Fnhon DB11: Frame and Fork

The time has come to build a new bike! For the year 2019, the major project was the Bike Friday Haul-A-Day, which is a really versatile cargo bike that I use to bring my kid out for rides. In the year 2020, I will start with a new folding bike project to replace my Dahon MuEX.

Why the need or desire to change the Dahon MuEX? It has been a very good folding bike, which has been customized to be a lightweight, high specification folding bike that rides really well. However, after a ride in the rain, that changed.

With V-brakes, the ride in the rain caused the rims to become really dirty with the residue from the brake pads. This is unavoidable, as long as you are using rim brakes (V brakes or caliper brakes) in the rain. I was so annoyed as I spent more time cleaning up the bike than the actual duration of the ride itself.

This can be fixed by avoiding rim brakes, which will cause brake pads to literally disintegrate in the rain. The brakes don't work so well in the rain, plus they make a mess of the rims, the brakes and the frame. I want to eliminate all these by switching to disc brakes, which I am using happily on my other existing bikes, such as the Canyon Endurace road bike, Fabike C3 commuting bike, Bike Friday Haul-A-Day cargo bike and the Polygon Cozmic CX3.0 MTB. The remaining bikes that are still using rim brakes are the Dahon MuSP and the Dahon MuEX, which is the one that I want to replace.

Amazingly, it is hard to find a folding bike with disc brakes that has all the specifications that I want as listed below.

1) Compact fold for easy loading into car
This requirement eliminates those that folds awkwardly or takes too much trouble. Examples are the Birdy and IF Reach.

2) Disc brake mounts
The majority of folding bikes still use V-brakes, with a small minority that use caliper brakes and disc brakes.

3) Lightweight
There are a few Tern folding bikes (such as Verge P10, Verge X11) that use disc brakes, but they are relatively heavy given the high price. I want to minimize the weight increase compared to the Dahon MuEX (8.4 kg without pedals).

There is practically no folding bike from the mainstream folding bike manufacturers (Dahon, Tern, Pacific Cycles, Tyrell, Brompton) that fulfills all these requirements.

There was a folding bike from Java that I tried (Java Neo 2), but it has too many drawbacks to be good enough to replace the Dahon MuEX. There is also a Dahon Horize disc brake version, but I would be paying just for the frameset, as I will be replacing all of the components.

After much searching, I found that the only way to get a bike that fulfills all my requirements would be to build one from scratch, from a bare frameset. This would be similar to how I built up the Crius AEV20 folding bike previously. Actually, this is the case for most of the other bikes that I built, as there is no bike in stock condition that satisfies all my requirements.

Fnhon is obviously a play on the original Dahon brand name, but it does make some frames that Dahon itself does not have (or that I am not aware of). As shown here, I chose a Fnhon frame which has a curved design, similar to the original Dahon Vector or the current Tern Verge series. It is equipped with IS (International Standard) disc brake mounts on the frame and also fork. Other specifications like bottom bracket width, OLD (Over Locknut Distance), seat post diameter, headset type, etc are the standard Dahon specifications which I am very familiar with.

New Fnhon frame! I chose matte black as it is the least ugly of all the colour schemes.

The curvature of the frame looks nice, and I have always wanted to own such a bike, but the Dahon Vector or Tern Verge were too expensive for me back then.

White Fnhon logo, on the gloss black area of the frame. Looks pretty good actually. Can't say the same about the other colour schemes.

Previously, on the Crius AEV20 frame, I had an issue where the head tube was not round, causing the machined step for the headset cups to be offset. The result was that the headset cups could not be pressed in easily. How about the condition of this Fnhon frame?

Top area of the head tube has good circularity, as the internal step can be seen to be of equal size all round. Compare this to the Crius AEV20 frame seen in the other post.

However, the bottom side of the head tube is not so well made, as the internal step does not look equal. Later on, during installation, we shall see if it will give me trouble or not.

Frame hinge and lever, which is of the newer design, different from the Crius AEV20 frame. Isn't the tagline "Personal Mobility" from Dahon?

Lots of big aluminium welds visible. Not polished unlike the higher end Tern frames.

Big hinge clamp which looks quite seamless from the outside, as the adjustment is done internally.

The Fnhon frame comes with the front derailleur mount and also the outer casing stopper for the FD inner cable. Very useful if you want to run a front double drivetrain.

Main frame runs along the outside of the seat tube, instead of joining or ending at the seat tube. This looks better than either of the Dahon MuEX or Dahon MuSP frame designs.

Made of A6061-T6 for lower cost, ease of welding and good strength.

68 mm wide, threaded bottom bracket shell! There is some paint found on the outside edge of the bottom bracket shell, wonder if it will affect the alignment of the bottom bracket bearings.

The model name of this frame is Tornado. Doesn't say anything about the type of frame though.

IS mount for the rear brakes! An IS to PM (Post Mount) adapter is needed to mount the brake calipers.

The surface of the mount was not faced. Rather, these two unpainted areas are merely covered by stickers during the spray painting process. I wonder if these surfaces are flat or not, since paint can be seen at the edges.

A quick check of the dimensions (about 40 mm) show that this is the standard distance of the rear IS mount.

Standard specifications for the rear IS mount.

RD dropout will be fixed here, similar to other Dahon bikes.

This Fnhon frameset includes both the main frame and the front fork. Let's also take a look at the front fork in detail.

Fnhon front fork, in full matte black colour.

There is no serrated surface on the inside faces of the fork dropout, which is quite unusual. Normally there will be some serrations to increase the friction between the dropout and the front hub axle nuts.

Same condition on the mounting surface of the front brake calipers. Not properly faced, but just covered with a sticker during spray painting.

A distance of about 50 mm shows that the front brake mount follows the IS spec for disc brake front caliper mount.

International Standard spec for front disc brake caliper mounting.

From this, we can see that this Fnhon frame follows the standard specifications for the front and rear disc brake caliper mounting. The Bike Friday Haul-A-Day used a rear spec for the front fork mount, which gave me some problems previously.

Weight of frame only (excludes RD dropout, seatpost shim and seatpost clamp) is 2476 grams, slightly heavier than expected.

Weight of front fork is 433 grams.

Compression bolt for fitting the handlepost to the fork steerer tube is 47 grams.

Rear dropout weighs 20 grams.

Stock seatpost clamp and metal seatpost shim weighs 84 grams.

From the weight of the components, we can see that the frameset (frame + fork + essential hardware) weight is 3060 grams. This is not even including the handlepost which will weigh at least 500 grams.

Compare this to the Java Freccia carbon mini velo frameset (an extreme comparison), where the frameset weighs around 1500 grams. Even if all other components on the bikes are the same, this folding frameset (including the handlepost) already weighs about 2 kg more than the carbon mini velo.

In other words, building a carbon mini velo with the same component specifications as this kind of aluminium folding bike frame (Dahon/Tern/Crius/Fnhon/etc) will save 2 kg off the final bike weight. Even an aluminium mini velo frameset such as the Ascent Bolt will save 1 to 1.5 kg off a folding bike. It is a big difference which you need to consider, as a folding bike can never be as lightweight as a mini velo with a non-folding frame.

The whole frame construction is very similar to Dahon, as they might even be made in the same factory. As for whether it is a good frame or not, we will know later, during and after assembly.

The official model name for this Fnhon frame, "Tornado" is too boring as it does not say anything about the type of frame or the specifications. As such, I will give it a name, "DB11".

DB11 means Disc Brake 11 speed, which clearly states the type of frame and specifications. Also, this name is the same as a certain high end Aston Martin car...

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