Cervelo Aspero: Revised Wheelset and Component Specifications

Finally, I think I have nailed down my ideal tire selection for the Cervelo Aspero, for both road and gravel configurations.

For fast road riding, I will use the Ascent Bikes Zenith Elite, which is a lightweight carbon wheelset with a 50 mm rim height. Paired with fast rolling Continental GP5000 tires, it rides really well!

As for gravel grinding, the wide and comfortable WTB Venture 47 650B tires are used, on a lightweight Hunt 650B Adventure Carbon Disc wheelset. The large air volume offers great suspension and traction on rough and loose off-road surfaces.

Both wheelsets and tires are different from what I initially started with, as I had to experiment to find out what works and what does not.

Initially, during the previous wheelset comparison (Part 2), I found that the 650B tire diameter (WTB Venture 47) was quite a bit smaller than the 700C tire diameter (GP4000). This was different from what I expected, as I have read that the tire diameter of a 700C x 28 mm tire should be similar to a 650B x 47 mm tire. 

I thought that maybe there was a mistake, as there was no way for a wide and tall 650B tire to make up for the difference in rim diameter (622 vs 584 mm, for 700C and 650B respectively).

However, after trying the new GP5000 tires, I found that it was due to the oversized GP4000 tires, which actually made the tire diameter of the road wheelset too big. The 650B tire and wheelset was actually the correct size, not too small.

Therefore, now I have the chance to compare the tire diameter of all three wheelsets.

1) GP4000 tire on Reynolds Assault wheelset (21 mm internal rim width).

2) GP5000 tire on Ascent Bikes Zenith Elite wheelset (17 mm internal rim width).

3) Venture 47 tire on Hunt 650B Adventure Carbon Disc wheelset (24 mm internal rim width).

I will leave out the Panaracer GravelKing SK 650B x 43 mm tire from this comparison, to make it less confusing. If you wish to know more about that, can check out Part 1 of the wheelset comparison.

GP4000 tire on Reynolds Assault wheelset, tire diameter is 695 mm.

GP5000 tire on Zenith Elite wheelset, tire diameter is 686 mm. This is 9 mm smaller than the previous road wheelset.

Venture 47 650B tire on Hunt 650B wheelset, tire diameter is 681 mm. This is 5 mm smaller than the GP5000 wheelset, instead of 14 mm smaller than the GP4000 wheelset.

From this, we can conclude that the GP4000 tires create an oversized tire diameter. Based on Continental's own estimates, a 700C x 28 mm tire should have a standard tire diameter of 686 mm. This is spot on when the GP5000 28 mm tire is mounted on the Zenith Elite wheelset.

Therefore, the final conclusion is that the GP5000 wheelset and Venture 47 wheelset have a tire diameter difference of just 5 mm, which is quite acceptable. The difference in BB height or ground clearance would be half the tire diameter difference, which is negligible to me. I think this is the ideal situation, where the BB clearance, toe overlap clearance and also trail is consistent across these two wheelsets.

Zenith Elite road wheelset with GP5000 tires. All black with high profile rims.

Road vs gravel wheelset. Very different look and capabilities, to suit different riding modes.

Road wheelset has high profile rims and a short tire sidewall, while the gravel wheelset is completely opposite, with a low profile rim and a tall tire sidewall.

Axle height comparison shows them to be almost the same, with the road wheelset just slightly higher up.

Tire diameter is almost the same, as shown from this picture.

Tire width is very different! 27.5 mm vs 47 mm, almost a 20 mm difference in width, and many times difference in air volume.

Gravel front wheel (including tire, sealant, rotor) is 1449 grams.

The road front wheel is almost 300 grams less at just 1163 grams.

Gravel rear wheel is 1895 grams, including tire, sealant, rotor and 11-34T cassette.

The road rear wheel is 380 grams less, at just 1515 grams with 11-30T cassette.

Full and final (maybe not) Cervelo Aspero specifications

Overall weight of the road bike setup without pedals is just 7.4 kg, which is a very nice weight for a hydraulic disc brake road bike.

When converted to the gravel setup, the heavier wheelset adds almost 700 grams to the bike weight, giving a gravel mode bike weight of 8.1 kg without pedals.

Due to the slightly different hub dimensions, the rear disc brake rotor will rub slightly on the brake pad for one of the wheels. The solution is to add a Centerlock rotor shim on the rear hub that has the rotor in a more inward position. The idea is to push out the rotor slightly, so that it is in the same position as on the other rear hub.

