Sunday, July 30, 2017

Brompton M6R: DIY Gear Indicator on Shifters

For pre-2017 Bromptons, the shifters do not come with gear indicators. This can make it challenging to know which gear we are currently in, and how to change to a higher or lower gear. Also, this is made more confusing by the design of the 6 speed Brompton, where changing to a higher or lower gear involves shifting both the left and right shifters most of the time.

Instead of having 2 discrete set of 3 gears (such as a front double with rear triple setup) for a total of 6 gears, the 6 speed Brompton has a wide ratio 3 speed internal hub, which gives large jumps in gear ratios when shifting the rear hub. The left side shifter (that controls the 2 speed derailleur) then compensates to give a higher or lower overall gear ratio.

The gear ratios of all stock Brompton setups. I have a 6 speed -12% setup on my Brompton.

Since there is no gear indicator on the shifters, I decided to create my own by sticking labels onto the shifters. What is required is just a label printer and a set of white-on-black labels.

Rear 3 speed shifter, labelled 1,2,3 with the arrow indicating the current gear position.

Front 2 speed shifter, labelled - and +, indicating the lower or higher gear range.

After testing it out, I found that an easier way to remember the gears is to think of it another way. Instead of thinking of it as 2 sets of 3 speeds (like on road bikes), a better way is to think of it as 3 speeds, with each of the 3 speeds having a low (-) or high (+) setting.

The 6 speeds would then look something like this:

Gear 1: 1-
Gear 2: 1+
Gear 3: 2-
Gear 4: 2+
Gear 5: 3-
Gear 6: 3+

By remembering the 6 gears in this way, it is much easier to understand. I first select 1 out of 3 speeds using the rear shifter. Then, I adjust it to be lighter or heavier by shifting the left shifter to - or + respectively.

With this method, I no longer get confused as to how to shift up or down.

Next, in order to improve visibility, I decided to upsize the labels on the shifters, so that the numbers and signs are larger and clearer.

Larger numbers for better visibility

- and + signs also upsized

With this, the DIY gear indication is completed! It is now easy to switch gears without getting confused.

Wednesday, July 26, 2017

Brompton M6R: Folded Size Comparison

For folded size, the Brompton is the undisputed champion as it gives the most compact fold among all the major brands of folding bikes. How does it compare to a Dahon fold? Let's find out.

I did a simple folded size comparison of the Brompton M6R with the Dahon MuEX. Not entirely a fair comparison, as the Dahon MuEX has 20 inch wheels which are larger than the Brompton's 16 inch. Still, this shows the size difference between the Brompton and the Dahon fold.

Top view, side by side

From the side by side view from above, it can be seen that the Dahon is longer than the Brompton. This difference is quite significant, as it is longer by at least 10cm. This difference is enough to determine whether you can put the bike sideways or straight into the back of a car. If you have space for two folded Dahon side by side, you can probably fit 3 Bromptons into that same space.

Top view, end to end

As for the width, both of them are actually quite similar. The Dahon MuEX is using non foldable pedals, which causes it to stick out more at the side. Ignoring the pedals, the Dahon is just slightly wider as the wheels are a little further apart. The chain and derailleurs are also exposed on the Dahon, which makes it more prone to damage.

Side view

Lastly, for the height comparison, the Dahon is just a little bit taller than the Brompton. This can be the difference that prevents the Dahon from being stored under the table or a shelf.

Overall, the Brompton is a little lower, a little narrower, and quite a lot shorter than the Dahon. This makes it ideal for compact storage, as it can fit under most tables or just into an unused corner.

Sunday, July 23, 2017

Brompton M6R: Pentaclip Design and Saddle Change

The Brompton comes with its special saddle clamp, which is designed to shift the saddle position forward. This is to keep the folded package small, by tucking as much of the saddle as possible within the frame dimensions. Also, when the saddle is pushed all the way forward, it places it in the correct position for efficient pedaling. This is different from full sized bikes where there is usually a rear offset on the saddle clamp.

As much as I tried to like the Brompton stock saddle, I could not get comfortable on it. The saddle has a concave shape that makes it hard for me to find a good position on the saddle and maintain that position. Therefore, I decided to change the saddle to one that is more comfortable for me.

Stock Brompton saddle

Since I have spare saddles lying around, I looked to see if there is a suitable saddle. The stock saddle from the Merida Scultura 5000 is actually quite comfortable, and I changed it out only because it was heavy. Also, the colour matches the Lagoon Blue Brompton quite well!

Blue saddle from the Merida matches the Brompton quite closely! Not 100%, but close enough to look matching.

First, I have to remove the stock Brompton saddle from the saddle clamp.

