Thursday, December 19, 2013

Road or MTB Components for Dahon / Tern Folding Bikes? - Part 3

For this third and last part of this series, we will discuss the remaining components on a typical folding bike. These are the drivetrain components that are closely interlinked, and must all be compatible in order to work well.

Do check out the first and second parts of this article in order to get the full story!

The drivetrain components are:
3) Crankset + BB
4) Cassette
5) Chain

3) Crankset + BB

The crankset and the BB are integral parts of the bike. The power that you apply through your legs needs to pass through the crankset before it goes to drive your rear wheel. The BB needs to be smooth spinning to minimise resistance. Therefore, choosing a good crankset and a smooth BB is important for efficient power transfer.

For folding bikes, the most commonly used cranksets are road bike sized cranksets. These usually come as a standard front double of 52/39T or compact 50/34T. However, most folding bikes come stock with single chainrings, as they are not designed for speed or touring and don't need a wide gear range. Most well designed 20" folding bikes come with the standard 52 or 53T front chainring. 

Dahon Mu P8 with a standard front single 52T chainring.

Other performance-based folding bikes such as the Dahon Vector X20 or the Tern Verge P18 come stock with a front double road crankset. The chainring sizes are usually a standard 53/39T or the larger 55/44T. The larger chainring offers higher top end speed for stronger riders, while the small chainring gives you the low gears required for steeper slopes. This wide gear range makes the bike a very versatile bike with the ability to go almost anywhere.

Tern Verge P18 with a larger 55/44T chainring to compensate for the smaller 20" wheels.

As you can see by now, Dahon / Tern folding bikes come with either a front single chainring of about 53T, or a front double chainring of 53/39T or 55/44T. Why don't we see MTB cranksets on Dahon / Tern folding bikes?

The answer is because of the gear range. Small wheeled bikes have a natural lower gear range due to their smaller wheel diameter compared to MTB or road bikes. Comparing to road bikes or MTB, even with the same drivetrain setup (cassette and chainring), the gear range will be about 20%-30% lower due to the smaller wheels.

For most riders, using a standard 53/39T crankset with an 11-28T cassette on a 20" folding bike will be sufficient for almost all terrain. Although the gear range is not as high as that on a road bike, it is sufficient because:

1) Most folding bikes don't go as fast as road bikes. In short bursts it is possible, but it cannot be sustained without greater effort than road bikes.
2) Small wheeled bikes are less stable at high speeds (>40km/h), thus the highest gears are seldom used.
3) The top gear combinations on the road bike (53/11 and 53/12 on 700C wheels) are too high for normal* usage anyway.

*My definition of normal refers to an average rider that rides mainly for leisure, with a cruising speed of 35km/h or below on a road bike.

Shimano 105 5700 road crankset, 53/39T. A popular choice for folding bike upgrades due to the affordable price and good performance.

If a MTB crankset is used, the gear range will be quite a bit lower. Using a front triple crankset as an example, the typical Trekking crankset is 48/36/26. The low end gear range is very good, especially on a small wheeled bike. However, the top end gear range will probably not be sufficient. If a Shimano Dynasys MTB crankset is used (optimised for 26/27.5" MTB), the front triple combination of 42/32/24 is definitely not enough for flat ground pedaling.

Deore Trekking crankset, 48/36/26T. Not quite enough top end speed for flat roads or downslopes. Great for touring though.

Deore XT MTB Dynasys crankset. Typically 42/32/24T, good for large wheeled bikes but not enough top end speed for small wheeled bikes.

Due to gearing limitations, road cranksets should be used on Dahon / Tern 20" folding bikes. MTB cranksets will also fit, but the gearing will not be ideal as there are too many lower gears and not enough high gears. The ideal gear range is where all the gears have a chance to be used on normal flat roads and slight up/down slopes. Having too many unused low gears or high gears means a gear range that is not optimized.

Another reason to use road cranksets is to facilitate the installation of a front derailleur (FD) if required. For Dahon / Tern folding bikes, an FD can be installed on the frame, either on the frame FD hanger itself or through the use of an FD adaptor. In either case, the FD type that can be used is only the braze-on type, which needs to be attached to the frame/adaptor directly. Only road FD come in braze-on models; MTB FD don't come with braze-on models, thus MTB FD cannot be installed on Dahon / Tern folding bikes. Since only road FD can be used, naturally only road cranksets should be used if front shifting is desired.

Braze-on road double FD mounted on Dahon Boardwalk using a LitePro FD Adaptor

Even for loaded touring on 20" folding bikes, there is no need to use a MTB crankset. A better choice would probably be a road triple crankset. A typical chainring combination for a road triple would be 53/39/30T. The 53T large chainring will give you some speed if required, while the 30T small chainring will get you up most slopes. Any steeper and you are probably better off walking!

4) Cassette
The choice of cassette has a very big impact on the riding characteristics of the folding bike. Cassette sizes can vary greatly, especially between road and MTB cassettes. As stated, there are two types of cassettes, road and MTB.

Road cassettes are characterized by the smaller gear range and closer gear ratios across the whole cassette. The common sizes for a 10 speed road cassette would be: 11-23, 11-25, 11-28, 12-27, 12-30. The advantages of a road cassette would be the smaller difference in gear ratios between the gears, which allows better cadence control. This in turn enables more efficient and comfortable pedaling at the preferred cadence. Another advantage is the lighter weight of a road cassette, due to the smaller sprocket sizes and thus lesser material.