Centerlock rotor shim installed on the Zenith Elite rear hub. The shim is 0.25 mm thick.

The shim is sandwiched between the rotor and the hub, pushing the rotor position more outwards.

After adding the shim, the rotor position between the road and gravel wheelsets are almost the same, which makes it possible to adjust the brake caliper, so that the wheelset swap is seamless with no brake pad rubbing on either wheelset.

Finally, some pictures of the Cervelo Aspero, in road and gravel modes!

Looks 100% like a road bike, with the high profile carbon wheelset.

The Ascent Bikes Zenith Elite wheelset rolls really well and suits this bike nicely.

WTB Venture 47 tires on the Hunt 650B wheelset makes this a true gravel bike, capable of tackling all but the most technical terrains.

I used it like a MTB, riding on actual MTB trails. Not the best bike for the job, but it was a lot of fun!

At this point, I would say that quite a fair bit of time was spent choosing and testing the different wheelsets and tires, and I am happy to finally find a combination that I like. Just by swapping wheelsets, the Cervelo Aspero transforms from a pure road bike to a great gravel bike that can take on gravel and light trails with ease.

Is there any other bike that can handle this road and gravel mode transformation as seamlessly? Maybe there is, but I bet the paintwork is not as unique and beautiful as the Teal on this Aspero!

Cervelo Aspero: Road vs Gravel Setup

As you already know by now, my Cervelo Aspero is a dual use bike, which means that it can be both a road bike and a gravel bike. This only requires a wheelset swap, as already demonstrated successfully on the Canyon Endurace.

Although the Cervelo Aspero is designed as a fast gravel bike, there is no reason why it cannot be a good road bike as well. All it needs is a fast set of high profile carbon road wheels and smooth rolling road tires. The frame geometry is very similar to that of an endurance road bike, which means it is not too upright for fast rides. Even though the frameset is quite a bit heavier than the Canyon Endurace, it is acceptable as it is not meant to be a pure climbing bike.

The road wheelset is the same old Reynolds Assault Limited Edition Disc wheelset that came stock with the Canyon Endurace, with Continental GP4000 28 mm wide tires. The actual tire width is about 32 mm due to the wide 21 mm internal rim width. This is a good wheelset that I like very much.

On the other hand, the gravel wheelset that I will use on the Aspero is the new Hunt 650B Adventure Carbon Disc wheelset, with 43 mm wide Panaracer GravelKing SK tires. Although the previous DT Swiss G 1800 gravel wheelset was good, it is for 700C tires, which is not what I want on the Aspero. Instead, I want to take maximum advantage of the big tire clearance on the Aspero, which is why I will use 650B wheels and wide tires.

As shown below, the road wheelset and gravel wheelset are different, which means that I do not need to compromise a single wheelset and tire to fit both road and gravel riding. The road wheelset can be optimized for fast road riding, while the gravel wheelset will be optimized for comfort and traction during off-road riding.

650B wheels are visibly smaller than the 700C wheels. The taller 650B tire is not enough to make up for the difference in rim diameter.

Cassette and Rotor Comparison

Road wheels use a Dura-Ace 11-30T cassette and a Dura-Ace RT900 160 mm diameter disc rotor.

Gravel wheels use a HG800 11-34T cassette and a Deore XT RT800 disc rotor, also 160 mm diameter.

Front Wheel Comparison

Road front wheel, with high profile rim and road tires.

Gravel front wheel, with a smaller 650B low profile rim, but high volume gravel tires.

It is necessary to use the same size of disc brake rotors and number of speeds on the cassette, if you plan to swap wheels like this. Remember, the idea is to make it as fuss-free as possible to convert between a road and gravel bike setup, with just a wheelset change. No adjustment should be needed.

On both wheelsets, the rotor is located at almost the same position, and I was able to setup the brake calipers to accommodate that. Therefore, there is no brake rotor rubbing when swapping between these two wheelsets.


Front Fork Tire Clearance Comparison

Lots of tire clearance at the fork around the 700C road bike tire. This frame can accept up to 700Cx42 mm wide tires.

Lots of clearance radially, when using the smaller diameter 650Bx43 mm tire.

Rear Wheel Setup Comparison

Road rear wheel

Road rear wheel with 11-30T cassette, using the GRX rear derailleur.

