Sunday, August 9, 2020

Cervelo Aspero: 700C vs 650B Wheel Size Comparison - Part 2

In the previous post about the Cervelo Aspero, I introduced my new gravel tire, the WTB Venture 47 650B Road Plus. Being a wider tire than the previous Panaracer Gravelking SK 650B x 43 mm tire, there are some differences in size and dimensions.

Let's start with the wheel size comparison between the Venture 47 tire and the GravelKing SK tire. A wider tire is usually taller in profile as well, so I would expect the Venture 47 to have an overall tire diameter that is slightly larger than the 43 mm wide GravelKing SK.

Both tires will be mounted on the Hunt 650B Adventure Carbon Disc wheelset, which has an internal rim width of 24 mm. This is pretty much the standard rim width (in first half of year 2020) for gravel wheelsets.

WTB Venture 47 on the left, GravelKing SK 43 on the right. The shade of brown on the sidewall is different.

The Venture 47 which is at the back is slightly larger in diameter.

This is due to the taller tire profile of the Venture 47, which can be seen by comparing the axle height difference as well.

Close up look at the different tire tread profile. Venture 47 on the left has nice big lugs at the side for good cornering traction.

Width difference of 47 mm vs 43 mm is noticeable as well.

In short, the wider Venture 47 tire is also larger in diameter as well. This is actually a good thing, we I found that the 43 mm wide GravelKing SK was a bit undersized in terms of tire diameter, compared to standard 700C tires.

Another comparison to be done is with the standard road setup wheelset, which has Continental GP4000 28 mm tires mounted on the Reynolds Assault Limited Edition carbon wheelset. Apparently a 700C x 28 mm tire should have roughly the same tire diameter as a 650B x 47 mm tire.

I think the calculations may have been something like this, where the rim diameter is added to the tire width/height to get the overall diameter. Not sure how accurate or true this is.

700C x 28 = 622 + 28 + 28 = 678 mm
650B x 47 = 584 + 47 + 47 = 678 mm

584 mm and 622 mm are the ETRTO rim diameter of 650B and 700C rims respectively.

Road wheelset vs new gravel wheelset

Road wheelset shown at the back is still larger than the 650B gravel wheelset.

Tire tread pattern is totally different!

Huge difference in tire width as well. Actual tire width of the road tire on the left is 32 mm, vs 47 mm on the right.

Here are some numerical data of the actual measured tire diameters, with the different tires and different wheelsets.

Continental GP4000 700C x 28 (actual 32 mm): 695 mm diameter
Panaracer GravelKing SK 650B x 43: 677 mm diameter
WTB Venture 47 650B x 47: 681 mm diameter

There is still a 14 mm diameter difference (7 mm radial difference) between the road wheelset and the gravel wheelset (with Venture 47 tires), which is a noticeable amount. I would say that instead of the gravel tires being undersized, it is the GP4000 tires being oversized, as the actual width is 32 mm instead of the rated 28 mm.

I suspect that this older generation of GP4000 tires were designed on narrower 15-17 mm wide road rims, so when installed on the wider 21 mm Reynolds wheelset, the actual tire width balloons out from 28 mm to 32 mm.

As a result, the BB to ground clearance is also affected by the different tire diameters.

BB to ground distance for GP4000 700C x 28 (actual 32 mm): 268 mm
BB to ground distance for GravelKing SK (650B x 43): 259 mm
BB to ground distance for Venture 47 (650B x 47): 261 mm

7 mm less ground clearance for the Venture 47 gravel wheelset, compared to the GP4000 road wheelset.

No wonder it is confusing for consumers to select the correct tire and wheels, as the actual width and actual diameter can vary so much, depending on your combination of tire and rim which is practically infinite.

Sunday, August 2, 2020

Wahoo Kickr Core: Usage

Carrying on from the first part of the Wahoo Kick Core introduction, this post will show the direct drive smart bike trainer in more detail.

In the first part, the bike trainer was assembled, but the cassette has not been installed yet. The axle adapters also need to be selected and installed, in order to mount the bike. Let's see how this is done.

Without any adapter in place. This recessed area will hold the selected axle adapter.

With the 12 mm thru axle adapter installed, for 142 mm width. If this adapter is reversed, it will be for 148 mm width, which is for boost type MTB.

On the other side, the 12 mm thru axle adapter is installed. This same adapter is used regardless of whether the bike OLD is 142 or 148 mm.

With the cassette installed! I selected a Shimano 105 CS-R7000 11-28T 11 speed cassette, as it is cheaper and does not wear out as quickly as a titanium Dura-Ace cassette. Any additional weight is irrelevant on the bike trainer.

View of the bike trainer with the cassette installed.

When plugged in, the indicator lights will turn on. This bike trainer can connect via ANT+ or Bluetooth.

