Wednesday, April 26, 2017

Avanti Inc 3: Installing Eccentric BB + Dura-Ace Crankset

Time to assemble the new components onto the Avanti Inc 3 bike! The new components are the Bushnell eccentric BB, the Dura-Ace 7900 crankset, the 46T Gates front sprocket and 118T Gates belt.

After I had changed to Alfine 11 Di2, the chain line has been moved inwards. Now, since the crankset will be changed, I will need to ensure that the chain line is maintained more or less the same. To make the job easier, I checked the clearance between the right side chain stay and the 42T Gates front sprocket, while still using the Deore crankset. The final clearance should be around this value after changing to road crankset and 46T front sprocket.

2.5mm clearance between 42T front sprocket and right side chain stay

As shown in a previous post, the stock eccentric BB was removed, and replaced by the new Bushnell eccentric BB. A shim was used to reduce the internal diameter of the frame BB shell from 55mm to 54mm, in order to be able to use the Bushnell eccentric BB.

Bushnell eccentric BB installed, with the shim visible around it

A road BB should be used since the width is 68mm and a road crankset is used. Shown here is the SM-BBR60 bottom bracket.

New road BB installed in the eccentric BB

New crankset, front sprocket and belt installed!

Good clearance between the right side chain stay and the 46T front sprocket

This clearance is measured to be about 3.5mm. Chain line is straight.

Black coloured Bushnell eccentric BB blends in well with the black frame

Shiny Dura-Ace 7900 crank arm, with 46T Gates front sprocket and 118T Gates belt

Final picture of the Gates drivetrain

The modification has been completed, and the Q factor has been reduced from 182mm to 146mm. This means a Q factor reduction of 36mm which makes a big difference in pedaling feeling and comfort.

At the same time, the gear ratio has been adjusted due to the changes in sprocket sizes. With the 46T front sprocket and a 28T rear sprocket, the gear ratios of the latest Alfine 11 setup can be seen below. On the Alfine 11, the lowest gear, Gear 1 has a big 29.2% difference from Gear 2, which some people like while some people don't. I personally don't mind having this big step, as it gives an extra low gear for climbing.

Range of Alfine 11 gear ratios with 46T front and 28T rear

With that, the objective to reduce the Q factor has been achieved. At the same time, the adjusted gear ratios means that most gears will be used most of the time, with a top and bottom gear reserved for slope riding.

Saturday, April 15, 2017

Avanti Inc 3: Dura-Ace 7900 Crankset + Gates Belt and Sprocket

In the previous post, the Bushnell Eccentric BB was used to replace the stock eccentric BB on the Avanti Inc 3. This changed the BB width from 73mm to 68mm, allowing the use of a road crankset.

The road crankset that I can use should have a 5 arm design, and 130mm BCD. I would have preferred to use the new 4 arm road crankset, but Gates does not make their belt drive sprockets in that specification. Therefore, I have to select the crankset to match the available belt drive sprocket from Gates.

The smallest 5 arm, 130mm BCD front sprocket from Gates is 46T. This is smaller than the stock 50T, but still larger than the 42T that I was previously using. Together with the 28T Alfine Di2 rear sprocket, the gear ratio will be changed again.

46T, 5 arm, 130mm BCD Gates front sprocket.

Weighs 81 grams

The road 5 arm cranksets that I can choose from are the Ultegra 6700 (on Dahon MuEX), and Dura-Ace 7900 (removed from Merida Scultura 5000). In order to maintain a full Ultegra 6700/6770 groupset on the Dahon MuEX, I decided to use the Dura-Ace 7900 crankset on the Avanti Inc 3. Only the crankarms will be used, while the chain rings will be removed.

Since the Alfine 11 Di2 hub has a blue accent line running around the hub shell, I was thinking if I should use some blue chain ring bolts to match that.

Blue accent line on the Alfine 11 Di2 hub

Blue chain ring bolts. However, too many colours on the crank arm (blue, black, dark grey, silver) makes it difficult to showcase the beauty of the Dura-Ace crankset. 

Using black chain ring bolts makes the crankset look less busy, giving a more stealthy look

Gates 46T front sprocket mounted on Dura-Ace 7900 crankarm

Front sprocket needs to be mounted behind the tab to maintain straight chain line with rear sprocket

409 grams for right side crankarm plus 46T Gates front sprocket

A comparison picture of the front single sprockets. Crankarm on the left will be installed on the Avanti Inc 3, while the Dura-Ace 9000 crankarm + Wolf Tooth chain ring on the right has already been installed on the Wheelsport Fantasy mini velo.

Next, due to the change in sprocket size, a new longer Gates belt is required. I have no choice but to order a new belt.

Gates carbon drive belts come in a large box to prevent mishandling (twisting, bending) of the belts

118T, which is the next step up in size from the previous 115T belt.

118T Gates belt weighs 90 grams

With all the components gathered, the next step is to install all of them on the Avanti Inc 3. This modification will allow the use of a road crankset, which will have a narrower Q factor for more comfortable pedaling. This is quite a lot of work and modification required just to change the Q factor! To be continued...