On the other hand, the disadvantage would be the limited gear range. Due to the smaller spread of gear ratios as compared to a MTB cassette, there would be times where you have an insufficiently low gear when going up a steep slope. This is less of a problem on small wheeled bikes, as the smaller wheels already mean a lower gear range.

Shimano 105 CS-5700 12-27T cassette

A MTB cassette is noted for its wide gear range, in order to tackle all sorts of terrain and slopes. MTB cassettes typically have a size of 11-32, 11-34 or 11-36. The advantages of a MTB cassette is definitely the wider gear range, as provided by the large low sprocket of 32, 34 or even 36T. This large sprocket will give you a low gear ratio that can help you climb up steep slopes.

However, the disadvantages are that they are quite a bit heavier than road cassettes. Depending on the actual cassette combination and grade of cassette, a MTB cassette will be about 50% heavier than a road cassette. Another point to take note is the larger steps between gears. Due to the need to achieve a larger spread of gear ratios across the same number of sprockets, the jump between each gear is quite big. This is OK for off-road riding, as there is no steady cadence anyway. However, it will be more difficult to maintain a comfortable cadence on the road, as the next gear is usually too low or too high, making it difficult to find the perfect gear and maintain the optimum cadence.

Shimano XTR CS-M980, 11-36T cassette

Comparing the sprocket sizes for road and MTB cassette:
10 speed road 12-27T: 12-13-14-15-16-17-19-21-24-27
10 speed MTB 11-36T: 11-13-15-17-19-21-24-28-32-36

Using these two cassette sizes for comparison, you can see that the MTB cassette has a larger difference in gear ratios between gears.

 Larger jumps in gear ratios on the MTB cassette. Close ratios on the road cassette is important for cadence control, especially for the higher gears.

 The gear steps between each gear on the MTB cassette is larger than the road cassette

From what I have observed, Dahon / Tern bikes with front single chainrings (Eg. 8, 9, 10 speeds) usually use a MTB cassette in order to achieve the gear range required. For example, the Tern Verge X10 uses a wide range 11-36T MTB cassette. This gives it a wide gear range that can cover most terrain. However, it suffers when riding on the road for longer distances, as the big jumps between gears will make it difficult to maintain a comfortable cadence. 

For 8 or 9 speed folding bikes, the gear range will be smaller. For example, the Tern Link D8 uses an 8 speed 12-32T cassette. The gear range is not as large as on the Verge X10, as the gear steps will be too big if we try to achieve 11-36T on an 8 speed cassette.

Tern Verge X10 with 11-36T cassette for a wide 10 speed gear range

As for folding bikes with a front double chainring, such as the Dahon Vitesse P18, they are equipped with a road cassette (11-28T) for better cadence control on the road. Although the cassette itself does not have the super low gear of MTB cassettes, the front double crankset with the small chainring will do the job of providing the lower gears.

Dahon Vitesse P18 with 11-28T road cassette, and front double crankset. Together, they enable better cadence control and also a wide gear range.

For Dahon / Tern folding bikes with a front single chainring, I recommend a MTB cassette for a wider gear range. This will enable the bike to be used even for steeper slopes. Of course, if you have powerful legs, or don't climb slopes, you can probably get by with a close ratio road cassette and a front single chainring.

As for Dahon / Tern folding bikes with a front double chainring, the best option here is to use a close ratio road cassette. The road cassette will give you the optimum gear at all cadences, and the front double crankset will give you the gear range required for flat road or slopes.

Note that the choice of rear derailleur (RD) needs to match the type of cassette used. A road cassette should use a road RD for best shifting performance. A MTB RD will work with a road cassette, but the shifting performance will suffer.

On the other hand, a MTB cassette must use a MTB RD. A road RD cannot reach the larger sprockets of a MTB cassette and thus cannot be used.

Indirectly, this also affects the choice of shifter, as MTB RD should go with MTB shifter, and road RD should go with road shifters...which brings us back to Part 1 of this article.

5) Chain

Lastly, the chain! The only purpose of the chain is to transmit the rotation of the crankset to the rear cassette. Although the role of the chain may seem simple, it is at the heart of the whole drivetrain! Without the chain, the bike is practically useless.

There are many different chains out there, but the main difference is the width of the chain. 8 speed chains are wider than 9 speed chains, which are again wider than 10 speed and 11 speed chains. Chains should always match the speed of the cassette and chainring, in order for rear or front shifting to work properly.

Even for chains of the same speed, there are also road and MTB chains. The differences are minor, which means that using a MTB chain on road drivetrain components or vice versa is likely to work normally.

The differences are the shape of the chain links, such as the chamfers on the edges of the links. The surface finishing of the chain links are also different. Road chains are normally more shiny due to the plating on the surface, while MTB chains are usually less shiny. High end chains are also differentiated from normal chains by the use of cutouts in the chain links for weight savings.

Of course, whenever possible, use road chains on road drivetrains, and MTB chains on MTB drivetrains for best shifting performance.

Dura-Ace CN-7900, with cutouts in the chain links for weight savings. It is also very shiny and corrosion resistant due to the Ni plating.

CN-HG73, a normal 9 speed chain. No cutouts in chain links or Ni plating.

For Dahon / Tern folding bikes, there is nothing special to take note for the chain. Just ensure that the correct speed of chain is used and the shifting should work fine.


