sunburst Since you're in the Bay Area, I have a Dahon Curl collecting dust in my garage. You're welcome to check it out. (East Bay, Richmond)

Rare bird! You must have the 4 speed IGH with discs? I wonder what the gear range is? (% range, or gear inches)

The Curl derailleur 9 (with other advances too) seems to have been vaporware in the USA, non-existent and non-priced though advertised on Dahon USA's website.

There were before the 4s IGH, 7s and 8s IGH Curl.

I never saw the Curl D9 available anywhere online, I think it was never commercialized. Note that all components on the published pictures of the Curl D9 were Dahon branded, so probably low end/low quality..

This poster listed bikes as Dahon Curl i8.

I have the i8... range isn't too bad.

Those are helpful numbers, thx. I have been reading specs and trying to get a feel for who (Citizen, Zizzo, Dahon, etc) is shipping a reasonable range. Zizzo Liberte and Dahon MU8 have won the contest so far, and Brompton M6L, but I'm not leaning in that direction anymore due to price. There's a nice used MU8 on FB that is the frontrunner currently. I should add that I'm only researching folders I see used on FB.

Someone suggested I try to fit my BF NWT into my trunk. Good suggestion, but when I went out to fold it, it reminded me why I never considered that an option. Mine is one of the first years, 1991, I think, and that damned thing (as good as it is!) does not fold well. I just missed two late-model used ones that were sold way below market, that might have been big improvements. I don't really follow this market so that's a guess.

So, I'm 70 and the low gear is way more important than the high, so I might go for a smaller chainring. The MU8 is 32-91", so I think I could shift it all lower and be OK with it. The Citizen Gotham only has a high of 64" for example. The Tern A7 has 72". Obviously, those bikes are just for putting around. There's been a lot of discussion back and forth, so I want to remind people, I'm not going to tour with this. Never, ever. I've got two touring bikes.

On a different but similar thread, a post about Brompton, and my response below:

That's 400% gearing, which is adequate IMO. Unless the user needs that racer high, I'd put a much smaller 35T chainring on it to achieve 21-85 gear inches, which I think is a more useful range for places with hills. Fit a 50/34 2X, and you have the best of both worlds, 21-114 gear inch range.

Other thread:
https://www.bikeforums.net/folding-b...lots-gear.html

The search is over. Picked up a Dahon yesterday and had a 2 hour ride over on the coast. This is essentially a MU8, but it came to Calif via London where they drop the 8. Low mileage, rarely used.
I found it very capable over varied terrain and elevations. It coincidentally has the same Marathon Racer that my BF has, and I've taken that on hardpack before so didn't hesitate.

Gearing: 52T chainring, 12-32 cassette, 30-81". It's not going to handle every SF hill (especially from the bay to the south entrance of the famous GG bridge, where I will be walking!), but not a bad compromise range. It's not as surefooted as the BF in descents, especially rough ones, but the one way it vastly outshines my BF NWT is folding, and that was my #1 goal.

btw, I threw the chain twice yesterday (outboard direction), shifting in the middle of the cassette (you can see tissue in the chain). It has a chain guide on the seat tube side. Anyone have a part they like that protects both directions?

https://cimg7.ibsrv.net/gimg/bikefor...3bfb48d907.jpg



https://cimg8.ibsrv.net/gimg/bikefor...5d68964884.jpg

https://cimg9.ibsrv.net/gimg/bikefor...7a1bcc2e30.jpg

(above) Congrats on the purchase! Interesting it has a 12 high, most 20" folders use 11 high which is actually used, unless it has a freewheel and not freehub. Crank: Most folders put the 1X chainring on the inside of the 2X crank, and have a circular chainguard on the outside to keep the chain in place and protect the chainring when folded, and a chain guide around the seat tube to keep the chain on inside, but you might need to change the BB spindle length to get best chainline. I lost both when I converted to 2X gearing, which occasionally drops the chain to the outside when upshifting chainrings if on an outer cog, and to the inside when downshifting chainrings if on an inner cog, however just reverse-shifting the front derailleur instantly puts the chain back on without any messy fingers or stopping.

Very weird that frame is designed for a separate replaceable derailleur hanger, yet they extended the dropout down and forward to take the RD directly.

Excellent - best of luck with it!

If you want lower gears for climbing, it looks like the spider of your crankarm will support much smaller chainrings, A 42T will probably get you in the low 20" gear range (that's a SWAG), a 39T even lower.

​​​Duragrouch alluded to, you might even be able to mount the new chainring inbound of the current one to help prevent the chain falling to the outside. It's hard to tell from the photos if the crankarm spider supports 2x.