Gravel rear wheel with 11-34T cassette, also using the same GRX rear derailleur. There is no need to adjust the rear derailleur setting after swapping wheels.

Rear Chain Stay and Seat Stay Clearance Comparison

Still plenty of tire clearance at the seat stay area, around the wide gravel tires. There will be even more clearance when the road tires are used.

Still lots of clearance around the rear road tire, along the seat tube and the chain stays.

For the gravel tire, there is more clearance with the seat tube due to the smaller tire diameter, but lesser clearance with the chain stays as the gravel tire is wider.

In the picture above, notice that the 4iiii power meter on the left side crank arm manages to clear the frame. There is actually a healthy amount of clearance with the left side chain stay. In fact, there is more clearance than on the Canyon Endurace frame (shown below).

Small clearance between the left side chain stay and the power meter, on the Canyon Endurace.

Initially I thought that the left side chain stay is pushed outwards due to the BBright construction. However, later I realized that it is actually the same as the standard press fit BB construction. At the same time, the left side chain stay also needs to be moved outwards to give wider tire clearance. In summary, the Cervelo Aspero can accommodate wide tires, and still have enough clearance for a left crank arm power meter!

Non drive side view of the road setup

Non drive side view of the gravel setup.

Drive side view of the road setup

Drive side view of the gravel setup

As you can see from the pictures, only the wheelset is changed between the road setup and the gravel setup. Visually it looks quite different, especially the tires. However, the drivetrain is almost completely the same, except for the cassette.

Due to the different tire diameter, the clearance between the bottom bracket and the ground is also different. The gravel setup has lesser ground clearance due to the smaller tire diameter.

There is a diameter difference of 16 mm between these two tires. Therefore, the radial difference is 8 mm. This 8 mm will be the difference in axle height from the ground, and also the bottom bracket distance from the ground. Tire deflection under rider's load is not accounted for in this case.

BB to ground distance for Continental GP4000 road tires (700C x 28): 268 mm
BB to ground distance for Panaracer GravelKing SK gravel tires (650B x 43): 260 mm

The ground clearance of 260 mm may seem to be too low, but it does not give me any problems. I don't encounter pedal strikes when leaning over on gravel or on smooth tarmac. This is likely helped by my usage of 165 mm crank arms, which are 5 mm shorter than the more common 170 mm crank arm length.

Cervelo Aspero: 700C vs 650B Wheel Size Comparison - Part 1

Before I tried gravel riding, there was no need to consider wheel size or tire width. Basically, a road bike setup means using a 700C x 25 or 28 mm tire. The tire diameter or width is just what it is, there is no concern if the tire ends up a bit wider or narrower than claimed, or even a bit bigger or smaller in diameter.

However, when I first used a gravel setup on the Canyon Endurace, I found that depending on the tire width, the tire diameter will also be affected significantly, especially if the tire width differs a lot. This can be a problem, as a bike is designed around a nominal wheel size, with only a small variance allowed. If the wheel size differs too much, it affects the geometry of the bike.

Crank clearance with the ground will be reduced if the tire diameter is smaller. Also, the trail of the bike will be reduced with a smaller wheel size, which can cause instability.

If the tire diameter is larger, the usual problem is frame or fork clearance, but the bigger issue is a slower handling bike due to larger trail from the larger tire size. This may be good or bad depending on your desired purpose.

In this case, it is difficult for the bike frame designer to optimize for a single wheel size, if it needs to accommodate a wide range of tire diameters, from small 700C x 23 to large 700C x 43 mm, for example.

Which is why the Cervelo Aspero has a Trail Mixer on the fork which allows the trail value of the bike to be adjusted, depending on the wheel size and also your preference for a more agile or more stable bike.

I will not go through the explanation again on why I chose 650B wheels and tires, you can read about it in my previous posts.

DT Swiss G 1800 Spline DB 25 Wheelset
Panaracer GravelKing SK 700C x 32 Tires

Hunt 650B Adventure Carbon Disc Wheelset
Panaracer GravelKing SK 650B x 43 Tires

Before I compare the new 650B wheelset, I will compare the wheels used previously on the Canyon Endurace. That would be the Reynolds Assault carbon wheelset for the road setup, and the DT Swiss G 1800 wheelset for the gravel setup. Both are 700C wheels.

The Reynolds Assault wheelset is equipped with Continental GP4000 700C x 28 tires, but the actual tire width is almost 32 mm. This is due to the relatively wide internal rim width of 21 mm.

