Wednesday, February 19, 2020

Cervelo Aspero: Headset, E-Thru Axles, Brake Adapter, Seat Post, Saddle

When you get a new frameset, other than the frame and fork, there will also be other parts that are included with it. With this Cervelo Aspero frameset, the headset parts, E-thru axles and also the seat post are included. Let's take a closer look at these parts, and also weigh them to help estimate the total bike weight.

Compression plug that goes into the carbon fork steerer tube. This compression plug is quite long, which is good for grip but also means that it is a bit heavier.

Top cap to pre-load the headset, by pressing down on the stem and pulling up on the steerer tube.

Headset sealed bearings, with the top 1 1/8 inch in size and the bottom 1 1/4 inch in size. The compression ring and headset cover are also included. Quite heavy as the bearings are quite big.

During initial installation, I found that there is quite a big gap between the headset cover and the frame. The upper headset bearing is visible through the gap.

The installation is correct, as the compression ring rests on the top bearing.

After checking with the dealer, we realized that the height of the compression ring seems to be wrong. It seems to be too tall, causing a bigger gap between the headset cover and the frame. Functionally there is no problem, just that it does not look as nice, while water will get into the headset more easily.

The dealer sent over the correct compression ring that very same day, allowing me to continue with the installation.

With the correct compression ring that is flatter.

Now the headset cover matches nicely with the frame, with no big gap.

For frames with thru axles, the axles will usually come with the frame, as there are different axle lengths and thread pitches, so aftermarket axles may not be 100% compatible.

12 x 100/142 mm E-thru axles that are included with the Cervelo Aspero. As there are levers on both the front and rear axles, they are quite heavy at 129 grams in total.

The length and thread pitch of the thru axles are laser marked on the sides for easy reference.

The Cervelo Aspero fork has a Trail Mixer feature, which allows the trail of the bike to be adjusted forward or rearward by 5 mm. Adjusting the Trail Mixer itself it not that difficult, as only 2 bolts needs to be loosened to flip the Trail Mixer around.

However, the more troublesome part is moving the front brake caliper, as the front axle and thus disc rotor is in a different position between the forward and rearward axle setting. When the Trail Mixer is in the forward setting, just use the original brake adapter that is supplied with the Flat Mount brake caliper. In the forward setting, you can use 140 or 160 mm diameter rotors.

In my case, I chose to use the Trail Mixer in the rearward position, for more stability, especially with the smaller 650b wheels. Therefore, the brake caliper needs to be moved rearwards by 5 mm to match the rotor. A special Flat Mount brake adapter is included with the Cervelo Aspero, to move the brake caliper rearwards by 5 mm.

Special Flat Mount adapter, to be used when the Trail Mixer is used in the rearward position. Heavier than the thinner stock Flat Mount adapter.

This adapter only allows the use of 160 mm diameter disc rotors.

A new seat post is included with this Cervelo Aspero frameset, but I would prefer to use the Canyon VCLS suspension seat post, as it is more comfortable. However, not all bikes can use the VCLS seat post, as it needs a minimum exposed length for flexing. If the seat tube is too long or high, and if the rider is not tall enough, the VCLS seat post cannot be used.

On the Canyon, the seat tube is purposely made short, so that there is more exposed length for the VCLS seat post. My objective here is to find out whether the VCLS seat post can be used on the Cervelo Aspero or not.

This comparison is made more difficult by the fact that the Cervelo Aspero has a lower bottom bracket (78.5 mm drop) than the Canyon Endurace (75 mm drop), which means that putting the bikes side by side is not accurate as the bottom bracket height also affects the seat post height used by the rider.

The most accurate way is to measure the distance from the centre of the bottom bracket to the top edge of the seat tube, or maximum insertion line on the VCLS seat post.

Distance from centre of bottom bracket to top edge of seat tube is 462 mm. This is considered quite short.

At my normal seat post height setting, there is an additional 26 mm of insertion possible. The VCLS seat post cannot be inserted further as the flexing area cannot fit into the seat tube.

This means that the distance between the bottom bracket centre and the top edge of the seat tube can be a maximum of 462 + 26 = 488 mm. If the distance is longer, the seat post cannot be lowered enough to fit me.

Based on my measurement of the Size 51 Cervelo Aspero frame, the distance from bottom bracket centre to top edge of the seat tube is 500 mm.

Since the Cervelo Aspero frame has a seat tube that is too tall, I will not be able to use the Canyon VCLS seat post. That is a shame as it is a really nice suspension seat post.

In this case, I shall use the Cervelo SP19 seat post that is included with the Aspero frameset.

Cervelo SP19 carbon seat post, with a round diameter of 27.2 mm.

Minimum insertion length is only 70 mm, which is shorter than the usual 100 mm.