Enjoy the ride!

Interesting, my (US, I assume) Mu came with an outer chain guard:

https://cimg4.ibsrv.net/gimg/bikefor...3bbb7e79af.jpg

That's what I need! But the Sugino crank spider is single ring only. Two previous responders said to put the chain ring on the inside, but there is NO inside! I've done this before on my Frankenbikes, either to solve a chainline problem or a spindle length problem. Is your outer chainguard super thin? I've already checked out the stack bolts to see if I have some wiggle room for a thin guard.

Yes, I checked the BCD on all the bikes I considered, and eliminated the ones that had either a fixed chainring or large BCD (rare). I may reduce the chainring, but would definitely have to find a 11T cassette (or can I just replace the smallest cog? I tried this with my son's 10-speed and we never could get it to shift well). Yesterday with the elevation changes I definitely needed my highest and lowest gears. Current gearing is a good compromise given the range.

This spider only supports one chainring. I noticed that when messing with the chain.
Another idea, I've got a few JIS cranks in my spares. One of them may be a solution.

Yes, very weird RD setup. They seem to use a proprietary(?) Dahon-labeled part also. Nothing I've ever seen before, but maybe common in Asia.

It is an 8-speed, so doesn't that automatically mean freehub? That's where I thought the cutoff was, while 7-speed could be either?
I will definitely be looking to replace the 12T with 11, if I can do it affordably (don't want to go crazy on a $200 bike!). If I have to buy a cassette to do that, will probably try find a 34T low as well, and hope the RD can handle it.

Yeah, I looked closer, there is no inner ledge for an inboard chainring. However if the back face is machined smooth, a chainring would probably hold fine and just be stud-piloted instead of shoulder-piloted.

If your freehub body has a small shoulder on the splines like the one on the left below, you can mount an 11T cog. If not (like the one on the right), no 11T:

https://cimg5.ibsrv.net/gimg/bikefor...92d1b1fbba.jpg

Cranks these days are cheap for decent quality. I replaced mine with a 2-piece hollow spindle one for $60 including crank, chainrings, and bearings. I used 5x110 BCD which can go as small as 34T ring either inside or outside. I use 50/34 and the rings have small holes to mount a chainguard, but none came with the crank. I can't tell if your chainrings have same holes, or those are lift pins. The chainline on mine is 43.5mm, assuming to the center of both rings, so just an inner ring would technically be a narrower chainline.

You can mount any standard rear derailler there, you are not stuck with Dahon parts. MY bike had NO hanger aft of the axle, just a mount way forward, so I needed a claw-mount RD or a claw mount to mount a standard RD:

https://cimg6.ibsrv.net/gimg/bikefor...c8747a16b0.jpg
https://cimg7.ibsrv.net/gimg/bikefor...9a11221914.jpg
https://cimg8.ibsrv.net/gimg/bikefor...988ea8cb25.jpg

You will NOT regret putting wider gearing on that bike, either with a wider-geared cassette cluster, or 2X crank, or both. I waited for years to do the above conversion, best thing I ever did. But others on here have done same with just 1X gearing at the cassette, and that is easier.

You may have only spent $200 on the bike, but it's worth more, and the gearing upgrade is not that expensive, and worth it. Then, you have the equivalent of a $1000+ folder, easy.

thx for all the pix and details, you have really mapped out an upgrade path for me!

I am accustomed to the claw-hanger RD approach, as I mostly work on vintage. I even have that same RD in my spares. Two, irrc.
I also have a vintage crank, 110 BCD, with 165mm arms that's I've been eager to put into service as a 50/34 compact, but have had zero need with my current bikes. Would probably just need a longer BB spindle and a FD. Btw, didn't you have problems mounting that FD? My seat tube is 40mm!!! So, you find a 50 front and 11 rear high enough? My cassette says hyperglide so hopefully I've got the "C" body. I would have checked for the 11T fit already if a friend didn't have my lockring tool.

You are absolutely right about upgrading the gearing. I went out today and the bike feels surprisingly good. With a wider range I can see it replacing my BF (and I do need to thin the herd!).
and btw, I was able to shift without dropping the chain if I only dialed in one cog at a time. But a chainguard would be nice to have anyway, so will be on the lookout. My chainring does have holes, not pins.

50x11 on 20"/406x1.75" is plenty high for me, 85 gear inches, I can pedal down mild descents, and steeper down I can coast.

