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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My Dahon frame is set up for 1-1/8" fork and the head tube has integrated(?) bearings, the cup does not stick out of the head tube. You'll need to look at your frame or bring to a bike shop to determine what kind/size you'll need.

My rim-brake Dahon has a 74mm OLD front hub, this is quite common on folders now. Dahon's and others' disc bikes usually have 100mm front hubs to be able to use available hubs with discs. I think Bike Friday always used 100mm front hubs for rim and disc brakes, in order to use standard off-the-shelf parts. My rear hub is 130mm, they vary between that and 135mm, or narrower like 120 or 110mm I think for some models with internal gear hubs, like Bromptons. Cold-setting the rear stays on that design frame... I can't say. The front hub width can complicate finding matching rims. Dahons on 74mm come with 28 and 20 hole front rims with rim brakes, and on 100mm with discs I think 28 hole.

Lack of rear derailleur hanger is easily solved; You can use a rear derailleur with a built-in claw-mount that goes under the axle nut (see pics below), or buy a claw-mount that will do same and accept any standard mount RD. My frame also had no standard RD mount, just the hole forward of the axle for Dahon's compact RD, which worked terrible, too far forward of the cogs so increased lateral flexibility of the chain meant it shifted awful into lowest cog. Now it shifts great.

Bottom bracket shells are typically 68mm wide and BSA threading. You can of course use square taper and cartridge, however when I upgraded my gearing to a double crank, I went with the newer design 2-piece hollow-spindle design (similar to Shimano Hollowtech 2), and LOVE it, and amazed that it's backwardly compatible into old bikes. I went with 24mm hollow spindle and ISO External standard bearings, the most common wrench standard. My chainline is 43.5mm (center of frame to middle of 2X crankset) which is perfect on my 7 speed cassette 130mm hub.

That seat post diameter: Will be easier to find accessories, like a clamp-style rear derailleur to fit the seat tube if no front derailleur braze-on, and more clearance to have a proper chainline. EDIT: No, I now see your seatpost is swaged down at top, below is larger, so worst of both worlds. My 33.9mm seatpost and 40mm seat tube, stronger, but no clamp FD fits, and adapter to use road FD was a really tight fit to still have good chainline, I had to grind away a small portion of the inboard lip on the FD for things to work.

You can use ANY handlebars on a folder, it just may be a less compact fold. I use 58cm flat bars, with bar ends (more comfy than my old 40cm bullhorn bars), plus bolt-on aero bars which complicate folding (need to remove forearm rests), but I don't fold it often.

Folding pedals: If plastic body like my stock pedals, they typically contain thin stamped steel races (cups) and with a lot of miles, mine cracked the cup after a year. There are better folding pedals, especially pedals that don't fold but disconnect quick and easy.

Pics: This was originally a Dahon Speed D7:





The folding bike market has become more competitive. Before building up the bike, you may want to check on the price of a Zizzo Forte, good reviews on multiple threads on here, may be a better deal with cost of all components AND fork AND wheels.

Also, that folding hinge design tells me that is a low-quality folding frame. And I now see a lot of rust. I recommend against investing in that frame. Start with a new frame or get a complete bike, it'll be both better and cheaper.

EDIT: Country code MY, Malaysia? Oh I think parts and frames are dirt cheap there. There's a member on here from Indonesia, he builds up bikes at incredibly low cost with top quality. Here in the USA, we can't get FnHon frames and good Shimano components near as cheaply. Look for complete folding bike buildup threads by Ron Damon, as well as threads from others reviewing the Zizzo Forte (I don't know if that bike is available there).

Thanks a bunch! I think I just order the stuff and hope it fits. After all, as you correctly deduced, I am currently stationed in Malaysia and the stuff is incredibly cheap here, headset 5us, fork 5us etc. just want to take the opportunity to take as much of the old stuff laying around on the shelf and use it for this bike. Will be a wild mix…the one thing which is a bit of head scratcher is the chain line. With a single speed this needs to be right.

