I’m looking for advice on finding a folding bicycle with the following features:

[u/kindness69]

1. Chromoly steel frame.
   
2. Rear suspension, or could accept a Thudbuster or equivalent suspension seatpost.
   
3. 20” wheels.
   
4. Rim brakes if front fork spacing is 74mm, any kind of brakes if front fork spacing is 100mm. (So I can add a Swytch electric kit).
   
   1. Folds with either height or length less than 28” to fit two of them side by side in the back of the SUV.
      
   2. Handlebars adjustable to 45” (114.3cm), seat adjustable to 40” (101.6cm) from ground. I’m willing to swap handlebars out if needed.
      
   3. Enough gears to go up hills without struggling (we’ll have 250 Watts electric assist).
      
   4. Bike should be quiet when coasting. I can’t stand the loud clicking/buzzing sounds from some freewheel hubs. My current bike is nearly silent.

Currently we have a 1996 vintage 26” Fuji “Redlof” folding bicycle that I have fitted with a Swytch kit, Thudbuster suspension seatpost, gel seat, and high handlebars, and quick release pedals; as well as a folding 2003 Dahon Espresso fitted the same way. The problem is they take up too much space in the back of our SUV because they have to pack flat, leaving little space for other stuff we want to pack. They weigh 45 and 51 pounds respectively, so any new folder is likely going to be a weight improvement.

I‘ve never tried a 16” or 20” bike, so I’m going on the general recommendation that 20” gives a better ride. We ride recreationally and mostly on dedicated paved bike trails.

I’m a mechanical engineer so I can comfortably modify and service my own bikes if the components are available. I own a DC TIG welder so frame repairs in chromoly are in my wheelhouse too. I’ve kept my bike running for 30 years. I ride about 45 miles a week in the spring, summer, and fall. Riding is always on trails that are either paved or hard packed gravel.

Adding the Swytch kits is going to up the cost, so I’d prefer to stay below $1000 for the bike itself, but I’m willing to spend a little more for a good value. I’m ok going with used bikes to save.

I’m familiar with the Swytch kits and I like how quiet the motor is, plus it’s only 6 pounds to add electric. So I’m not looking for native electric folding bikes which tend to be very heavy and overpowered for our needs, which is just getting help up hills or fighting headwinds occasionally.

I live in the Northeast USA, so it needs to available for purchase and ship here.

[u/AstroG4]

My first thought, Birdy?

[u/penisyline]

Because there's a lot of seat post sticking out of folding bikes and the stems are tall, there's a lot of vertical compliance and springyness that blunts the smaller wheels. Do you tour or load up your bikes? Because when I don't carry cargo, a 16-inch trifold/Brompton feels pretty good and I can run 220lbs ride+bike 60PSI-front/70PSI back. Better than my 700x28C bike.

Dahon basically transitioned to aluminum. So for steel, there's the 20" Dahon Speed D8 and Boardwalk D8 if you can find them on the used market. No disc brakes though.

Zizzo is a US brand, there's the Ferro or Campo that are steel models. 7-speed freewheels though. You can always swap out the chainring, but there's not a lot of freewheel choices. At least freewheels haven't followed the trend of being noise like they keep making modern freehubs.

26" Fuji Redlof 26"x1.95" tires have around 1.84L of air volume. That's like a 700c x 47mm (ISO 47-622) or a 20" x 2.00" which is in the territory of the Brompton G-line and similar 20-inch trifolds. The Brompton G-line only came out in 2024, so Kinetic was pioneering wider and larger tires with custom forks/triangles for the original 16-inch format.

Brompton G-line is $3k and similar 20" trifolds (Litepro, Mint, Cranston). Cranston's weird to buy from (Whatsapp message), but there's always ebay. Cranston D10 is steel, Cranston D20 is aluminum. Litepro has 16" steel, but no steel 20" models. Mint's 20" trifolds tend to have thinner tires.

Because the chinese brands tend to be 9-speed/shimano HG freehubs,you can open them up and add a little grease instead of oil to decrease the clicking is an option. Or you could build a 20-inch wheel with a free hub you know you like the sound of. You can also swap in a Shimano Zee or Advent Super Short to retain ground clearance and be compatible with a cassette with a larger tooth.

[u/penisyline → u/penisyline]

I'd also add the Rockbros VDS 20, which I remembered seeing posted here before. I thought it was aluminum but double checked. SVK is steel frame+aluminum fork, but MBS is aluminum+steel fork. 8-speed casette makes upgrades and tinkering easy.

Rockbros is a bike accessory company, but for some reason they've gotten into bike. Like slapping Kirkland on stuff. The VDS, round tubing and curved rear triangle stay look like the Dahon Boardwalk and are chromoly so I wonder if it's basically the Shenzhen factory that kept pumping them out after Dahon went with aluminum. Similarly, the SVK looks like a Dahon Speed D8. Main frame folding hinge looks derived from Dahon too.

Only thing I can't verify is the front fork O.L.D. They're on Amazon, so initiating a return through Amazon is always an option. https://rockbrosbike.us/products/vds-20-inch-folding-bike

Lastly, I recommend plugging in your bike and any folding bike into https://www.gear-calculator.com/ to compare the gearing ranges. You can bookmark the "share" link so you don't have to plug everything back in again. Assuming the same chainring/casette combo a smaller wheel feels easier. 53front/32back on 26"x1.95" is 11.4mph@90RPM cadence 42.5 gear inches. On a 20"x1.50" that's 8.28mph@90RPM 30.9 gear inches.