Comparing the axle height from the ground, between the bike trainer and the actual bike. I'm surprised to find that the actual height of the bike trainer is slightly lower than the actual bike!

Cervelo Aspero installed on the bike trainer! I placed a spacer between the rear brake pads, so that the piston does not pop out if I accidentally press the brake lever with no rotor in place.

Due to some differences between the bicycle wheel freehub and the bike trainer freehub, there may be a need to adjust the rear derailleur index position when switching between the wheel and the trainer. With a Di2 rear derailleur it is easy, you just need to take note of how many clicks to adjust it. With a mechanical rear derailleur this can also be done, you just need to take note of how many clicks is needed to adjust the barrel adjuster on the rear derailleur.

When the bike is installed on the bike trainer, the RD position needs to be offset outwards for proper indexing. This will vary between bikes.

Full view of the bike on the bike trainer. A front wheel block is not necessary as the rear axle height is almost the same as the front axle height.

A direct drive bike trainer uses the same drivetrain on the bike, just with a different cassette that is on the bike trainer.

The good thing about the bike trainer is that it can be switched between different bikes easily, provided the axle requirements are standard (130/135 mm QR or 142/148 mm E thru), and the number of speeds are the same.

Therefore, it is easy to put on the Dahon MuSP folding bike as well, as it has a 11 speed drivetrain too.

1x11 speed Dahon MuSP on the Wahoo Kickr Core bike trainer. The axle adapter needs to be switched to the 130 mm QR type.

Closer view of the bike mounted on the bike trainer. The rear wheel is higher up than usual due to the different wheel sizes.

The rear axle to ground distance is measured to be about 33 cm.

Using the front wheel block and a suitable book, the front axle is propped up to roughly the same height as the rear axle. I think a difference of +/- 1 cm should be fine.

Getting ready for a ride on Zwift! Water bottles and a towel is a must, while a good fan is strongly recommended.

The Wahoo Kickr Core provides the controllable power meter and also the cadence. Heart rate is via my Samsung Galaxy watch which can transmit heart rate over Bluetooth. Both the watch and bike trainer connects to my phone.

After a good tough ride! If you don't already know, a Zwift ride is usually tougher than outdoor rides as you can't rest at all.

Check out the gradient! This is pretty much my max effort as my heart rate is already so high.

Another one of the weekly West Coast Riders virtual ride.

Other than joining others on virtual rides, it is also possible to ride structured workouts on Zwift. What it means is to choose one of the pre-determined workouts, where the power and cadence targets are set for you. You can adjust the targets according to your ability. Once done, you can use the ERG mode to control the training effort.

ERG mode is only available on a smart bike trainer, where the software can control the bike trainer to vary the resistance level. Power is basically a function of cadence and pedaling force. You can achieve the same power either by pedaling hard at a slow cadence, or pedaling lightly at a fast cadence.

What ERG mode does is to adjust the resistance such that your power output is constant. For example, if your target power is 175 watts, the bike trainer will automatically provide a certain amount of resistance in response to your cadence. Usually there is a cadence target as well, so you just need to focus on achieving the required cadence, and the resistance will be adjusted for you automatically to hit the power target. There is no need to shift gears in ERG mode.

Training in ERG mode. Note the stable power output at the bottom of the screen. And the horrible 16% gradient as well.

The only way to get such perfect power graphs is via ERG mode. It is very good for consistent training as there is a target to work towards.

So far I am loving the Wahoo Kickr Core, as it works as well as advertised. I shall list out some of the good and bad of this bike trainer.

1) Quiet. Slight whirring sound, but easily drowned out by the drivetrain sound or the fan. Much quieter than the previous Minoura LR340 bike trainer.
2) Smooth and balanced flywheel rotation, for a freewheeling effect.
3) Easy to connect to my phone and Zwift via Bluetooth.
4) ERG mode is super awesome for consistent training purposes.
5) QR and thru axle adapters makes it possible to switch bikes easily.
6) Works as both a power meter and also cadence sensor.
7) Enables riding regardless of weather.
8) Does not wear out your tire, although it still wears out your drivetrain.

1) Heavy at 19 kg. But this is due to the heavy flywheel which is apparently necessary to replicate realistic road feel.
2) Expensive at SGD 1,399.

Wednesday, July 22, 2020

Cervelo Aspero: WTB Venture 47 650B Gravel Tires

As you already know, I like gravel riding, as it allows me to explore unpaved roads anytime I come across them. Previously I have tried the 700C x 32 mm Panaracer GravelKing SK tires on the Canyon Endurace, followed by the 650B x 43 mm version on the Cervelo Aspero gravel bike.

The GravelKing SK tires are nice and fast rolling, even on the roads. On light gravel trails they are fantastic as they roll really well. However, they tend to lose grip when cornering fast on loose surfaces. The result is a sliding rear end that can feel disconcerting if you are not expecting it or ready for it. This is due to the absence of raised side knobs on the tires. 

