Wheelsport Ultegra Di2 2x11 Speed: Part 9 - Summary of Challenges and Solutions

After writing many posts about the Wheelsport Fantasy mini velo, I feel that it is time that I write a summary of all the challenges that I encountered while building up this bike from scratch. At the same time, I will also show how I managed to work around each of the issues or solve them. This will be helpful for those who are also thinking of building their own bike up from scratch.

I have built two Wheelsport Fantasy mini velos. The first is the red and black themed, 2x10 speed mini velo that belongs to my friend, while the second one is the 2x11 speed matte black mini velo that is my own. The details of the builds can all be found at this page here.

All together, I have identified eight main issues that I encountered during the building of the bike. Most of the issues are not a problem with the design of the bike or the components, but with the challenges of building something less common, such as a mini velo with Di2 components.

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1) Using a 406 wheelset in a bike frame designed for 451 wheels, and 74mm front hub width in a frame designed for 100mm front hub width.
The Wheelsport Fantasy mini velo is designed for 451 wheels, which are about 22 inches in diameter, as compared to about 20 inches for 406 wheels. The reasons for me deciding to use 406 wheels instead of 451 wheels are;
i) Can use current custom 406 wheelset, transferred over from Dahon Boardwalk
ii) Common inner tube size with my other folding bikes, the Dahon Vitesse and Dahon MuEX
iii) Gold coloured rims and hubs for a more unique look

Another issue with this is that the custom gold wheelset has a front hub width of 74mm (for Dahon and Tern folding bikes), while the Wheelsport frame requires a more standard 100mm front hub width. To solve this, a 74mm to 100mm front hub adapter is used to fit the wheelset to the frame.

Using the Elosix front hub adapter, to convert the 74mm front hub to a 100mm width to fit the Wheelsport Fantasy front fork.

Although having the adapters is not as good or strong as having a proper 100mm wide front hub, I did not detect any flex or play while riding the bike, which is good. This can be a viable solution for those who need to install a 74mm wide front hub in a frame for 100mm front hubs.

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2) Extra Long Reach brake calipers required
Another effect of using 406 sized wheels in a frame designed for 451 wheels is that the wheel rims are further away from the brake mounting points. Extra long reach Tektro R559 caliper brakes are thus required to let the brake pad reach the rims.

Tektro R559 Extra Long Reach brake calipers are required to bridge the large distance to the rim

With these extra long reach brake calipers, it is possible to use 406 sized wheels in a frame designed for 451 wheels. This is not an ideal case, but it will work if you want to continue using your 406 wheels.

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3) Cutting carbon spacer
During installation of the stem to the top of the fork steerer tube, the long carbon spacer is needed to let the stem press down on the headset. I found that the stock length of the carbon spacer is too long, and thus I needed to cut short the carbon spacer.

Using pipe cutter to cut the carbon spacer

However, I found that using a pipe cutter to cut the carbon spacer is difficult, as the carbon spacer has thick walls. Also, the final edge is not smooth, and needs to be filed to be flat. On hindsight, I should have used a proper cutting jig and a carbon saw to cut the carbon spacer.

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4) Moving the location of the bottle cage, to make space for the Di2 battery
As I installed the Ultegra 6870 Di2 groupset onto this bike, there is a need to install a Di2 battery on the frame. I considered getting an internal Di2 battery to fit inside the seatpost, but due to the lack of wire access holes on the frame, it would be very difficult to run the wires properly. Therefore I used a standard external Di2 battery for the system. The challenge is to find a suitable place to install and fix the battery and battery mount.

After some trial and error, a neat place to install the Di2 battery would be near the BB area, below the bottle cage. However, there is no space to fit both the Di2 battery and the bottle cage, unless the bottle cage is moved upwards. The solution is to get a Shimano bottle cage adapter to move the bottle cage upwards to make space for the Di2 battery.

Final location of the bottle cage and Di2 battery, after using the bottle cage adapter

By moving the bottle cage mounting point upwards, it makes space for the Di2 battery, and also for a second bottle cage mounting on the seat tube.

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5) Extra bottle cage mounting on seat tube
With the use of a special bottle cage mount, a new bottle cage mounting point can be created on almost any part of the bike, provided there is sufficient space. This will be used on the seat tube to create a second bottle cage mounting area.

Special bottle cage mount installed on seat tube, above the Di2 battery

Just enough clearance within the triangle of the frame to fit a water bottle, a Di2 battery and a tool bottle.

With this second bottle cage, a tool bottle can be used to carry the spares and tools for the bike, eliminating the need to have a saddle bag. This gives a neater look at the seat post area, and also frees up the seat post to use the Fly 6 rear camera + rear light.