Wednesday, March 29, 2017

Avanti Inc 3: Bushnell Eccentric BB Comparison

The recent upgrade done on the Avanti Inc 3 was a major change, where the drivetrain was changed to an electronic shifting, Alfine 11 Di2 version. Also, the controls and brakes were changed to a drop bar set up with road hydraulic disc brakes.

It was a good change as the drop bar set up makes it easier to cycle faster, as compared to on a flat handlebar bike. The road hydraulic disc brakes also works well, especially when riding this bike in the rain. It is my version of a road hydraulic disc road bike, that is also an all-weather commuting bike.

However, changing to a drop bar set up also means that the cycling geometry and fit is different from before. I noticed that the pedaling stance seems rather wide, as compared to my other bikes. In other words, the Q-Factor of this bike is wider than my other bikes, such as the Merida Scultura 5000 road bike and the Wheelsport Fantasy mini velo.

Q Factor on a bicycle

This is due to the Deore crankset, which was designed for a triple chain ring. As such the Q factor of this MTB crankset is wider than road cranksets. There are two reasons why I had to use a MTB crankset on this bike.

1) I wanted to use a 42T Gates front sprocket, which is only available in 4 arm, 104mm BCD. This restricted my choice of crank arms to MTB types.
2) The eccentric BB that came with the bike has a 73mm width, which does not allow the installation of road cranksets (68mm BB width required).

When using the flat handlebar setup, this wider Q factor was not an issue for me, as it rides more like a MTB that a road bike. However, after using a drop bar setup, this wider Q factor becomes more obvious. The ride feeling is quite strange and a little uncomfortable when the narrower drop bars are paired with the wide Q factor crankset.

I did some research and found that this Deore crankset has a Q factor of about 182mm, while a road crankset has a Q factor of less than 150mm. This is a huge 30+mm difference in Q factor that will definitely be felt. Reducing the Q factor will make this Avanti Inc 3 ride more like a road bike instead of a MTB.

In order to use a road crankset, I had to overcome the two limiting factors as explained earlier. First, to use a road crankset, I need to change the BB width from 73mm to 68mm. This requires the eccentric BB to be changed.

Secondly, the Gates front sprocket that is available for road cranksets are only available in 5 arm, 130mm BCD. The smallest sprocket available with this specification is 46T, which is larger than the 42T that I currently have. This means that the gear ratio will be changed again.

Stock Gear Ratio: 50T / 24T = 2.08
1st Mod Gear Ratio: 42T / 24T = 1.75
2nd Mod Gear Ratio: 42T / 28T = 1.5
Proposed Gear Ratio: 46T / 28T = 1.64

Once I change the front sprocket to 46T, together with the 28T Alfine Di2 rear sprocket, the gear ratio will be 1.64, which should be fine for my usage.

First of all, I need a new eccentric BB. The Bushnell eccentric BB seems to be the best eccentric BB available on the market, which I why I decided to get it to replace the stock eccentric BB on the bike. However, there were some issues with the order...

I ordered the Featherweight version, which has cutouts to reduce weight. However, they sent the normal (Retro) version without cutouts.

Credit to them, once I notified them of the error, they immediately sent out a Featherweight version of the eccentric BB. Which is why I ended up with two Bushnell eccentric BB. Might as well make a comparison then.

Featherweight version on left with many cutouts, normal (Retro) version on the right.

This Bushnell eccentric BB works differently from my stock eccentric BB. The Bushnell design has two wedges that will push open the two "wings" on the BB, expanding the diameter of the eccentric BB. This design applies a symmetrical load and should distribute the stresses better within the frame.

Strictly speaking, both orders were actually wrong as I ordered a black coloured, featherweight version. Instead, I got a black, retro version and a silver, featherweight version. However, I will just make do with what I have as they have already sent over another eccentric BB at no extra cost to me.

Available in silver or black

Featherweight version on left has cutouts at non-essential areas to reduce weight

Featherweight version is 154 grams

Normal (Retro) version at 211 grams. 57 grams heavier.

Now I have a choice to make. Should I use the silver coloured featherweight version, or the black normal version? It is a choice between weight and appearance.

In the end I decided that the weight difference was insignificant compared to the whole bike weight. The black version would look better as it will blend in well with the black coloured frame.

Black, normal version of the Bushnell eccentric BB will be used

Let's do a detailed comparison of the Bushnell eccentric BB vs the original eccentric BB. Weight, working principle and dimensions will be compared below.

Original eccentric BB. Uses a wedge on one side, similar to old school type quill stems. Also has cutouts to reduce weight.

Good weight of 177 grams, lighter than the Bushnell normal version

Side view

Top view. See the different wedge mechanisms.

Original eccentric BB disassembled.

Bushnell eccentric BB. More parts in this design.

