I came into possession of a folding bike frame (by way of throw-in sweetener in a swap deal for "real" bike parts). Always wanted to build up a folding bike for travel in Europe (rock up at the train station, fold it, ride the train, hop off, unfold it, ride off). Now that I had a first proper look at the frame I realize that there are a lot of things that are vastly different from 700c road bikes which I ride normally. The purpose of the post is to run a few things by the experts here who hopefully will/can help my clueless self to find the way to a rideable bike. So here's the plan: Single speed, reasonably priced, and sturdy are the main objectives; low weight is not a consideration. Making use of my parts bin and avoid buying too many parts is another goal.

• The head tube has an inner diameter of 44mm. My understanding is that this a specific folding bike standard. It seems for this type of head tubes there are only headsets available for forks with 1 1/8 diameter. What I have found so far is a head set from a company called litepro. Unfortunately they don't give information on their website regarding the inner diameter. Anybody knows if that is for 1' or 1 1/8' forks? I suspect that it is for forks with 1 1/8 diameter. If so, can I use both, forks explicitly for folding bikes and bmx forks as well? Also, when looking at steerer column: are there two different standards; one similar to quill stems and one similar to ahead-set type stems? The former for 1' forks and the latter for 1 1/8' forks? Are there any alternatives for this litepro head set which you could recommend?
• Are folding bike forks for 100mm hubs like road bikes or do they have a different standard? If I run disc brakes, are the calipers the same standard as road bikes? Or do I need some kind of adapter?
• The bb shell width measures 68mm. I presume, therefore, it is BSA. The spindle of the bb which is currently still stuck in there has an insane length of approx. 145mm with some threads at the end. (the thread is part of the spindle - never seen anything like that) Are there specific folding bike cranks that require these ultra long, threaded spindles? I was planning to use an old (2001) Campagnolo square taper crank with a 1x chainring. They would normally be combined with a 102mm bb. What would be the chainline implications when using a road crank on a folding bike? What is a normal/ideal chainline for folding bike 1x drive trains measured from the center of the seat tube? 48.5mm? or something else entirely? Can I use a road bike crank at all?
• The rear dropouts are 135mm. No rd hanger. I suspect folding bikes are run with internal gearing hubs - at least this one sure is. Has anybody heard of 135mm single speed hubs? Or are there specific rear hubs for folding bikes that meet some chainline requirements which I am not aware of? Has anybody tried to cold set these "monocoque" chainstays? (it's a steel frame)
• The required seatpost diameter is 28.6mm. I am tall, so I need a 600mm seat post. So far I only found one post 28.6/600mm from a company called Woodman. Are there any alternatives out there?
• I remember having seen some foldable pedals. Couldn't find them anymore on the internet. Anybody has a link and/or an opinion regarding those pedals?
• Anybody running drop bars on a folding bike? Experience? Does it fold reasonably well?
• Any recommendations for sturdy 20inch rims with 28h or 32h?

I know, a lot of question, a lot of them probably stupid, but I'd appreciate any input as I am a thoroughly confused currently with the uncommon (for me) standards on this bike. Thanks a lot!
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