Thursday, August 17, 2017

Brompton M6R: Shimano Crankset and Bottom Bracket

Today, I am going to upgrade the stock Brompton crankset. The stock crankset is a square taper crankset, with a 5 arm design and 130mm BCD for the chain ring. What I found was that if you point the crankarm downwards and step hard on the pedal, you can actually see and feel the crankarm flex inwards. To me, this is not acceptable as the excessive flex is unsettling, and also means less efficient pedaling.

I plan to change to a Hollowtech II crankset, where the spindle is integrated with the right side crankarm, and mounted through an external bottom bracket. This setup will be stiffer than a square taper system.

After consulting some friends, I was advised that it will not be a straightforward swap, as the clearances around the crankset and chainring are tight. If the chainline is too inwards, the chainring will interfere with the frame. If it is too outwards, it will interfere with the folding.

This means some trial and error is needed to adjust the chainline and avoid interference. Before installing the new crankset, let's take a look at the original setup.

Original setup has a gap of about 3mm between the chain and chainstay.

After removing the stock crankset and bottom bracket, the bottom bracket shell is confirmed to be standard 68mm English threaded.

Threads are cleaned and ready to accept a new Hollowtech II bottom bracket

Original 130mm BCD, 44T chainring + chain guard is 89 grams

Original square taper bottom bracket is FAG branded, and weighs 242 grams.

Original Brompton left side crankarm is 213 grams...

...while the original Brompton right side crankarm is 300 grams.

Together, the original crankset (without chainring) is 513 grams.

In order to match the colour scheme of the Brompton, I wanted to get a crankset with polished silver colour to match the rims. A black crankset is nice on its own, but it does not match this Brompton. I tried to get a Dura-Ace 7800 crankset, as the polished finishing is really nice, but it is hard to get a suitable one in good condition as it has already been out of production for almost 10 years, having been replaced by the newer 7900, 9000 and R9100 series.

The closest one that has a similar finishing would be the Tiagra 4600 crankset, which is also in polished silver. Of course it is not as lightweight as the Dura-Ace crankset, but it is OK as weight is not important for this bike.

Tiagra left side crankarm, 250 grams. Heavier than the Brompton left side crankarm as I guess it has more material for stiffness.

Tiagra right side crankarm, 424 grams. Also heavier than the Brompton right side crankarm, as it has more material for stiffness and also includes the weight of the spindle.

Normally, for a road crankset such as Tiagra, if it is installed in a 68mm wide bottom bracket shell, a road bottom bracket will be used, with no spacers required under the bottom bracket cups.

However, with advice from friends who have installed a Hollowtech II crankset on a Brompton before, a spacer of 3 to 4mm is required to push out the right side chainring to clear the frame.

From my experience, it is possible to fit a spacer with maximum thickness of around 2mm under the bottom bracket cups, before the left side crankarm runs out of sufficient spindle length to be safely fixed on. In this case, since I needed more than 2mm, some creative modification is required.

From a modification done previously on the Avanti Inc 3, I know that the MTB Hollowtech II bottom bracket is 1mm slimmer on each side, compared to the road type.

Therefore, I decided to use a MTB Hollowtech II bottom bracket, instead of a road bottom bracket. The slimmer bottom bracket cups will allow me to put an additional 2mm of spacers, enabling a maximum spacer thickness of 4mm.



Summary of crankset + bottom bracket weights (excluding chainring):
Brompton crankset + FAG BB: 752 grams
Tiagra crankset + Hollowtech II BB: 764 grams

The new setup will be a little bit heavier than the stock setup, as the Tiagra crankset has more material for stiffness, and is just a mid range crankset that is not lightweight. As already stated earlier, weight is not important for this bike, so this is no issue at all. If your objective is to reduce weight, you will need to get the higher end cranksets, such as Ultegra or Dura-Ace.

As I have read that the plastic chain guard on the chainring is an integral part of the Brompton folding, I plan to use the original 44T Brompton chainring + chain guard. Installation of this chainring onto the Tiagra crankset is no issue, although the appropriate length of chainring bolts are required.

For a start, I installed a 2.5mm spacer under the right side bottom bracket cup, and installed the right side crankarm to test out the chainline and frame clearance.

With a 2.5mm spacer, there is practically no gap between the chainring bolt and the chain stay when the Brompton rear triangle is folded.

To be safe, a clearance of at least 1mm is necessary. Mixing and matching my stash of spacers generated a spacer of 3.6mm thickness.

