Folding “gravel” bikes
 

So I figured I’d start a thread for people interested in folding bikes that can still be useful over various terrain: gravel, unpaved roads, rough surfaces, potholes, stairs, etc. basically 99% of Earth.

For riding comfortably over such terrain you really need wider, high volume and relatively low pressure tires. It also means you probably want a somewhat larger wheel size. Although a 50mm Big Apple on an ERTRO305 may get you through in a pinch, you próvido y want to do too many cobblestone miles on such a setup. Then again, anything larger that 24” is probably going to be too cumbersome for a truly practical folder. This puts the sweet spot at 20”.

I will share my own experience with my 20” FnHon storm, which I built up with 50mm Big Apples, Shimano Deore hydraulic disc brakes and a Shimano Alfine 11 IGH


https://cimg0.ibsrv.net/gimg/bikefor...499e0fcef.jpeg
My FnHon Storm on a Tokyo bridge, next to my son’s 20” Takachia trifold

Pros:
-Very nice ride, agile, comfortable, great climbing and cornering.
-Able to fit front and rear racks, full sized panniers and water bottle/gear holder, able to fold without removing any of these.
-Flawlessly smooth shifting with the maintenance free Alfine11, even able to jump any number of geared while stopped or riding.
-Build in suspension with the BA tires, good puncture protection (1k kms with no flats so far), good traction in wet and light gravel.
-Not expensive. Frame set was under $200USD shipped. Entire build for under $800USD with premium components.

Cons:
-Pretty large fold. Had to use the largest rinko bag I could find and was uncomfortable to carry as metal bits stick out at weird angles. It’s always just a bit too large for luggage compartments, sharing trunk space, squeezing through escalators, etc. The fold is also larger than airline reg, although I’ve taken it on 9 flights so far without having to pay extra fees (no disassembly, packed in rinko bag with cardboard and shrink wrap). It still is cumbersome to carry and gets thrown around more by baggage handlers due to size.
-Doesn’t stay closed when folded. This can be remedied can be remedied with a bungee or piece or inner tube to strap it together, but adds another step in the folding/unfolding process.
-Availability. I’ve only ground this for sale as a frame set on AliExpress, and it is an older gen version. Don’t know where else it can be purchased without sourcing direct from China.


While I found this setup most practical and enjoyable for touting and daily riding, the large and cumbersome fold of the Dahon-based design was the biggest challenge with this bike.

A folder with all the pros of the Storm but with a quicker, more compact, airline friendly fold would be my dream bike.

I welcome any and all contributions and testimonials on alternative wide-tire folding bikes! Hopefully this thread brings insight or even some innovations to this neglected folding bike sector!

To go on cobblestones and on trails, on top of wide tires, a good solution is to add a suspension to the wide tires.

The Birdy 3 with 50x355mm and full front+rear suspension is an excellent solution and for touring with its rear folding rack, front rack and Brompton block, it accepts full size rear pannier + front low rider pannier + a Brompton bag.

The folded size, 72x61x33cm is also smaller than an FnHon Storm.

This is my latest iteration of my Tern Link D8.
Changes include:
Dropped bars;
MKS detachable pedals;
Microshift Advent groupset with 11-46T cassette;
Litepro 47T chainset;
Travel Agents to ensure vee-brake compatibility with the drop-bar shifters;
50mm Big Apple tyres;
Blackburn rear rack;
Tern front luggage truss and low rider; and
Brooks B67 saddle.

The aim was to build something that could be stored easily in an apartment and also could be transported by bike rackless buses across the city to its rural fringe for riding on the mainly gravel tracks and quieter roads there.

Derailleur ground clearance is okay for gravel paths and roads but isn’t really enough for off road. I’m undecided between the use of brifters and travel agents versus Tektro R520 brake levers and bar end shifters with a vee-braked frame, as the improved ease of shifting comes with a spongier braking experience.

Fortunately, AliExpress doesn’t sell the latest Fnhon Storm frame with the luggage mount on the headtube, so my wallet is safe for now from the disc braked, dropped bar, IGH oversized BMX that I’ll inevitably build…

https://cimg1.ibsrv.net/gimg/bikefor...c4c42224b.jpeg
Don’t worry Ron, since the photo was taken I’ve trimmed back the cables somewhat - the Tern’s requirement to turn the handlepost 180 degrees before folding combined with a luggage truss requires a degree of slack though.

