Seized EBB

[Whitestone]

How I got here:

A couple of years ago I bought a second hand steel frame (Singular Puffin fat bike) with an EBB. I don't know the maintenance history of the frame before this time but there were rust stains coming from the set screws. I've done no maintenance myself to the EBB.

Last weekend I was getting a lot of pedal strikes so thought I'd try a different position to its current 6 o'clock position.

It took 40 minutes to clean and remove the two set screws. I have applied penetrating lubricant to the shell of the EBB through the set screw holes, at either end of the EBB and down the seat tube then left for a day. So far the unit has resisted all attempts at moving it. I don't know the make of the EBB but looking at it it appears to be a solid billet of aluminum with the eccentric milled out and the BB threads tapped in to it. This probably means that the entire frame shell to EBB surface are in close contact and have fused Singular have some help on removing a seized EBB http://www.singularcycles.com/2016/09/19/ebb-maintenance-beginners/ but so far none of the tactics have worked.

So any further techniques to try? Is it just a case of time: apply penetrating lubricant, wait, try to move the EBB, repeat?

[rogerzilla]

Have you tried just riding it with the set screws removed?  Not too far, obviously, but I wouldn't be surprised if it worked loose.  This technique also works for stripped-out cotterless cranks.

[Paul H]

There's several types and it looks like yours is the type where the set screws dig into the BB shell?  If so try overtightening them a bit to break the seal while trying to pour penetrating oil in the gap.  Also if the method of adjustment  is two holes for a pin spanner put two set screws in those and a flat bar between them, that should give the leverage to turn it.  Once it's turning, knock it out, if that's still tight, get it a bit in one direction, oil the exposed part and the gap the other side and then knock back in the other direction. 
Stuck EBBs are pretty common, just keep at it and they eventually move.

[PaulF]

In the Puffin it's Singular's own EBB which is a copy of the Phil Wood design. Your assumption on the design is correct but the EBB has a waist so only makes contact with the shell at the edges. That means that anything down the seat tube will have little effect

I've had them stick in the past and Rogerzilla's suggestion is a good one. This is made easier if you ride single speed with a very tight chain Otherwise remove the BB, place the frame on its side with good support and drift the EBB out with a piece of wood as described in the link.

Good luck!

[Brucey]

the good news is that most aluminium eccentrics only bear against the BB shell over a fraction of the shell width. The bad news is that they can get very badly stuck anyway.

If you have not seen what the eccentric looks like yet there are some pictures of various types here

https://www.sjscycles.co.uk/eccentric-shells-spares/

which show what they can look like.

If riding on it with the bolts loose doesn't shift it, you can try and press/beat it out (but this can deform the thing so its worse stuck than ever and/or ruined) or you can heat it up.

Heating works because the hot eccentric expands against the steel, which then makes it a fraction  looser once it has cooled down.  If you can get the  cups out of the eccentric, you can usually apply a naked flame to the eccentric bore, without risking damage to the paint on the frame.

cheers

[PaulF]

The closest one in Brucey's link is this one https://www.sjscycles.co.uk/bottom-brackets/eccentric-bottom-bracket-insert-fits-raven-mk2-sport-tour-etc-732mm-for-external-bearing-bottom-bracket-gold/

[Whitestone]

I did wonder if it was "waisted".

I have ridden it since trying to remove the EBB and there were a couple of, shall we say, satisfying "cracks" but it didn't subsequently move. I'll try a longer ride with the screws removed.

I'm not sure about tightening the set screws as the EBB is pretty solid and the screws aren't that beefy.

[PaulF]

I did wonder if it was "waisted".

I have ridden it since trying to remove the EBB and there were a couple of, shall we say, satisfying "cracks" but it didn't subsequently move. I'll try a longer ride with the screws removed.

I'm not sure about tightening the set screws as the EBB is pretty solid and the screws aren't that beefy.

I wouldn't tighten it - Sam at Singular specifically warned me against that as there is a risk that you'll distort the shell.

The cracks are a good sign Just need to be patient...

[Whitestone]

When I started trying to free things up earlier this week I did the usual Googling and came across a video on the Thorn cycles site. Their bikes have a split BB shell and their technique was to tap coins (or similar) in between the flanges at the split. That got me thinking: rather than doing that have a pair of threaded holes in one flange that you could insert a bolt into which would push against the other flange and open up the shell a touch which would break the seal.

I'm going to have a bit of free time shortly so can give more time and effort to it.

[Paul H]

When I started trying to free things up earlier this week I did the usual Googling and came across a video on the Thorn cycles site. Their bikes have a split BB shell....

That's only on the Mercury model, most of the others have the same design as yours, I've had both and prefer the split shell.

[PaulF]

When I've forgotten to remove the Allen key that I use to adjust the BB and turned the pedals it has turned the BB as well - but that was with a free moving one but leaving a sacrificial Allen key in place and turning the pedals may give more leverage but I'd only use as a last resort as it may damage the pedals or EBB.

[Brucey]

this photo (I think) shows what the 'puffin' setup looks like;



with two grub screws bearing against the eccentric insert. This configuration is (IME) very prone to seizure unless regularly stripped and regreased. On some frames the water gets in (down the seat pin, through the breather holes, via the headset/steerer) and rots from the inside out; rusty stains at the grub screws hint at this. [If you really cannot stop the water getting in, a drain hole in the BB shell is called for.]

I don't think it is an accident that tandems have had eccentric BBs for about a hundred years (or more) and the design that was most commonly found (for many decades) was to have a split BB shell with a clamp that nips the insert up tight.  This holds more securely than the grub screw type (some folk experience persistent loosening with this sort), and should seizure occur, the split can be opened up so that the blessed thing can be moved/removed. The downsides of the split shell type are aesthetic (in some folk's eyes) and that there is a reduction in stiffness/ a slight increase in weight.

If push comes to shove you could perhaps convert the frame to a split clamp design; it would just require a little cutting and welding...  and note that if the shell were cut so as to make a split, the eccentric insert could be removed in a re-usable condition, no matter how seized it is.

cheers

[PaulF]

Yes that's a Puffin. To be honest I've only had the BB seize once (3 bikes with that design over a total of 20 years) and that came free with a little gentle persuasion

[Whitestone]

I can't see your photo Brucey but PaulF says it's a Puffin.

The insert is very similar to the one linked to on the SJS site but just one pin hole at either end not two.

"Gentle persuasion", hmm, not what my wife called it last night

[mzjo]

FWIW and just for general information LOOK A2 tandem frames have the grub screw arrangement with the screws screwing into a thicker plate welded on for the purpose. Aluminium frame made by Kinesis (at least the early ones were Kinesis, even had a sticker to say so). The screws are actually normal hex head screws and the whole plate breaks away eventually at the weld (bad placing directly in line of the crud off the front wheel) if overtightened adequately. DAHIKT. My tandem frame which is coming up 90 yrs old is steel and has the clamp arrangement is still fine (been greased a couple of times in the last century and has a modern shell to get around the oversize cup problem)