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6) Front derailleur mounting point not ideal
During the installation of the front derailleur (FD), I found that the chain would rub against the bottom of the FD chain guide in certain gear combinations. Upon further investigation, it was found that the FD mounting bracket was not designed to accommodate the different chain stay angle of this mini velo frame. For more details check out this link.

My solution for this is to use a series of spacer and angled shims to move the FD backwards, and also tilt it to the correct angle.

Using the spacer and angled shims to move the FD to the correct location relative to the rear cassette

With this setup, the FD shifts well with no chain interference issues. I have seen the latest 2016 Wheelsport Fantasy mini velo frames, and the FD mounting bracket has been moved to the correct location after receiving customer feedback, which is good to see.

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7) Lower than usual BB height
Another side effect of using 406 wheels in a frame designed for 451 wheels is that the overall ground clearance will be lowered, due to the smaller radius from the wheel axles to the outer circumference of the tires. The worry is that during cornering, we may experience pedal strike if the crankarms are not positioned properly to avoid touching the ground.

BB to Ground Height:
Wheelsport Fantasy Ultegra Di2 2x11 Speed (406 wheels): 267mm
Dahon MuEX and Dahon Vitesse: 284mm
Merida Scultura 5000: 275mm
Avanti Inc 3: 274mm

Lesser clearance between pedals/crankarms and the ground

From the comparison, the Wheelsport mini velo with 406 wheels has the least ground clearance. The good news is, during my rides, I have tried to initiate pedal strike by cornering and also pedaling at certain critical areas, but it did not happen. This means that even with the lower ground clearance on this mini velo, pedal strike is not an issue to worry about.

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8) Insufficient braking power, solution is to change to 451 wheelset and Ultegra brake calipers
Finally, after testing out the bike for a few weeks, I realised that the braking performance is not good enough for me. This is mostly due to the extra long reach brake calipers which have less braking power than standard reach brake calipers. The only way to improve braking performance is to use standard reach brake calipers.

In order to do that, I would have to use 451 sized wheels, which is what I should have done in the first place, had I known that it would create so much extra work and compromises by using 406 wheels. It was a good learning experience, but for ideal performance, 451 wheels should be used for this Wheelsport Fantasy frame.

Therefore, I ended up changing to a Wheelsport Smart 1.0 451 wheelset, along with the excellent Ultegra 6800 caliper brakes. The tires and inner tubes also had to be changed to 451 sized.

Ultegra 6800 brake calipers and Wheelsport Smart 1.0 451 wheels

With this upgrade, the braking performance has improved greatly, and the whole bike rides and feels really good. Great shifting and braking performance, and is also lightweight and fast.

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Wheelsport Ultegra Di2 2x11 Speed: Part 8 - 451 Wheelset Installation + Ultegra 6800 Brake Calipers

Part 1: Frame Design and Carbon Fork
Part 2: Compatibility Check for Wheelset and Brake Calipers
Part 3: Component Selection
Part 4: Installation Issues and Solutions
Part 5: Final Assembly
Part 6: Accessories and Geometry Comparison
Part 7: Wheelsport Smart 1.0 451 Wheelset + Schwalbe One 451 Tires

Continuing from the previous post where I changed the wheelset from the custom 406 gold coloured wheelset to the Wheelsport Smart 1.0 451 wheelset, it is now time to upgrade to better caliper brakes! That was the primary objective of changing from 406 to 451 wheelset on this Wheelsport Fantasy mini velo. This frame was originally designed for 451 wheels anyway.

By changing to 451 wheels as originally designed, it will allow the use of standard reach caliper brakes, which have better braking power than long reach caliper brakes. Why is this so? It can be explained by using the brake ratio of the caliper brakes.

For caliper brakes or V brakes, the brake ratio is defined as the distance between the pivot and the cable fixing bolt area, divided by the distance between the pivot and the brake pads. The higher the brake ratio, the higher the clamping force applied to the brake pads, and hence a higher braking power. This assumes that all other factors (such as activation force at brake lever) remain the same.

Brake Ratio = Distance from Pivot to Cable Fixing Bolt / Distance from Pivot to Brake Pad

Graphic showing the dimensions for determining brake ratio and hence brake power

The brake ratio of the brakes must be compatible with the brake ratio of the brake levers, in order for optimum braking performance and feel. If there is any mismatch, there will be insufficient or excessive braking power, either of which can be unsafe. To find out more about brake lever and brake caliper compatibility, check out this article for the details.