Great idea for a thread! Here's my contribution:

Bike-Friday All-Packa on a 5-day/200km trip from Malaga, Spain to Utrera, Spain with >5,000 m vertical along backroads and dirt and gravel farm roads, including 20%+ grades up into Andalucia's pueblas blancas (white villages). We flew with the bikes in suitcases as checked-in luggage and stayed in budget hotels.
https://cimg5.ibsrv.net/gimg/bikefor...44810b6d15.jpg


The All-Packa on a 7-day/330 mile/2,800' vertical ride along the Great Allegheny Passage (GAP) and Chesapeake & Ohio (C&O) trails. Transportation to start and from finish via Amtrak train with the unfolded bike checked in ($20). Rail trail style gravel. Camping most of the way.

https://cimg1.ibsrv.net/gimg/bikefor...41934a7499.jpg

All-Packa on 5-day/255 mile/10,000ft vertical from Rochester, NY to the Finger Lakes, and back. Travel to start and from finish via Amtrak train. Camping along the way. Mostly road, but significant portions on rail trails and gravel farm roads. Some well groomed, others deep, chunky, loose gravel, roots and rocks, and steep downhills and climbs.

https://cimg7.ibsrv.net/gimg/bikefor...46e336f5f6.jpg

Some of the pieces have been changed over the past year depending upon conditions and replacement of rear derailleur. Currently running Microshift Advent Super Short 11-38 9 speed on the rear Frankensteined to a 34/46 2x on the front. The rear mech is ostensibly for 1x drivetrains but 2x is working, and provides 16.7 - 78.1 gear inches (468%) range. The 16.7 is critical, as I seem drawn to 25%+ gradients. I've also managed to push 46x11 to over 24mph for short stretches, sometimes with the aid of a downsloping road and a tailwind.

When traveling via train, I put the panniers and fork bags in this Ikea bag/backpack. Makes carrying/folding/unfolding a lot easier. When riding, the bag is strapped to the rear rack and help control spray when it rains.
https://cimg1.ibsrv.net/gimg/bikefor...83373eaeda.jpg

This semi-fold is quick and often sufficient for rail travel. Bike sat on rear rear rack for 7hr train ride and didn't budge.

I've also ridden some singletrack with to see where it's limits are. It was slower than a mountain bike but fun.

PROS

1. It's handled everything that I've thrown at it.
2. 3-pack fork mounts, 4-pack mounts on top tube, 3-pack mount on underside of down tube, 3 pack mount on back of seat mast
3. Very agile on singletrack. Agility helps you pick your line.
4. Handles loaded touring great.
5. Main triangle/front-end has some give built into the design, helping to provide a smooth ride. But feels great when sprinting out of the saddle.
6. Easy to carry onto train when quick-folded
7. Handles 2.4" tires. 2024 model handles 2.8"
8. Packalope Bars have inner-mounted bar-ends that provides a very aerodynamic position. Pleasantly surprised that I can click off 18mph+ when so motivated.
9. Can fit into a check-in suitcase (officially ~2" larger than max 62" but that hasn't proven to be a problem yet). Very convenient vs. a 700c bike/large bike box when going to/from airport (the suitcases fit into the back of a sedan), especially when there's more than one bike.

CONS

1. Even with the Microshift Advent Super Short rear derailleur, clearance is still worse than a larger bike. I've already lost a rear derailleur to deep mud, but the steel derailleur hanger was easily bent back with proper tools. Field repair might be tougher.
2. Fold not as neat or compact as other folds
3. When quick folded, chain usually drops, and chainring/derailleur are the sharp end of the package.
4. If your trip is not a loop, dealing with the suitcase is an issue
5. Not cheap
6. Not the lightest. I assisted a fellow cyclist get their bike on the train; when I picked up their carbon front wheel, it nearly flew out of my hands!
7. Wheels spin faster than 700c, so best to get good, smooth hubs
8. When ridden back to back vs a touring bike like the Surly Long Haul Trucker, the All-Packa feels like a VW Golf while the Long Haul Trucker feels like a Lincoln Continental. In other words, it may be more fatiguing on longer trips.
9. Average speed 0.5-1.0mph slower than 700c
10. Terminal velocity seems slower than 700c
11. People ask me all the time what kind of battery range I get

I may experiment with an Alfine-11 or a Rohloff if I sell a kidney. I'm looking for a bike suitable for a round-the-world type of trip (including some multi-modal transit), and so far the All-Packa has been a pleasant surprise.

