Saturday, January 23, 2021

Fnhon Gust: Folded Size Comparison (16 vs 20 inch)

This will be the final post on the Fnhon Gust 16 inch folding bike, and I shall compare it to a 20 inch folding bike. Both are folding bikes, which are designed for portability. However, a 16 inch folding bike is expected to be smaller in size, due to its smaller wheels and more compact frame. Let's see if this is true!

Previously I have done folded size comparisons, between the Java Neo 2 and Dahon MuEX, and also between the Tyrell IVE/Dahon MuEX/Brompton. These comparisons are very useful, if folded size is important for you.

This comparison will be between the Fnhon Gust and the Fnhon DB11. The Fnhon DB11 has a similar size to the Dahon MuEX, which is pretty much the standard for 20 inch folding bikes.

Fnhon Gust folded, looks compact! Highest point is the saddle.

Dura-Ace drivetrain can be seen here

Overall folded length is about 680 mm. Shorter than the 800 mm of 20 inch folding bikes.

Folded width, at its widest point is about 370 mm.

Height at its highest point is about 610 mm.

The Fnhon Gust thus has a folded size of approximately 680 x 370 x 610 mm (L x W x H). This is more compact compared to 20 inch folding bikes, as you will see below.

There is no place to install the frame magnets

Just for info, the frame magnets weigh about 59 grams.

A long velcro strap is used instead to hold the frame together when folded.

Top view of the folded bike. A folding or removable pedal would reduce the folded width significantly.

Gold frame latch on display here! Take care not to scratch it as it is very exposed in this position.

Next, I will place the Fnhon Gust beside the Fnhon DB11 for comparison.

Fnhon Gust at the front, Fnhon DB11 at the back.

The length of the Fnhon Gust is about 120 mm shorter, at 680 mm vs 800 mm.

Folded width is roughly the same, mainly determined by the pedal that you use.

View from the back.

The 20 inch Fnhon DB11 is taller, as the highest point is the handlepost, not the saddle.

Both saddles are at the same height when folded, as the seatpost is the same length. In summary, the 16 inch Fnhon Gust is shorter than the 20 inch Fnhon DB11 in both length and height, with similar width. It is still not as compact as a Brompton, which is still the champion for smallest folded size.

In my opinion, the Fnhon Gust is a very nice bike for casual riding, and also very portable for easy transportation. The weight of 8.4 kg without pedals is also lightweight, making it easy to carry around. Best of all, this bike is not expensive, especially if you put mid-range components instead of high end components.

Sunday, January 17, 2021

Fnhon Gust: Assembly Completed

Here is how the Fnhon Gust looks, after assembly is complete. It is a smart looking frame, with good proportions all round. For the details of all the components, check out the Fnhon Gust page.

Drive side view

View from non-drive side

View of the handlebar, with the Sora brake levers that matches well with the frame.

V brakes installed at the front fork, along with some gold accents on the frame.

Dura-Ace 9000 crankset with Stone 52T narrow wide chain ring.

Dura-Ace 11 speed drivetrain

Dura-Ace 9000 rear derailleur and cassette

11 speed drivetrain on the all black 16 inch 349 wheelset

More gold lettering at the back of the seat tube

Litepro seat post with PRO saddle

V brakes installed under the chain stay, replacing the caliper brakes.

Small clearance between the crankarm and the V brakes, and also the chain stay.

No more chain interference with the caliper brakes, even when at the lowest gear.

Pedals installed on the bike for test riding

Here are the final specifications for this Fnhon Gust. Despite the heavy steel frame and fork, it still manages to weigh just 8.4 kg without pedals, which is pretty impressive.

Just 8.4 kg without pedals.

As expected, a few challenges were encountered along the way, as building this bike is new to me. From this experience, knowledge was gained and I learnt a lot about this Fnhon Gust frameset.

