++1 to nicobecs sugestions especially the pvc pipe trick. when removing any press fit part that requires significant effort the rule of thumb is surface area, squareness,even pressure, and effort without shock, and patience. if you can remember these principles you cant go wrong, this applies to anything.
surface area:
the idea is that you don't want any distortion or, to damage the part being removed ,or the part's housing- effort distributed evenly on the load will minimise the distortion which is very important as effort placed on one side (such as a screwdriver) can throw the press fitted part out of square and grab on one side, further damaging the shaft, spline,or housing that the part is being removed from. worst case scenario is both part and housing become damaged.usually you will find that the part is made of a more robust material than the housing as it is the part that does all the work, not the housing in which case you are talking about a mild steel tube which is very easy to be subject to deformation usually by ending up ' out of round '
squareness:
unless you are talking about tapered fittings squareness ensures that the part is removed without grabbing, flaring (expanding) and or possibly scoring the shaft/spline/housing making new press fitment very difficult and can result in ill fitment where repairs to the machined surface can make (in the case of bearing fitment) chattering at high speed which could have catastrophic failure of the bearing through vibration, but that depends on the quality of bearing etc.
even pressure:
basically it is to avoid all of the above.
effort without shock:
this is getting down to nano size science. Panel beaters use a technique called 'splashing' which can manipulate stretched metal back into its original shape, sort of. it is a principle where the metal molecules are re-aligned and shocked back to where they were due to the metals 'memory' , it involves lots of tapping with a panel beaters hammer and dolly if i can remember back to when i studied welding about 18 years ago!!!!! so don't quote me on this, anyway i think to a lesser degree, shock placed on forged parts can result in micro fractures that will weaken the part/housing and if its a bearing cup- the chattering thing can happen and when the little individual bearing balls run over the crack they ever so slightly open up the crack and so on until your cups and bearings feel like your trying to grind up pebbles in a pestle and mortar!!
patience:
think of the patience you have had reading another of my long winded extreme answers-that's what you need to avoid damaging and ruining whatever it is you are doing.
ive often used a steering wheel puller to press fit the bearing cups- threaded rod, nuts, washers or holes drilled through thick plate sheet metal and you cant go wrong, just make sure your threaded rod or bolt is central inside the tube, and not to one side. once again +1 to nicobecs for his suggestions. im a bit rusty with some of my terminology when explaining things Ive learnt in days of old, so please don't take what Ive said as gospel but rather food for thought.
and by the way- your bike is very impressive
7 fattie
i know all about missing bikes when you go away somewhere... I plan on taking my little folder everywhere I go now. 