Shimano Steps eP8 question

BigG · Aug 24, 2023

Hello all
i ride a recumbent trike with an ep8 motor.
Each time I start riding and the clutch/motor engages, likewise when I move over the 25km cut out i get a notchy feel through the cranks like they’re slipping a couple of degrees through their range of movement. And whenever the motor engages and disengages I get a squeaking noise. There is a little lateral movement of The crank arms however I don’t believe this is an issue
I’ve also ridden a Shimano STEPS 6001 and a 6010 which have a similar issue, but much much less prominent, and without the squeaking noise.
just wondering a) if anyone else experiences the same thing, if this is a Shimano characteristic And b) if there is a solution.
the motor has been replaced twice under warranty for the issue.
thanks in advance.
G

A.D. · Aug 25, 2023

While you described the noise as a squeak, I did find this online...

Motor Rattle
I remember dealing with a rattling noise when riding the EP8-equipped bike for the first ride article, but I was too focused on other impressions to dig deeper. On my next ride after the article was published it became clear when rolling down nothing more than a short fire road transition that the distinct noise was coming from the motor.

The noise is best described as a metallic rattle, similar to chain slap on bikes without chainstay protector. It's also very similar to Bosch's Gen 4 motor rattling, but maybe even at a higher frequency. Once you hear it, you cannot unhear it and it's simply annoying.

Here is Shimano's official statement to the questions of what the reason for the rattling noise is, and if they are working on a fix:

The new EP8 drive unit provides incredibly quiet assistance under pedal load. However, when coasting on rough terrain the unloaded system can exhibit a normal clicking sound that may be detectable to the rider. The clicking sound has no effect on the function or durability of the drive unit.

EP8 delivers significant performance improvements with higher peak torque, greater range, lower driving noise, better heat resistance, and reduced drag. These metrics are balanced with other important priorities such as durability and overall ride experience, with the best combination of key benefits ultimately resulting in a minor noise being detectable under specific riding conditions.

Shimano works diligently to deliver the best overall product experience and will continue to listen to rider feedback as we strive for continual improvement of our product line.—Shimano

In my mind, the noise generated by the motor when coasting should have been deemed as unacceptable (I feel the same way about Bosch's approach).

From having tested two EP8's, one embedded in a carbon and one in an aluminum front triangle, the pitch and intensity of the noise might change slightly from frame to frame (the same as we've seen with Bosch), and of course I cannot speak for every motor that will be equipped, but colleagues have confirmed that they've experienced the same issue. While we didn't get a clear explanation on what is happening inside the motor, I assume it's a similar cause as found with Bosch, where the gears are moved slightly by the bike kinematic's chain pull or vibrations caused by uneven ground when there is no load on the motor. So while it might not cause any technical issues, it's still annoying.

Source: https://m.pinkbike.com/news/review-shimano-steps-ep8-2021.html
Click to expand...

So he may be describing something entirely different. However, just the fact yours has been replaced under warranty would lead me to believe Shimano thinks its's doing something it should not be doing.

Log in or Sign up

Shimano Steps eP8 question

BigG

A.D. #1 Custodian

Share This Page

Log in or Sign up

Shimano Steps eP8 question

Thread Tools

BigG

A.D. #1 Custodian

Share This Page