While I understand the urge to rescue this frame, I think it is not worth it. If it came with a fork, may be. You are going to need a specific folding bike fork and steerer post, a specific saddle post that is your case seems smaller than the regular 33mm. Looking at the frame, you will need a wheelset with rear gear hub rather than cheaper cassette/derailleur setup.
Basically, a lot of expenses for an unknown frame when you could start with brand new something such as a Fhon frameset and litepro wheelset (or other) for pretty much (if not cheaper than) what you would have to spend to rescue this frame.

If you had already owned several folding bikes and accumulated a large spare part bin (inc wheelset) than, the rescue subject would be different.

I understand. But what Fentuz and I both said is good advice. Let me put it another way. Versus a new bike, perhaps you save 50% on cost; 50% on USD$1000 is a lot different than 50% on $300. If you can get a complete folding bike as cheaply as parts there, go for that, it will be far superior. However, if you start with a quality frame like an FnHon and build up the bike, it will be even better as you can choose to use better quality parts. Just make sure things like "Shimano" parts are genuine, as many fakes are being sold on Alixxx and other sites. Buy through a reputable dealer of those brand parts.

I would start first by deciding what size tires you desire, both diameter and width, then what style folding on the frame, and what style brakes, then correct size to fit you, and obtain a frame and build up from there.

Both Ron Damon, and a member called ChiapasFixed, started great threads on buildup of multiple folding bikes, the latter did 4 different ones for a family tour of southeast Asia:

Folders for Family Fun

It's a steel frame? Really? It must be heavy. The bike this frame is copied from, the Dahon MU, has an aluminum frame that's not particularly light. Copied in steel it would weigh ~3x as much.

Most folding pedals are lower quality. Suggest removable pedals: MKS Ezy, Wellgo QRD, etc.

Yes, a few folks use drop bars on their folding bike. No, they typically don't fold well.

Use a regular X-speed cassette hub, one cog and a bunch of spacers. Any chainline you want, bob's your uncle.

+1. Probably also easier to find replacement freehub body, and replace cog when needed, than freewheel body with fixed cog or that allows cog replacement. Only question, if not using narrow chain and typical cassette cogs, but rather, wider single-speed cog and crankset, is if they make wider tooth cogs like that to fit on a standard pattern cassette body? But if using standard multispeed chain, not an issue.

yeah, it’s steel. And it is heavy…just under 4kg.😂 with regard to the chain line: I did some research and found that surly makes a 135mm rear single speed hub with a chain line of 50mm. When I use an old campa square taper crank with the campa chorus 102mm spindle bb (which produces a chain line of 48mm) or a JIS 107mm bb and mount the outer chainring it should be near perfect…the real problem is this gnarly fluted seat tube. I think I am going to make some vertical cuts on the seat tube, bend the fluted part outwards and braze a seat post clamp onto the outside, thus getting a seat tube which accepts a 33.9mm seat post. Seat posts with 33.9mm diameter and 600mm length are much easier to source…

Yes, but 33.9mm diameter seatposts, are designed to fit into a slotted aluminum bushing (Dahon calls it a shim) that is only 75-100mm long, that fits into the frame tube. I forget what the outside diameter of the bushing is supposed to be, it's really thin wall, but just enough; There is clearance fit between the seatpost and seat tube, below the bushing. Without the bushing, and with the hugely long seatpost, the inside diameter of the seat tube had better be perfectly round, and dead straight for the whole length, otherwise the seatpost will not go down to fold. I think that is the reason for the bushing, because there are multiple welds to the seat tube on most folders, that can cause the tube to not be perfectly straight or round for its whole length. I had problems with a long seatpost that was still WAY shorter, going into a mountain bike whose seat tube was not kept straight enough from the factory. Most bikes, the seatpost only goes in, what, 6"/150mm?

Take heed, and abandon the siren song luring you to the rocky shore of bike-build heartache. Make a clean break to a reasonably priced but virginal frame that will place you in good stead with the bicycle-building gods. Or, rather than creating your own religion as it were, go for the package deal with a folder that is turn-key fully equipped to go. As it is said.

Undoubtably the safest advice, but as someone who is unable to keep from altering bikes to better suit me, and has experienced successes as well as failures, I would listen to the sirens so long as you see no you think it would work.