Now that we have come to the end of the 3-part article, let me summarize the key points:

Shifter + RD/FD
- For front single folding bikes, either road or MTB components (shifter + RD) will work equally well.
- If you want to use MTB shifters and MTB RD on your folding bike, I would suggest using a short cage RD, such as a Shimano Saint or Zee RD.
- Avoid mixing road and MTB shifters + RD.
- For a folding bike with a front double drivetrain setup, a road setup is the only way to go.
- Only road double FD will fit on Dahon / Tern folding bikes.
- If you want to have a front double drivetrain for your Dahon / Tern folding bike, use standard road double components.

Brake Calipers + Brake Levers 

Crankset + BB
- Due to gearing limitations, road cranksets should be used on Dahon / Tern 20" folding bikes.
- The ideal gear range is where all the gears have a chance to be used on normal flat roads and slight up/down slopes. Having too many unused low gears or high gears means a gear range that is not optimized.
- Only road cranksets should be used if front shifting is desired.

Cassette / Chain
- For Dahon / Tern folding bikes with a front single chainring, I recommend a MTB cassette for a wider gear range.
- For Dahon / Tern folding bikes with a front double chainring, the best option here is to use a close ratio road cassette.
- The choice of rear derailleur (RD) needs to match the type of cassette used.
- Chains should always match the speed of the cassette and chainring, in order for rear or front shifting to work properly.
- Using a MTB chain on road drivetrain components or vice versa is OK.

With this knowledge, you should now be able to choose the correct type of road or MTB components for upgrading your folding bike!

Friday, December 6, 2013

Moon Comet Rear Light Review

Yet another new rear light for my bike! It is obvious that having more lights on the bike will make you more visible to the traffic. If you have a strong rear light that can be seen from far away, this makes it much easier for the vehicle behind you to spot you from a greater distance. The driver will be more willing to move over to the next lane, as they have plenty of distance and time to execute a proper lane change.

On the other hand, if you only have a dim rear blinker, the driver will only be able to spot you when they are quite near. This gives them very little time to properly change lane when overtaking, making it more likely that they will pass close to your bike.

With that in mind, I decided to add on a rear light for my Avanti Inc 3. Although the current NiteRider Solas 2 Watt rear light is very good, an additional light will complement the Solas and make my bike even more visible.

Another reason is that using both at the same time will practically eliminate the chance that my bike has no rear light if one of the lights suddenly spoils. There is such a possibility as my Avanti is a wet weather bike, and riding in the rain may cause the lights to spoil (even though they are advertised as rain resistant).

I am a fan of the Moon Comet series of lights, mainly because these lights use COB LEDs, which gives off a really nice organic glow which I like. They are also small, lightweight, and have a decent battery life. The rubber strap mounting provided is really versatile and easy to use, with quite a bit of room for adjustments. For more details on COB LEDs and the Moon Comet Front Light which I have on my Dahon Boardwalk, just check out this link!

Moon Comet Rear Light. 35 lumens compared to 100 lumens for the front light.

The various modes and the estimated runtime for each mode

Viewing angle and the range of the light

The rear light comes with an additional saddle rail mount, which the front does not have

Looks exactly like the front light, except that the LED is red in colour. For more details on the light, check out the Moon Comet Front Light review.

What's inside the box: The various mounting options that come with the rear light

Saddle rail mount. Useful if you are not using a saddle bag, and don't have enough seatpost length to attach the light onto the seatpost.

Even though I did not attach a saddle bag onto the saddle of my Avanti, I am still unable to use the saddle rail mount for the rear light, as the rear-rack-mounted-saddle-bag gets in the way. The picture below shows what I mean.

No way to use the saddle rail mount or the rubber strap mount on the seat post as the saddle bag on the rear rack will block the rear light

To overcome this issue, I decided to mount the rear light onto the tail end of the rear rack instead. That was my original intention for the NiteRider Solas 2 Watt rear light, but unfortunately I was unable to engineer an elegant and unobtrusive solution for that.

With this new Moon Comet Rear Light, it has different mounts, and after some experimentation, I was able to fix up something that looks simple and works well. Check out the pictures below!

Light clip (shown on bottom left) is taken from the saddle rail mount. That is the part that I need to fix the rear light to whatever DIY jig that I have.

I used an L-shaped stainless steel plate as my DIY mounting. It was sprayed black to match the colour of the bike. Mounted onto the rear rack with some standard bolts, nuts and washers. Nylon locknuts were used to prevent self-loosening.

When mounted, the Moon Comet rear light is positioned exactly in the middle! Just what I wanted.

The Moon Comet rear light nestles nicely on the rear rack, protected by the saddle bag and the rack itself. This prevents me from kicking the light accidentally when I swing my leg over the rear of the bike.

On/Off/Mode button is easily accessible on the top, and the light can be removed easily for charging. This is what I mean by a simple and elegant solution! It is also very secure and does not droop down on bumpy roads.

With this additional rear light, I feel much safer as there are two very good rear lights doing the job of lighting up the rear. I normally set the NiteRider Solas 2 Watt rear light to blinking mode, and put the Moon Comet into the steady mode. This gives me both an eye catching blinking light and a constant rear light.