The saddle clamp on the Brompton is called Pentaclip, and it is rather unique that I have not seen other brands use this design before. As shown below, it is made up of so many parts that it can be rather confusing to put everything back properly.

One side of the clamp disassembled. Made up of multiple copper washers and steel washers. Too many parts I feel...

The advantage of this Pentaclip is that it offers infinite angle adjustment, without any discrete steps of most other saddle clamps. I just wonder if they could have designed it so that it does not have so many separate parts...

Upon removing the Brompton saddle, I found a M5 threaded hole that can be useful for mounting a rear light. There are also two loops at the side for saddle bag straps.

Merida saddle installed! Flat top profile is what I prefer over the concave profile of the Brompton saddle.

Blue colour looks quite matching. Pushed all the way to the front for correct positioning and also compact folding.

From this picture, you can see why a saddle that is pushed all the way forward will make the whole folded package more compact.

This is a free upgrade since I am just using a spare part that I have lying around. Makes the ride more comfortable and also looks better in terms of colour matching. Many more upgrades to come!

Wednesday, July 19, 2017

Brompton M6R: DIY Front and Rear Light Mounts

Next, after upgrading the hinge clamps, the rear suspension, and the Eazy wheels, the next modification would be to fix front and rear lights onto the Brompton. Due to the nature of the folding, there are not many places on the frame where you can fix a light permanently and not affect the folding or folded size.

Most people install a light onto the rear of the seatpost, with the light sticking out at the rear. This means that when lowering the seatpost, care must be taken not to lower it all the way down and damage the light clamp. Also, depending on the rear light design, it may or may not interfere with the seat post clamp.

Instead of doing that, I decided to mount a rear light onto the rear rack, using the mounting used for the rear reflector. Of course, this only works for Bromptons that have a rear rack.

Original rear reflector on the Brompton rear rack

It took me quite some time, trying out different brackets and mounting positions before I could find a suitable place to mount the rear light. The main challenge is to mount the rear light without it getting in the way during folding, while still pointing at the correct angle. At the same time, the rear light should be easily removable for charging. The rear light that I want to use is the Moon Comet rear light, which is a compact and bright rear light.

After much trial and error, I finally managed to use the Cateye mount (for saddle rails), and combine it with the Moon Comet rear light mount. The Cateye mount is clamped onto the two original L-shaped brackets used to mount the rear reflector.

L-shaped brackets + Cateye saddle rail mount + Moon Comet mount

Moon Comet rear light mounted at the rear of the rack

At the same time, note that I have managed to reinstall the bungee cords onto the rear rack! Previously they were removed as I could not hook the bungee cords onto the bolt of the rear Eazy wheels, like in the stock condition. However, I realised that since the bungee cords end in a loop, I can just put it through the rear rack as shown. Simple solution!

The light is protected by the Eazy wheels, and also does not protrude out from the rack, making it possible to fold the bicycle without hitting the rear light.

Good clearance with the ground, will not hit objects when rolling the folded bike 

Rear light DIY installation completed!

Next, after installing the rear light, the front light also needs to be installed. The obvious solution is to install the front light on the front bracket, which comes stock with a front reflector.

Front bracket with original front reflector

Studying the position of the front bracket when folded, to see the clearance and space available for mounting a front light

Instead of making a complex bracket mounting due to lack of space, I decided to just bolt on a QR axle extender...

...and wrap the rubber strap of the Moon Comet front light onto it!

No interference with the frame or cables during folding

Compared to the rear DIY mounting, the front mounting is much easier and straightforward. I basically just placed some material on the front bracket for the rubber strap to wrap around.

With this, the DIY front and rear light mounts are completed! There are no protruding parts that will interfere or compromise the compact folding. These DIY mounts also allow me to use the existing spare lights that I have, instead of buying more lights.

Sunday, July 16, 2017

Brompton M6R: BikeFun Suspension Block

After upgrading the hinge clamps to the better looking and more well designed Imperium Cycle hinge clamps, and also upgrading the Eazy wheels, the next upgrade for the Brompton M6R would be the suspension.

The stock suspension comes in two different hardness, the Standard type and the Firm type for those who are heavier or just want a more responsive ride. I opted for the Firm type, but I still felt that it was a bit soft, especially during hard pedaling when the bike will bob with every pedal stroke.

There are many aftermarket suspension blocks available for the Brompton, in different designs and many different colours. For me, the criteria is to get a suspension block that is more firm, and also in a colour that matches the Lagoon Blue frame colour.

Original Brompton Firm suspension block, which is basically just a rubber block for dampening the road vibrations. Picture taken before upgrading the Eazy wheels.

I came across the BikeFun suspension block, which has a rather nice looking external coil and comes in many colours to perfectly match all the available Brompton colours. Of course, I will need the Lagoon Blue suspension to match with my bike frame.