Measuring the dimensions of the brake calipers will give us some theoretical values regarding the brake ratio. The standard reach brake caliper that I decided to use is the Ultegra 6800 brake calipers, as this would match the Ultegra groupset on the bike perfectly. Comparing the Tektro R559 Extra Long Reach brake calipers to the Ultegra 6800 brake calipers, here are the dimensions.

Tektro R559 Extra Long Reach Brake Caliper
Distance from Pivot to Cable Fixing Bolt: 84mm
Distance from Pivot to Brake Pad: 55mm
Brake Ratio: 84/55 = 1.5

Ultegra 6800 Brake Caliper
Distance from Pivot to Cable Fixing Bolt: 70mm
Distance from Pivot to Brake Pad: 33mm
Brake Ratio: 84/55 = 2.1

From the calculations, the Ultegra brake caliper has a brake ratio of 2.1, which is 40% higher than the brake ratio on the Tektro brake caliper. The longer arm Tektro brake caliper will probably also flex more during hard braking, causing some loss of braking force. Also, the Ultegra brake caliper has a new cam mechanism that improves the braking power. This means that the increase in braking power is likely to be more than 40% when the brakes are changed from Tektro R559 to Ultegra 6800. This is a big jump in performance that can definitely be felt.

That was all theoretical calculations, it is time to upgrade the actual brake calipers to try it out for myself!

Tektro R559 Extra Long Reach brake calipers on the rear of the Wheelsport Fantasy mini velo, with 406 sized Kojak tires.

Tektro R559 on the front fork, with 406 sized Kojak tires. The large gap between the brake caliper and the tire is due to this frame being designed for 451 wheels instead of 406 wheels.

Swapping the brake calipers is straightforward, as there is no need to remove the brake cable from the shifter or outer casing. At the same time, the SwissStop brake pads were also transferred over from the Tektro brakes to the Ultegra brakes. Also, more work is required to change the wheelset, as the cassette also needs to be transferred over from the 406 wheelset to the 451 wheelset. Finally, the most time consuming job is aligning the brake pads nicely with the rims to ensure optimum braking performance and good braking feel.

Ultegra 6800 rear brake caliper

Small clearance with the Schwalbe One 23-451 tires! Not possible to use wider and taller Durano tires (28-451).

Ultegra 6800 front brake caliper

More clearance at the front, and it may be possible to use a wider tire at the front if necessary.

The black and white design of the wheels match well with the matte black frame with white decals

No more gold coloured wheelset or gold bling on the brake calipers. Black, white and silver is the new look

Ultegra Di2 6870 2x11 speed drivetrain, with the new Wheelsport 451 wheels

Other than allowing the use of standard reach brake calipers, the larger wheels will also raise the height of the bike slightly, as the centre of the wheelset is now higher off the ground due to the larger wheel radius. This also increases the BB to ground height, which will improve the pedal clearance when cornering with the bike.

Previously, when this bike was using 406 wheels, the BB to ground height is 267mm. With the new wheelset and tires, the BB to ground height is now 277mm. Comparing to the other bikes that I have:

BB to Ground Height:
Wheelsport Fantasy Ultegra Di2 2x11 Speed (406 wheels, Kojak tires): 267mm
Wheelsport Fantasy Ultegra Di2 2x11 Speed (451 wheels, Schwalbe One tires): 277mm
Dahon MuEX and Dahon Vitesse: 284mm
Merida Scultura 5000: 275mm
Avanti Inc 3: 274mm

This new BB to ground height of 277mm is similar to that of the Merida Scultura 5000 road bike. Not that I had any issues with pedal strike when cornering, but this shows that the original design of the frame is such that it will have the geometry of a road bike when using 451 wheels.

As a recap, this latest modification to change wheelset and brake calipers is to improve the braking performance of the bike, by allowing the use of a standard reach brake caliper that is more powerful. It is not about more speed or lighter weight, but about improving braking performance. In fact, this modification added about 50 grams overall to the bike due to the larger and heavier 451 wheelset, although this increase is partially offset by the lightweight Schwalbe One tires.

During the test ride of this bike, the improvement in braking performance can be felt immediately. Previously, it took quite a bit of effort to pull hard enough on the brake levers to stop the bike quickly. Both brakes needed to be used at the same time to generate sufficient braking power for strong braking.

With the new Ultegra 6800 brakes on the 451 wheelset, the braking power has been increased by quite a lot. It is now possible to apply only one brake to get sufficient braking force. Also, the return springs on the Ultegra 6800 brake calipers are lighter than the Tektro R559, and together with the smoother mechanism, it takes much lesser effort to apply the brakes. Being able to stop quickly and confidently is what I look for in my bikes, and this latest modification has made this possible.

