Any tips to loosen seized EBB?

Post a picture of it

Use a proper penetrative oil, not gt85. Spray morning and night. Will give eventually

I would next try the usual freezing or cooling it and then hammering? As a last resort you could cut it out?

Can you recommend a good penetrative oil?

Plus Gas is far better than GT85.

Can you not get a BB spanner on to the BB then turn the EBB unit in the frame to free it off?

ScrewFix own brand fluid in a massive aerosol- the smell takes me back to the seventies, and it still works!

Singular's used to come with Phil Wood EBBs, which have a allen key fitting for turning. Might be more effective than a mallet if you haven't tried it already.

Back in the day seized was my preferred state for an EBB, helped with slipping issues.

Try screwing in a HTII bb cup then use the bb tool and a bar to rotate the insert from the cup.

Won't work if the insert if properly seized, but if it's just a bit stiff this is a useful approach.

Support the BB shell and wack the EBB sideways. Shock loads are far larger and more effective than trying to turn it with an Allen key.  If you have one then an air hammer makes light work of that sort of thing.

I had an EBB on my cannondale tandem that seized and the solution was to drill and tap another part of the BB for a couple of M5 bolts that I could use to pull one half of the EBB out.  Worked, but does require you to have the kit to do that.  wacking it hard might have worked but might not have depending on which half was seized.

Try using some Innotec De block oil, amazing stuff used it on many seatpost, bb and pedal/cranks situations.

Support the BB shell and wack the EBB sideways.

This. The Singular EEB type is a fixed insert with 2 radial bolts that push the insert into the opposite side of the shell. The insert will probably have bonded to the upper side of the BB shell in a small area so a sideways force seems the way to go.

Assuming the EBB is designed how I imagine.

With the clamp bolts removed, reinsert them the opposite way (threaded side first) and drop a penny or similar to block the opposing holes. Add penetrating fluid and wind the bolts in against the pennies pushing the frame apart. Do this gently turn by turn. This in conjunction with the other methods above should have it out.

Plus Gas worked for me on my Rooster. And a good sideways whack too as suggested.

have tried giving it a smack with a rubber mallet.

Try a proper grown up man's hammer made of steel?

Can you recommend a good penetrative oil?

3 in 1 penetrant spray. Orange and black can. Always worked better than plus gas on old vw bolts that haven't been touched for 30 years.

If you can put the BB and cranks back in, you could also try riding it about a bit with the pinch bolts removed. Put them back in just nipped up if you feel it free off, you wouldn't want it rocking in the shell for too long.

Assuming the EBB is designed how I imagine.

Singular used Phill wood (or copies of) EBB insets and grub screws on their steel frames.  The Ti frames might have had split shells but I don't think any of the steel ones did.

Try a proper grown up man’s hammer made of steel?

+1   Rubber mallets are great when you want to softly knock something without marking it, they're not going to give the shock needed to break apart bits of rusty metal.

A friend was rebuilding his 1980s Muddy Fox a few months ago and we managed to remove / rescue the very stuck aluminium quill stem using plumbing pipe freezer spray, making a wooden plug for the bottom of the steerer to hold a cold puddle in contact (the aluminium contracts more than steel).

You'd hold a good puddle down the bottom of the seat tube where it is really stuck, and remove the bb and cut two discs to make a closed chamber to fill in the middle. You only get one hit at it so prep / seal as much as possible and you need to whack it out quickly when cold.

The spray isn't cheap and don't bother with the combined freezer / penetrating sprays - you want maximum cold.

I bought an old jump frame off ebay, BB was totally seized in there, I bought a massive wrench, used some shock & unlock cold spray from halfords and just yanked on it so hard, it eventually went, but I was leaning over it with the bike upside down & caught my beer belly in between the spanner and the seatstay and it hurt a LOT , left me with a really weird bruise

sorry about the picture

and fwiw Im a bit trimmer these days!

@kimbers Phhht! That's nothing on Derekstarfish's bar end damaged belly pic for those that recall it :puking emoji

managed to get it out by whacking it with a hammer. But obviously now I've damaged the thread so can't screw back in the bottom bracket - damn it! Gotta buy a new one now 🙁

LBS and clean/retap the thread

You can make a crude tapered tap by sawing four slots into an old BB cup at right angles to the thread

managed to get it out by whacking it with a hammer. But obviously now I’ve damaged the thread so can’t screw back in the bottom bracket

Are the threads definitely gone? I spent quite a while trying to screw my BB back in before realising that I'd put the EBB insert in the wrong way around!

If the threads are damaged the LBS might be able to run a face/chase tool through to restore them.