That is really helpful. (not to discourage me ) No seriously, that makes sense out of this whole seat tube affair...already found a shim which I will braze into the neck of the seat tube. that should give both stability and seamless "slideability" to the seat post. (I realized that I mis-measured the seat tube. it's actually 34.9 not 33.9mm. I have a reamer and will go through the entire seat tube to smoothen it out a bit and then insert the shim which is 34.9-33.9mm.

The voice of reason and sanity...always unheeded as my ever distraught teachers and parents can attest to.

Ah, a fellow traveler on the rocky roads towards Ithaka, i.e. in this case towards the final folding frame folly fantasy frontier...but with the financial stakes so low (outside of the rear hub which is about 80USD) the whole shebang will cost me no more than max 70-80USD in parts I shall set sails for the unknown! Wont be able to say that I haven't been duly warned by Duragrouch if my ship hits Scylla or is swallowed by Charybdis!

Yeah, that doesn't fold well indeed. I reckon it's gonna be a flatbar for me. The MKS pedals look neat (as one would expect from a Japanese manufacturer). Not sure, however, if I should buy pedals that cost more than the rest of the parts combined...

I've rehabbed a lot of bikes over the years. The difference is that they were whole bikes, with forks and wheels and most parts fine, and not just a questionable frame. Usually, just needed overhaul, not changing configuration. I converted my mid-low-end Dahon to 2X gearing so have the performance of a Bike Friday NWT at multiples lower cost. And when I did that, all the advice I could find on here, whether this was possible, was "No." (I had not yet discovered the Folding Bikes group.)

The labor time and effort, and parts cost to restore a Ford Pinto, is the same as restoring a '65 Ford Mustang. But it's easy to argue the Mustang is worth more. Still, if Pintos are your thing, do what makes you happy. Usually this happens with boats. I would argue that the cheap steel folder frame is more of a fungible commodity, and it would pay to start with a better canvas on which to paint.

But I have seen on here, truly lovely restorations of several Dahon Mu, down to stripping the paint and powder coating, just lovely.

Took me over a year but it's finally finished...much appreciated all the input! Got lucky with the chain line. I screwed in an old Shimano square taper bb with 110mm spindle just to see how the chain line would play out and it was perfect...a nice surprise. A shade over 12kg; not great but not terrible either.

Looks good! I'm jealous of your front disc brake, that eliminates rim sidewall wear. I've seen that front rack before, and the only thing I don't like, is the aft portion of the deck supported only by the center bolt in the fork crown, I'd prefer some vertical struts there like in front; Lateral offset loads there will try to twist the rack deck. At the front of the deck, fine, fully supported. But the further from the fork, the more the weight affects steering. But keep the aft load balanced left and right, and you should be good.

Thanks, I wouldn't go so far as to call this thing good looking but appreciate your comment! The steering with a standard airline carry-on bag strapped to the front rack it is indeed rather wobbly...tried it out on the weekend with one of those bungy cords. Terrible idea. I reckon the way to go is with cargo straps and really tie it down to the rack firmly. The mechanical disc is not a revelation...it's a 3USD no-name mechanical caliper from Indonesia (the new centre of cheap bike production). I really was determined not to turn this thing into a money pit...but I agree: at least you don't have wear on the rims. Overall I am pleasantly surprised - as this is my first ever folding bike - how similar this rides to a 700c road bike.

Did someone say carryon?

This is after buying at Goodwill, strapped on for 1 mile trip home.


You want cam-buckle non-stretchy straps, not bungies.

It was stable, due to it sitting on side panniers, but I would have done more strapping for a longer trip. I've also strapped there vertical, a nice upright vacuum; A "front block" rack on the head tube, feels better because the weight does not move with the steering. However, on the fork rack, tall loads can easily be strapped to the handlepost, because it moves with the fork rack. I have transported there, no less than another bifold frame, in shipping box.

This is impressive. Not sure I want to take it that far with my luggage though. ;-) I found this for just over a 1USD:

If you mount this to the steerer column at the height of the handle of carry on bag and then use two straps it should be pretty secure...

Excellent. Thanks for coming back with an update! Looking good!

Yeah, you don't want to use that alone, as then the bag will swing. Two straps will help, in fact then the hanger might not be necessary, but can't hurt as a backup so if the straps come loose, it starts to swing before falling off completely. The rubbery padding is there because most folder handleposts are tapered, though a very slow and shallow taper, so that should work.