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Old 04-05-17, 11:48 AM   #1
Robyx
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Restoring an old MCB folding bike(?)

Hi! (Hopefully this posted in the correct section)

I just recently got into vintage folding bikes. I've never owned one until now, a 20" MCB folding bike from the 70's I found standing outside my apartment complex - abandoned.

It's a real fixer upper but I will focus on getting the rust off all the details and wheels, and hopefully be able to restore the folding mechanism which at this point is stuck and doesn't work in any way.

I'm quite used to fixing bikes, but only the most basic. So therefore I would really appreciate some guidance.

To get to some questions:
  • What is this model called?
I've researched some and found out as little that MCB is short for Monark Crescent Bolagen, but I have no idea of the model.
  • How much reinforcement will the folding hinge need to work properly and with no chance of breaking?
  • Which other things would you recommend me taking a look at restoring?

Thank you for looking and helping out.





Last edited by Robyx; 04-05-17 at 01:19 PM.
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Old 04-05-17, 12:10 PM   #2
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that hinge is shot
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Old 04-05-17, 01:18 PM   #3
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that hinge is shot
Thanks for the (not so) constructive and positive input

I realize that it's totally wrecked, but in many cases that doesn't mean it's impossible to fix. Therefore I asked how much, and of course what kind of reinforcement/fix the hinge would need to work again. Welding isn't a problem...

Maybe you have any other pointers on what to take a look at instead?
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Old 04-05-17, 01:30 PM   #4
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Can we have a pick of the front badge? I don't know too many details, but folding bikes have been made for a very long time. I think the type with 21", 24" or there-about wheels ow a lot to the Moulton bike, though few copied it's special frame. A lot of brands had this type of bike in the 60s, 70s, up until the mid 80s. It was a sort easy going style, for shorter rides, with or with out the hinged foldable frame. A lot of them were very nice.

I think Monark / Cresent is a Swedish brand, and in general these models went under the term "mini bikes".

Edit, sorry I was a bit slow there, I notice a bit late you are in Sweden :- )

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Old 04-05-17, 01:44 PM   #5
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Can we have a pick of the front badge? I don't know too many details, but folding bikes have been made for a very long time. I think the type with 21", 24" or there-about wheels ow a lot to the Moulton bike, though few copied it's special frame. A lot of brands had this type of bike in the 60s, 70s, up until the mid 80s. It was a sort easy going style, for shorter rides, with or with out the hinged foldable frame. A lot of them were very nice.

I think Monark / Cresent is a Swedish brand, and in general they went under the term "mini bikes".
Thank you! Yes, it's Swedish. Okay, so the model is probably just called a "MCB mini bike", more or less.

Here's the front badge.


I also found this picture online:

On that site they claim that these kinds of MCB bikes got imported and replaced many other well known local folding bikes during the mid 70's.
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Old 04-05-17, 01:53 PM   #6
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I couldn't find much from a web search, next step would be to track down an old sales catalog. There's good chance somone who knows about them will reply to the thread. Some of them had Sachs "kick-back" two geared hubs, with a slight back pedal movent it shifted between the two speeds.
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Old 04-05-17, 03:50 PM   #7
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Hate to say it... these are dime a dozen ... made under different logos , lots of the in Yugoslawia
all of them cheap cheap cheap ...
If you have somepersonal story with this particular bike than bring it to a welder and try to get it back with a lots of work and money
Some old bikes like a Raleigh twenty are worth it for the hardcore peep but these are really not


sorry
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Old 04-05-17, 04:27 PM   #8
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These types of bike were shipped over from behind the iron curtain in the 70's and were sold in places like petrol stations. This one looks like it was abandoned for a reason, like it had reached the end of its useful existence. You're looking at sinking a lot of time and money into it for little reward. For what you'd pay just to get someone to align and weld the frame you could probably buy one in decent condition, given that these bikes were bought by non-cyclists and most probably ended up unused in the back of garages.
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Old 04-05-17, 04:45 PM   #9
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Like Thor says, they were mass produced and not expensive bikes. There are the odd exeption with better parts. The frame and fork vary too. The ones I have seen have welded steel frames, but far from the worst quality. The hubs I see on them here, where standard German made one-piece cranks (durable and smooth enough), single speed or two hubs, often Sachs or Sturmey 3 speed hubs. There are enough of them around to hold out for one in better condition. They became popular with students some time in the mid to late 1990s, and demand has lasted long enough for brand new to turn up in stores. These are the same standard bikes, reasonably good quality, but with lighter aluminium frames. I have never seen any made in Colombo or Reynold steel frames.

Complete restorations is hardly ever worth it when it comes to costs or value of bike, but a thorough clean up and DIY rebuild often is. When welding is involved it's always a labor of love, but you can end up with a nice and fun bike. If it was me I would wait for one in better condition, with better wheels and brakes, Sturmey or Sachs hubs. When cleaned and regreased it's easier to make them hold up to regular use again. Another thing is I don't think it's legal to ride with out front brakes these days.