I put BMX tires on my Birdy, and I guess you can call it a folding gravel bike. A friend borrowed it for the long term, and installed the tires. He likes it, though I have yet to try it out.

A pink FnHon Storm frameset with front block is available for purchase here in case you want to build your lady a lovely Wide-terrain Folding (WTF) Tourer.

https://cimg0.ibsrv.net/gimg/bikefor...e369d944cb.jpg
$160, handle post included
​​​​
I'll add that those Shimano Deore M6100 hydraulic brakes in the OP are excellent, providing good stopping power and modulation. The best part is that a set of levers and calipers with hoses will set you back only $85. Add a pair of Shimano SLX RT66 rotors compatible with both resin and metal pads for an additional $30. I run them on my minivelo with an 180mm rotor in the front, and the easy, smooth yet staggering stopping power on tap is inebriating, addicting.

Nice job installing the fenders. I cringe when I see fenders installed that aren't uniformly spaced around the tires.

She likes the ride of the Storm, but after her 20” trifold she doesn’t want anything that folds bigger. I’m still working on getting the 18x2” tires on her Mint, it will happen - just have to source the correct spokes.

Never a bandwagoneer or trend follower, one who rode a fully rigid MTB on gravel and other gnarlier, far more technical terrains already in the 1990s, I don't fancy my ongoing Storm build a "gravel bike", but rather a Wide-terrain Folding (WTF) tourer. It's all built now with only the hydraulic brakes left to install. All in all, with not a single bum or proprietary part, about $650 to build.

https://cimg2.ibsrv.net/gimg/bikefor...11517867cd.jpg

https://cimg3.ibsrv.net/gimg/bikefor...56667c76b0.jpg

https://cimg4.ibsrv.net/gimg/bikefor...803db7af73.jpg

• 32-spoke, three-cross wheel set
• 2.30", 60tpi kevlar tires
• Shimano SLX RT66 180mm resin & metal compatible rotors front and back
• Shimano Deore M6100 hydraulic brakes with finned pads (TBI)
• 455% range, 19-84GI 1x drivetrain
• Eyelets for fenders and racks front & rear
• Front block on head tube

​​​

For slamming off-road, I think the Bike Friday All-Packa is best; The triangulated frame is based on the earlier Diamond Llama, which BF's website showed employees catching serious air off jumps riding it. They were marketing it as exactly what you are seeking, a serious off-road folder.

Other frames like bifolds, the mid hinge I think might be the achilles heel in terms of longevity off-road. However Dahon's Deltech and improvised versions like mine, triangulate the frame, and the bottom segment is in tension so can be cable-thin. The oblong main frame tube takes all the torsion, which does go through the hinge, but deltech tightens up the hinge a lot, so far it's staying a lot tighter under climbing standing over 18 months now I think. The Dahon Launch D8 with Deltech AND a greatly improved hinge design (real intermeshing jaws, versus just a pivot pin and overcenter clamp on their other bikes), I think might hold up well in off-road use, TBD.

Yeah...I mean, the Surly Long Haul Trucker has long, long had the reputation of being a ocean liner of a bike. Just look at the length of those chain stays at 46cm! Even compared ito a Bridge Club, it's a boat. Most all bikes folding or not will feel spritely and agile next to a LHT, a relic of sorts.

Indeed the All-Packa must ride pretty well in gravel use.

But it is very big folded.

Bike Friday change the folding on the new All-Day, the difference is obvious when you see both bikes folded in a car trunk (and nevertheless, the All-Day is still big folded):
https://cimg2.ibsrv.net/gimg/bikefor...8d85d32720.jpg
https://cimg4.ibsrv.net/gimg/bikefor...af3480de12.jpg

Im sure both are great bikes, but the fold on either is too cumbersome to make them interesting to me. I’m not so much in search of an off road folder, just one that can sport wide tires and can fly/commute easily.

