Cervelo Aspero: Panaracer GravelKing SK 650B Tires

Since I will be using 650B wheels on the Cervelo Aspero, I will also need new 650B gravel tires. The whole idea of getting the Cervelo Aspero frameset is to enable wider gravel tires to be used. This will allow lower pressures to be run, which will improve grip and comfort when riding on off-road terrain. If you have the correct setup and riding skills, you can even ride off-road on single track trails using the Cervelo Aspero. I tried that on the Canyon Endurace and it was really fun!

I was really happy with the Panaracer GravelKing SK gravel tires that I used on the Canyon Endurace. Those were 700C tires with a claimed width of 32 mm. Therefore, I decided to get the same type of tires, but in a wider but smaller diameter 650B size. This time, I can fit wider tires since the Cervelo Aspero has a much bigger tire clearance.

Previously, when I installed the 32 mm wide (claimed) GravelKing SK tires on the DT Swiss G 1800 wheelset, the actual tire width became 35 mm, which is 3 mm wider than expected. This is probably due to the relatively wide internal rim width of 24 mm.

This time, I will also be installing the same brand of tire, on the Hunt 650B Adventure Carbon Disc wheelset which also has an internal rim width of 24 mm. Therefore, I am expecting the tire width to expand by about 3 mm as well.

The Cervelo Aspero has a frame clearance of about 57 mm when using 650B wheels. Given the recommended 4 mm of clearance between the tire and frame on both sides, the maximum tire width that can fit safely is about 49 mm.

I wanted to use the widest tire possible, but without going too close to the frame. The area with the tightest tire clearance is almost always between the chain stays, just behind the bottom bracket.

Panaracer GravelKing SK 650B tire comes in two tire widths, 1.75" and 1.9", which roughly translates to 43 mm wide and 48 mm wide. However, if I use choose the 48 mm width tire, it may expand by 3 mm, making it 51 mm wide and too big to fit safely into the frame.

Therefore, I decided to get the 43 mm wide version, as I am expecting it to expand by 3 mm, making it about 46 mm wide. At this point in time (January 2020), the 43 mm version was still very new, and it was very difficult to get hold of it, until I found it available on one website. If you are in Singapore, you can probably get it from The Bike Settlement, which is the official distributor of Panaracer tires.

New Panaracer GravelKing SK tires, in 650B size!

It has 5 rows of knobs, instead of 3 as found on the narrower 700C version.

Nice and wide size! 650B is the same as 27.5", which means that MTB 27.5" rims and tires are interchangeable with 650B. Official ETRTO size is 43-584.

Lots of knobs and "hair" on each knob of the tire.

Each tire weighs 460 grams, which is about 200 grams more than a typical Continental GP4000 700x28C road tire. This is due to much more rubber from the width and knobs.

650B inner tubes are also necessary. These inner tubes can be used for wider MTB tires as well.

Each Schwalbe SV21 inner tube weighs 199 grams, which is again additional weight over slimmer road inner tubes.

By now, you can see that using smaller 650B wheels will not give you any weight savings, as the heavier tires and inner tubes more than compensates for any weight reduction from the smaller rim and shorter spokes.

Shape of the tire after being installed and inflated. Lots of knobs for grip!

However, the actual width of the tire is 43 mm, which is the same as claimed.

Official tire width is 43 mm, but no one knows which rim width was used.

To my surprise, the actual tire width and the claimed width is the same at 43 mm. There was no additional tire width created by mounting on the 24 mm (internal) wide rim. I was quite disappointed as I expected the tire width to become wider, as I wanted to run tires that were as wide as possible.

Perhaps, the previous 700C tire width was judged on narrower rims, while these new 650B tires are judged on wider rims. That could be a reason why the actual width was the same as claimed. If I had gotten the wider 48 mm Panaracer GravelKing SK tires, they might have turned out to be exactly 48 mm, which would fulfill my plan to have the widest possible tires.

Regardless, since I already have the tires, I will put them on and give it a try. Here is how it looks when mounted on the Hunt wheelset!

Panaracer GravelKing SK 650B tires installed on the Hunt 650B Adventure Carbon Disc wheelset.

Front wheel + tire + inner tube weighs 1336 grams.

Rear wheel + tire + inner tube weighs 1451 grams.

Deore XT MT800 160 mm disc rotors installed on the front wheel.

MT800 160 mm disc rotors and HG800 11-34T 11 speed cassette installed on the rear wheel.