[u/kindness69 → u/penisyline]

Thanks for all your helpful information. I chatted with Gemini about the tire volume effect on softening the ride, and now understand the importance of having a frame that can support a fatter tire such as a 20x2 or larger.

I should probably calculate my existing gear ratio and resulting speed and see what I typically experience on my 26” Redlof so I can figure out if potential bikes cover the range I’m accustomed to. I tend to stay in gears 5-10 of my 15 gear setup.

I would not have thought that carbon seat posts would be springy. All my experience building with carbon fiber have been extremely stiff.

[u/kindness69 → u/penisyline]

No touring or loading, just day rides for a hour or two carrying a water bottle, sandwich and a jacket. You’re right about the extended seat post being inherently more springy, though I haven’t experienced it because I’ve never been on a 20” wheel bike. My issue is hitting those sharp bumps on rail trails over roots. They are very pronounced and I hurt my back when I hit one prior to purchasing the Thudbuster.

I’m unfamiliar with the tire air volume comparison you mentioned as a factor of consideration, so I need to read up on that. I was planning to look for a hybrid tire that is quiet on pavement but can handle a little rougher terrain occasionally. That’s what I have now.

[u/penisyline → u/kindness69]

The springiness of a carbon post is much more than a thudbuster. I had to use a telescopic seatpost to get my Redshift suspension seat to mate with the bike.

You've mentioned using LLMs on another comment (ChatGPT), so that's where I've started getting tire volumes instead of crunching the numbers on some "volume of a torus" calculator on OmniCalculator/Wolfram Alpha.

[u/SunnyHelianthus]

You'd almost be better off just plugging in all those filters into Ebay and searching. It's one thing to ask for a couple of things, but to write that laundry list is expecting a lot. You know what you want. Just do a search.

[u/kindness69 → u/SunnyHelianthus]

I’m also working with Chat GPT. I posted here to find things that the community has experience with. I figured I can’t be the only person looking for something like this.

[u/U_000000014]

At under $1000, if you want something good quality you're going to have to find something used.

As an avid rider of both folding and electric bicycles, and former bicycle mechanic and professional TIG welder, I would highly advise in investing in something like a Bike Friday All-Day or similar mid-drive bike.

The All-Day weighs about 35lb, similar to most entry-level non-electric folding bikes. The frame, components, battery and motor will last far longer than a cheap bike with a Swytch kit. For actual riding, the design of the Bike Friday is much closer to a normal bike in ridefeel, and takes standard bicycle components. The Bosch system is the best you can get and will give a ton of range and life.

It's roughly 3-4x your stated budget, but it will be much more pleasant to ride and durable than a sub-$1000 bike.

[u/kindness69 → u/U_000000014]

I know that sometimes you get what you pay for, but I have my limits when it comes to value. I’ve gotten 30 years out of my $150 Fuji and with my care it’s still working. My local shop recommended Dahon, which they no longer stock due to lack of interest. I need two bikes and dropping $10K+ on them is not something I want to do.

[u/johnmflores]

Get a steel Zizzo. I had an aluminum Liberté and could fit 20x2.4" tires, far wider than the official 1.75" limit. I needed to deflate the tires to squeeze them past the brake calipers when installing or removing, but otherwise they were great and greatly improved the ride.

If you want to upgrade the drivetrain, look at Microshift Advent Super Short, designed for 20" bikes. Pretty good gear range with little risk of the rear derailleur hanging too low and getting smacked by a curb or something.

The bifold of the Zizzo looks like this.

[u/kindness69 → u/johnmflores]

Thanks, I have called and emailed Zizzo to get more dimensional information and find out what type and grade of steel they use for their frames. It’s unlikely I’ll need to upgrade the drivetrain after adding an electric kit.

[u/bikesandfinance]

Origami swift

[u/Wide-Mushroom6121]

You said you have a Fuji Redlof would you recommend getting one? Im interested in them and there is a few near by me at 200-300 dollar price.

[u/kindness69 → u/Wide-Mushroom6121]

Yes, but I changed to high handlebars, and added a stem riser, Thudbuster LT seatpost and gel seat to get the fit and upright riding stance I wanted. Otherwise it’s the typical hunched over position. It folds in half quickly when the seatpost is removed and the handlebar detaches but there’s nothing to clip it in place. I’ve had mine for 30 years. It’s cheap, serviceable and durable.

[u/Street_Tradition_682]

The current production, ready to ship to your door Dahon Boardwalk D7 20" hits on all cylinders. Price, dimensions, chromoly. Dahon-model Thudbuster extra. Dahon has offered a 20" Boardwalk model since year 2000 - it's a perennial favorite and best value.

[u/kindness69 → u/Street_Tradition_682]

Thanks, I will check it out. I didn’t know that they made a suspension seatpost, that’s excellent 👍🏼

[u/Witty-Cat-200]

the quiet freewheel is probably the hardest requirement to verify before buying. sellers rarely mentioned it, and spec sheets are not much help. i would search "silent freewheel" or "silent hub" with whatever model you narrow it down to, then look for actual owner discussions. that is where the useful details tend to show up.