TQ HPR50 Grinding Noise

[prolix2]

OK, I''ve just now figured the factors that produce the grind sound, for me. Any time, and for me every time, the pedal rate and force i apply on the crank fall below what's needed to activate the motor, the grind sound occurs. For example this will occur while riding on a level surface in a middle gear at a middle speed and starting to coast. When coming out of the coast and starting to pedal, and before applying any real force to the crank, just when you're peddling , kind of free peddling without resistance, the grinding sound will occur. Once you increase your pedal rate and force enough to actually apply some torque to the crank, and I think, turning on the motor, the grind will go away. If you are leisurely coming out of the coast the grind may last for two or three strokes. If you are rapidly coming out of the coast and apply torque rather immediately the grind will not occur at all. If you take your time coming out of the coast and keep no force on the pedals, or very little force on the pedals for an extended period of time the grind will last indefinitely. The grind happens every time I'm coasting into an uphill slope and starting to re-pedal, again lasting as long as it takes for my pedal rate to catch up with the speed of the bike. This may take a half stroke or two strokes. Today after establishing this "undermatching " idea I was able to reproduce the grind by simply pedaling along at grade and slightly backing off on the torque but continuing to pedal with almost no torque and the grind with occur essentially without coasting significantly.

My current thinking is that the Sprag gear mechanism in the motor housing is not engaging or disengaging completely at these times.

Earlier on I told someone this sounded like a plastic gear meshing sound to me.

As I look at the exploded views of the motor it looks to me like there are a couple of ring gears that have ramps on them. one looks like it is plastic, and I'm not talking about the harmonic ring gear that is definitely plastic. I will look at them again now but my memory is they had about 30 little ramps on each gear..... I just looked at it again and it looks like neither of those gears is plastic. The outer bigger gear is looks like it has about 22 points of engagement the inner one looks like it may have 16. My naïve impression is that it's one of these two gears that's making the sound

I listened to the grind carefully today while riding, especially since I can now reproduce it 100% of the time, and I think the frequency of the grind is the same as one of the barely audible frequencies of the motor itself when it's working normally.

When the motor is completely off , I'm not able to produce any of this stuff.

 

[DugT]

If it only makes the grinding noise when someone is “under matching “ pedalling speed, maybe it isn't much of a problem because that is a rare occurrence. At least it is for me because I am usually pedaling or coasting. Others have had the grinding noise problem constantly while climbing. That would be an annoying cause for alarm but it seems to be a rare problem.

 

[prolix2]

And since, for me, this depends on the electrical system to be turned on, it may mean that tracks report that it takes 150 miles, for the sensors to calibrate, May have some validity. Maybe the crank torque sensor doesn’t interact well with the clutch torque sensor, assuming there is some kind sensing mechanism for the clutching engagement business

The grind may be a little dependent on cadence, And seems to be a little louder at higher cadence

 

[Rob Rides EMTB]

Do you think the noise is a fault, or is it just part of the motor design that causes it (like the bosch / shimano backlash rattle)?

Does the grinding noise cause any issues, or is it just an unpleasant sound?

I havent noticed it on mine, but can sometimes hear more of a slight ticking noise...

 

[prolix2]

Do you think the noise is a fault, or is it just part of the motor design that causes it (like the bosch / shimano backlash rattle)?

Does the grinding noise cause any issues, or is it just an unpleasant sound?

I havent noticed it on mine, but can sometimes hear more of a slight ticking noise...

Excellent points. My grind noise is not associated with any performance issues at all. Perfect performance from the motor and the transmission. I also have heard a rare isolated ticking noise. May be only two or three ticks at a time, And could not decide whether it was from the motor or the transmission or a twig in a spoke Or a frame creak. And extremely rare. So short-lived are the ticks that I can’t experiment with changing torque or weight distribution etc. Just a curiosity.