Friday, January 15, 2021

Fnhon Gust: Bike Geometry

The Fnhon Gust 16 inch folding bike has been completed successfully, even though a few problems were encountered along the way. This bike has a beautiful frame which impressed me. A high end drivetrain was supplied, which I installed onto this bike.

Let's check out this bike and some of its dimensions.

Full bike view, looks very good with black frame and components, with a bit of gold accents.

Dura-Ace 9000 components helps to reduce the weight of the bike and elevate it to premium status.

Some bike geometry that I will measure will be the chainstay length, wheelbase, and bottom bracket height. These values will affect how the bike rides, which will surely be different from a full-sized bike with different geometry.

Chainstay length is only 347 mm.

Chainstay length is measured from the centre of the bottom bracket to the centre of the rear axle. This Fnhon Gust has a really short chainstay length, as it is usually 400 mm or more, even on 20 inch folding bikes. The Java Freccia carbon mini velo has a chainstay length of 380 mm, which I thought was already quite short.

If the chainstay length is very short, it will be less stable when travelling fast, although it will also be very nimble for navigating tight areas. For this 16 inch folding bike, which is not meant to go fast, it will probably be OK.

A short chainstay length also means that the chain angle will be quite extreme at the top and low gears. This will likely cause excessive chain noise, and even poor shifting performance. If you backpedal when in the lowest gear (largest sprocket), most likely the chain will fall off the sprocket. This is the same issue which I encountered on the S-Ride 12 speed 11-50T cassette.

Next, the wheelbase is measured. This is the distance between the front axle and the rear axle, which also contributes to stability. A long wheelbase is stable, but also less maneuverable.

Wheelbase is a relatively short 910 mm.

A normal road bike has a wheelbase of about 990 mm or more, so this Fnhon Gust has a really short wheelbase. 

The bottom bracket height is the distance between the ground and the centre of the crankset spindle. A low BB height is good for stability, but there is also increased chance of pedal strikes. On the other hand, a high BB height gives good ground clearance, but cornering feel will not be as good due to the higher centre of gravity.

Bottom bracket height is about 298 mm, which is pretty average. Nothing of concern in this case.

I found that for my height of 168 cm, with inseam length of 78 cm, I needed the seatpost to be fully extended, right at the limit line. In other words, if you have longer legs, you will not be able to extend your legs fully, as the seatpost does not go any higher. You will need to get a longer seatpost in this case. This is one disadvantage of having a small bike frame, where the seat tube is short and the seat post clamp is low.

Seat post insertion depth is at the minimum. In other words, this is the highest the seatpost can be safely used.

Finally, I measured the wheel diameter of this 16 inch, 349 wheelset. 349 mm refers to the diameter of the rims, but it increases once the tire height is added. In this case, 32-349 Schwalbe Kojak tires are used.

Wheel diameter is 420 mm.

The overall bike length (front tire to rear tire) is thus wheelbase plus wheel diameter, giving an overall bike length of 910 + 420 = 1330 mm. This is really short and compact, as a normal full sized road bike has a length of around 1800 mm. The Bike Friday Haul-A-Day cargo bike has a slightly longer length of 1870 mm.

In summary, this is a compact and agile bike, which makes it fun to ride as it can navigate around tight corners easily. However, travelling at high speed will be less stable due to the short wheelbase. Even without folding, the overall length is short which makes it easy to store. I think it can go straight into the backseat of a car, just by folding down the handlepost.

Friday, January 8, 2021

Fnhon Gust: Assembly Difficulties and V Brake Installation

The Fnhon Gust is different from what I have built previously, as it is a 16 inch folding bike frame, instead of the usual 20 inch bike frame which I am familiar with. Therefore, some problems and unknowns are to be expected.

However, some problems that I encountered were issues with the frame or component quality, which is unacceptable. It should not be happening, regardless of 16 inch or 20 inch bikes.

Starting with the headset, the top bearing was unable to seat in fully into the bearing cups. This is due to the frame headtube not being round enough, causing the aluminium bearing cups becoming non-round as well after being pressed in. Same as what I encountered on the Crius AEV20 folding bike.