Saturday, November 30, 2013

Road or MTB Components for Dahon / Tern Folding Bikes? - Part 2

Continuing from the first part of this article, Road or MTB Components for Dahon / Tern Folding Bikes? - Part 1, let us now continue with the brake components. In this second part, we will look at the different types of brake calipers and brake levers, and learn which brake levers are compatible with which brake calipers. With this understanding of the different brake systems, you can better determine what brakes to use on your folding bike.

Before you read on, I strongly recommend that you check out Part 1 of this guide, and also the other Guide To Upgrading your Dahon / Tern folding bike. This will give you the necessary background and info for basic folding bike upgrading.

2) Brake Calipers + Brake Levers

On modern bicycles, there are 3 main types of brakes: Linear pull brakes (commonly known as V brakes), caliper brakes and disc brakes. Some other less common types are cantilever brakes (still found mostly on cyclocross bikes only), roller brakes, coaster brakes or drum brakes. For more info on each of these brakes you can refer to this link here.

Wikipedia: Bicycle Brakes

V brakes and disc brakes are normally classified under MTB components, while caliper brakes are normally seen only on road bikes. Sometimes, when we upgrade a folding bike, we will be faced with a choice of using V brakes or caliper brakes. This will be dependent on the type of brake lever that you have. Before we look at the compatibility, it will be good to have some background info about these different brake systems. If you are only interested in what works with what, then skip right past this section to the part below labeled "Compatibility Between Brake Levers and Brake Calipers".

Background Info for Brake Systems:
Each brake system is made up of two main parts: The brake lever that is installed on the handlebar, and the brake caliper that is installed around the wheel.

Each type of brake lever and brake caliper has two important attributes that determines compatibility between brake levers and brake calipers: Mechanical advantage (or leverage ratio) and cable pull.

Mechanical advantage refers to the leverage provided by the brake lever or brake caliper. This is derived based on the distance of the activation point to pivot, compared to the distance from the brake pad to the pivot. Using brake levers and calipers of incompatible mechanical advantage will lead to an abnormal braking feeling in the brake lever, and also undesirable braking performance.

Cable pull refers to the amount of brake cable that the brake lever or brake caliper needs in order to function properly. It is important to match the cable pull of brake lever and brake caliper, for the brake system to function effectively.

Mechanical advantage and cable pull are directly related: For example, a V brake caliper has a high mechanical advantage, and requires a long cable pull. On the other hand, a road caliper brake has a lower mechanical advantage and thus requires a shorter cable pull to function.

Confused? Don't worry, each brake system's mechanical advantage and cable pull will be listed below, and there will be a summary to show you the compatibility between different brake components.

For the 3 most common types of brake systems, there are advantages and disadvantages to each of it. Let us take a brief look at them before we move on.

Brake Calipers:
V Brakes:
 Avid Single Digit 7 V brakes on my Boardwalk. One of the first few upgrades.

V brakes are found on more than 95% of Dahon and Tern folding bikes. From an entry level Dahon Eco 2 (SGD 300+) to high end Tern Verge X20 (SGD 4000+) folding bikes, they come with V brakes of different levels. Why are V brakes so common on folding bikes?

Advantages of V brakes:
1) Cheap
2) Easy to set up
3) Spare parts such as brake pads are cheaply and easily available anywhere
4) Simple mechanism makes it very reliable
5) Sufficient stopping power for almost all usage (except for perhaps loaded touring or downhill bikes)
6) Relatively wide pad clearance to accomodate out-of-true rims
7) Comparatively lightweight
8) Large clearance for fenders

Disadvantages of V brakes:
1) Less stopping power than disc brakes
2) Poor braking performance in the wet
3) Brake pads disintegrates very fast in the wet
4) Maintenance and cleaning is necessary after riding in the rain or wet roads, as the brake pads will leave a lot of residue on the rims
5) Wears out wheel rims (usually not a problem as it takes a long time and high mileage)

Mechanical Advantage of V brake calipers: High
Cable Pull of V brake calipers: Long

Caliper Brakes:

Very few Dahon or Tern folding bikes come stock with road caliper brakes, with the rare exceptions being the Dahon Speed Pro TT or the Tern Verge X30h. The reason why these bikes come with caliper brakes is NOT because caliper brakes work better, but because they are needed to pair with the road shifter/brake lever combo, or Dual Control Levers (DCL) in other words.

These two bikes are equipped with bullhorn bars and Road DCL, which means that they need caliper brakes for proper brake compatibility. So what are the pros and cons of a road caliper brake?

Advantages of road caliper brakes:
1) Lower frontal profile for less aerodynamic drag (not sure if it is true?)
2) Brake pads are easily available
3) Reliable

Disadvantages of road caliper brakes:
1) More expensive than V brakes
2) Less pad clearance to accomodate out-of-true rims
3) Less clearance for wider tires and fenders
4) Small clearance between tires and brake arch causes mud buildup in wet conditions
5) Less stopping power than disc brakes
6) Poor braking performance in the wet
7) Brake pads disintegrates very fast in the wet
8) Maintenance and cleaning is necessary after riding in the rain or wet roads, as the brake pads will leave a lot of residue on the rims
9) Wears out wheel rims (usually not a problem as it takes a long time and high mileage)

Mechanical Advantage of road caliper brakes: Low
Cable Pull of road caliper brakes: Short

Disc Brakes (Mechanical and Hydraulic): 
Hayes Mechanical Disc Brake Caliper

Very few disc brake systems are found on Dahon or Tern folding bikes. Some bike models which come with disc brakes are the Dahon Formula S18 and the Dahon Dash P18, which both have a mechanical disc brake system.

