Avanti Inc 3: Installation of 60mm FSA Stem

After completing the modification of the Avanti Inc 3 to have a narrower Q factor, it seemed that the geometry had been dialed in already. However, even after using a road crankset with road drop bars, something still did not feel right.

I found that while riding, the reach on the Avanti Inc 3 seemed longer than the Merida Scultura 5000 road bike. When holding the shifters, I felt that I had to reach further than what I am comfortable with. This is not my intention as the road bike should have the most aggressive posture out of all my bikes, since it is the fastest bike that I have.

During the previous modification to change to Alfine 11 Di2 with a drop bar setup, I used a shorter 80mm stem to compensate for the longer top tube of the Avanti Inc 3 frame. To double check my previous measurements, I measured from the saddle (area where the sit bones contact the saddle) to the centre of the handlebar.

Distance on Merida road bike is about 665mm.

Distance on Avanti Inc 3 is about 668mm.

The distance from saddle to handlebar is almost the same. Both the bikes are using a compact drop bar from FSA, which means a 80mm reach on the drop bar itself. Therefore, the different reach is not from these areas. Finally, I realised that the bracket on the shifters might be different in length.

Ultegra Di2 6770 road shifters, gripping distance is about 100mm from centre of handlebar.

ST-RS785 shifters, with a gripping distance of about 120mm from centre of handlebar.

Finally, I realised that the bracket length on the shifters are different in length, which means a different reach distance. On the Avanti Inc 3, the road hydraulic disc brake shifters ST-RS785 has a bracket that is about 20mm longer, which is probably to fit in all the hydraulic components.

This extra 20mm of reach is the difference that I feel when riding the bikes. As I ride all my bikes often, I am able to feel any subtle geometry differences.

It is easy to fix this, as I can just change to a shorter stem. There is no worry of a shorter stem making the steering less stable, as the longer shifter bracket makes up for it. As long as the overall distance from the steerer tube to the gripping area on the shifters are the same, it should feel the same.

Simple FSA stem with a 60mm reach

+/- 6 degrees of tilt, depending on which way you fix the stem

Weighs 115 grams for this 60mm length. If it was a more expensive stem, it will weigh less, probably 100 grams.

Comparing the difference in stem length. 60mm in front, 80mm behind. See how much difference it makes to the handlebar position.

New FSA 60mm stem installed! Short stem indeed.

Now the handlebar reach and height is the same as on the Merida road bike!

With this modification, both bikes will ride more similarly as the geometry is now almost the same.

The Avanti Inc 3 can now be classified as an all-weather commuting road bike

Some rearrangement of the accessories is required, due to the shorter stem. Looks rather cluttered, think it needs more work.

View of the full bike. Handlebar area looks a bit cramped due to the short 60mm stem, but it rides really nicely.

With this change of stem length, the geometry has been nicely adjusted and feels perfect. After testing the bike on a half round island ride, passing through Mandai road, I was pleased to find that the gear range is perfect. The highest gear was just sufficient for continued pedaling even when rolling down the Mandai slopes at close to 50km/h. The lowest gear has not been used yet, but it will definitely come in useful if I need to go up steeper slopes such as in NTU or Mount Faber.

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 crankset after some wet weather usage

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.

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...

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...