Seat post weight is just 188 grams, which is considered quite lightweight. Saves about 50 grams over the Canyon VCLS seat post.

One good thing about using the Cervelo SP19 seat post is that it is more lightweight. Another benefit is that I can install the internal Di2 battery inside the Cervelo seat post, instead of somewhere else on the frame.

On the Canyon Endurace, due to the VCLS seat post, the internal Di2 battery cannot be placed inside the seat post. Therefore there is a special Di2 battery holder inside the downtube of the bike frame. Now, since the Cervelo SP19 seat post is just a standard round seat post, I can install the internal Di2 battery inside the seat post. This is similar to how it is done on the Fabike C3.

Finally, I need a good saddle for this bike, and it needs to be lightweight. As you have seen above, the seat post is actually made by FSA, as seen from the FSA branding on the saddle rail clamps. Due to the design of the saddle rail clamps, carbon saddle rails are not compatible. Titanium rails will work though, and with just a small weight penalty (~20 grams) over the carbon rail version.

I already have a Selle Italia SLR Titanium saddle which was on the Canyon Endurace, but that saddle has a matching red colour, which does NOT match the Teal colour of the Cervelo Aspero frame. In order to avoid colour clashes, I decided to buy a new saddle of the same model, in a generic black and silver colour.

Selle Italia SLR Titanium saddle, lightweight and comfortable! Got it at a good discount, plus it is already tried and tested to fit me well.

Titanium rails to minimize the weight.

Just 142 grams!

With most of the miscellaneous parts of the Cervelo Aspero accounted for, we will move on to the other key parts, such as the wheelset and the components.

Friday, February 14, 2020

Cervelo Aspero: Fork

After taking a close look at the Cervelo Aspero frame in the previous blog post, let us now take a look at the front fork.

The Teal colour does not show up well in photos when using indoor lighting. Looks almost like a black fork.

Here is how the Teal colour should look like, with some glitter and paint specks visible.

There is no need to install a crown race as it is already integrated into the carbon steerer tube. Bottom steerer tube diameter is 1 1/2 inch for extra stiffness.

Hose entrance for the front brake hose, located on the left side fork leg.

Hose exit on the left fork leg, near the brake caliper mount area.

One of the main feature and key highlight of the Cervelo Aspero is the ability to adjust the trail of the bike. For a super detailed explanation about the amount of fork trail on a bike, refer to this excellent article.

The way that the Aspero adjusts the trail is by moving the front axle forward or rearward, relative to the fork. This is done by using a reversible dropout called the Trail Mixer, which can be set in the forward or rearward position. The trail difference between the two positions is 5 mm.

The theory is that for wheels with larger circumference (such as large 700c x 40 tires), the trail naturally increases, making it too stable and not so easily steered. In that case, the Trail Mixer is set to the forward position to reduce the trail and make it steer more easily.

On the other hand, if you are using smaller wheels (such as 700c x 25 or 650b x 43), the trail will be too small if you set it in the forward position. In this case, you should set the Trail Mixer to the rearward position, to increase the trail to make it more stable. Or, if you prefer a more agile bike, you can still set it in the forward position to reduce the trail.

For me, I will be using the rearward position, as my wheel sizes are relatively small (700c x 28 and 650b x 43), so I want more trail for more stability.

Trail Mixer is at the forward position, which reduces the trail.

The Trail Mixer is held in place by a small screw that clamps the Trail Mixer to the fork.

The slot is symmetrical,which allows the Trail Mixer to be swapped between the forward and rearward position simply by flipping it around.

Trail Mixer is made of aluminium, which also has the threads to match with the front thru axle.

Theoretically, it should be possible to swap the Trail Mixer parts between the left and right side. The thru axle lever is by default on the right side on the front fork, but for the rear, it is located at the left side. It would be neater and more convenient if both thru axle levers are located at the left side of the frame.

However, there is another problem that complicates this matter. The problem is that when the front hub axle is seated into the front fork, the hub axle hole does not line up properly with the hole on the Trail Mixer. This makes it difficult to insert the thru axle fully for tightening.

The hub axle hole is not concentric to the hole on the Trail Mixer, as the hub axle is unable to sit in further on the step of the fork inner surface. As all the tolerances are tight, a little offset is sufficient to cause this problem. What makes it more difficult is that there is some looseness between the Trail Mixer and the fork, which means that when I tighten the little bolt on the Trail Mixer, it will shift slightly.

Area circled in red shows the offset in concentricity between the hub axle and the Trail Mixer.

It took a lot of adjustments and fine tuning before I could insert the front thru axle through the Trail Mixer and hub axle, and tighten it to the other side of the Trail Mixer.

Finally, after lots of trial and error, I managed to align the Trail Mixer within the fork, such that the thru axle is able to be fully inserted. I did not want to realign the Trail Mixer again, which I why I used the default thru axle setting, with the front thru axle lever located on the right side of the frame.