Other brands of folding bikes such as JAVA and Bike Friday do have a few more models with disc brakes. However, disc brakes are still not common on folding bikes, as the rotors can be prone to damage or bending when the bikes are folded and transported around.

The advantages and disadvantages of disc brakes listed below are with respect to folding bikes, which may not necessarily apply to full sized bikes such as mountain bikes.

Advantages of disc brakes on folding bikes:
1) Excellent stopping power for all terrain and riding conditions
2) Works well in all weather
3) Little to no maintenance required after riding in the rain
4) Does not affect tire choice or impede fender installation
5) Less affected by muddy conditions as compared to V brakes or caliper brakes
6) Does not wear out wheel rims
7) Not affected by out-of-true rims as the braking surface is on the rotor and not the rims

Disadvantages of disc brakes on folding bikes:
1) Slightly heavier than V brakes or caliper brakes
2) More expensive
3) Difficult to bleed hydraulic systems as compared to fixing mechanical brake systems
4) Spare parts are less readily available and more tricky to install
5) More prone to brake rubbing due to small clearance between rotor and brake pad
6) May not be suitable for folding bikes due to possible tight bends on the hydraulic hose when folded
7) Rotor is prone to damage when the bike is folded and laid on its side
8) More difficult to DIY as compared to V brakes and caliper brakes
9) May interfere with some rear racks, if the rear brake caliper is mounted on the seatstay

Hydraulic disc brake systems are more powerful than mechanical disc brake systems, but the tradeoff is heavier weight and higher price.

For hydraulic disc brake calipers, they can obviously only be used with hydraulic brake levers. These usually come as a set (including the hose and already pre-bled) and so there is no compatibility issues. The only problem is the hydraulic hose length. If the hose length is too long or short, they will need to be cut or changed, which involves bleeding the hydraulic fluid in the brakes.

As for mechanical disc brakes, there are models that are compatible with V brake levers, and models that are compatible with road brake levers (such as drop bar DCL). As such, they have different mechanical advantage and cable pull.

For use with V brake levers:
Mechanical Advantage: High
Cable Pull: Long

For use with road brake levers:
Mechanical Advantage: Low
Cable Pull: Short

That was a lot of info regarding brake calipers! Now, we need to look at the different types of brake levers out there, and from there we can determine the compatibility with brake calipers.

Brake Levers:
There are 2 main types of brake levers, flat handlebar (FHB) brake levers and drop bar brake levers. FHB brake levers are for bikes with flat handlebars, such as most folding bikes and practically all MTB. Drop bar brake levers can be dedicated brake levers, or available as a DCL with the shifters. Examples are shown below.

Avid Speed Dial 7 brake levers for FHB. Customised with gold coloured cable adjust bolts.

Shimano drop bar shifter/brake lever DCL on the left, drop bar brake lever on the right

Flat handlebar brake levers:

Flat handlebar brake levers are available as V brake specific only, road caliper brake specific only, or both V brake and road caliper brake compatible. If your brake lever is from a MTB or Trekking groupset, such as Deore or SLX/LX, then the brake lever is likely to be V brake only. There will only be one hole or hook for the brake cable.

Avid FR-5 V brake levers, for use with V brake calipers only. From

 Shimano BL-R550, for use with road caliper brakes only. Note the short distance between the pivot and the brake cable hooking area (not shown). This is what gives it a short cable pull but high mechanical advantage.

There are also brake levers that are compatible with both V brakes and road caliper brakes. These brake levers feature a selectable position for the brake cable hook, which allows it to have the correct leverage ratio and cable pull for the different brake calipers.

Shimano BL-R780, with a slot on the lever itself. This makes it compatible with V brakes or caliper brakes. Picture from Ebay.

A clear illustration showing how to set the brake lever to be compatible with either V brakes or caliper brakes.

V brake levers are actually also compatible with most MTB spec mechanical disc brakes. However, they are not compatible with road-specific mechanical disc brake calipers, such as Avid BB7 or Shimano BR-R505.

Drop Bar Brake Levers:

Most drop bars use a drop bar brake lever such as the Shimano BL-R600, or the shifter/brake lever combo type of Dual Control Lever. These brake levers are only supposed to be used with caliper brakes and not V brakes.

Shimano BL-R600 for drop bars or bullhorn bars. Only a brake lever and not a shifter.

SRAM Apex shifter/brake levers. It is both a shifter and also a brake lever. Used on drop bars or bullhorn bars.

Mechanical Advantage (Leverage Ratio) and Cable Pull of Various Brake Levers:

Each type of brake lever also has a different mechanical advantage ratio and cable pull. This determines which type of brake caliper it is compatible with!

V brake specific brake lever:
Mechanical Advantage: Low
Cable Pull: Long
Examples: Avid FR-5, Deore BL-T610

Road caliper specific brake lever (Mostly drop bar brake levers):
Mechanical Advantage: High
Cable Pull: Short
Examples: Shimano BL-R550, Shimano Ultegra 6800, SRAM Force 22

Brake Lever with selectable cable pull:
Mechanical Advantage: Low (for V brake) / High (for caliper brake)
Cable Pull: High (for V brake) / Low (for caliper brake)
Examples: Avid Speed Dial 7, Shimano Tiagra BL-4600, Sora BL-3500

Compatibility Between Brake Levers and Brake Calipers

After all the background info, we will now go back to answering the question: Road or MTB components for Dahon / Tern folding bikes? To be more specific, V brakes or caliper brakes for Dahon / Tern folding bikes?