As I did not have the headset tool with me, I had to improvise and make a DIY tool to press in the bearings. For details on headset installation, refer to this guide.

This is as far as the headset sealed bearings can go by hand, it is a tight fit.

I rigged up a jig, using the fork and the compression nut, plus some headset spacers, to press in the headset bearings.

The headset bearings were quite a tight fit inside the bearing cups. This is not normal as it is supposed to be able to be installed by hand. It would be quite difficult to get the bearings out next time.

That was only the first problem! Next, I found that the handlepost could not slot onto the steerer tube of the fork smoothly. Upon measurement, I found that the inner diameter of the handlepost was slightly smaller than the outer diameter of the steerer tube.

Once again, this is a new problem to me, as I have not encountered this on the many folding bikes that I have built previously. It is a problem with the quality control, which I find unacceptable.

Luckily, I had experience solving problems like this, many years ago. On the Dahon Boardwalk, the seat clamp was too tight, and I used a similar method to remove it.

Using a coin as a metal plate, I screwed in the clamp bolt from the other side. This pushes the slot apart, increasing the inner diameter of the handlepost.

By temporarily enlarging the hole, the handlepost can fit over the steerer tube.

Once the handlepost slots onto the steerer tube, the clamp bolts can be fixed normally.

Next, the most tricky problem is with the brakes. As shown previously, there are some issues if you install standard reach caliper brakes on the Fnhon Gust.

At the front, the reach is insufficient to reach the rims. At the rear, the chain will interfere with the brake bolt at the lower gears.

One of the solutions is to change to V brakes, as there are V brake mounts on the frame. Since the initial plan was to install V brakes, I had already ordered Litepro V brakes, so I could test it immediately.

One pair of Litepro V brakes weigh 185 grams. Two pairs are needed for one bike.

When switching from caliper brakes to V brakes, the brake lever should actually be adjusted or changed, as there is a different pull ratio. For details, refer to this post which I wrote many years ago.

In short, the correct pull ratio on the brake lever should be used, so as to achieve proper brake power and brake feeling.

Luckily, the Sora brake levers that were used on this bike has a selectable pull ratio. These brake levers can be used with either V brakes or caliper brakes, instead of just V brakes like MTB brake levers.

The cable hook on the Sora brake lever can be moved between two positions. The outer position for V brakes has a longer cable pull, but lower leverage.

One problem which I had expected using V brakes on the Fnhon Gust is the position of the brake pad, relative to the V brake caliper. From other pictures, the brake pad seems to be very high up the brake arm. This is not normal, as the brake pad is usually much lower down, closer to the brake caliper pivot for more leverage.

That was the reason why I chose the Litepro V brakes, because they have a very long slot for brake pad adjustment. If a normal Shimano V brake is used, the brake pad might not be able to go so high up.

Brake pad is half way up the brake arm, instead of the usual 1/4 of the way up.

Litepro V brakes are thus recommended for the Fnhon Gust, due to the long slot for proper brake pad placement, and also a suitable arm length to clear the tires.

As for the rear, it is tricky, as the V brake mounts are located under the chainstay, making it difficult to install and adjust.

At the rear, the V brakes go under the chainstay. Brake pad also needs to be half way up the brake arm to reach the rims.

Very small clearance between the V brakes and the 52T chain ring!

Brake noodle of the rear V brakes also go very close to the chain ring.

On the non-drive side, the V brakes also go very close to the left crankarm.

The rear brakes barely fit, as it is so close to the chainring and also the crankarm. Locating the V brake mounts on the underside of the chainstay is not ideal, as that area is already quite full, with the drivetrain components all around it.

In the end, the switch to V brakes was successful. However, there are many areas that you need to take note, if you build the bike yourself.

I was glad that all these issues could be solved with a bit of DIY work. Not as straightforward as it looks!