in as I normally would and get on with it.
Any opinions?
What actually happens if I don't do it, but it needed doing?

It's quiet… too quiet…

BB facing was essential when external bearings came in because some frames were all over the place. Now the manufacturers seem to be a lot more accurate the last 2 frames I had faced didnt need it the guy who did it for me said they were perfect basically all he did was clean a bit of paint overspray off.

Nope won't make any difference, then again maybe it will, who knows… 😉

I am not using an external BB, it is a 9 speed Dura Ace Octalink thing so I guess I don't need to worry too much.
The frame should be reasonable quality too as it is a Cervelo but you never know….

Thread alignment and the shell facing looks after your bottom bracket for external bb cups mainly. The seals work better and the bearings run smoother.

Your bb could possibly only last a few weeks.

If you change your components with the seasons.. then they will sell better if you have fitted them to a faced bb shell… and state that.

Octilink is fine with out…you would be better with paint protecting you frame!

Zone

Never understood the logic of facing a BB shell
Unless the threads in the shell are crooked on either side (And its the same thread the whole way through anyway) then the BB cups will be perfectly inline with each other, there is no way they couldn't be even with a smidge of extra paint on one bit etc.

i agree with barry, i am an ex engineer and keep seeing this facing for bearing question. as above said. your bearings are going to do exactly what the threads dictate and that is it. so having perfectly aligned faces will not make a jot of difference, save your money.

barrykellet – there is clearance in the threads themselves (components wiggle about a bit until you tighten them against a surface), so it's the alignment of the surface your tightening against, rather than the alignment of the threads. and the threads aren't necessarily aligned with each other anyway

BB facing is bike shop con #408.

clause 408a allows them to add straight profit to any frame they sell you.
clause 408b means they can blame anything from poor HT2 life through to the typhoon in Taiwan on you not having had your BB faced.

And clearly there's no need to face for Octalink.

I've come to the conclusion that facing doesn't really matter; mainly because the external BBs in my faced MTBs last a few wet rides, while the badly-faced one shown below on my (dry weather) road bike has outlasted them all (while the supplier agreed to reface the shell, I said I'd wait until the BB failed).

So I'm not going to bother getting it faced. Now I just have to get that lower bearing race onto the fork and the star nut into the steerer tube.

Stop.

Hammer-Time…

I'd only worry about it if the BB didn't screw in easily. Most frames are ok these days.

I would do it for external bearings though.

luckily my frame and bb are in pieces so i have just tried the fit, on such a fine thread that is about 10mm long no play at all when screwed in with a 1mm left out. SO A BEARING WILL DO WHAT YOUR THREADS DICTATE. plus unless whoever is facing the frame does it to align with the thread which i doubt! they are just going to make sure both faces a parallel to each other with what looks like being straight with the frame. pointless!

just a thought

Bike shops recommend you get your BB faced, is it because they sell sub standard frames?????

perhaps it should be done by them prior to sale

Is it not a bit like buying a new car and the dealer saying the tracking should be checked and adjusted before you drive because manifacturers do not build cars properly. bet you would not buy that car would you

For external BB's then yes I'd get them faced – had one bike were the BB was tightened up and the bearings weren't parallel until the frame was faced.

If buying a new bike the lbs should do it for free. If buying a BB off the lbs they should face/fit it for free. If you walk in having just bought a BB off CRC then I would expect them to charge.

no

Unless it's a facing tool that also ensures that the threads on each side of the bb are in line then it's pointless. Afaik, no facing tools do this (i've certainly not seen one)…

Facing a bb shell is included in the fitting charge of the bb! You put a bb thread cutter /cleaner through to make sure the alignment of the threads is correct first.

The bearings run better in faced frame.

If you torque the external cup up against an uneven edge it forces the thread to apply uneven pressure against the axle and bearings.

It's also one less gap for water to get in behind the bearings.

I fit loads every year and had none back!

BB30 makes this irrelevant!

Zone

hazeii, your BB is clearly not square, but as there is daylight between BB shell and BB cup, surely the problem is in the threading not in the bb shell being faced (as its not touching the BB where it is furthest away from being square there is nothing to face).

see above MC.

Fun to see the old myths continuing…

Munqe-chick, ta for reply but the problem seems to be that the facing was done badly; the cups aren't cross-threaded, and the crank spins perfectly freely (with the chain off). So it appears that whoever did the facing just did it wrong (the other side is sitting perfectly flush).

Based on my experience with MTB BB's, I figured it would soon die, at which point I'd take up the maker's promise to fix it for free. As posted above, my speculation is the reason it's way outlasted the external MTB BBs is simply because the road bike doesn't get wet often. Must admit I'm interested to see just how long it'll go on like that!

When i fitted HT2 to my bike, i didn't bother facing the bb. It's got dobby thick powdercoat on it , but the xt bearings are still good after 17 months. I'm pretty happy that it's not entirely nescassary and tell my customers so. If anyone wants facing, it's a little extra on their labour bill.

Never faced my Handjob frame, BB is just starting to go and thats 10 months of riding on a Raceface X-Type.

There's plastic spacers in there too don't forget that will take up some if any irregularity in the BB face.

One thing worth asking when a BB shell is faced, are the threads in the shell perfectly square? If not it defeats the object. So I must ask, prior to facing do people check their BB shell threads for squareness to the ideal/perfect BB shell face?

Our BB facing tool has sat unused for at least 2 years. It's a gimmick.