Both wheels are ready to go, since the disc rotors and cassette have been installed.

Complete front wheel after adding the MT800 disc rotor weighs 1448 grams, about 200 grams more than the road front wheel.

Complete rear wheel after adding the MT800 disc rotor and cassette weighs 1900 grams, about 300 grams more than the road rear wheel.

Note that this 650B gravel wheelset is LIGHTER than the 700C gravel wheelset which I used on the Canyon Endurace, as the lighter carbon rims have managed to offset the heavier and wider 650B tires. Of course, the gravel wheelset is still about 500 grams heavier than the Reynolds carbon road wheelset, which I cannot avoid. The only way to reduce weight from the gravel wheelset is to use narrower and lighter tires, which defeats my objective of running wide tires at low pressure.

Just for fun, I installed the new Hunt 650B front wheel on the Canyon Endurace, just to see how it looks like.

43 mm wide, 650B tires on the Canyon Endurace front fork.

Still plenty of radial clearance, as the wheel diameter is smaller. However, there is practically no clearance at both sides of the tire.

The wide 650B rear wheel definitely cannot fit onto the Canyon Endurace, since there was already very little clearance when using the previous 35 mm wide tires. Of course, it is not safe to ride the Canyon Endurace with this 43 mm wide front tire, as there is no frame clearance.

You may have noticed that there is a difference in wheel diameter between this 650B wheelset and previous 700C road and gravel wheelsets. In the next post, a detailed comparison will be done to compare the sizes of these wheelsets.

Cervelo Aspero: Hunt 650B Adventure Carbon Disc Wheelset

The heart of every good bike is a good wheelset. My main objective for getting a new Cervelo Aspero to replace the Canyon Endurace is the much larger frame clearance for wider tires. This is due to the generous tire clearances at the fork and also at the frame, more specifically, at the chain stays.

For gravel riding, 650b wheels are becoming more popular. 650b wheels have a smaller diameter than traditional 700c road wheels, if the tire width is the same. The ETRTO rim diameter is also different.

700c wheels have a ETRTO rim diameter of 622 mm, which is actually the same as 29" MTB wheels. 650b wheels have a ETRTO rim diameter of 584 mm, which is the same as 27.5" MTB wheels. However, the point of smaller 650b wheels is not to have an overall smaller wheel size.

Rather, the idea of using smaller 650b rims is to allow a wider tire to be installed, such that the final tire circumference is similar to that of a 700c tire. This is due to the natural fact that when the tire width increases, the tire wall also becomes taller, resulting in a larger tire diameter.

Generally speaking, the tire diameter of a 700x28c tire is similar to that of a 650x47b tire. This is just a very rough estimate, as the exact size depends a lot on the tire manufacturer, width of rim used, and tire pressure.

Wheel size comparison. Picture from Salsa Cycles.

The final objective of this 650b wheel size is to allow a much wider tire to be used, without increasing the tire diameter too much. If you merely increased the tire width for a 700c tire, such as from 28 mm (typical road bike) to 43 mm, the diameter will also increase substantially, making the tire diameter really big and not compatible with many bike frames.

However, if you step down the rim size to 650b, you can install a much wider 650b tire (47 mm for example), and still maintain a similar tire outer diameter as a 700x28c tire. This makes it a bit easier to design the frame, as it is usually possible to widen the chain stays or fork for a wider tire clearance, than for a larger tire diameter, where the only option is to increase the chain stay length.

The Cervelo Aspero will match nicely with 650b or 700c wheels, as it has good tire clearance. Plus, it also has the Trail Mixer feature, which will allow you to adjust the trail of the bike to ensure good riding characteristics regardless of wheel size and diameter.

One downside of using wide 650b tires is that they are heavy, compared to 700c tires. Although 650b tires are smaller in diameter, they gain weight from the much larger width, plus the addition of knobs for grip on off-road surfaces. For example, a Continental GP4000 700x28c tire is about 260 grams, while the Panaracer GravelKing SK 650x43b tires weigh 470 grams, a massive 210 gram increase.

Not only does it make the overall bike heavier, the weight is added at the worst place possible, which is at the outermost part of the rotating wheels, which will increase the rotational inertia greatly. This will make acceleration more sluggish as you need to overcome the inertia when starting off.

Check out this detailed comparison between 650b and 700c wheels!

