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This is my Magene P505 spider power meter review.
I’ve been using and testing it for the last couple of weeks. I compared its data with Saris H3 smart trainer and Favero Assioma DUO pedal power meter.
P505 is a decent spider power meter considering its price. You can buy it here. However, it has some minor flaws.
Learn more about them below.
Magene P505 Summary
Here is a summary of the main features, my findings, and the tech specs of the Magene P505 spider power meter.
- P505 can measure left and right balance and pedaling smoothness
- Auto zero-offset
- Multiple colored stickers included
- Affordable price
- Pairing with the Magene app doesn’t always work
- 2-year warranty
- Claimed accuracy: ±1.5%
- Claimed battery life: 200h (rechargeable)
- Compatibility: 4-arm or 5-arm chainrings
- Active temperature compensation: Yes
- Connectivity: ANT+, BLE
- Weight: 110g
Who Is Magene P505 for?
Magene P505 spider power meter is for riders looking for an affordable spider power meter without sacrificing too much data accuracy*.
*Skip to the accuracy tests section for more info.
It’s suitable for beginners and average cyclists who look for advanced features like L/R leg balance or pedal smoothness.
Magene P505 Unboxing
P505 is sold in multiple options. The compatible chainrings are:
- P505-S1108/R110X/S1103: Shimano 110BCD 4-arm chainrings, and 5-arm chainrings of SRAM, ROTOR, FSA, etc.
- P505-S1078: SRAM 107BCD chainring
And the compatible crank arms:
- P505-S1108 / S1078: SRAM 8-bolt crank arm (with SRAM Red AXS, Force AXS, Red 22, Quarq, etc.)
- P505-S1103: SRAM 3-bolt crank arm (with SRAM Force 22, Rival 22, S-900, etc.)
- P505-R110X: ROTOR Aldhu, Vegast etc. 45-tooth crank arm
Because I have a Shimano groupset, I opted for the S1108 version.
The power meter comes in a bright orange box. It includes the spider, charger, and colored stickers.
Magene P505 Installation
The biggest downside of spider power meters is their compatibility and installation. It’s not as straightforward as the installation of power meter pedals.
You also need a compatible crankset that I didn’t have. I had to buy SRAM Force D1 DUB, SRAM DUB BB386 bottom bracket, and an SRAM 8-screw set.
I visited my friend who runs a bike store to help me replace the BB and install the power meter. I also needed free hands to take some pictures, haha.
Throughout the installation, we (luckily) didn’t experience any issues. Everything went smoothly. We just had to adjust the front derailleur to ensure smooth shifting.
Once we installed the power meter, I paired it with my phone using the Magene app.
The Magene app showed the power meter almost immediately. Then I had to fill out my email address where I received the activation code. Finally, I completed the pairing process by submitting it.
However, during further use of the power meter, I noticed that the app doesn’t always connect to it. Even when I followed the instructions like turn off/on Bluetooth, the app showed it as not connected.
Magene P505 Features & Benefits
One of the things that surprised me about Magene P505 was the auto zero-offset. It is pretty handy because you don’t have to think about it, and the power meter will set it automatically once you start pedaling.
Data geeks will appreciate advanced measurements like the L/R leg balance. I was pretty surprised when I found out my L/R balance was 55/45. My left leg is about 1 cm longer than the right leg, so I guess this explains the disbalance.
The pedal smoothness data are interesting and valuable if you plan to improve your pedaling technique. However, I don’t have ambitions to pedal smoothly as pros, so they are “just” interesting for me.
Like most of today’s power meters, P505 offers ANT+ and BLE connectivity so that you can connect it with indoor cycling apps and cycling GPS units. I tried to connect it with Zwift, TrainerRoad, ROUVY, and Wahoo ELEMNT ROAM, and everything worked without issues.
Magene P505 Accuracy Tests
To better understand the P505 accuracy, I did multiple tests indoors and outdoors.
For outdoors testing, I compared them with the Favero Assioma DUO pedal power meter. I use them as a benchmark for most of my accuracy tests.
I used Wahoo ELEMNT ROAM for recording data from Favero Assioma DUO, Wahoo ELEMNT BOLT for Magene P505, and indoor cycling apps for Saris H3.
Indoor Test #1 (ERG Mode)
Here are the results from testing the ERG mode of the Saris H3 that are also valid for this test. As you can see, all three power sources are almost on point with each other.
And here is the cadence. Also accurate from all sources.
Indoor Test #2 (Freeride)
Below is the indoor freeride of the Pienza route from Wahoo RGT. Assioma DUO and P505 are close to each other (except for the maximum power). H3 spiked at the beginning of the ride.
The cadence chart shows multiple drops of the Saris H3 cadence readings. P505 is again on pair with Assiomas.
Indoor Test #3 (Race)
And the last one is a Zwift race. Unfortunately, I had to crop the first 30 seconds because my connection dropped right at the beginning of the race. Therefore, Zwift didn’t capture the data from Saris H3. The lack of data from the trainer would cause larger average deviations.
The cadence was, again, on point.
Indoors, Magene P505 performed pretty well. So what about the outdoors?
For outside tests, I didn’t create any specific workouts. Instead, I used two head units (Wahoo ELEMNT ROAM and Wahoo ELEMNT BOLT) to record the data of a few rides.
Outdoor Test #1 (Long Group Ride)
Here are the results of the first group ride. Note that the empty spaces are breaks for food and enjoying nice views.
The average power was within 1% of accuracy. P505 struggled with maximum power and read about 35W higher power.
The following cadence chart doesn’t show cadence drops caused by the connection or power meter but drops when I stop pedaling.
Outdoor Test #2 (Short Solo Ride)
The following picture shows the data from my solo ride, where I made multiple 30×30s high/low power efforts. Again, P505 overcalculated my maximum power. The deviation from the average power was also higher (almost 2%), but we are talking a few watts here.
Again, no problems with cadence.
P505 is pretty accurate during lower and mid-range power efforts. However, it struggles with estimating the maximum efforts and usually overestimates my power.
Other Things to Consider Before Purchase
Magene is a relatively young brand with not as much experience with power meter development as established power meter brands.
I read in a few reviews that they sometimes struggle with releasing firmware updates to fix bugs and other issues.
But, they seem to be pretty responsive to customers’ feedback and take things seriously. They want to make their products more accessible to average cyclists, but sometimes they struggle to ensure their products are on point (you can watch this video from GPLama for more details on Magene P325 CS).
I’ve been using the P505 power meter for a few weeks, so I can’t comment on its long-term reliability. Will it stand out the test of time? We will see. If you have the P505 for a longer period, share your experience in the comments.
Magene Fitness FAQ
Magene P505 is a relatively affordable spider power meter suitable for beginners or people on a tight budget.
Except for the standard power + cadence, you also get advanced data like your L/R balance and pedal smoothness measurements.
Based on my testing, P505 is accurate and consistent in low to mid-range power. However, high power efforts like sprints are not too accurate and deviate by about 5% from Assioma DUO.
It also often struggles to connect with the Magene mobile app. Hopefully, they will sort it out with future updates.
In short, if you are looking for an affordable spider power meter with minor flaws, Magene P505 is worth your consideration.
The product for this review was kindly provided by the manufacturer. This did not influence my overall verdict or my opinion about the product.