Chasing the threads however is something I do to just about every new frame- that's pretty important in my eyes.

So how, exactly, does a BB facing tool work? From the above, as long as it gives you nicely parallel faces that are at right angles to the axle, it seems a technically nice thing to do. However, if it just screws into the existing threads, the result is presumably quite random? (and depends on how carefully the frame was prepped).

It doesn't screw into the threads. It clamps to one side and then essentially scrapes the paint off.

Ah, so we're talking about facing only.

I wouldn't be picking up a facing tool unless I had chased the threads. Can't see the point of facing if you can't guarantee the threads are parallel.

Threads in the frame have to be square for the facing tool to work properly.

That's why the threads are chased first.

We use the threaded section and guide rod of the campag facing tool to fit bb30 adapters as well…again this is so the the bearings run with equal pressure 360 as much as possible.

Zone

Chatting about this to a mate who is an engineer he reckons the only way to guarantee absolutely square BB faces and threads would be to mount the frame in a cnc milling machine and cut the threads and machine faces at same time.

He had a look at the facing tools on the internet and reckons they are a waste of time he says if both faces are out which face do you cut first. There is no reference point to cut to (not sure if I totally understand what hes saying there) and your relying on threads that were probably cut in 2 seperate operations which could be miles out,

When I mentioned the plastic spacers he just laughed and said anything that invoves plastic could not be considered precision.

In his opinion Octalink was the best but then he is fat and ugly

Chasing won't square the threads if they weren't cut square on the first place.

Chased and checked…If that bad re-cut then!

Conspiracy theories… are just that ….theories! I have enough experience with this to draw the conclusion that we have problems and repairs with units that have not been faced before being fitted and have no issues with ones faced. For the last 5 years any way 😯

The original facing tools where used for the old style cup and axle bbs … they worked for them.

And as for the "my mates an engineer" … FFS 😯

Manufacturers stipulate the facing for fitting job.. they have nothing to gain but happy customers…. If it's included in the fitting price, What's the problem….

Basically your saying facing bottom bracket shells is not needed and total horse shite.
🙄

Rolf Harris, the campag facing tool we use does thread into the frame.

Zone

pantsonfire – Member

Chatting about this to a mate who is an engineer he reckons the only way to guarantee absolutely square BB faces and threads would be to mount the frame in a cnc milling machine and cut the threads and machine faces at same time.

Threads – can you ever guarantee perfectly true thread? Faces – if they are cut on a lathe, why would they not be straight?

He had a look at the facing tools on the internet and reckons they are a waste of time he says if both faces are out which face do you cut first.

I'm not sure the degree of precision most engineers love to quote is required, but I'd have thought an iterative process of alternating sides would get one close enough.

Çlüßßér – Member
Chasing won't square the threads if they weren't cut square on the first place.

True, but completely irrelevant.

Rolf Harris, the campag facing tool we use does thread into the frame.

Zone

But there is always movement between the male and female threads though. Or have you actually used it?

pantsonfire – Member
Chatting about this to a mate who is an engineer he reckons the only way to guarantee absolutely square BB faces and threads would be to mount the frame in a cnc milling machine and cut the threads and machine faces at same time.

He had a look at the facing tools on the internet and reckons they are a waste of time he says if both faces are out which face do you cut first. There is no reference point to cut to

That may be so in theory maybe, but in practice using the thread chasing tool when needed results in a much nicer fit of the BB.

Shimano don't say anywhere in their instructions that facing is necessary.

Oh and while chasing may be a good idea, it still does nothing for alignment and is therefore irrelevant to this thread.

So in conclusion people who run bike shops say you have to have it faced BB manufacturers dont seem to mention it in the instructions and most people couldnt be ar*ed unless the bikeshop does it for nowt.

Me I have it done because I am picky and I get it done for the price of a pint. 🙂

But there is always movement between the male and female threads though. Or have you actually used it?

yep!

hundreds of times! If not more! at least in the last 25 years anyway!

Amazing how stubborn people can be when presented w/ the obvious.
Facing was /is a non-issue for those blessed with one-piece sealed BB units everyone used for 15+years; before that, and now again even more with external (“infernal”) cups, if you don’t have a faced frame, you will find it very unlikely that the bearings will not bind, grate, and wear even faster than they tend to do anyway.
The threads alone don’t adequately align the cups, because they’re generally too loose, too short in depth, compared to the cup width, and a non-parallel face will apply pressure unevenly as the cup is tightened, until it forces the cup to lay against the face.
One-piece BBs were great, because all the parallel issues were kept perfectly true inside the integrated unit, sealed and made to very tight tolerances. Facing became an underappreciated step, because the face was only aligning with secondary washers or lockrings not directly applying any force to a bearing or race.
External BB cups are inherently sloppy, and some like FSA are notoriously even made to incredibly lousy tolerances; I will gladly sell anyone an Enduro ceramic bearing/cup that spins free alone, but binds when pressfit into their own cup, using their press, before even installing into a frame.
Facing isn’t supposed to be an issue with carbon, as mfg techniques bypass the issue; any metal frame should be faced (Ti can be faced w/ standard cutting dies, use lots of cutting oil) or you risk poor bearing alignment and premature wear.

hazeii – Member

I’ve come to the conclusion that facing doesn’t really matter; mainly because the external BBs in my faced MTBs last a few wet rides,

I should be trying to figure out why that is tbh. Unless your idea of a wet ride means riding under the sea.