Note that this spacer thickness is only possible as I am using MTB bottom bracket cups that are slimmer than road bottom bracket. If not, using this spacer thickness will make it impossible to install the left side crankarm safely on the spindle.

After using 3.6mm spacer, there is a minimum clearance of 1mm

No clearance between the end of the crankarm and the plastic chain tensioner!

Although there is now clearance between the frame and the chainring bolt, I found that there is no clearance between the crankarm and the plastic chain tensioner when folded (as shown above). The crankarm only just manages to slide past the plastic surface. As this condition only occurs when folded and not during pedaling, it is acceptable. Just need to take note of this if you plan to do the same modification. Final spacer thickness installed under the right side bottom bracket cup is 3.6mm.

During installation of the left side bottom bracket cup, I found that the cup did not rest flat against the frame when fully tightened.

As I was afraid that I had cross threaded the left side cup, I reinstalled it, trying to align the cup properly while screwing it in. This time, I ended up really cross threading, causing damage to the threads on the cup.

Damaged threads on the aluminium left side cup due to cross threading

Luckily, this cup is made of aluminium, while the frame is made of steel, so no damage was done to the steel thread on the frame. All I needed to do was to get a replacement left side cup and reinstall it. Although the left side cup did not rest fully flat against the frame, there was no problem installing the crankset, so I left it as it is. The conclusion is that the bottom bracket shell on the Brompton frame is not faced properly to be parallel.

Tiagra crankset with original Brompton chainring installed! Silver colour matches better than a black crankset.

The plastic chainguard allows the front fender stays to rest against it when folded, preventing excessive movement of the front wheel.

This upgrade was a little tougher due to the tight clearances around the crankset, making it more technically challenging. Nevertheless, the crankset has been successfully upgraded to a stiffer Hollowtech II crankset, which provides stiff and efficient pedaling.

In summary, what you need to install a Hollowtech II crankset on the Brompton are as shown:
1) Road Hollowtech II crankset, double (not triple, as the spindle length and chainline are different)
2) MTB Hollowtech II bottom bracket cups
3) Spacer of approximately 3.6mm
4) 5 x chainring bolts for single chainrings
5) The right tools to remove the original crankset and BB, plus tools to install the new BB and crankset

Saturday, August 12, 2017

Cateye Padrone+ Cycle Computer and REC Mount (Cateye/GoPro)

Most combination mounts available in the market are designed for a Garmin on top and a GoPro type mount below. There are very few mounts that can cater for other cycle computers on top, such as a Cateye.

As I did not want to get another Garmin unit for the Avanti Inc 3, and also did not want to share the Garmin Edge 510 with the Avanti Inc 3, I decided to get a Cateye cycle computer as a standalone cycle computer for the Avanti Inc 3.

Prior to that, I searched on Taobao to find a combination mount with Cateye on top and GoPro type mount below. There were a few, and I bought two of them to try out, since they were not too expensive. However, the quality of the Cateye mounts from Taobao were quite dreadful.

As you may know, most Cateye computers are activated by pressing the bottom of the screen, which tilts the whole unit to depress the small button at the back of the unit. However, after inserting into the first Cateye mount, I could not press down the screen at all. The design is flawed and this makes the Cateye computer useless as I could not interact with it at all.

As for the second mount of a different brand, I could barely depress the button after inserting the Cateye computer. Worse still, upon removing the Cateye, the snap fit arm of the mount broke! This is really poor quality. Either the button does not work, or the mount breaks. Seems that it is not so easy to copy and make the Cateye mount...

I have no choice but to get a mount of a higher quality in order to ensure that it works properly. I found the REC mount which is designed and made in Japan, which should work better since Cateye is also from Japan. It can be found at The Bike Settlement.

In any case, I decided to get a large screen Cateye computer to match with the new REC mount. Last time, when I first saw the Cateye Padrone, I thought it was ridiculous as the screen was so much bigger than the Cateye Strada that I have.

However, I recently realised that it is actually very useful, as it makes it so much easier to read the numbers on the screen. Besides, the Garmin computer also has a large screen.

The Cateye Padrone+, which has backlight compared to the non-plus version of the Padrone

Comes with the standard Cateye sensors which I have already installed so many times

Comparing the size to my hand, it does not look so big...

...but compared with the Cateye Strada, it is huge!

The user manual which is the usual Cateye style. Highly detailed but also utterly confusing.

The backlight function can be set so that it only activates during a preset timing, such as when it is dark. I set it to activate at 6pm and deactivate at 7am.