BikeFun suspension unit, with matching Lagoon Blue spring coil.

It comes with two rubber blocks of different hardness. The one with the white dot is the firmer block, which is what I will use.

BikeFun suspension unit weighs 70 grams, mainly due to the heavier steel spring coil.

Original rubber block only weighs 33 grams

Installation was quite easy, just need to follow the instructions to see which part goes where. For this Brompton, lightweight components are not necessary as no matter how many components I upgrade, the heavy steel frame will prevent any meaningful overall lightweight bike.

Blue suspension installed on the bike! The colour matches perfectly with the frame.

The suspension looks like it came stock with the bike. And it actually should, instead of just a rubber block.

With the new suspension, the ride feels more rigid and much more responsive. I can feel just a little bit of suspension, but not so much that it causes the bike to bob during pedaling. Some time ago, I had the Flamingo bike which is a replica of the Brompton, and it really bobbed quite a lot during pedaling, which makes it inefficient for faster rides.

Best of all, it looks good and matches perfectly with the Lagoon Blue colour of the Brompton frame!

Wednesday, July 12, 2017

Brompton M6R: Imperium Cycle Eazy Wheels

For a Brompton, one of the main advantage over other folding bikes is the ability to roll the bike easily when folded. The ability to roll the folded bike eliminates the need to carry a heavy bike when moving through the MRT station or into a shopping mall. This is especially important for a bike such as the Brompton, as the steel frame makes it heavier than many other folding bikes of equivalent specifications.

The "R" in the model type M6R refers to the inclusion of the rear rack, which has two more Eazy wheels (in addition to the two on the rear triangle), giving a total of four Eazy wheels for stable and easy rolling. The stock Eazy wheels (as the rolling wheels are called) seem to be made of a rubber outer ring fitted onto a plastic center core, which is then fixed to the frame or rear rack using a bushing type construction.

This bushing type construction is simple and cheap, but tends to have more friction when under rolling under load. There are many different types of aftermarket Eazy wheels for Bromptons, all of which claim to offer smoother rolling and better appearance. In the end, the main deciding factor is the appearance of the Eazy wheels.

Stock Brompton Eazy wheel

New Eazy wheels by Imperium Cycle. Uses sealed bearings which should be smoother than using bushings.

The wheels are sold in pairs. What I like about these set of wheels is the silver 5 arm design.

Comparing the width to the stock Eazy wheels, they are narrower by about one-third, which will be good for more heel clearance during pedaling.

As for the diameter, the new wheels are a bit larger. 60mm diameter vs the stock wheels which are 54mm in diameter. This will create an additional ground clearance of about 3mm.

New aluminium wheels weigh 61 grams...

...while the stock plastic wheels are a bit lighter at 55 grams.

Stock Brompton Eazy wheels have just a bolt, a bush and a washer through the center of the wheel.

New Eazy wheels installed onto the rear triangle! Installation is easy, as it is just a matter of removing the original ones and screwing in the new ones.

Looking good!

After that, the Eazy wheels on the rear rack will also need to be changed. This means that two pairs of Eazy wheels are required for the four wheels on a "R" type Brompton. However, the swapping of Eazy wheels on the rear rack is not so straightforward...

Comparing the bolt length. New bolt is much shorter than the original bolt on the rear rack, which also holds the roller for the bungee cord.

New bolt is about 10mm shorter than the original bolt.

Since the new bolt is shorter, it means that the bungee cord cannot be attached to the roller on the bolt any more. I tried using a generic M6 bolt to replace the bolt from Imperium Cycle, but it does not work as the diameter of the bolt head needs to be of a specific diameter to avoid pressing on the sealed bearing in the wrong place. If the wrong bolt head size is used, it just jams up the whole Eazy wheel. Therefore, I have no choice but to use the shorter bolt for the new Eazy wheel.

As the new Eazy wheel is slightly larger, it will touch the rear rack. A washer is needed to create clearance between the wheel and the rear rack.

With both Eazy wheels installed on the rear rack! Note that both wheels are supposed to be installed to the right side of the rack mounting.

Close up look of the bolt and the nylon locknut. The bolt is barely long enough to cover the locknut.

All four new Eazy wheels installed!

How it looks when the rear triangle is folded down

Just a bit more clearance between the rear rack and the ground, due to the larger Eazy wheels.

Brompton fully folded. The silver wheels seem to fit the overall look of the bike quite well.

Clearance with the stock foam grips. Just a bit more clearance than the stock condition.

Rolling the folded bike around with the new Eazy wheels is definitely smoother than using the stock Eazy wheels, although the stock Eazy wheels are not too bad in the first place. I would say that this is more of a cosmetic upgrade than any functional (performance?) upgrade.