To ensure compatibility, the key here is to ensure that the cable pull of the brake lever and brake caliper matches. For example, if you are using a drop bar brake lever (such as Shimano 105 5700 road shifters) with a short cable pull, you will need to pair it with a brake caliper with a short cable pull (such as a road caliper brake).

The best way to understand and check the compatibility is to use a table such as the one I created below.

Compatibility table for brake levers and brake calipers

Another way to look at it is that a brake lever with low mechanical advantage must be paired with a brake caliper of high mechanical advantage. An example would be to pair a V brake lever (low mechanical advantage) with a V brake caliper (high mechanical advantage). The resulting mechanical advantage would be not be too high or too low for proper braking function.

So what happens when you pair incompatible brake levers and calipers together?

Scenario 1:
Your existing folding bike uses a V brake lever and V brake calipers, such as a Dahon MuP8. You upgrade the bike to use a drop bar with road shifter/brake levers, but you did not change to caliper brakes and instead continue to use V brakes.

Drop bar brake lever: High mechanical advantage, short cable pull
V brake calipers: High mechanical advantage, long cable pull

What happens in this case is that you get very high overall mechanical advantage, which means that the braking force is very high. However, this is much higher than designed, and you will get a very spongy feeling at the brake levers due to the excessive leverage. What you are feeling is the flexing of the brake calipers or stretching of the brake cables due to excessive leverage.

Also, the cable pull ratio does not match. The V brake calipers require a long cable pull to activate fully, but your brake lever can only supply a short cable pull. You will need to set your brake pads very close to the rims in order to ensure that the brake pads can touch the rims when the brake lever is pulled. Even then, the brake lever will go very close to the handlebar when activated, which can be dangerous if the brake lever "bottoms out" on the handlebar, which prevents you from pulling any harder on the brake lever if required.

End result: Spongy brake feeling, chance of brake lever hitting handlebar, high chance of brake pad rubbing the rim due to small clearance.

You could use something such as a Travel Agent on the V brake caliper to alter the cable pull ratio, but the end result is usually not satisfactory. For more info check out the links below.

Travel Agent on Dahon Boardwalk
Caliper Brakes on Dahon Boardwalk
Travel Agent on Dahon Vitesse
Caliper Brakes on Dahon Vitesse

Scenario 2:
Your existing bike is a Tern Verge X30h with bullhorn bars, using road shifter/brake levers and road caliper brakes. You decide to ditch the bullhorn bars and convert the bike to using a flat handlebar. Due to that change, you change to a standard V brake lever, but you continue to use caliper brakes as there is no mounting point available for V brake calipers.

Brake lever for V brakes: Low mechanical advantage, long cable pull
Road caliper brakes: Low mechanical advantage, short cable pull

What you have here is the exact opposite of Scenario 1. The overall mechanical advantage is very low, as both the brake lever and brake caliper has low mechanical advantage. The cable pull ratio also does not match; the caliper brake only requires a short cable pull, but your V brake lever is generating a long cable pull.

The effect of this set up is that you will only need to pull your brake levers a very short distance before the brake pads touch the rim. The braking feeling will be very firm, which may seem good, but the actual fact is that this is caused by the low mechanical advantage of this brake setup. You will be unable to apply sufficient braking force, due to the low mechanical advantage of this system. Even if you pull hard on the brake lever and the feeling is firm, the actual braking force acting on the rims will be quite low.

End result: Firm braking feeling but poor braking power. The fingers will need to pull extra-hard on the brake levers to generate sufficient braking force.

This scenario is much less common than Scenario 1, but there is such a possibility if someone changes from a drop bar to a flat handlebar.

This incompatibility issue can be easily solved by using the correct FHB brake lever. Just get those types are are specific to road (such as Shimano BL-R550), or those with selectable cable pulls (such as BL-3500, 4600, R780). You can use either V brake calipers or road caliper brakes, and setup the brake lever to match accordingly.

Shimano Tiagra BL-4600, with selectable cable pull ratios. This makes it compatible with all cable actuated brake systems.

After reading through this long article, you should now understand the advantages and disadvantages of each brake system. Also, the compatibility between different brake levers and brake calipers can be found easily using the compatibility table above.

Almost all Dahon / Tern folding bikes come stock with V brake calipers, and it is possible for some to use road caliper brakes. Before you change your brake levers to road DCL, it is best to check if your bike frame can accept caliper brakes.

My recommendation is to always use caliper brakes with road shifter/brake levers, and not resort to other methods such as Travel Agents or short arm V brakes, as these do not work well enough in my opinion.

In the next part of this series, we will look at the other components, such as the crankset and cassette, and see if it is better to use road or MTB variants of these components on Dahon / Tern folding bikes.

3rd Part of this series!

Saturday, November 23, 2013

Road or MTB Components for Dahon / Tern Folding Bikes? - Part 1

After the hugely popular blog post, Guide to Upgrading your Dahon / Tern folding bike, here is a follow up for that article! Assuming that you have read and understood the basics of bicycle upgrading, the next question is, what components should you install on your folding bike? There is such a wide variety of components available out there, with different specifications and requirements. Without any prior experience or in-depth knowledge, it is very difficult to figure out the correct type of components to use for your folding bike.