Video of gravel biking with the Change Bike.
650b to take care of all the issues with rollover that smaller wheels have.
It starts to get big, but it can be pushed on one wheel when folded.
Furthermore, when one has loaded up the bike with more than a front and rear bag, its a chore to take down the bags to fold the bike anyway.
The bike has gone up trains, buses, van buses and of course cars.
A larger wheeled folding bike is a "bike first/ vehicular transport later" type of approach.
42mm tires are a good balance of speed on the road and handling off road.
A suntour /NCX suspension seatpost and a Meroca suspension stem takes care of all sorts of bumps for light trails.

https://cimg8.ibsrv.net/gimg/bikefor...220584a859.jpg
https://cimg4.ibsrv.net/gimg/bikefor...28295ba5ac.jpg
https://cimg6.ibsrv.net/gimg/bikefor...7441086242.jpg
https://cimg7.ibsrv.net/gimg/bikefor...32fbfa0ed7.jpg

For the type of family travel that you just did, the All-Packa would have been an extra hassle than what you rode. But it is doable. At the end of my recent trip, I had to

1. ride to the train station
2. put the panniers and fork bags into an Ikea bag/backpack
3. take the elevator down one level
4. carry the bike down another flight to the platform (an elevator was available but I was impatient and there were 4 other bikes waiting)
5. roll the bike onto the train
6. do a quick fold (10-20 seconds, rear triangle folds underneath main triangle, seat mast folds down, handlebar mast removed) and stowed it in the corner reserved for luggage. Coincidentally, other bikers on the trip had to remove their front wheels and hang their bikes on hooks, which took longer
7. relax on the train

And then when we arrived in New York City, I had to...

1. Unfold the bike (10 seconds)
2. Roll off the train
3. Carry up the stairs (I could have taken the elevator)
4. Leave Moynihan station
5. Rush the bike across the street to make sure I could catch the next train
6. Enter NY Penn Station
7. Take a set of escalators down one level
8. Roll through the station
9. Carry the bike down another set of narrow stairs
10. Roll onto the next train
11. Quick fold the bike (not required but it was a crowded train and I did not want to take up more space than necessary)
12. Take the train two stops.

And then there was another station with more stairs down and up and finally my home station, where I could unfold the bike on the platform, remount the panniers and bags, and ride down the accessibility ramp and ride home.

I could handle this because I was traveling solo and am fit enough to manage the carrying of the bike and an oversized backpack filled with gear. I cannot fathom doing this with a family of four!

The new Brompton G might have been better during the train part of the trip, but the Alfine-8 would not have worked out on the actual ride, where we were regularly going up 15%+ grades with loaded bikes. And my buddy, who I dubbed "Freight Train" likes chugging along flat roads at 18mph. He's in better shape than me too, so it took all I had just to sit his draft the first couple of days. I managed to take some pulls in the latter half of the trip, where the inner bar ends of the Packalope bars helped me achieve a pretty aero position and set a decent pace. I do not know yet if the Brommie G is as capable.

I do know that my Zizzo Liberte, even with its oversized 2.4" tires, would not have worked. Just not enough gearing, not enough carrying capacity, not enough speed, and simply not enough comfort for this trip. I've taken it one rides close to 30 miles, and it did the job, but I know that other bikes would have been better. It does make me wonder how much better I could make the Liberte, with better hubs, better gearing, better seat, more hand positions, etc... Hmmm....maybe a winter project...

At the end of the day, there is no single answer. We all have varying needs and requirements that changes from trip to trip even. Every gear choice we make is a compromise of competing factors. I do wish the All-Packa folded smaller and neater, but they clearly prioritized rideability, and that was key on the last trip.

I think that changing the rear frame folding axle position from behind the seatpost and bottom bracket as on the All-Packa to in front of the bottom bracket like on the All-Day could be a solution to make the bike fold smaller while not changing anything in its ride ability.

Then, I think that it would be possible to mount a folding stem similar to the one on many Tern on the All-Packa to make folding faster (if I understand well, all these Bike Friday have a ahead type of fork mounting).

Yes, on our last trip to Thailand/Japan we rode multiple airplanes, trains, buses and vans. the narrow tires on three of the bikes was not a major issue, but the one with the 2” BA’s was definitely the most comfy.

The real issue was carrying the folded bikes plus all our gear through train stations and airports, and also finding vans big enough to carry all of us.

The kids are just slightly too small to carry their bags plus their bikes, so my wife and I had to carry two bikes and a backpack each. This made getting onto trains and to airline counters the least enjoyable part of the trip, and was definitely a limiting factor in our mobility and route planning.

It would not be possible for one of us to carry two All-Packas folded in rinko bags.

