Any tips for removing pedals that are seized on?

a nice new, big spanner, with a long handle, gently tapped with a rubber faced hammer

How about if your pedal doesn’t have cutouts for a pedal spanner – like a Crank Bros Mallet axle for example, which refuses to let go of a Race Face X-Type arm, having claimed two allen keys while attempting to shift it?

Yep, I’ve tried immersing in boiling water too.

you are turning the right way?

Had this at the weekend. Shattered a Halford professional 6mm in the back of the axle. Started deforming a Park pedal spanner. Tried soaking them in penatrating fluid and then boiling water. In the end, we gave up and replaced the cranks.

These pedals were given a generous dollop of copaslip 4 years ago when they were fitted but commuting through winter is hard on a bike.

Be warned people.

in which case I have no idea. Ive been avoiding pedals without a spanner face for exactly that reason

not going to help the OP but remove and refit pedals every few of months. Make it routine with other maintenance.

I wish I listened to advice to remove and refit stuff more often, it would save me a fortune. seatposts, freehubs and pedal cleats all spring to mind 🙁

I’ll try the spanner and hammer approach, thanks!

Dismantle the pedal.
Remove the crank.
Clamp the pedal spindle in a vice.
Turn the crank.

Or try a hot air paint stripper first if you’re not fussy about the lacquer or paint on the cranks.

If that doesn’t work, try a kitchen blowtorch to heat up the cranks (obviously not if you’ve just WD40’d it). Presuming the cranks are alu, they will expand more than the (steel) axle, allowing you to prise the buggers out.

I had a little contraption for this once – was effectively like a small breaker bar that you could put over the allen key or spanner to give it a bit more leverage (about 70-80cm or so in total). Worked a treat.