We’ve tested and ridden both motors several times before. But we decided to do a new comparison of these motors as they’ve changed quite a bit since they were launched.
Riding with maximum assistance, the CX motor was a tad twitchy to control on technical trails. It immediately got a reputation for being a powerful motor that responded well to high pedaling frequencies. It felt strong while riding at motor cut-off speed.
In 2021, Bosch introduced the Smart System refresh. The motor appeared unaltered as looks and specs remained the same. Smart System brought things like new batteries, a GPS module plus new displays and remotes with Bluetooth support.
But that was not all. I was surprised to discover the CX gen 4 motor was now much easier to control in Turbo mode. The motor felt so pleasant and well behaved while remaining just as powerful.
Two and a half years later, Shimano introduced the refreshed EP801. The old EP8 had earned a reputation for not being among the most reliable. So, when Shimano needed to add hardware for automatic shifting to the motor, they took the opportunity improve it.
The EP801 is still an 85 Nm motor, but Shimano claims peak power is up from 500 to 600 W. And that can be felt. The EP8 has become more powerful and inspiring to ride when pedaling above 90 rpm. Motor cut-off speed has been increased to match the Bosch CX and most others. Thankfully, the Shimano motor remains just as generous and easy to control on slippery trails. And it seems durability is improved too.
We decided to do an uphill test in the lowest gear. Both bikes have 29er wheels and a 34-51t gear ratio. The hill is about 100 m long with 20 m of elevation, and we rode it at 60, 80 and 100 cadence. We measured how hard the rider pedaled using Garmin Rally pedals. If the rider puts less force to the pedals, we know the motor has done more of the work as both bikes completed the segment in the same time with similar cadence.
Finally, we did a short trail loop of just under one kilometer. The loop starts with a section of smooth surface where we briefly went above cut-off speed, before entering rocky and rooty trails. There is little difference in elevation. We went all out on this test and we only measured time. We tried measuring power input, but there was just too much variation in the average power caused by things like gear choice and time above motor cut-off. It’s a less precise test, but it’s interesting to see if we could find huge, significant differences.
The EP801 is greatly improved. It feels like a very complete motor. The CX is still great, but one could argue the slightly older and slightly heavier Bosch has a bit of catching up to do.
Changes to the Bosch Performance CX
Our first ride on the Bosch Performance CX gen 4 happened well into 2019. This nice and compact motor weighs just under 3 kg and was rated at 75 Nm. It didn’t take long before Bosch dropped a software update for the Performance CX, taking it up to 85 Nm.Riding with maximum assistance, the CX motor was a tad twitchy to control on technical trails. It immediately got a reputation for being a powerful motor that responded well to high pedaling frequencies. It felt strong while riding at motor cut-off speed.
In 2021, Bosch introduced the Smart System refresh. The motor appeared unaltered as looks and specs remained the same. Smart System brought things like new batteries, a GPS module plus new displays and remotes with Bluetooth support.
But that was not all. I was surprised to discover the CX gen 4 motor was now much easier to control in Turbo mode. The motor felt so pleasant and well behaved while remaining just as powerful.
Changes to the Shimano EP8
Late 2020, Shimano launched the EP8 (EP800). This was a more compact and lighter motor at just under 2.7 kg. It was a very well-behaved and could be ridden on wet and rocky trails with maximum assistance. The EP8 felt very strong at lower speed and we could ride steep hills with little effort. But as we pedaled faster and approached cut-off speed, this motor didn’t feel as fast. It turned out the EP8 would cut the assistance about 1 kph earlier than the Bosch, and the EP8 felt less powerful at high cadence.Two and a half years later, Shimano introduced the refreshed EP801. The old EP8 had earned a reputation for not being among the most reliable. So, when Shimano needed to add hardware for automatic shifting to the motor, they took the opportunity improve it.
The EP801 is still an 85 Nm motor, but Shimano claims peak power is up from 500 to 600 W. And that can be felt. The EP8 has become more powerful and inspiring to ride when pedaling above 90 rpm. Motor cut-off speed has been increased to match the Bosch CX and most others. Thankfully, the Shimano motor remains just as generous and easy to control on slippery trails. And it seems durability is improved too.
Both have improved significantly
Based on previous experience, the EP8 was stronger pedaling below 80 rpm while the Bosch was stronger above 80. And when going on group rides and riding at around cut-off speed on the transport sections, it was more work riding the EP8 as motor power cut earlier. But now, all of this has changed! They’re equally as fast on the transport sections, and they’re both very good on technical trails with maximum assistance.About the test
So, how do we determine which is stronger? There are two sides to this, peak power and power amplification. If we ride uphill in a low gear while pedaling slowly, we’re not getting maximum power. This is a test of power amplification. If we push hard, we’ll be limited by the peak power. It’s interesting testing both. Before we start, we make sure that both motors are set to the highest power settings in the app, Both bikes were set to the highest assistance mode.We decided to do an uphill test in the lowest gear. Both bikes have 29er wheels and a 34-51t gear ratio. The hill is about 100 m long with 20 m of elevation, and we rode it at 60, 80 and 100 cadence. We measured how hard the rider pedaled using Garmin Rally pedals. If the rider puts less force to the pedals, we know the motor has done more of the work as both bikes completed the segment in the same time with similar cadence.
Finally, we did a short trail loop of just under one kilometer. The loop starts with a section of smooth surface where we briefly went above cut-off speed, before entering rocky and rooty trails. There is little difference in elevation. We went all out on this test and we only measured time. We tried measuring power input, but there was just too much variation in the average power caused by things like gear choice and time above motor cut-off. It’s a less precise test, but it’s interesting to see if we could find huge, significant differences.
|
|
|
Uphill test
60 cadence results
Riding with a cadence of 60 felt much easier on the EP8 (801), and the numbers reflected this. We had to pedal 95 W on the CX, that’s almost 50% more than the EP8 which required 65 W. For real life riding, it doesn't make much difference though, it took little effort going up this steep hill with both motors.80 cadence results
Based on previous experience, we expected the motors to be similar when pedaling 80 rpm. But the difference still was huge, the EP8 required an average rider input of 71 W while the CX needed 115 W.100 cadence results
Spinning as fast as 100 rpm, we actually recorded the exact same power input of 154 W for both motors. This was surprising as the CX used to be more powerful when pedaling faster.Short trail loop results
When riding as fast as possible on trails with little elevation, there wasn’t much of a difference between them. It was difficult achieving a high cadence when pedaling over chunky and bumpy terrain, so the EP8 had an advantage as it’s more generous at lower cadence. But when we got to spin the pedals at 100+ rpm, the CX felt stronger. According to Strava, the CX clocked in at 1 min 42 seconds, a whole second quicker than the EP8. It’s hard to argue the difference is significant. For riding hard, the Bosch felt fast, and the Shimano felt much improved over the old EP800.Which motor is more efficient?
Shimano has a reputation of being less efficient and draining the battery quickly. But is that due to efficiency? This test shows the EP8 offers more support, which means power consumption will be higher. It might not be less efficient; it just does more of the work.Conclusion
The EP8 won the lower cadence tests because of the high power-amplification, it’s rated at 400% compared to the 340% for Bosch. When pedaling faster and harder, both motors reached their peak power of about 600 W and performance was similar.The EP801 is greatly improved. It feels like a very complete motor. The CX is still great, but one could argue the slightly older and slightly heavier Bosch has a bit of catching up to do.