Flat Mount disc brake caliper mounting. Seems like the surface is prepared properly to ensure that the brake caliper will rest properly on the fork.

Weight of the front fork with uncut steerer tube is 416 grams, which is a bit heavier than the 361 grams of the Canyon Endurace.

The Trail Mixer concept is good but it feels that it is not being done properly, as there is some difficulty in aligning the Trail Mixer to the front hub axle. There are some other issues which I discovered, which I will share in a later post after assembly is completed.

Friday, February 7, 2020

Fnhon DB11: Brake Levers and Brake Calipers

On the new Fnhon DB11 folding bike, I will be using hydraulic disc brakes, which is a big performance upgrade over the V-brakes used on the previous Dahon MuEX. Not only are hydraulic disc brakes more powerful, they work better in the rain, and does not dirty the rims with brake residue. I am a firm supporter of hydraulic disc brakes as they just work better.

However, there are also downsides to using hydraulic disc brakes. The initial set up is more troublesome, as you need to use brake fluid to bleed the brakes, instead of just installing the outer casing and inner cable. Also, the hydraulic brake system weighs more than a traditional cable operated brake system, mainly due to the addition of the disc brake rotors and stronger hubs, frame and fork.

I want to minimize the weight increase when I change from V-brakes to hydraulic disc brakes, which is why I decided to utilize high end, lightweight brake components.

As I am setting up a completely new brake system, I can choose freely between the different brands and types of brakes available on the market. In reality, there is only Magura or Shimano for me to choose from, as these two big brands use mineral oil, which I much prefer over other systems that use DOT fluid. For a detailed comparison between mineral oil and DOT fluid, you can check out this link.

The weight of the Magura MT8 SL is about the same as the XTR M9120, both weigh about 200 grams (brake lever + brake caliper). However, the Magura MT8 SL brake system costs over $100 more than the XTR, which itself is already expensive. Therefore, the XTR system was chosen, with the added benefit of being similar (setup, brake fluid, tools) to the brake systems on my other bikes.

XTR BL-M9120, which is the Trail spec instead of Race spec. Note the new I-Spec EV clamp design, which is supposed to stiffen up the brake lever due to multiple contact points with the handlebar.

The Trail spec has tool-less brake lever reach adjustment, which is something that I like. It also has Free Stroke adjustment, which the Race spec also lacks.

High brake lever stiffness is possible, due to the additional bracing point between the brake lever and the handlebar.

Servo Wave technology to increase the leverage ratio after pad contact, for increased brake power deeper into the stroke.

One side of the Trail spec brake lever weighs just 100 grams! The Race spec would have been even lighter.

Product specifications that I found online, showing the differences between BL-M9100 and BL-M9120. Note that the Clamp Bolt, Brake Lever and Master Cylinder use different materials.

With a pair of XTR BL-M9120 brake levers weighing just 200 grams, this setup will turn out to be very lightweight. If I had used the Race spec BL-M9100, the weight would be even lower, as the master cylinder would be made of magnesium instead of aluminium. 

I did more research and found that the actual weight (online information) of BL-M9100 is just 68 grams each! This will give a total weight of just 136 grams per pair of BL-M9100, 64 grams (32%) lighter than a pair of BL-M9120. Now I kind of regret my decision to get the Trail spec instead of the super lightweight Race spec.

Moving on, let's take a look at the brake calipers. Normally the Race type brake lever will be paired with lighter 2 piston brake calipers, while the Trail type brake lever is paired with powerful 4 piston brake calipers.

Depending on the purpose and usage, we can increase the brake power by using 4 piston brake calipers, or reduce some weight by using 2 piston brake calipers.

Previously, when I first tried hydraulic disc brakes on small wheeled bikes, I found that the brake power was a bit too high. That was on the Ascent Bolt mini velo which I tested, which were using basic MT200 brakes with 2 piston brake calipers. Therefore, for a similar type of bike (small wheel, similar purpose) such as this Fnhon DB11, a 2 piston brake caliper is more than enough, as the smaller wheels naturally increases the brake power compared to a bike with larger wheels.

On the other hand, the Bike Friday Haul-A-Day is a heavy cargo bike, which will need to have sufficient stopping power to slow down safely when rolling downhill with extra weight. Although it also has smaller 20" wheels that naturally increases the stopping power, I chose the more powerful Deore XT 4 piston brake calipers on that bike to further improve the stopping performance.

XTR BR-M9100 2 piston brake calipers

Looks very high quality, with the polished metal and anodized surface treatment.

Note that the hydraulic hose connects directly to the brake caliper with a connecting bolt, instead of using a banjo bolt like on most other MTB brake calipers.