Yes, FD mount is tricky. I just detailed on a different thread perhaps a week ago. Let me try to find that.... ah, here it is:

If you go with a folder and want to put on a 2X crankset, here are the challenges, not huge, just be aware:
- You'll need a front derailleur adapter, UNLESS your frame already has a welded ("braze-on") FD bracket/hanger for a road style FD, if so, the following *does not apply*, everything is a LOT easier! If no welded bracket, you need an FD adapter, because no one makes a clamp-style FD in that large a seat tube diameter. If Dahon steel frame or clone, probably 40mm seat tube diameter. If Dahon or Tern aluminum frame or clone, probably 41mm seat tube diameter (because both use a 33.9mm seatpost, and the aluminum needs a touch thicker wall seat tube for strength). My 40mm adapter worked well, sort of: The fore-aft position of the derailleur was perfect, the adapter mounted the FD generally forward, and had sliding adjustment for that, HOWEVER, the large seat tube diameter, plus thickness of the FD adapter, combined with an overly large top inner lip on the FD cage, prevented the FD from going in far enough for the 2X inner chainring (and totally out of the question for a 3X crank). Spacing the crank out 4mm caused chain drops, the chainline needs to be perfect (see below). The solution was to grind off that top inner lip on the FD, only in the area of interference, which was small and well forward on the inner cage, FD worked perfect. 41mm adapters for aluminum frame were different in mounting the derailleur much further aft, I believe these were designed for the different frame configuration of the Dahon Mu which had rear monostays; If your frame is a traditional rear triangle like mine, that config may not be optimum. I'll try to post pics on this.
- Check chainline for the cassette, i.e., dimension from the centerline of the rear dropouts/hub Outer Locknut Distance (OLD) to the centerline of the cassette. 2X crankset must match cassette chainline. My 7-speed cassette on 130mm dropouts is 43.5mm I think, because the 2X crank I bought that specifies 43.5mm chainline works perfect; As mentioned above, spacing the crank out even a little caused chain drops, but once set up as designed, worked perfect.
- My FD adapter fit Microshift 3X 9-speed FD fine (I originally bought to fit 3X, but liked because of long cage, so chain never drags on small/small combo). However, spring on that is ridiculously strong, could not shift with gripshift. Changed to Microshift trigger shifter, broke after 1 year, replaced with Shimano trigger, durable, but still need to push with right thumb straight for upshifts, cannot sweep with left thumb, force too high. Shimano front derailleur with lighter spring, linkage sticks forward enough that it won't mount straight onto 40mm adapter (first pic below). (Microshift is cantilever linkage, Shimano linkage is double-shear, more durable, but larger linkage.) This issue still unresolved.

Those above are the big challenges, but not insurmountable. While upgrading the crank to 2X, I also tried the "2-piece hollow-spindle" crankset with "ISO External" bearings (most common external standard), i.e., a clone of Shimano Hollowtech 2; LOVE IT, LOVE IT, LOVE IT! Main reason: As bearings wear so slight slack in bearings, I can simply loosen left crank arm, retorque spindle cap to restore bearing preload, tighten left arm, takes 5 minutes. Maintaining preload is critical for improved bearing life; With taper spindle cartridges, once begins to loosen, unable to retighten, so shorter life. Crank is also lighter, and can be removed at home or in the field without a "crank tool". But you will need to buy a special wrench for the external bearings; I bought a 4-way wrench so can fit that many different bearing styles. If you have a bike shop do the conversion, they will have the correct wrench. I also was able to find a "road" crankset so has a "low Q-factor", the pedals closer together laterally than a "mountain" crank. And, in 5x110mm spider which I prefer over 4 arm spiders, however 110mm means smallest chainring is 34T, no smaller; If you need smaller, the inner chainring must be on a smaller BCD.

Everything else is easy, mounting the left shifter, running the cable to the front derailleur, all same as any other bike. Oh and my front derailleur is typical "bottom pull", so I run the cable under the bottom bracket shell and then up to the FD adapter.

Any questions, feel free to ask.

I'll look now for pics of those FD adapters. Got'em:

Steel frame 40mm adapter; Note forward mount and fore-aft slider:
https://cimg8.ibsrv.net/gimg/bikefor...9b0263d47a.jpg

Aluminum frame 41mm adapter; Note more rearward mount and fore-aft slider:
https://cimg3.ibsrv.net/gimg/bikefor...c4c8cb8c14.jpg

Newer style adapter; Note forward mount and fore-aft adjustment. Vertical mount is held in place with one bolt, I've heard this is not as strong/durable as above designs, however there *might* (don't know) be less interference with the FD cage:

https://cimg7.ibsrv.net/gimg/bikefor...b6853a5d23.jpg

Is yours different, maybe it doesn't have the quick-releases at the fold points?

This guy admittedly works for the company and is very good at it, but he folds and unfolds it in 31 seconds. The only janky thing I see is that the stem and bar are kind of flopping around loose when it's broken down.

