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.

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!

Fnhon Gust: Caliper Brakes Setup and Chain Interference

With all the components ready, assembly of the Fnhon Gust can begin!

To complete the groupset, a pair of Dura-Ace 9000 caliper brakes were also supplied, to match the rest of the components. Previously, I have used caliper brakes on a few folding bikes, but they were never ideal. For example, I had to use long arm Tektro caliper brakes on the Dahon Boardwalk and Dahon Vitesse, but they were not ideal as the bike was not designed with caliper brakes in mind. Using long arm caliper brakes means less braking power.

Later, the Dahon MuSP was built, and it was designed to use caliper brakes by default. This is much better as the brake caliper position matches the rim diameter perfectly, allowing the use of standard reach brake calipers which have better braking power.

For this Fnhon Gust frame, I have seen both caliper brakes and V brakes being used. However, I am not sure how well they fit, as I am not familiar with this frameset. This provides a good opportunity to learn about this frameset.

Dura-Ace 9000 caliper brakes. Powerful and relatively lightweight at about 300 grams per pair.

As the crown of the fork has a curved surface, a curved spacer needs to be added to stabilize the caliper brake.

Original fixing nut is too long and cannot be used on this fork.

Luckily, I have a whole bag of fixing nuts with various lengths, and I chose one that fits.

Also found a curved spacer, which goes between the fork crown and the brake caliper.

For the rear brake, a curved spacer is not necessary.

With this combination of fixing nut length, the pair of brakes weigh exactly 300 grams.

At first look, it seems that caliper brakes can be fitted onto the frame with no issue. However, that is not the whole story. The next step is to see if the brake pads are able to touch the rims properly, and whether there is sufficient tire clearance.

Normally, the claimed tire clearance is about 28 mm, when used on standard frames and rims. However, this clearance can be a bit bigger, if the caliper brake is further away from the axle.

Surprisingly, the caliper brakes can clear a 35 mm wide Kojak tire!

For this frame, the caliper brakes are able to clear the 35 mm wide Kojak tires, but that is because the caliper brakes are further away from the axle. This poses another problem, where the brake pads cannot reach the rim braking surface. Starting with the front fork, let's see the problem in detail.

By purposely adjusting the centering bolt to favour one side, it is possible to make one brake pad lower, so that it just manages to clear the tires...

...while the other side will not be able to reach the rim.

The alternative is that both sides will not be able to reach the rims. As there is strong preference to use caliper brakes, I will try my best to make it work. I have a trick up my sleeve, which is to use brake pad extenders to shift the brake pad position downwards.

Using brake pad extenders, the brake pad can be offset by about 10 mm. This effectively increases the reach but also decreases the brake ratio and thus braking power.

After adding a brake pad extender on one side, it is able to clear the tire and touch the rim properly.

Front caliper brake with brake pad extender on one side only. 

Not much clearance for the rear tire, as the brake bridge is quite close to the tire.

The brake pad is barely able to clear the rear tire, with no margin at all. Possible to use but not so safe.

Small but sufficient tire clearance inside the brake caliper.

Based on these testing, it is possible to install caliper brakes on this frame to match the 16 inch 349 wheelset. However, there are some compromises, which means that it is not a direct and easy fit.

It seems to be possible to use a 18 inch (ETRTO 355 mm) wheelset, which is slightly bigger than 16 inch (ETRTO 349 mm) wheels, to fit caliper brakes. This will allow the standard reach caliper brakes to reach the rims properly without brake pad extenders. This is the size that is used on most Birdy folding bikes.

However, due to the tight tire clearance at the rear, a narrower and thus smaller diameter 18 inch tires will need to be used. There is a slightly narrower 18 x 1.25 (32-355) Schwalbe Kojak tire, but I think the diameter might be too big to clear the rear brake bridge. Maybe can, maybe not.

Moving on, I used a Rear Derailleur Hanger Alignment Tool to check the alignment of the rear dropout. This is to ensure that shifting performance is optimal, as a bent hanger will cause strange shifting problems.

Using the expensive but important tool to check the alignment of the rear dropout. This should be done before installing and adjusting the rear derailleur.

However, I soon discovered a big problem. When shifting the chain to the lowest two gears (Gear 1 and 2), the chain will touch the brake pad fixing bolt on the rear caliper brake!

At low gear, the chain rubs on the bolt.

Another view from the top.

Bolt of the caliper brake interferes with the chain path at the lowest two gears on the cassette.

At gear 3, the chain will be able to avoid the bolt. But this is not a solution as 11 speeds will be restricted to just 9 speeds.

I can't see a solution to this problem, unless we change some of the parts of the drivetrain. Some ideas which I had:

1) Change to a larger cassette sprocket, so that at low gear, the chain is higher than the bolt on the caliper brake. However, this small wheelset is unable to support a larger cassette sprocket, as the rear derailleur cage is already very low.

2) Change to a larger chain ring, so that at low gear, the chain is higher than the bolt on the caliper brake. Later on, I was told that a front 58T chain ring (instead of the current 52T), with a rear low 28T sprocket is able to clear the bolt.

3) Use a 9 speed drivetrain, as the low sprocket position is not so inwards.

4) Change to V brakes (the frame has V brake mounts), to avoid the interference.

From this view, a larger sprocket and/or larger chain ring will lift the chain to be higher than the bolt, at the low gear position. Hard to tell how much bigger is enough though.

View of the Dura-Ace drivetrain. Chain interference problem still pending to be solved.

For now, the problem that we have is interference between the chain and the brake caliper. Something needs to be changed, in order to solve this. It is a new problem which I have not encountered before, even though I have modified many 20 inch folding bikes. Something new to be learnt from this Fnhon Gust frame.

Cervelo Aspero: Great for All-Terrain Riding!

Do you know what is so awesome about the Cervelo Aspero bike? It is not just the frame that looks good, it is the sheer versatility of the bike that makes it so awesome.

Although it is mainly designed as a gravel bike, it is also a great road bike, once you put on the carbon aero wheels. It has a stiff frame with a relatively aggressive road bike geometry, which is why I had no regrets about using the Aspero to replace my Canyon Endurace road bike.

From fast road rides, to relaxed park connector rides; from light gravel tracks to off-road single tracks, this bike can do it all!

Here is a collection of some pictures, showing the Aspero on the different terrains.

Exploring the park connectors on a beautiful morning. This is near Sunset Way.

On the gravel trail, inside Jurong Lake Gardens.

Hunt 650B Adventure Carbon Disc wheelset, with WTB Venture 47 tubeless tires.

This frame looks best under direct sunlight, where the paint glitter is the most obvious.

On the smooth dirt track on the Ulu Pandan park connector.

On these cushy wide tires, the bike flies down the path smoothly!

Dirt track + gravel bike matches perfectly.

Suitable for light gravel too. This is on the Green Corridor, at Buona Vista.

GRX rear derailleur with clutch works extremely well on uneven terrain.

With a custom frame bag to fit perfectly inside the frame triangle!

2x11 speed drivetrain is suitable for both road and gravel riding, just with a quick wheelset swap.

Rides well on grass too, with the knobbly Venture 47 tires.

OK to ride on actual off-road single track as well. Just need to be more careful due to the narrower handlebars.

100% gravel bike setup!

With a front double crankset, there are low gears for hill climbing as well.

Gravel wheelset with 2x11 speed gearing.

If there are paved roads, changing to the high profile carbon wheelset will get you there even faster.

Other than taking on all the different off-road terrains using the gravel wheelset, this is also a fast road bike!