The 20” trifolds are noticeably easier to carry and roll, and we could have gotten smaller rinko bags for them. The compact fold opens up worlds of globe-trotting possibilities. With 2”+ tires and capable disc brakes it would not be too hard to solve the luggage capacity issue, as people have been doing with Bromptons for decades.

As for 18mph, well… we were quite happy averaging 10 throughout our travels, but a low gearing - at least as low as 20gi - is a definite must have.

That derailleur is almost scraping the ground; have you had any issues with rock strikes?

@John Flores: amazed that the Super-short tensioner, stated capacity 27t, is handling 39t. Are all combinations viable?

For ground clearance on a 20" folder with 2x and 500% range, there's an exceptional option I learned about from a little essay by Grant Peterson on the Rivendell site: the Altus 310. Capacity 43t, with "Smart cage" system that shortens the arm, in part by using big tensioner pulleys - 13t & 15t. I replaced my old Tourney - the only other Smart Cage RD, I think (it's 13/13, capacity also 43t) & was delighted to gain a few more millimeters of clearance.

For slugging up steep hills, I figured an oval chainring would help - shortening the dead spot in the stroke that kills momentum - so I got an Absolute Black 26t, and it really works. They only come in narrow-wide for 64 BCD; I had to Dremel the shoulders off the wide teeth, but it's a tiny amount of material and doesn't take long. I don't think the oval matters much at higher speeds, but it substantially reduces the jerkiness at 4 mph.

This bike is not yet operational so no, no problems yet, but I have several years of experience (since 2018) with four other bikes that have seen quite a lot of action with similarly low RD, including long-distance tourung. I have faced no problems with them save for increased dirt deposition on the chain. The RD position in the picture is deliberately the worst case scenario. The RD will be higher on all other nine gears. Here's an 11-46T setup that sees daily action without incident.

https://cimg6.ibsrv.net/gimg/bikefor...7e6205dc92.jpg

Save for the triangle bag which is not very big, I am pretty certain you can mount, attach and carry everything that's on the Allpacka on a bi-fold like the Zizzo. Look at Reddleman's Tern, for example, with front and rear racks and with front block. With the rise of backpacking there's now a myriad ways available of mounting bags on bikes. The gearing and comfort issue too can be fixed, improved and dialed in on a bi-fold. There's nothing in a bi-fold preventing that.

https://cimg8.ibsrv.net/gimg/bikefor...abbb5fadad.jpg

How much do you reckon your ChangeBike build costs (sans bags, racks, etc), just the bike?

I avoid big/big and small/small for obvious reasons, but I've mistakenly shifted into big/big without consequence and small small works but the chain is a bit long for that combo and it rubs against itself by the lower jockey wheel.

The short chainstays of the Liberte require extreme rearward mounting of panniers, well aft of the rear wheel. This rearward weight bias would have deleterious effects when climbing steep hills. On the All-Packa already, I am thinking of loading up the front with more weight because the front end starts to get light when the incline exceeds 20%.

https://cimg8.ibsrv.net/gimg/bikefor...8b20da8b60.jpg

Additionally, the Zizzo has just one set of bottle cage mounts on the main tube. There are no other built-in mounts. I do have other means of attacking cage mounts in other locations on the bike but they won't be as secure as a built-in mount and another potential point of failure.

I've already added a front block, but it's a single arm; I don't think I would trust it on a gravel trail. I could try a two arm front block, as there's no other way to mount bags to the front as the forks do not have mounting points for a rack and they are tapered in such a way that any bracket that I may add may slide down from vibrations and work their way loose.

I think turning the Zizzo into an overnight rail trail camper carrying tent, sleeping bag/pad, and camp kitchen might be doable. Especially since I know that I can mount up to 2.4" tires. Beyond that though would be considerably more challenging, and Duragrouch made an excellent point about the off-road stress on the hinge; I might have to fashion my own Deltech cable. Years ago I used a FiberFix kevlar spoke to replace a broken spoke; it held for years. I wonder if it's long enough...

I can’t take the credit for it, they’re the standard installation out of the factory from Tern!

In terms of luggage capacity, I’ve not yet needed the low riders. However, in previous summers I’ve loaded it up for camping trips with 2x 27l rear panniers, a 23l saddlebag and a 5l bar bar bag on the front luggage truss. I now also have 2x 14l front panniers added to my Carradice collection for this coming summer’s trips. Yes, my Tern Link wants to be a Surly LHT when it grows up…