Here is the component list for this Wheelsport Fantasy mini velo after the latest upgrade.

Component list for this mini velo after the latest upgrade

This is still a lightweight mini velo that weighs only 7.9 kg without pedals, which is significantly lower than other mini velos such as the Tyrell FSX (8.6 kg) or Tern Verge X18 (10.4 kg), both of which are small wheeled drop bar bikes.

View of the mini velo with Wheelsport Smart 1.0 451 wheelset, Schwalbe One tires and Ultegra 6800 brake calipers

All ready to go! Very little gold bling left on the bike except at the BB area. The colour theme for this mini velo is now black and white.

With this upgrade, the objective to improve braking performance has been achieved! In the next blog post, I will summarize all the things that I have learnt from building this mini velo, and how I overcame all the challenges and issues that occurred along the way.

Wheelsport Ultegra Di2 2x11 Speed: Part 7 - Wheelsport Smart 1.0 451 Wheelset + Schwalbe One 451 Tires

Part 1: Frame Design and Carbon Fork
Part 2: Compatibility Check for Wheelset and Brake Calipers
Part 3: Component Selection
Part 4: Installation Issues and Solutions
Part 5: Final Assembly
Part 6: Accessories and Geometry Comparison

After riding the Wheelsport Fantasy Ultegra Di2 2x11 Speed mini velo for a while, I realised that the bike rode very well, but the braking performance was not good enough for me. To recap, this bike was built using a set of 406 wheels, and this required using the Tektro R559 Extra Long Reach caliper brakes. This was because the frame was originally designed for 451 wheels and standard caliper brakes. Using a smaller rim would require longer reach brakes. Although these brakes work, the leverage and braking power suffered due to the extra long reach.

I have changed the brake pads to the better SwissStop brake pads, but the braking performance was still not good enough. The only way to get more braking power is to use better caliper brakes, which are all of standard reach. An example would be Shimano 105 or Ultegra caliper brakes.

In order to use standard reach caliper brakes, it would be necessary to use the larger 451 wheels. I have been resisting changing to 451 wheels, as I still want to use my custom wheelset with gold rims and Chris King rear hub. It will also allow me to have common sized inner tubes across three different bikes (the other two being Dahon MuEX and Dahon Vitesse).

However, it seems that I have no choice this time, if I want to improve the braking performance on this bike. The decision was thus made to change to 451 wheels, so that I can use better caliper brakes to improve braking performance.

As previously reviewed, the Wheelsport wheelsets are actually good value for money, and so I decided to get a new set of Wheelsport 451 wheels for use on this mini velo. Note that there are many specifications for a wheelset, such as rim size, hub width, 11 speed compatibility, etc. In this case, I would require a 451 wheelset, with 100mm/130mm hub width, 11 speed compatibility, and in black colour.

The specific wheelset has been found! 451 wheels, 100mm/130mm to fit this frame, and 11 speed compatibility for the Ultegra Di2 2x11 speed drivetrain.

Sweet pair of new Wheelsport Smart 1.0 451 wheels! Black and white matches the frame perfectly.

11 speed compatible free hub body

QR axles are included, but I will use my own QR axles that are better.

Stock plastic rim tape that came with the wheelset. Will change it out to cloth rim tape which is better for high pressure tires.

Velox cloth rim tape, best for high pressure tires. Prevents mysterious inner tube punctures.

793 grams for the 451 rear wheel with rim tape

584 grams for the 451 front wheel with rim tape

This gives a total of 1377 grams for the pair of 451 wheels, which is more than 200 grams heavier than the 1152 grams of the custom 406 wheelset. This change of wheelset would add 200 grams of rotating weight to the bike, which is not ideal for acceleration. Nevertheless, it is necessary to improve the braking performance.

Before installing the cassette, I decided to clean and regrease the ratchet mechanism in the free hub as it usually comes with very little lubrication. What I found was yet another free hub construction that differs slightly from the other two Wheelsport freehubs that I had previously seen.

Ratchet design is the same.

6 pawls are held down by 1 circular spring. I actually prefer to have 3 pawls with individual springs, as there would then be less freewheeling resistance and also redundancy design.

Regreasing the ratchet with fresh free hub grease

A new 451 wheelset also requires new tires! However, I was told that there are limitations as to what tires I can use on 451 wheels, as there is limited frame clearance for tires. When I was previously using 406 wheels, I could put on wider and taller tires as there is plenty of clearance. With 451 wheels, I can only use narrow and slim tires, which is why I decided to get the 23mm wide Schwalbe One tires. I am also using Schwalbe One tires on my Merida Scultura 5000 road bike, which works really well.