The exit angle of the direct hose connection (at the back) seems to be ideal, which means that it should line up neatly along the frame. 

I prefer to connect the hose directly to the brake caliper, instead of using the banjo bolt. As previously explained, the banjo joint requires the hose to be factory prepared at the banjo end. Therefore, it is a bit more tricky to shorten the hose as it can only be done at the brake lever side. This is another reason for choosing this XTR brake caliper, as it is one of the few brake calipers to actually use a direct connection without a banjo. The next brake caliper with a direct connection is all the way down at Deore level, where the weight will be quite a bit heavier than this XTR brake caliper.

Brake pads with no fins for a bit of weight savings.

Brake caliper (inclusive of brake pads, 2x caliper fixing bolts, connecting bolt) weighs just 101 grams.

Titanium caliper fixing bolts, with an aluminium washer.

This pair of titanium bolts weigh just 5 grams. Every little bit counts when it is XTR grade.

Even the brake pads have a titanium backing to save a bit of weight, I certainly was not expecting this.

A pair of titanium brake pads plus spring weighs 13 grams. I don't have a chance yet to weigh standard non-finned brake pads so I am not sure how much lighter this is.

4 of the standard steel connecting bolts weigh 10 grams, which means about 2.5 grams each.

4x olives and 4x connecting pins don't register at all on my weighing scale. At low weights such as this, the weighing scale is not precise enough to give proper readings.

4950 mm of BH90 hydraulic brake hose weighs 99 grams, which works out nicely to be 1 gram per 50 mm of hose length.

In order to make it possible to bleed the brakes off the bike, I decided to measure the length of the hose required, by mounting the brake levers and brake calipers on the frame, and routing the hydraulic hose externally. This means not threading the hose through the cable guide holes on the frame. By doing so, once the brake lever + hose + brake caliper has been joined together with the correct hose length, I can remove the whole set from the bike for easy bleeding, away from the bike. This concept is the same as what I did on the Bike Friday Haul-A-Day. By doing so, it is possible to bleed the brakes more easily and also more thoroughly as compared to bleeding the brakes when on the bike.

Front brake kit with hose length 740 mm (without hydraulic fluid) weighs 217 grams.

Once filled with hydraulic fluid, the weight increases by 8 grams to 225 grams for the front brake kit (740 mm length).

Rear brake kit with hose length 1430 mm (without hydraulic fluid) weighs 230 grams.

Rear brake kit weight is 241 grams, once filled with hydraulic fluid.

As shown below, here are the standard disc brake mount dimensions for IS type of frame mount. Note that the distance is different for the front and rear mounts, as the rear mount is closer to the hub axle by about 10 mm. This 10 mm difference in radius corresponds to a rotor diameter difference of 20 mm (Eg. between 180 mm and 160 mm rotor), when the same adapter is used.

Standard specifications for front IS mount


Standard specifications for rear IS mount

We need a IS type to PM type adapter, so that the PM type brake caliper can be mounted to the IS mounts of the frame. Different adapters are used to match different rotor sizes.

In other words, a 180 mm adapter for the front would become a 160 mm adapter when it is mounted onto the rear mount.

Front 180 mm adapter = Rear 160 mm adapter
Front 160 mm adapter = Rear 140 mm adapter

On this bike, I will be using the smallest disc brake rotor that is possible, as the smaller wheels already mean a higher-than-normal brake power. Also, I want to minimize the weight of the bike, and smaller rotors will help.

At the front, I will use the smallest rotor and adapter, which will be 160 mm. There is no lightweight IS to PM adapter that will allow a smaller 140 mm diameter rotor to be used at the front, due to physical frame limitations. I have seen third party IS to PM adapter for 140 mm rotors, but it is very bulky and will defeat the purpose of running the smaller rotor to save weight.

This is when I would have preferred the non-standard disc brake mount used on the Bike Friday Haul-A-Day, where the front fork actually used the specifications for rear brake mounting. The result is that a smaller-than-usual rotor can be used at the front.

As for the rear brakes, using a front 160 mm adapter would mean that it becomes a rear 140 mm adapter. This would prove to be critical and absolutely necessary for clearance later on, as I will find out later during assembly. If I want to use a 160 mm rotor at the rear, then I will need to get a front 180 mm adapter or a rear 160 mm adapter, both of which are the same things.

To save a bit of weight from the adapter, I got the lightweight version of the IS to PM adapter, which is less bulky than the OEM version.

Lightweight XTR grade IS to PM adapter at the top, usual OEM version at the bottom.

This adapter with the 2 adapter fixing bolts weigh just 21 grams.

I will be using the same adapter type for both the front and rear brakes, and the result is a 160 mm front rotor and a 140 mm rear rotor. With the brakes settled, we can move on to the other parts of the bike, such as the wheelset and rotors.