I am willing to invest quite a bit of time and effort into a bike, even if it's not a highly priced gem, but as long as I aim for a bike I plan to use and enjoy riding it's always worth it. Choose bikes for these kinds of projects carefully :- )

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Old 04-05-17, 10:59 PM   #10
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Originally Posted by Mickey2 View Post
I couldn't find much from a web search, next step would be to track down an old sales catalog. There's good chance somone who knows about them will reply to the thread. Some of them had Sachs "kick-back" two geared hubs, with a slight back pedal movent it shifted between the two speeds.
Thanks for the info! I've seen those, truly practical, but this one doesn't have that kind of mechanism. I would like one though, is it a hassle to change the hub?

Do you have any pointers on any parts I should take a closer look at restoring/maintain?

Thanks!
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Old 04-05-17, 11:07 PM   #11
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Oops missed your other posts.
Thanks for the feedback guys, means a lot. The thing is I want a vintage folder which actually is a folder and not an take-apart. Here in Stockholm they're hard to come by.

But yeah, you're all correct in mentioning its probably a cheap bike to begin with. And it might not be worth it moneywise. But at the same time, as Mickey pointed out, I'm willing to put a bit of effort and money into it. I still like it. I'll keep looking for others as well, until I've got a clue about the total cost of welding and so forth.
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Old 04-06-17, 07:21 AM   #12
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It is a bit of a hassle to loosen spokes, polish them and the rim. If the hub diameter is exactly the same size as the original it's much easier. I find it difficult to measure unknow spoke length to match a specific hub and rim, but nothing is impossible. The easy way about is to find a same size wheel with a Duomatic hub, but then rims will likely not match perfectly.

I can let you know I picked appart a seriosly bent 28" wheel (with a 3 speed gear hub) from an old worn bike. I took the rim from the front wheel which was straight and nice, and rebuilt using only the old parts. This is the first time I did this on my own and it worked out fine. It's not perfectly true since I didn't have a proper wheel stand, but I managed reasonably well using the frame of the bike. It wasn't worth handing in to a repair guy, since I didn't know the condition of the hub. I was lucky, it turned out to only need oil, shifts and turns smoothly now. I'm just the average guy who likes to fix up an old bike and at least do something on my own. I don't have lots of tools, or chance to do anything like welding, but I always have room for a spoke wrench or three in my tool box :- )

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Old 04-06-17, 09:53 AM   #13
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Regarding the hinge:
- If it was me, with the tools and materials I have access to, I'd try to rebuild rather than repair that hinge. Find/make some stubby pieces of tubing perhaps and weld those in rather than repair the folded-over and cracked metal. One possible source are hinges for steel doors. Maybe replace the latch with something like a spare part for trailer gates.
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Old 04-06-17, 10:18 AM   #14
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Oh yeah, in that case it sounds better to find a new rear wheel with duomatic for sure - and get a matching front wheel. Sounds like a lot of work haha, good job!
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Old 04-06-17, 02:31 PM   #15
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LOL, it took me three days, but not too much work. First day I picked the wheel appart, cleaned and polished the parts. The next day I assembled it, and spent a bit of time the third day getting it further straighter and more even. It's firm and ridable now, and today was day 5 on the bike :- )

This is an easy way about it, however, the project of a fixup bike is fun and we learn a lot along the way (I have to admit I haven't found away around cottered cranks yet, they can be a terrible struggle). I can almost guarantee you once you have spent hours on this old bikes, other similar type bikes will come your way with out much effort.

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Old 04-07-17, 10:56 AM   #16
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... I'll keep looking for others as well, until I've got a clue about the total cost of welding and so forth.
If you found someone willing to repair that hinge I'd be leery. First off I wouldn't trust brazing or building up a weld on a broken hinge like that with such deep rust... it's like attempting to sew a necrotic toe back onto your foot. So IMHO your best option is to cut the old hinge off and weld a good one in its place but I think the cost of that kind of work would be more than you're willing to pay.
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Old 04-08-17, 03:42 AM   #17
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If you found someone willing to repair that hinge I'd be leery. First off I wouldn't trust brazing or building up a weld on a broken hinge like that with such deep rust... it's like attempting to sew a necrotic toe back onto your foot. So IMHO your best option is to cut the old hinge off and weld a good one in its place but I think the cost of that kind of work would be more than you're willing to pay.
Thanks for your thoughts. I'll bring that kind of information when I go to the local welder next week.
He said it would all and all cost about 60 bucks per hour of work, and he would probably need an hour. But maybe some more if I ask him to cut the old hinge off and create a new one.
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Old 04-08-17, 05:16 AM   #18
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I would keep looking for one in better condition. Don't be too eager to fix the 1st one you find - there'll be others. Keep looking.
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Old 04-08-17, 06:16 AM   #19
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What I do is I replace such wheels with good wheels from a childrens bike. The 20" childrens bikes is not worn at all and you get nice alu rims, 3 speed shimano hub and maybe a shifter.

