TQ's Harmonic Pin Ring Motor is Simpler Than it Seems - Eurobike 2022

Jul 15, 2022 at 15:34
by Travis Engel  
When Trek launched the Fuel EX E just a few days ago, the biggest news was not the Fuel EX E itself. It was the motor that drives it. Trek likes to use the right tool for the right job, having chosen the minimalist Fazua motor for their cross-country Supercaliber and the full-power Bosch for the heavy-duty Rail. Problem is, there weren’t a compelling option in between the two that would suit the Fuel EX E. But there is now.

Eurobike 2022

Hidden among the countless wholesale e-bike-component booths that tessellate Eurobike 2022’s remote Hall 8, TQ Systems started buzzing with activity the moment the show opened. With experience in industries like robotics, aerospace, and medical technology, the Munich-area engineering firm may seem like they’d be a little above making parts for electric bikes. But one of their specialties happens to be just too perfect not to be on a bike.

Eurobike 2022

Despite the very futuristic name, ”harmonic pin ring,” TQ’s motors aren’t new to bikes. They actually entered the market over a decade ago with this beast first featured on some models from Haibike. It offered 120 Nm of torque. By comparison, the full-power Shimano EP8 offers 85 Nm. The new IQ motor used on the Fuel EX E is the result of dialing back that overkill with the benefit of 10 years of experience. You can read what all that means on the trail in Matt Beer’s review of the Fuel EX E. It covers loads of details that we won’t cover here, including the most important one: how it rides. But what we wanted to understand, at the most basic level, was how it works.

Eurobike 2022

Thankfully, there were a couple bits and pieces of TQ’s motor at their booth, though by the time we got there, TQ had hidden them because too many suspicious competitors were taking too many high-resolution photos. The exploded version of the whole motor, to an untrained eye like mine, just kinda looks like… a motor. But what it doesn’t look like is an e-bike motor. Traditionally, an e-bike motor needs a device that offers “reduction,” which I put in quotes because I needed TQ to explain it to me. In the case of an e-bike, it’s the method used to get a front chainring spinning at the desirable speed and with the desirable amount of torque. This is usually done with a belt or a chain or a stack of cogs. But TQ does it with its harmonic pin ring. And because it’s concentric to the rest of the motor components, it’s almost hidden among them. That’s why the Fuel EX E’s motor unit is so small and light.

Eurobike 2022

While electric motors are good at spinning fast, they need reduction to turn their natural talent for speed into something more useful on an e-bike. The TQ e-bike motor’s approach to the harmonic pin ring concept does this in a unique way. There is an inner gear that is on an eccentric, which is driven by the motor. It is one tooth smaller than the outer gear, which will be what drives the chainring. Because that inner gear is not rotating around its own center, but around the center of the bearing to which it is attached, it forces the gears of the outer ring to move, just much slower than it does.

Eurobike 2022

There are benefits to this beyond light weight and small size. It creates an instant, direct relationship between input and output. That’s why it’s so useful in robotics. This is similar to the mechanisms used in robotic open-heart surgery. It’s why the power comes on so naturally on the Fuel Ex E. It’s also why it’s so quiet. There’s no slop like there is when there are gears on gears on gears. In fact, the teeth of the inner gear don’t ever really leave the teeth of the outer gear. They almost just slide over each other. And that’s fine, because there’s very low friction between the two. The inner ring is aluminum, but the outer ring is a sort of polymer. But still, TQ has tested their motors to over 20,000 miles, and they still behave like they were designed to when they were new.

Eurobike 2022

It just takes a very high degree of precision to make a system this durable and this efficient, so despite its simplicity, it’s still a pretty pricey little gadget. But time will tell if that changes down the road. The TQ booth was filled with representatives from other brands, ready to get in line. And though, like Fazua, Bosch, and Shimano, the motor itself will stay more or less the same as we see it pop up on other bikes in the coming years. But it could also be scaled up, or even scaled down to fit other applications. And when it does, now you won’t have to wonder how they did it.


  • 35 1
 "It's cycling but better" ... TQ really trolling the haters with that one Big Grin
  • 13 15
 Agreed, the motor looks impressive but that marketing slogan is a f**king insult.
  • 3 3
 @tremeer023: Why do you feel insulted?
  • 4 1
 @smoothmoose: Well, I think it was supposed to be a bit of a tongue in cheek insult for starters.
I think it insults riders who don't need to rely on a motor to make cycling better though. There is almost a subtle assumption that the only way to make cycling better is with a motor.
Maybe I'm just reading too much into it.
  • 6 0
 Nobody uses the 2.0 anymore. It's all Hyper Encabulation these days: youtube.com/watch?v=5nKk_-Lvhzo
  • 8 1
 @DirtBagTim: Reciprocating dingle-arms that help reduce Soinosoidal Finulation is crucial for any bike drivetrain.
  • 1 0
 @DirtBagTim: Nice! That's from the Retro Encabulator: youtu.be/RXJKdh1KZ0w
  • 27 1
 Im really loving this tech... great move in the right direction..
  • 7 1
 This is the way. Maybe combine it with something like Canon’s USM tech too.
  • 19 1
 Here’s a great explanation
  • 2 0
 That was great
  • 2 0
 That video was gold. The snippets of video from TQ didn't make it clear how it works.