Pair of folding Schwalbe One tires for 451 wheels

23-451 means 23mm wide, or about 0.9 inches wide. These tires are even narrower than the 25mm tires I am using on my road bike!

These tires are lightweight at only 323 grams for a pair (about 162 grams each).

451 sized inner tubes are required too

A pair of Schwalbe SV7B inner tubes weigh 156 grams (78 grams each).

Recommended tire pressure is 100 to 160 PSI! That is quite high, and is only achievable using a floor pump. The advice given to me is to pump it to 120 PSI for a fast and comfortable ride.

With the Schwalbe One tires installed on the Wheelsport Smart 1.0 451 wheelset! Once again, a black and white design theme can be seen.

Comparing the 23mm wide, 451 sized Schwalbe One tire against the 35mm wide, 406 sized Kojak tire.

The Kojak tire bulges out quite a lot from the rim, creating a light bulb shape

The slim Schwalbe One tire is flush against the rim, making it more aerodynamic too.

Comparing the front wheels. 406 wheels with Kojak tires vs 451 wheels with Schwalbe One tires. The overall wheel diameter is actually quite similar!

New 451 wheel on the left vs old 406 wheel on the right

Changing from 406 wheels to 451 wheels also causes the overall gear ratio to increase, as the wheel size is now increased from 20 inch to effectively 22 inch. This is an increase of 10% which is quite significant. The tables and graph below will give you a better picture of how the gear ratio (in gear inches) is affected.

Gear ratio is increased by 10% across the board, which translates to bigger gaps at the higher gears as compared to the lower gears.

Entire gear range is pushed up by 10%.

Increasing the overall gear range would make the top end gear range higher than was previously intended, but I believe that this higher top gear will still be utilized as the faster 451 wheels would allow a higher speed to be achieved. The gear range has been increased from 65.7 gear inches (94.5 - 28.8) to 72.3 gear inches (104 - 31.7).

Now that the wheels have been upsized from 406 wheels to 451 wheels, the next step is to change to standard reach caliper brakes for better braking performance! To be continued in the next post.

Click here for Part 8

Dura-Ace 9000 vs Ultegra 6800: Road Brake Calipers

Finally, after comparing the many different components of Dura-Ace vs Ultegra on the Merida Scultura 5000, the next component to compare would be the brake calipers. Prior to this, the rear derailleur, front derailleur and crankset were compared.

I had also previously compared the Ultegra 6800 brake calipers against the 105 5800 brake calipers. This time, the Dura-Ace 9000 brake calipers will be compared against the Ultegra 6800 brake calipers. Let's find out what are the differences and similarities!
  

Dura-Ace 9000 brake calipers, only 298 grams per pair!

Ultegra 6800 brake calipers are heavier at 341 grams per pair

More similarities than differences, especially in terms of construction and design. The surface finishing is of course different.

Slightly different design of the center brake arm. The Dura-Ace design is slimmer.

Titanium pivot bolts on the Dura-Ace brake caliper, as compared to normal stainless steel on the Ultegra brake caliper

Different brake arm design. The Dura-Ace design has the bolt and connecting parts going through the middle of the brake arm, while the Ultegra design is reversed, with the connecting parts going around the outside of the brake arm.

Black finishing on the Dura-Ace main axle, and a different anti-loosening washer design.

The quick release lever for the Dura-Ace brake caliper is actually behind the brake arm, together with the cable fixing bolt, while the Ultegra design has the QR lever at the front.

Titanium cable fixing bolt and magnesium brake pad holders on the Dura-Ace brake caliper, as compared to stainless steel and aluminium on the Ultegra

Similar resin cable adjust bolt used

Design of the rivets and axles looks more high end on the Dura-Ace brake caliper

More standard looking bolt and axle design on the Ultegra brake caliper, but still looks better than the 105 brake caliper with external bolts and axles.

What I found is that there are actually more similarities than differences between these brake calipers. Most differences are cosmetic, and do not actually affect the function. The Dura-Ace brake caliper uses expensive titanium, magnesium and other specially designed hardware that are more costly, which is why it has a much higher price and also lower weight. The tire clearance is similar for both models.

The Dura-Ace brake calipers feels just a little bit smoother than the Ultegra brake calipers, but I am not sure if it is really the case, or is it just because the Dura-Ace brake caliper is newer than the Ultegra brake caliper. In any case, the difference in performance is very small. I would recommend the Ultegra brake caliper as the cost effective choice, as it is half the price of the Dura-Ace brake caliper, and yet has practically the full function of Dura-Ace.