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.

Good:

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.

Bad:

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.

Wahoo Kickr Core: Introduction

In normal times, indoor bicycle trainers are not hot sellers. They are usually used only when the weather makes it impossible or unpleasant to cycle outdoors, such as areas with cold winters.

However, amid the ongoing global pandemic, indoor bike trainers have surged in popularity. Due to the severe limitations on outdoor cycling (and most forms of outdoor activities), cyclists are finding ways to continue cycling indoors. This sudden surge in demand for bike trainers led to them being sold out everywhere, in stores or online.

In the first place, bike trainers are not items with high stock levels, as they move really slowly. Now, with many people looking to buy them, even stores with substantial stock (>10 units) will run out of stock very quickly.

I am also one of those who want to continue cycling indoors, which is why I found a way to make my Cervelo Aspero fit on the Minoura LR340 Bike Trainer. However, I am not a big fan of wheel-on-roller bike trainers, or in other words, dumb bike trainers. That is because there are various downsides to these kind of dumb trainers.

Disadvantages of dumb bike trainers, compared to direct drive bike trainers:

1) Noisy.

2) Heats up fast.

3) Gives off a burning smell from the heated tire rubber.

4) Very high wear rate on the tire (unless you use dedicated bike trainer tires).

5) Sheds rubber bits from the tire as it wears out.

6) Riding characteristics differ greatly from actual road riding as the rear wheel cannot freewheel properly or carry momentum.

The Minoura Thru Axle Adapter is just a temporary solution, while I find a better long term solution for a direct drive smart bike trainer. Although I tried to buy a direct drive bike trainer in early April, it was already too late, as there was no stock of direct drive bike trainers anywhere.

My only option was to place a pre-order and be patient. I was given an estimated delivery date of end May, which is the earliest date I could find. This is for one of the highest rated direct drive smart bike trainers, the Wahoo Kickr Core. This decision was no doubt helped by the super detailed review by DC Rainmaker.

The feature that really stood out for me was the low noise level of the trainer, which is really important for me. Being a direct drive type was also critical, in order for a more realistic ride. For more details, you can check out the review by DC Rainmaker, or read on below for a more simplified version.

This Wahoo Kickr Core actually arrived ahead of schedule, in the middle of May. I was expecting the delivery schedule to be delayed to June, due to the production and logistics difficulties around the world. It was a pleasant surprise to receive the Kickr Core early, as it means more time to use it!

The Wahoo Kickr Core is here! It is a big and heavy box.

As a direct drive bike trainer, it replaces the rear wheel of the bike, which I think is a great system.

You get lots of power cables, to fit the power sockets of every region.

In Singapore, this is what we need. The power adapter is shown on the left. Yes this smart trainer needs to be plugged in, unlike dumb trainers which are not powered.

Main trainer unit all wrapped up, as it still requires some assembly.

It is important to connect the smart trainer to the Wahoo app for some updates.

Here is the freehub body! Standard Shimano splines, for 11 speed road cassettes. The cassette is not included.

Here are the legs for the bike trainer. The long one attaches to the front, while the short one is attached to the rear.

Lots of small parts and adapters included, plus the manual.

4 bolts to attach the 2 legs to the main trainer unit.

The hole on the trainer legs are actually square holes, which is unusual.

The square hole matches to the square head of the bolt, to prevent rotation during tightening of the nuts.

Bolts are inserted from the bottom, and are tightened with a nylon lock nut on top.

The nuts are covered with a black plastic cap, for better appearance and to prevent rust due to sweat.

The adapters provided by Wahoo will cover most conventional bikes. The steel QR axle is also provided.

Self-explanatory graphics, very easy to understand. Adapts between 130/135 mm QR type, or 

142/148 x 12 mm thru axles. 148 mm means you can put your Boost spec MTB on this bike trainer!

As always, tighten the QR axle or thru axle fully and securely.

And here is the secret to the quiet operation of the Kickr Core. A new belt drive system that lowers the driving noise compared to previous models.

The cylinder with the arrows is the flywheel, and that is what makes this whole bike trainer so heavy.

Kickr Core assembled! Driving the freehub body will move the belt, which rotates the flywheel via a pulley ratio that makes the flywheel spin much faster than the cassette.

According to the manufacturers of direct drive bike trainers, a bigger flywheel is an advantage as it can replicate the road riding feel more realistically. However, this also makes the whole bike trainer really heavy, as there is a big flywheel attached to it. If you need to move the bike trainer around often, it will be quite inconvenient.

Wahoo Kickr Core weight as measured: 19 kg without cassette

I also checked out the freehub body, to determine the engagement angle. Normally a smaller engagement angle means a shorter lag time between pedaling and the wheel actually moving. However, it also depends a lot on the gear ratio and also the type of usage. For me, 15 degrees or less is sufficient for on-road riding, while for off-road riding, it needs to be less than 10 degrees.

The freehub on the Kickr Core has a 15 degree engagement angle, or 24 clicks per rotation of the freehub body. The actual points of engagement is unknown, but it is most probably 2 points of engagement, as this is usually sufficient for strength.

So far I have set up the Kickr Core, and it was easy. The adapters are easy to identify and swap. Next step is to install the cassette, attach a bike, and connect it to an app for some indoor riding! Watch for the next blog post where I will show how I attach my bikes to the Kickr Core.