Small but useful backlight

Weight of entire speedometer setup is only 53 grams

At the same time, I also got the REC mount which has a Cateye mount on top and a GoPro mount below. Having tested it at the shop before buying, the Cateye mount works well like the original. It has to work, since it is actually more expensive than the Cateye Padrone+ cycle computer!

REC mount for Cateye. Garmin mount is also available as an interchangeable piece as seen above.

The dazzlingly array of mount combinations and types available from REC mount

Close up look at the mount. Very minimalist design.

See how thin the clamps are!

You can change the mounting bolts to black ones (supplied) if you prefer

A spare Garmin mount is supplied

The Cateye mount is actually an adapter that allows the Cateye to be fixed onto the standard Garmin mount

Big Cateye Padrone screen on the slim REC mount

Mounting hardware for the GoPro mount at the bottom

Bottom of the REC mount for mounting the GoPro mount or other light mounts (sold separately)

Position adjustment is possible by using alternative mounting holes or by flipping the whole mount upside down

REC mount weighs 77 grams on its own

Cateye on top, Cycliq Fly12 below 

Still looks bulky from the side 

From the top view and rider's point of view, at least it still looks quite neat, with only the Cateye and the Spurcycle bell visible.

With the installation of this REC mount completed, the Cateye and Fly12 can now share the same mount, and take up much less space on the handlebar. Not a commonly used combination, which is why it was difficult to find a suitable mount to fix these items onto the bike.

Tuesday, August 8, 2017

Dahon MuEX: Kinetix Pro Wheelset

Recently, my friend upgraded his Tern folding bike to a 1x11 speed setup, and the rear wheel had to be changed to be 11 speed compatible since the original wheelset cannot accomodate an 11 speed road cassette. As such, I had the chance to buy over the original wheelset from the Tern bike. This wheelset is the high quality Kinetix Pro wheelset, originally seen on top end Dahon bikes such as the MuSL or MuEX. It is my dream wheelset for a Dahon folding bike, having first seen it through the glass facade at a bike shop many years ago. This wheelset is compatible with 8/9/10 speed cassettes.

This second hand Kinetix Pro wheelset is still in great condition as it has not endured high mileage or heavy loads. Due to the low spoke count, there is greater chance of spoke breakage than other wheelsets, although they claim that the stronger rims and spokes make up for the lack of spokes. Nevertheless, I wanted to get the wheelset and install it on my Dahon MuEX.

Kinetix Pro wheelset with red rims, black hubs and black spokes

With smooth rolling Kinetix front hub...

...and the high quality American Classic rear hub. Aluminium freehub body has steel inserts to prevent damage from the cassette splines.

Kinetix Pro wheelset, the top level 20 inch wheelset available in the market. Spoke nipples are hidden within the rim.

Front wheel weighs only 408 grams

Rear wheel weighs only 590 grams!

This reminds me that I need to do a wheelset weight comparison. This will be between the Wheelsport Smart 1.0 wheelset, the custom Novatec/Chris King wheelset, and this Kinetix Pro wheelset, all of which are 20 inch 406 sized wheelsets. All the weight includes cloth rim tape.

Wheelsport Smart 1.0 front wheel: 452 grams
Wheelsport Smart 1.0 rear wheel: 692 grams
Total weight of Wheelsport wheelset: 1144 grams

Novatec front wheel with LitePro rim: 494 grams
Chris King rear wheel with LitePro rim: 658 grams
Total weight of new custom wheelset: 1152 grams

Kinetix Pro front wheel: 408 grams
Kinetix Pro rear wheel: 590 grams
Total weight of Kinetix Pro wheelset: 998 grams

As you can see from the comparison above, this Kinetix Pro wheelset blows the competition out of the water with the total wheelset weight of only 998 grams, below the magical 1000 grams. This is one seriously light wheelset!

Putting on fresh cloth rim tape

Comparing the Kinetix Pro with the Wheelsport Smart 1.0 front wheel, which is also a good wheel.

Rim width is almost the same

Kinetix Pro front wheel with Schwalbe Kojak tires

Kinetix Pro rear wheel installed

Red coloured rims stand out from the rest of the bike components

The red rims really stand out from the rest of the black components on the Dahon MuEX!

Loving this Kinetix Pro wheelset on the Dahon MuEX!

Full specifications of the Dahon MuEX after upgrading to the Kinetix Pro wheelset

With this upgrade, the weight of the Dahon MuEX has been reduced to just 8.7 kg without pedals! Even with pedals, it is a relatively lightweight 9.1 kg, which is the lightest that has been achieved on this bike throughout all the modifications.