Also, these motors should have an impressive lifespan (depending on seals and bearings).

  • 3 0
 This is not the explanation for the gearbox shown. TQ's new gearbox is a so-called G-rotor or Gerotor. Originally developed decades ago (1921) for industry pumps.


The named Pin-Ring gearbox is also different, as the name implies, it uses multiple pins mounted on an oval rotating ring. TQ uses the pinring name simply because that's what they're known for. They used it also for their first e-bike product some years ago.

The Harmonic Drive in your video is something completely different in design and has nothing to do with TQ.
  • 1 0
 @Namrek: I've now watched other TQ videos and agree that it looks more like a georotor and not a harmonic drive. Makes me wonder why they went for that design, the harmonic drive seems better balanced.
  • 1 0
 @Richridesmtb: Quite simple: they prefer a low gear ratio below the typical 40-50, around 15-20, in order to run the entire system at relatively low speeds and an accompanying lower noise level. The aforementioned Harmonic Drive does not work with such low ratios, so they choose a cycloidal drive or G-Rotor design that manages the full ratio in just one gear stage.
The disadvantage of this concept is that you still have relatively low power and torque at the output. This is not enough for a powerful e-bike with excellent climbing behavior in really technical steep terrain.
  • 10 2
 “…electric motors are generally pretty weak.”
Whoooo boy that’s a doozy of an error!
  • 2 0
 very true, electric motors are unbelievably reliable, its the stuff around them that fails.
  • 3 0
 @b45her: I think they meant that smallish DC motors don't have a lot of power, especially at low speeds, even though they can produce a lot of torque, relative to size and weight, at those low speeds.They need to run faster than a bike needs in order to get the power that a bike needs, hence the need for reduction gears such as a planetary set or harmonic drive. Not necessarily that the motors will wear out before anything else.
  • 7 1
 Now they come out with the better technology after I already bought a heavier ebike. Blah. However, the heavy ebike is much better than I thought it would be. Definitely legit given I have a overuse knee problem.
  • 3 0
 Get used to a frequent upgrade cycle if you ride an electric mountain bike and want to have the latest and greatest. Electronics improve quickly.
  • 8 0
 For a more entertaining view of how a similar gearbox works youtu.be/dYVPU47c9WA
  • 3 0
 Uncle bumblef@ck is my favourite canuckstanian enginerd.
  • 3 0
 Tangent was making a retrofitable ebike motor called the Ascent that was using the same reduction method (it's called cycloidal reduction). It was a lot bigger and heavier, but also 6000 watts. I'm glad to see a mainstem brand using the same tech in a miniature package
  • 5 0
 Looks nice, but how do you replace BB bearings? I hope the answer isn't a new drive unit, as with almost every motor brand.
  • 6 0
 when the grit gets in it works just like your pepper grinder at home
  • 2 0
 Do they have the patent on this idea, or will we see the other big names coming out with similar versions of this?
  • 8 0
 Harmonic drives and similar strain wave gears have been around since the 1950's and are not proprietary. Most other manufacturers currently use planetary gear sets to achieve a similar effect.
  • 1 1
 Like car manufacturers, the ebike motor manufacturers are heavily invested into their particular motor setup and will incrementally evolve their systems over time. If this system turns out to be much better than planetary gears then they may move across over time, but thats years away.
  • 3 0
 This technology is already in widespread use. Robotics used in manufacturing need extreme accuracy. Because this provides an extreme ratio reduction with no backlash, it allow precise movement/orientation at the same time as a ton of torque.

It's exciting to see this come to cycling. Fingers crossed it decreases the weight and size of ebike motors.
  • 1 0
 @dfiler: Do you know anything about the durability of these motors?
  • 3 1
 Welcome to other side Travis
  • 1 0
 Anybody who knows how the output shaft is connected to the output of the gearbox in the TQ HPR50?!

  • 4 3
 That’s cool. But “tested to 20,000 mi” isn’t that reassuring.
  • 7 11
flag greenblur (Jul 16, 2022 at 16:03) (Below Threshold)
 Most of the fat f**ks riding these thing will never clock 20k mi.....
  • 1 0
 I’m told by industry friends to avoid TQ like the plague
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