If you need a folder for cheap I`d go for a used Biltema folder. Peopel tend to buy them and not use them and then sell them at half price. Some of them has got a short wheelbase- stay away from them (unless you are short).

The bike in your pictures also have a short wheelbase, I`d stay away from it for that reason (plus the hinge).

A lot of Scandinavian small bikes was detatchable but soma also folders and I think you can find a better one than this one. I fear this bike has been trough something that could have destroyed bearrings and bent other parts as well.

For some time I had a Nexus7 on one of he old detatchable ones with the shifter mounted on the seattube. Now I use a cable splitter so the shifter is on the bar so I can split the bike in two even with the 7 speed hub.

Edit:
If you use a two legged kickstand on this bike the rear part can stand on its own when you take it apart. Then two velcro straps to connect the two parts together.

https://www.blocket.se/stockholm/Dam....htm?ca=11&w=1

This bike is much stronger and has got a much longer wheelbase. One or two gears but uou can modify it to take more. Depends if you want to keep it as is or modify to make it into a more practical bike. These seats is the best seats ever made but also the heavyest . If you want to carry these heavy old bikes up stairs or similar it is good that you can split them in two and carry each part separately.

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Old 04-08-17, 07:54 AM   #20
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My sister had a DBS like the red bike badmother links too (I actully looks like a DBS Kombi). The hub brakes front and rear made it very durable, very few parts that needed replacing, but a bit of maintanance. It likely just needs cleaning, greasing and tightenting of parts. The rims are aluminium, very simple single wall, but they tend to last decades on these bikes because of the hub brakes. The hubs where usually standard Sachs hub, often a Duomatic rear hub.
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Old 04-11-17, 08:40 AM   #21
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I've now come across a big sale at a place that collects massive amounts of parts from bankrupt companies. Here I can get new 406 wheels both front and rear for about 30 bucks.

I also found a shop that sells an old 406 rear wheel with a two geared duomatic, but that sells for 70 bucks, shipping of approx 10-20 bucks excluded.

All wheels are reconditioned.

So now I'm asking myself, and you guys, is the duomatic rear wheel worth about 80 bucks?? And then get a cheap front wheel.

Thanks for the input!
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Old 04-11-17, 09:01 AM   #22
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If you are determined to keep this bike your priority has to be getting the frame repaired, get that costed out and done to a satisfactory standard before you start spending significant amounts of cash on wheels, etc. There will always be bargains in used gear later on, but right now it could be money wasted.

When you say "bucks" do you mean Swedish krona ?
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Old 04-11-17, 09:18 AM   #23
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To make it clear, I'm only window shopping at the moment. Until they have taken a look at the busted frame I'm not sure about putting an effort in saving this bike.
But the question remains, is the duomatic wheel worth that much?

And no, I converted krona to dollars, "bucks", to save you the hassle.

During the past week I've found another abandoned MCB which frame looks to be intact. Also found a Monark with only a punctured rear wheel. They've both been standing locked up for quite some time.

I'm going to report these to the police in order for them to determine that they are indeed abandoned. In that case I'm actually allowed to take the bikes.

Thanks!
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Old 04-11-17, 02:05 PM   #24
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I have an old wheel whith a Duomoatic hub. I picked it off a bike with very rusty chrome parts and missing front wheel. It was on it's way to the dump but when I noticed the duomatic hub I took the rear wheel. The chromed outer shell has a few rust spots. The brake arm that's fastened to the frame is bent, but I have kept it. It turns and shifts, but I don't know if it's usable yet.

The new duomatic hubs, or a NOS duomatic is worth 80 US dollars. I'm not sure what used hubs go for, but I have to pay $50 to get a gear hub regreased (and it's hardly cleaned at all then). If they are nice looking and chrome is not pitted or flaking I would say they are worth it. The oldest type Duomatic with the oil cap is rather sought after. Vintage and used parts are hard to value, sometimes they turn up for no cost at all, others ask a lot for something that's in very poor condition. As a point of referance, a brand new Sturmey Archer kick shift hub costs around 68-80 (exluding p&p), but I'm not sure of the quality. For the vintage stuff, the old Duomatic Sachs hubs had the best reputation by far.

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Old 04-12-17, 07:55 AM   #25
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Okay that sounds fair. I've researched some about the abandoned Monark I found a couple of days ago. Don't know if it's a duomatic, but it's a Monark MCB Automatic if that gives you any information. According to some sites and others on the market they are told to be 2-geared. The bike itself doesn't look to good, and I want a folding bike not a take-apart. But I'm reconsidering using it for spare parts, particularly the hub.
https://digitaltmuseum.se/0210264681...Monark%22&i=17

I've now been to the welder and he could probably make it look and work OK, but regarding the reinforcement he told me that the welding usually get weaker than the original build.

Therefore I'll probably try to get the abandoned bikes and at the same time keep looking for some second hand ones on sale sites.

Thanks again for all your input!
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