In order to cancel out some of the additional tire weight, I decided to get a lightweight set of 650b wheels, so as to minimize the weight increase. After much comparison, I decided that the Hunt 650b Adventure Carbon Disc wheelset is a good balance of weight, cost and quality.

You can get the wheelset directly from the Hunt website, with free shipping. Or, you can get it directly from the Singapore local dealer, which is OneBike Asia, as they work with Hunt to bring in the wheelsets. The prices are the same, either from the shop or online. In this case it is a better idea to get from the shop, as they can offer after sales service and also other advice.

Hunt 650b Adventure Carbon Disc wheelset. Plain graphics suit me just fine.

Spare spokes and spoke keys are included. So are the tubeless valves and Centerlock to 6 bolt rotor adapters.

External rim width is 30 mm. Tubeless rim tape is already pre-installed.

Internal rim width is 24 mm, just as advertised.

Rim height is just 22 mm, which helps to keep the wheelset weight low.

Carbon rim surface is smooth and looks good.

Hookless rims means that it is best suited for low pressure tires.

Maximum tire pressure allowed for different tire widths, to prevent the tires from blowing off the hookless rims.

Even then, these are the maximum tire pressures allowed. Actual tire pressure used will and should be lower.

Simple Hunt logo. Bladed spokes are used on this wheelset.

Standard J-bend spokes, with Centerlock disc rotor interface.

Hub axle end caps can be removed easily for maintenance. They can also be swapped to quick release axle types, but the adapters are not included.

Road 11 speed freehub body, with a ceramic coating on the freehub body to prevent damage by the cassette.

This freehub has an engagement angle of just 5 degrees, or 72 engagement per round. My guess is that there are 36 ratchet teeth in this hub, with 2 sets of 3 pawls. With the 2 sets of pawls offset by 5 degrees, it doubles the engagement from 36 (if all 6 pawls engage at the same time) to 72 (3 pawls engage at any one time).

Front wheel weighs 657 grams, which I think is really lightweight!

The rear wheel weighs 780 grams, which is also considered lightweight.

This gives a total wheelset weight of just 1437 grams, which is really lightweight! It is quite close to the claimed weight of 1425 gram. Hopefully this lightweight wheelset will help to offset some of the additional tire weight.

Curiously enough, the wheelset also comes with Centerlock rotor lock rings. Normally lock rings are included with the disc rotor, not the wheelset. Is there a reason for including these lock rings?

I noticed that these lock rings are of the external serration type, which means that they need to be assembled with a Hollowtech II bottom bracket tool. This is different from the more common internal serration type, which uses a cassette lock ring tool. Either way, there is no need for a special tool as it uses existing tools.

External serration lock rings are usually used on hubs with a larger axle diameter, such as the 15 mm thru axle type used on MTB front wheels. In those cases, the hub axle is too big for the cassette lock ring tool to be used. The lock ring thread on the hub is the same, regardless of internal or external type of lock ring.

Two external serration type lock rings are included with the wheelset.

For some strange reason, these two lock rings are different. The one on the left is a thinner steel lock ring, while the one of the right is a thicker but lighter aluminium lock ring.

As you can see, the thickness of the serration area is different between the aluminium and steel lock rings.

Just for fun, I found that the steel lock ring is 21 grams. 

The aluminium lock ring is 11 grams, which is a lot lighter.

Both are aluminium lock rings, but the internal serration type on the left is just 8 grams, still lighter than the external serration type.

My initial thought was that the external serration lock rings are provided because the Hunt wheelset hubs have a larger diameter axle, which will prevent the internal serration type from being used. However, upon testing, I found that an internal serration type of lock ring works just fine.

Internal serration type lock ring used on the Hunt hubs.

No problem with the insertion of the cassette lock ring tool to tighten the internal serration lock ring.

Therefore, I could not understand the reason for Hunt to provide the lock rings, as they are not necessary at all.

However, after taking a look at the instructions for the Centerlock to 6 bolt disc rotor adapter, I realized the reason. The external serration lock ring is needed if the adapter is used.

Also, upon further research, I think the flatter steel lock ring is needed for the front hub, to prevent interference between the lock ring and the fork leg.

Hunt wheels instructions state that if the Centerlock to 6 bolt adapter is used, the Hunt-provided lock ring should be used.

Anyway, I will just be using the internal serration lock ring that comes with the Centerlock disc rotor.

With the new 650b wheelset ready, it is time to check out the new 650b tires as well! That will be a story for the next post.

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.