With this article, I hope to provide more information regarding the components that are suitable for a folding bike. Although the focus is mainly on Dahon or Tern folding bikes, this may well apply to other brands of folding bikes that have a similar setup or construction.

An empty Dahon Vitesse frame. What are the components that will be suitable? Read on to find out!

There are hardly any groupsets or components that are dedicated to folding bikes or small wheeled bikes (with the exception of Shimano Capreo), thus most folding bikes use Road or mountain bike (MTB) components. This works well most of the time, unless you mix and match incompatible components.

This article will compare and explain the differences between some road and MTB components, and the suitability for folding bikes. For a more focused and simple analysis, only conventional derailleur setups will be discussed. Other types of drivetrains such as single speed or internal gear hubs will not be discussed.

Before we go into the different components categories, some background information will be useful. For me, I feel that there is no need to get top level components, unless you are racing competitively. Of course, if you can afford it, by all means get the top end stuff if that is what you like! For the rest of us, second tier components are more than good enough, as they have most of the features of top level components but at a much more wallet friendly price. In fact, even mid range components will work well enough for everyday use.

The two major bicycle component makers are Shimano and SRAM, with Campagnolo, Microshift and a few other brands making up the rest. Again, for simplicity's sake, I will only be showing components from Shimano and SRAM.

Each of these two companies have two major types of components, road and MTB components. Some components may look and work very similarly, but others will differ greatly. Here are some second tier road and MTB components from Shimano and SRAM.

Shimano Ultegra 6800, 2x11 speed road groupset.

SRAM Force 22, 2x11 speed road groupset

Shimano Deore XT, 2/3 x 10 speed MTB groupset

SRAM X0, 2x10 speed MTB groupset

Listing down the groupsets, from top level to mid range,
(11s = 11 speed, 10s = 10 speed, 9s = 9 speed, 8s = 8 speed)

Shimano Road (2013): Dura-Ace (11s), Ultegra (11s), 105 (10s), Tiagra (10s), Sora (9s), Claris (8s).
SRAM Road (2013): Red (11s), Force (11s), Rival (10s), Apex (10s).

Shimano MTB (2013): XTR (10s), Deore XT (10s), SLX (10s), Deore (10s), Alivio (9s), Acera (9s), Altus (9s).
SRAM MTB (2013): XX (10s), X0 (10s), X9 (10s), X7 (10s), X5 (10s).

Before we continue, my stand on mixing and matching components between different brands is: Don't do it! There is no advantage to mixing components from different brands, as the cable pull ratios are different and will give poor shifting performance. Besides, the appearance of the parts will be mismatched. Always use components of the same brand, and preferably the same series/groupset for best performance and appearance.

Some acronyms:
RD = Rear Derailleur
FD = Front Derailleur
SS = Short Cage RD
GS = Mid Cage RD
SGS = Long Cage RD
DCL = Dual Control Levers, which refers to the drop bar road shifters / brake lever combo
BB = Bottom Bracket (bearing unit supporting the crankset)
FHB = Flat Handlebar, usually used to refer to MTB-style road shifters for flat handlebar road bikes

The different types of components will be discussed separately, and the suitability for folding bikes evaluated in each section. The gist of each section will be underlined for easy reference. For many components, the suitability will depend on other components used as well. For example, a wide range cassette is only suitable/possible if a MTB RD is used.

1a) Rear Shifter + RD (Front single setup)
1b) Shifters + RD + FD (Front double setup)
2) Brake Levers + Brake Calipers
3) Crankset + BB
4) Cassette
5) Chain

1) Shifter + RD (Front Single Setup)

Front single chainring drivetrains are very common for folding bikes, as they are relatively easy to maintain and have sufficient gears for normal city riding. The number of speeds will then purely depend on the rear cassette. It can vary from 6 speeds for an entry level Dahon Eco 2 to 10 speeds for a high end Tern Verge X10. 11 speed Dahon / Tern folding bikes are not available (yet).

6 and 7 speed bikes have virtually no chance of a meaningful upgrade, as components for 6 and 7 speeds are rare nowadays. Even 8 speed drivetrains are becoming less popular as the price of 9 speed drivetrains drop.

As a front single drivetrain setup, there is a lot of flexibility, as the only components you need to match are the rear shifter and RD. Of course your chain and cassette needs to be of the same speed, but that is not an issue here. For front single folding bikes, either road or MTB components (shifter + RD) will work equally well.

1 x 9 road drivetrain on my Dahon Boardwalk about 2 years ago

In the recent couple of years, Shimano has introduced a series of FHB road shifters, in addition to the standard DCL road shifters. There is the 10s Ultegra-grade SL-R780, 10s Tiagra SL-4600, 9s Sora SL-3500 and 8s Claris SL-2400. The shifter should be matched with the RD from the matching groupset for best performance.

Shimano Sora SL-3500 9 speed FHB road shifter

If you like to use MTB shifters (with Instant Release and Multi Release features for high end models), it is also viable. 10s MTB Dynasys shifters are available from XTR all the way to Deore, while 9 speed shifters are available in the Alivio, Acera and Altus series. Once again, use the RD from the same series for best performance.