No offense intended, but maybe your technique needs some attention?

haha, he makes it look easy. Not my experience! I used the same approach. But I may give it another try.
If it works, it's a little late, since I've got the Dahon already (5 lbs lighter!). And I've got a too-many-bikes-problem anyway. I'm determined to (try to) sell at least 4 this summer, even more if I can get them road worthy.

Mine is similar, although it's 18 years older and the frame design is a bit different. It does have the quick release points.

very impressed with the effort you put into this and what you achieved. Within the last year I fixed some tricky problems on two old bikes that made me feel like a real mechanic for the first time (and this is after having done 100+ bikes), but I'm not in your league! Finding parts like this is not trivial either. Thx for the detail.

I'm guessing the tissue is from putting the chain back? The technique I teach customers is to take two leaves,or pieces of paper(tear one in half),or two sticks(break one in half). Use the first leaf/paper/stick to push the derailleur forward to slack the chain,then use the second to put the chain back on the ring. Keeps your hands clean.

Those small holes around the edge of your chainring should be for a guard. Also,inspect the back(left) side of the ring. Are there any ramps/pins? If so,that's not a 1x chainring,that could also be an issue.

Thanks for the good words, appreciated.

I was going to detail the whole conversion in a treatise on here, until I discovered the folding bike group, and found there are others here way ahead of me in knowledge. On mine, I got a bit lucky:
- The FD adapter (top one shown for 40mm steel frame) I got from a well-known online folder dealer who is now retired. I had the steel frame, chose that one. He also stocked the 2nd one shown for aluminum frames, but I never could figure why it had the mount further aft, until this past year realising that was probably due to the Mu frame style; I have another bike that is the aluminum Vitesse frame with same frame configuration as the steel frame and Dahon Mariners, so has a 41mm seat tube, but that Mu adapter may not work well. I bought the 40mm one many years before finally doing the conversion, and fortunately it worked out, but it was definitely NOT plug-and-play.
- I chose the Microshift 3x9 FD based on price, and was lucky that at least fits the adaptor without skewing. But I did have to take a grinder to the cage lip. To reduce shift force, I'd like to fit a Shimano road FD but the linkage on those interferes. What I *really* want is to fit a Shimano road (10?) FD that has both a softer spring AND a longer arm so different shift ratio, and use a gripshift to shift 1-3 for the single upshift, but I don't know yet if the ratios match, but also the linkage on that FD doesn't allow it to sit straight on the adapter, I need a "road spacer" for it to fit just a skosh aft.

I've expressed great pleasure upon seeing on here, folder frames with a FD bracket, and others have said, what's the big surprise, this is common, this is the 21st century! On FnHon frames (not available yet in USA), yes, but Dahon and Tern frames, no, so still need to dig up FD adapters, and yes, they are hard to find. The early promo for the Dahon Launch D8 showed it having a FD bracket, but at production, that was gone, so typical, saving a few cents on a $1000 bike.

I'm very familiar with the technique you describe. Been cycling for 50+ years:)

The chainring has no ramps or pins on the reverse side. The five holes are ~4.2" (~106mm) apart. They are not threaded however, so I figured they weren't for a chain guard, yes/no? I looked for chain guards but couldn't see any that had the mounting holes spec'd. Would those holes be expressed in BCD? How to translate my measurement to BCD? and would a chainguard even be spec'd in BCD? The chainring bolts are 110 BCD.

Surprised I didn't notice during my initial 2-hour ride, but the brakes are reversed, with the left lever controlling the back brake. Is this how they do things in England!?
In my motorcycle safety class, the instructor said (some) motorcyclists crash when/if they take up mountain biking (right lever is front brake on a moto).
I swapped them yesterday. Easy enough, and didn't have to cut new cables.

Also, I discovered I do not throw the chain if I upshift one cog at a time. Still, I ordered a $4 chain guide from Temu. Hoping to adapt this to the 41mm seat tube.
I was thinking if I decide to lower my gears via the chainring, I would get a narrow/wide chainring. I assume that would be a big help, yes?
I run a 1x6 and 1x7 setup on two other bikes without this problem. Although my 1x7 (rigid fork mtn bike) used to throw the chain until I noticed the chainring was bent. No problem since I straightened it.

Some guards mount to the spider,some screw into the ring,some have screws that go through the ring and into the guard(so the chainring isn't threaded). They also have nothing to do with BCD,but with the specific ring they're intended for(tooth count,manufacturer). I tried looking at Sugino's Japanese site and didn't see anything. I saw some random listings,you might want to try searching by the ring to see what comes up.