Also, the 650B x 43 mm tires were true to size, measuring 43 mm on the Hunt 650B Adventure Carbon Disc wheelset. I had purposely chosen the smaller 43 mm version, as I was expecting it to get wider once installed on the 24 mm wide Hunt rims. Since it didn't expand as I expected, I was not maximizing the tire clearance on the Cervelo Aspero frame. I would have gotten the wider 48 mm version if I knew it would be true to size.

So, I have two main reasons to change the gravel tires. The first being that the GravelKing SK does not corner as well as I like, while the second reason is because it is not maximizing the tire width available on the Aspero frame.

The Aspero frame has a maximum frame clearance of 57 mm when using 650B tires. With a recommended 4 mm clearance on either side of the tire, the maximum 650B tire width allowed is 49 mm.

After reading many tire reviews, it seems that the WTB Venture 47 650B tires may just be the tire that I am looking for. Let's take a closer look at these tires.

WTB Venture 47 650B tires. Of course I must get the brown sidewall version for the gravel look.

WTB calls 650B tires as Road Plus tires. The highlight are the rows of outer knobs for extra grip during cornering.

Tightly packed centreline for fast rolling, with lots of soft flexible ribs for grip on rough surfaces, and large side knobs for cornering traction.

Due to some quirk of manufacturing, they are labeled as 44-584 tires, which is different from the 47 mm tires that they are advertised as.

These tires are heavy! At 550 grams, they are 300 grams more than a typical 28 mm wide road bike tire. This is due to having much more rubber and width on the tire.

When mounted on the wheels, this is the actual tire profile. Ideally, only the centreline portion will touch the road when riding on smooth paved surfaces.

Lots of flexible ribs for extra grip on loose and uneven terrain.

Actual tire width is just over 47 mm when measured across the knobs. This leaves about 5 mm of tire clearance on either side of the tires.

If you measure without the knobs, it is about 45 mm wide.

WTB + Hunt! Tire height is a lot taller than the shallow Hunt rims.

Venture 47 650B Road Plus is the model of this WTB tire.

Both tires installed onto the Hunt wheelset. With inner tubes for now.

Looking good! Very gravel-like appearance.

Front wheel weighs a massive 1538 grams, inclusive of wheel, tire, inner tube and rotor.

Rear wheel weighs exactly 2 kg, including the wheel, tire, tube, rotor and also the 11-34T cassette.

As you can see, having a gravel wheelset with wide gravel tires is heavy, mainly due to the heavier tires and larger inner tube required. Any weight savings from a smaller 650B wheelset is totally cancelled out by the tire weight. On the other hand, a MTB tire weighs even more, so a gravel tire that weighs 550 grams seems lightweight in comparison.

6 mm side clearance between the front tire and the front fork. Lots of clearance in the radial direction too.

Lots of clearance at the rear seat stays as well.

Another view of the tire clearance at the rear seat stays.

5 mm tire clearance at the chain stay area, which is the area on the frame that has the smallest clearance. I'm very comfortable with this amount of clearance.

View of the rear wheel with WTB Venture 47 650B tires.

Here is how the whole bike looks with the wider and more aggressive Venture 47 tires!

View from the drivetrain side. I really like how the change of wheelset totally transforms the bike's character.

The tires in its natural habitat! Works super well on loose gravel and sand as seen here.

With these new tires, I am able to corner faster with more confidence, as the pronounced side knobs are effective in providing traction during cornering.

A downside of having lots of flexible ribs is that lots of small stones are collected between the ribs. Doesn't bother me too much, as they tend to fall out on their own after some riding.

Full list of component weights, updated with these WTB Venture 47 tires.

Cervelo Aspero in road bike setup is 7.6 kg without pedals, which is decent but not really lightweight. My personal benchmark is still the Canyon Endurace, which weighs just 7 kg without pedals. When converted to the gravel setup, it adds almost 700 grams, due to the heavier tires, inner tubes and cassette.

Cervelo Aspero road setup without pedals: 7.6 kg

Cervelo Aspero road setup with pedals: 8.0 kg

Cervelo Aspero gravel setup without pedals: 8.3 kg

Cervelo Aspero gravel setup with pedals: 8.7 kg

The gravel setup is now approximately 200 grams more than the previous setup with 43 mm wide GravelKing SK tires. I guess it is the price to pay for wider tires that weigh even more.

On the other hand, the off-road capabilities have been greatly enhanced. With wider tires, I can run even lower tire pressure, which enhances off-road grip. The taller side knobs of the Venture 47 tires also improves the cornering traction. In fact, this gravel setup should have no problem tackling mild MTB trails, such as Track 15 or some stretches of the Bukit Timah MTB trail.