Focus Paralane: Switching to 105 R7000 Power Meter

It was not long ago when I completed upgrading the Focus Paralane to a full Dura-Ace Di2 groupset. However, on that groupset, there was one component which is not from the latest R9200 groupset, and that is the left crank arm.

I was still using the older R9100 left crank arm with 4iiii power meter, as it is useful to have power readings even though I am not training with the help of a power meter.

When I was using the Dura-Ace R9100 2x11 speed crankset, the right and left crank arms were matched as a set. Then, when I changed to 12 speeds, I only swapped the right crank to R9200, leaving the left crank arm still as R9100 with power meter.

Now, I plan to install the unused R9100 crankset on another bike, and I would like to move the R9100 left crank arm with power meter over as well. Therefore, I need a left crank arm for the Focus Paralane.

I actually have many spare left crank arms, as I have two different left crank arm power meters, the R9100 and also a cheaper 105 R7000 version. In fact, the R7000 power meter was on the Focus Paralane previously, when it was a 1x11 speed setup.

The 105 R7000 left crank arm with power meter is currently on the Cervelo Aspero, but I think it would be more useful on the Focus Paralane, given that I ride it more often and on the road, where power readings are more useful than when riding on gravel.

This gives me a rare chance to have both the Dura-Ace R9100 and 105 R7000 power meter left crank arms off the bikes, for a side by side comparison.

105 R7000 crank arm on top, Dura-Ace R9100 crank arm below. 

They are both of 165 mm crank arm length.

Different surface treatment, and the R9100 crank arm looks more well used given that it has been in use since it was first installed on the Canyon Endurace.

Focus Paralane: Shimano 105 R7000 4iiii Power Meter

This Focus Paralane is basically a road bike with mudguards, as I want to commute in a fast and enjoyable way, not bogged down by a slow and heavy bike. Previously I was using the Fabike C3 as my commuting bike, which was a nice bike, but not very fast as the internal hub system adds some drag.

However, as I have tested, a chain drive system would work much better. I plan to run a front single drivetrain, as 11 speeds is more than enough for commuting, especially since there are no steep slopes along the way.

I planned to use an Ultegra crankset with a Wolf Tooth chain ring on this commuting bike. While collecting the components for the Focus Paralane, I came across a good deal for a power meter. In this case, it is a 4iiii left side power meter, very similar to the one I have on my Canyon Endurace (and now on the Cervelo Aspero).

The only difference is the crank arm that is used. Instead of using a Dura-Ace R9100 crank arm, this power meter that is on offer is using the 105 R7000 crank arm. It is basically half the price, since the 105 crank arm is much cheaper. I decided to get this 105 R7000 4iiii power meter, since it was a really good deal. Do I need it? No, but it is nice to have.

4iiii Precision Power Meter, more details in this post.

What you get is the 105 R7000 left side crank arm, with the power meter on it.

I have been switching over to 165 mm crank arms on my bikes, as I find it more comfortable than the standard 170 mm crank arms.

4iiii pod glued onto the back of the 105 crank arm.

The ANT+ code and serial number is here, in case I ever need it.

Weighs 199 grams, which is just 17 grams heavier than the Dura-Ace crank arm with power meter (182 grams). Why bother with Dura-Ace when this 105 crank arm is so much cheaper and has practically the same weight?

4iiii Power Meter weight: 9 grams

105 R7000 165 mm crank arm: 190 grams

Ultegra R8000 165 mm crank arm: 189 grams

Dura-Ace R9100 165 mm crank arm: 173 grams

There is only a tiny amount of weight difference between the left side crank arms of Dura-Ace, Ultegra and 105.

If you include the plastic crank arm fixing bolt, it adds 5 grams to the weight.

Since the 4iiii power meter only comes with the left side crank arm, I will still be using the Ultegra R8000 crank arm on the right side. This will give a different appearance between the drive and non-drive side.

However, I am OK with that, as both are a dark grey or black colour, so the difference is not that obvious. Beside, it is not possible to see both sides of the cranks at the same time, so it doesn't bother me. I just made sure that both sides have the same crank arm lengths of 165 mm.