One other thing to take note is that the frame needs to be compatible with the Bushnell eccentric BB. The important dimensions are the internal diameter of the frame BB shell, and the overall width of the BB shell.

BB shell internal diameter on the frame is about 55mm

Width is about 66.6mm

Original eccentric BB outer diameter, fits into the 55mm BB shell nicely.

Width of original eccentric BB. 66mm at area that contacts BB shell.

About 73mm wide at the area that the BB screws into. This is the dimension that limited my choice of cranksets to MTB type.

The Bushnell eccentric BB is designed for 53.8-54mm internal diameter BB shells, so the BB shell on the Avanti Inc 3 is too big. Luckily they also provide shims to allow usage of 55mm or 57mm BB shells.

Bushnell eccentric BB outer diameter, too small to fit securely into the 55mm BB shell.

Shim of about 0.5mm thickness is used, to reduce the internal diameter of the 55mm BB shell to 54mm

Bushnell eccentric BB, also about 66mm at area that fits into frame BB shell

About 68mm wide at the area where the bottom bracket cups screw into. This allows the use of road cranksets.

The main objective of this modification is to change the BB width from 73mm to 68mm, so that I can use a road crankset. Next, we will need to use a suitable road crankset, and also get a new front sprocket. Since the sprocket size has changed, a new Gates belt is also required...

Tuesday, March 21, 2017

Wheelsport Fantasy Mini Velo: Full Dura-Ace 9000 Groupset

After the Merida Scultura 5000 road bike has been fitted with a full Ultegra 6870 Di2 groupset, it is this bike's turn to get a full groupset too. The Wheelsport Fantasy mini velo currently has a 1x11 speed setup with a mix of Ultegra 6800 and Dura-Ace 9000 parts. 

Before: Mix of mechanical Dura-Ace and Ultegra components

The right shifter, rear derailleur, cassette and brake calipers are Dura-Ace 9000, while the left shifter and crankset are Ultegra. To make a full Dura-Ace groupset, the crankset, brake calipers and left shifter will be changed to Dura-Ace.

Before swapping the components, I wondered how the crankset would look if the Ultegra crank arm is changed to the Dura-Ace crankset.

Before: Ultegra crankarm with Wolf Tooth chain ring and gold chain ring bolts. Looks very good!

Trying to visualize the Dura-Ace crankarm on the Wolf Tooth chain ring...

It actually looks pretty good! The silver on the crankarm actually matches with the silver on the rims and rear derailleur.

Instead of gold coloured chain ring bolts, I will use black chain ring bolts to let the Dura-Ace groupset stand out.

Length of 8.5mm for the chain ring bolts is just right, as the Wolf Tooth chain ring is thicker than normal flat chain rings.

Ta-da! Dura-Ace 9000 crank arm with Wolf Tooth chain ring and black chain ring bolts. Looks good too!

Close up view of the interface between the crank arm and the chain ring

Weighs exactly 400 grams. 25 grams lighter than the Ultegra equivalent.

While reinstalling the chain onto the drivetrain after replacing the crankset, I found that the original 11 speed chain had a few rusty links and did not move smoothly. Therefore, I had to replace the chain too.

Dura-Ace grade 11 speed chain for maximum rust resistance. Also common use with 11 speed XTR.

Dura-Ace 9000 crank arm with Wolf Tooth chain ring installed

Left side Dura-Ace 9000 crank arm

Using the KMC 11 speed MissingLink

Full Dura-Ace 9000 drivetrain! Silver and black goes well together.

With the drivetrain settled, the next component to change would be the left side shifter. The left side shifter was a modified Ultegra 6800 left side shifter, with the internal shifting mechanism removed to save weight. As this is a 1x11 speed setup, the left side shifter only acts as a brake lever, no shifting function is required.

Nevertheless, to complete the full Dura-Ace 9000 groupset look, I decided to put on the Dura-Ace left side shifter too, even though the shifting function will not be used.

Dura-Ace 9000 left side shifter, 184 grams.

Modified Ultegra 6800 left side shifter, with internal shifting mechanism removed.

Shiny Dura-Ace 9000 left side shifter installed. The superior grade of gloss finishing is obvious when compared to Ultegra.

Matching pair of Dura-Ace road shifters. I took the chance to replace the Lizard Skins bar tape which were starting to peel off after a few years of use.

The final component to change to Dura-Ace would be the brake calipers. By swapping the brake calipers with the ones on the Merida road bike, both bikes will have a complete groupset.

Dura-Ace 9000 brake calipers

Lightweight and powerful brake calipers

Full mechanical Dura-Ace 9000 groupset on the Wheelsport Fantasy mini velo!

Black and silver surface treatment on all the Dura-Ace components match nicely with the black and silver colours of the wheelset, and the black and white design of the other components.

This mini velo is still a lightweight mini velo, since it has all the lightweight Dura-Ace components. The final weight of the Dura-Ace mini velo is just under 7.3kg (excluding pedals).

Final specifications of the Wheelsport Fantasy 1x11 speed mini velo with full Dura-Ace groupset