Shimano Alivio SL-M430 9 speed MTB shifter

The main difference between road and MTB shifters are the cable pull ratios, or pitch. The pitch for road and MTB shifters are slightly different. There have been many cases where a MTB shifter is paired with a Road RD, or vice versa, and it seems to work OK. However, tuning the drivetrain nicely will be nearly impossible as it is difficult to get all of the gears to work properly. Avoid mixing road and MTB shifters + RD.

As for the RD, there are more differences. The most obvious one is the cage length, where MTB RD have a longer cage than road RD. Road RD are available in SS and GS cage lengths, whereas MTB RD are usually available in GS or SGS cage lengths. Some MTB RD have short cage lengths, such as Shimano Saint, Shimano Zee, and a few other SRAM MTB RD.

Shimano Saint RD-M820, short cage. Looks very tough!

SRAM X9 MTB RD, short cage. Comes stock on the Tern Verge X10.

The other difference is the tilt of the parallelogram, where the MTB RD tilts more in order to reach the larger sprockets on a MTB cassette. This is the part that determines the largest compatible sprocket, and not the cage length. The cage length merely determines the chain capacity, which is dependent mostly on the choice of front crankset and the cassette size.

If you are using a close range road cassette, such as a 11-25T or 11-28T cassette, a road RD will shift better (although a MTB RD will also work). If you are using a wide range MTB cassette, such as a 11-32T or 11-34T cassette, you will definitely need a MTB RD (a road RD will not work).

There is no compatibility issues with using road FHB shifters and RD on Dahon / Tern folding bikes. As for MTB shifters and RD, the only point to take note is that MTB cages are long, and in some cases it will go very close to the rear tire in the 1st gear. Therefore, if you want to use MTB shifters and RD on your folding bike, I would suggest using a short cage RD, such as a Shimano Saint or Zee RD.

2) Shifters + RD + FD (Front double setup)

As for a front double setup, it is more tricky as we have to deal with the compatibility issues of the FD and front shifter. Folding bikes that come with a front double crankset are less common. It usually starts from the mid range price point, such as the Dahon D18 (2x9 speeds) to top end models such as the Tern Verge X20 (2x10 speeds).

My opinion is that for a folding bike with a front double drivetrain setup, a road setup is the only way to go. A MTB setup just will not work. I am assuming that you are actually using front shifting, to get 2x9 or 2x10 speeds. If you did not install an FD, it means that you actually have a front single setup (even if you have double chainrings), in which case you can just refer to the section above for front single drivetrains.

Before I explain why a MTB setup is not suitable, let us see why a road setup works. Almost all Dahon and Tern folding bikes have a 68mm BB shell width, which is the BB shell width of road bike frames. This means that a road double crankset will fit nicely onto the frame, using a standard 68mm road BB. The chainline will then be optimum for a road double crankset, which is required for good front shifting performance. A brazed-on road double FD will also fit nicely, either on the welded FD hanger or the aftermarket LitePro FD adaptor.

Front double road crankset, with a 68mm BB on the Dahon Boardwalk frame

It is possible to install a MTB front double crankset on a folding bike. With the appropriate BB spacers, you could install a front double MTB crankset (such as Shimano Deore XT FC-M785), but you will not be able to install the required front double MTB FD. This is because MTB FD does not come in brazed-on mounting, and the clamp band options will not fit (largest clamp size is 34.9mm, which is far off from the seat tube diameter of 40/41mm for Dahon / Tern folding bikes). Only road double FD will fit on Dahon / Tern folding bikes.

Now, you may ask, can I use a road double FD with a MTB double crankset? The answer is no, the road double FD is not compatible with a MTB double crankset. Not only is the cable pull ratio all different, the curvature of the FD chainguide is also different. A road FD chainguide is optimised for a chainring curvature of 50-55T, while a MTB double FD can only cover a maximum of about 40T. With the wrong curvature, there will be a big gap between the FD chainguide and the chainring, and the shifting performance will be very bad.

Shimano XT FC-M785, MTB double crankset. Not recommended for folding bikes as you cannot fit a compatible MTB double FD.

After a bunch of explanation (hope you understood at least some of it!), the moral of the story is, you cannot have a MTB front double setup for a Dahon / Tern folding bike. Some people will try to be clever and ask, can I use a road front double setup, but a MTB rear setup? This is actually possible!

You could actually set up the drivetrain such that the front and rear are distinct groups. MTB rear shifter + MTB RD, and road front double shifter + road double FD + road double crankset. As for the cassette and chain, either the road or MTB version will work (surprise! to be elaborated on in Part 2 of this article).

This would give you a truly hybrid drivetrain setup, with a MTB rear and Road front system. It would work, but it will look really weird! The appearance of the RD and FD will not match, while the shifters on the left and right side of the handlebar also will not match. You could probably try this if you have a bunch of spare components lying around, but it is not recommended if you are buying new components. Just get components from the same brand and series and everything will work and look so much better.

Tern Verge P20, upcoming new model for year 2014. Should be of great value, and is all ready for upgrades!

In summary, if you want to have a front double drivetrain for your Dahon / Tern folding bike, just get a standard road groupset. All the components (except for maybe the caliper brakes) will go on nicely. Of course, depending on the frame you have, you may need an RD adaptor and/or FD adaptor. The FD should be of the brazed-on type and not the clamp band type.

This article is getting rather long, which is why I have to split it into two parts. The compatibility of the remaining components will be discussed in Part 2. Stay tuned!

Part 2 of the article is now up!
Brake Calipers + Brake Levers