The DT Swiss G 1800 wheelset is equipped with Panaracer GravelKing SK 700C x 32 tires, with an actual tire width of 35 mm. This rim has an internal width of 24 mm.

Rim diameter looks almost similar, with the gravel wheelset being just a little big larger.

Close up look at the different tire tread patterns.

Tire diameter is very similar.

In this case, if the tire diameter is almost the same, swapping between the wheelsets will not cause significant differences in ride geometry. This was the case on the Canyon Endurace.

Moving on to the new Hunt 650B wheelset, the rim diameter is smaller, but the tire will add back some of the diameter by having a taller sidewall. A 700C rim has an outer diameter of 622 mm, while a 650B rim has an outer diameter of 584 mm. This is a difference of 38 mm, which means 19 mm on either side. If a 650B tire is to have the same outer diameter as a 700C tire, the side wall needs to be 19 mm taller, which is a huge difference.

650B x 43 mm tire on the left, 700C x 32C tire (actual 35 mm) on the right. The diameter difference is quite obvious.

The 650B wheelset on the right has a smaller diameter, as seen from the difference in axle height. This will also be the difference in bottom bracket or crank arm clearance.

Another view showing the difference in tire diameter.

Using a long thru axle to align the centre of the hubs, the difference in radius can be measured more accurately.

650B tire has a gap with the ground. Multiply this gap by 2 and you get the diameter difference.

Using a 10 mm Allen key as a gauge, there is still a tiny bit of clearance. I would say that the gap is about 11 mm.

Other than the diameter difference, there is a big tire width difference as well. The wider 650B tire on the right has 5 rows of small knobs instead of 3.

43 mm width on the left, versus 35 mm (actual) width on the right. This 8 mm width difference is quite obvious.

There is some difference in sidewall height, as the 650B tire on the left will have a taller side wall as it is wider. The height of the brown sidewall area is about the same, but the black sidewall area is much taller on the 650B tire.

Finally, let's also compare the 700C road wheelset with the new 650B gravel wheelset. These are the two wheelsets that I will use on the Cervelo Aspero. I will explain more about the road and gravel setup in a later post.

Hunt 650B wheelset on the left, for gravel riding. Reynolds Assault 700C wheelset on the right for road riding.

Significant difference in tire diameter between these two wheelsets.

Another view of the different tire diameter. Despite the wider tire width, the 650B tire does not add enough tire height to come close to the 700C tire diameter.

Difference in axle height, which is about 8 mm.

Big difference in tire width and tread pattern. 32 mm tire width vs 43 mm tire width.

Comparison of the tire sidewall height. The 650B tire is taller with much more volume, but not enough to make up for the smaller rim diameter.

In summary, here are the tire diameters as measured, and also the difference in BB to ground distance (which is calculated as half the difference in tire diameter).

Continental GP4000 700C x 28 (actual 32): 695 mm diameter
Panaracer GravelKing SK 700C x 32 (actual 35): 699 mm diameter
Panaracer GravelKing SK 650B x 43: 677 mm diameter

On Cervelo Aspero (Size 51)
BB to ground distance for Continental GP4000 (700C x 28): 268 mm
BB to ground distance for GravelKing SK (700C x 32): 270 mm
BB to ground distance for GravelKing SK (650B x 43): 259 mm

The differences between the 700C road and 700C gravel tires are small, while there is a big difference between the 700C road and 650B gravel tire. What does this mean?

Swapping from the 700C road wheelset to the 650B gravel wheelset will lower the bike by about 9 mm. That is 9 mm less crank arm clearance. Not sure if pedal strike will be an issue, as it has even lesser ground clearance compared to my other bikes.

On the plus side, a lower centre of gravity will help in cornering and descending at speed. A smaller tire diameter also means a lower trail value, which increases agility. Is increased agility good or bad for a gravel bike? This is up for debate, as increased agility can allow you to tackle twisty trails more easily, but also make a speedy descent less stable.

Regardless, the proof of the ride quality will require actual riding. Whether good or not, I will have to use the tires to see if it is suitable for my usage.

From left to right: GP4000 28 mm, GravelKing 43 mm, GravelKing 32 mm

The 650B wheelset is the junior here, having a smaller diameter than the other two.

This concludes the first part of this comparison, which is between these three tires. Later on, in Part 2, there will be an additional tire added to this comparison, stay tuned!