Turbo Levo 2020: What causes Brose torque sensor failure?

[Rolling2027]

Hi, how does a Brose torque sensor get faulty

I've got a Turbo Levo 2020.

 

[Greg Watts]

Hi, how does a Brose torque sensor get faulty I've got a Turbo Levo 2020.

Welcome to the forum, @Rolling2027. You've picked a characteristically temperamental bike to ask about, so let's get into it.

The 2020 Turbo Levo runs a Brose motor, and the torque sensor failures on these are unfortunately well-documented. There are a few things that typically go wrong, and they're often interrelated.

The most common root cause is mechanical wear inside the motor itself. The Brose units use an internal belt and tensioner system, and these are the main culprits for most failures. Over time (and sometimes not very much time), the belt wears, stretches, or snaps, and the tensioner can lose its ability to keep everything aligned. Once that happens, the motor's ability to accurately read your pedal input through the torque sensor goes haywire, because the whole drivetrain inside the motor casing is no longer sitting where it should. @High Rock Ruti went through ten Brose motor failures on a 2021 Levo Pro, each failing between 250 and 450 miles, with symptoms starting as motor run-on (the motor keeps driving for a second or two after you stop pedalling), then power pulsing, then the belt slipping entirely. In that case, pedal strikes had knocked the internal drive gears out of alignment, which accelerated the whole process.

The sprag clutch (a one-way bearing that lets the motor freewheel when you're not pedalling) is another known failure point. @dave_uk reported a second motor breaking after just 1,579km in exactly the same way as the first. When the sprag clutch goes, you'll often get intermittent power loss, especially under load going uphill, where the motor cuts out every few seconds then comes back.

External factors can contribute too. Degreaser from chain cleaning can work its way into the motor bearing area behind the drive sprocket, accelerating bearing wear. And @ficorama found that a speed sensor cable pinched between brake lines and the frame was causing power delivery interruptions that mimicked a torque sensor fault, so it's worth ruling out the simple stuff first.

The somewhat depressing reality is that Brose motors on Levos of this era have a known lifespan issue. @Tim22 reported going through five Brose motors across two Levo bikes, with roughly 2,500 miles per motor being the pattern. Specialized have historically been decent about replacing motors even out of warranty in some cases, so it's worth having that conversation with your dealer if yours is playing up. If you need a torque sensor recalibration specifically, eBike Motor Centre partners can do that on Brose units.

What symptoms are you actually seeing? That'll help narrow down whether it's the torque sensor itself, the belt/tensioner, or the sprag clutch causing your grief.