This gives me another spare left side crankarm from the R8000 crankset, in addition to the previous spare left side crank arm from R9100 crankset. I wonder if the crankarm works well as a door handle?

Canyon Endurace: 4iiii Precision Power Meter on Dura-Ace R9100 Crankarm

In recent months, I decided to get a powermeter to use on my bike, in order to gauge my effort numerically. Although I can generally feel the resistance, and roughly tell whether it is a "strong headwind" or me having an off-form day, it is more accurate to have a powermeter to show the actual wattage used during the ride.

The speedometer can tell you the actual speed, but it cannot indicate how much effort is used to travel at that speed. When you are moving fast, it can be due to you pedaling hard, or it is just the benefit of having a good tailwind. On the other hand, when you feel that you are moving slowly even though you are putting in considerable effort, it can be due to tiredness or something else (such as slight uphill, slight headwind or rubbing brakes, for example).

With a powermeter, it will be easy to tell the power required to sustain a certain speed. Most people use powermeters for training purposes, so that they can gauge their effort and stick to their training plan. However, I only intend to use it to collect some data, not for training.

There are many brands and types of powermeters available, such as pedal type, chainring type, rear hub type, crank arm type, etc. I decided to get a simple one-sided powermeter, as I don't need the accuracy of a dual-sided powermeter.

For one sided power meter, Stages and 4iiii are the more popular ones available, with a similar cost. Stages came out with the left crank arm powermeter first, but they have been having some quality issues from what I heard. Therefore I decided to get the 4iiii power meter which is also a left crank arm type.

Installation is as straightforward as it can be, as you basically just replace your existing left crank arm with the one from the 4iiii factory, which has already been fitted and calibrated with the strain gauges on the left crank arm. It is also possible to send in your existing left crank arm for them to install the power meter, but that may be too much trouble especially if you are located halfway around the world.

4iiii Powermeter, which claims to be the lightest left side powermeter.

Set up instructions are printed on the inside of the box.

As I plan to install the powermeter on the Canyon Endurace road bike, I got a crankarm that matches the groupset. As already done earlier, the Dura-Ace R9100/9170 groupset has already been installed on the bike, therefore I need to get the model that uses the Dura-Ace R9100 left side crankarm.

When I ordered the powermeter, the crankarm was not in stock, so I had to wait about a month before I received it. Here it is!

Dura-Ace R9100 left side crankarm

Super glossy surface finishing as seen here

4iiii sensor glued to the back of the crankarm. Most of the bulk is actually taken up by the coin type battery.

Relatively low profile, should clear most chainstays, unless your bike has a special chainstay profile.

165mm length to match the right side crankarm

Battery cover taken off to show the battery. Easily replaceable when it runs out of power.

Weighs 182 grams including the sensor! The regular crankarm without the sensor weighs 173 grams, so the sensor weighs just 9 grams. Super lightweight powermeter indeed.

Sufficient clearance between the sensor and the chainstay. 

Installation is easy, just use this crankarm with powermeter instead of the normal one that comes with the crankset. After that, link it to your cycle computer via ANT+, then calibrate and zero the powermeter as per the instructions.

From the data, I can see that it takes roughly 130 watts to pedal at 30km/h on the Canyon Endurace, on flat ground and no wind, and without drafting. To go at 40km/h will require about twice the power! I can only sustain this power over a short stretch.

Pro cyclists regularly cycle at over 40km/h, which means that their power output will normally be 200 watts or more. This is already accounting for the drafting effect when riding in a group.

In a way, having this data helps you judge your pedaling effort and how much more you need to go faster. For example, if I want to sustain 35km/h instead of 30km/h, I will need to raise my power output from 130 watts to 180 watts! That is a big jump and it will take a lot of training to sustain this power for a meaningful amount of time.

However, if you are drafting, you can save about 30% of your energy if you do it correctly. Therefore, if you are drafting behind somebody, you can go at 35km/h while using about 130 watts. In other words, if you can output 130 watts, you can ride at 30km/h solo, or 35km/h when drafting.

The best part about this powermeter is that it is super low maintenance and fuss free. The battery lasts a long time, and there is no need to calibrate or pair it every time you ride. It is also very lightweight and small sized, and is hardly visible on the bike.