Further guessing on the grind noise is that it is a design thing combined with perhaps very slight production variability, combined with software inability to oordinate clutching with motor…. To a variable degree in a indeterminate number of motors.. combined with the fact that most people are high screeners, And the trails are noisy and tires are noisy and the motor is SO quiet.

 

[Mteam]

Do you think the noise is a fault, or is it just part of the motor design that causes it (like the bosch / shimano backlash rattle)?

Does the grinding noise cause any issues, or is it just an unpleasant sound?

I havent noticed it on mine, but can sometimes hear more of a slight ticking noise...

I just went for a quick test ride on my brand new fuel exe 9.5, this is literally my first ride on it, all I did was a quick ride round the roads and parks near me.

If I pedal in the way that the poster up there says to pedal (ie catch up pedalling) I can get it to make the noise, but in my opinion this is just a characteristic of the motor, its not a fault. when pedalling 'normally' the motor is virtually silent.

 

[levity]

. . . but can sometimes hear more of a slight ticking noise...

Rob - around 200-300 miles both of our EXe bikes began to develop a “slight ticking noise” under load. The lockring securing the chainring was coming loose, and tightening it to 50Nm cured it. No further issues at 500+ miles. Check (recheck?) yours if you haven’t.

 

[DBSwiss]

Do you think the noise is a fault, or is it just part of the motor design that causes it (like the bosch / shimano backlash rattle)?

Does the grinding noise cause any issues, or is it just an unpleasant sound?

I havent noticed it on mine, but can sometimes hear more of a slight ticking noise...

I have not heard a clicking noise, just the grinding noise. It may be normal for the motor but without an explanation it is worrying as it could also be an issue, especially as some have reported that it is getting worse over time. I guess there is always the warranty if it turns out to be a reliability issue. So far I don’t see it impacting the normal operation of the bike but if there was a drag from the motor coming from a defective part it would also be difficult to feel, given that the motor power may be covering up the drag. Hopefully Somebody from TQ will put together an explanation soon.

 

[Kinger]

My 9.8 XT has a serious crack / tick when pedalling, especially standing up and really cranking in it.
Checked crank tightness - Nope
Checked lock ring / chainring torque - Nope
Checked all bearings on the bike (cleaned and greased and torqued) - Nope
Dropped the motor and checked mounting bolts - Ah Ha!

No grease on the mounting bolts. (Cleaned / Greased / Torqued)
Absolutely perfect now.

Jsyk.

 

[Emailsucks98]

in my opinion this is just a characteristic of the motor, its not a fault. when pedalling 'normally' the motor is virtually silent.

This is what I have been suspecting. I haven’t noticed any weird sounds on mine yet, but in my experience with other eBikes (shimano/Norco and Specialized) they all have some unfortunate quirks.

Unless it stops/interrupts the ride, or leads to a parts failure, it shouldn’t be labeled a defect, in my opinion.

I do appreciate the variety of reviews so far. TQ has a tough customer base with some people expecting the power of a full fat but with others expecting near silence.

 

[Rob Rides EMTB]

I made a video. Comparison video between TQ and Fazua



An update I received today from TQ on Noise:

We are currently working on this topic. It has no influence on the motor’s performance or durability and seams to be no more than a peculiarity of one of the sprag clutches of our motor.

If the motor’s assist is very low (less than ~ 10W) it seams that the electric motors torque is not enough to rotate the clutch, but not fully engage it. This can lead to the weird rattling/grinding noise. The forces in such a scenario are however extremely low and do not put any mentionable wear on the internals of the motor.

From everything we know and all the 1000s of field testing kilometers we have already done this issue is nothing to worry about.

Nevertheless the low noise is one of our strongest USPs and we are working on a solution. We believe that some tweaks in the motor controller algorithm could reduce or even completely remove this noise. Our goal is to roll out a software update before the end of this year.

 

[DugT]

I made a video. Comparison video between TQ and Fazua



An update I received today from TQ on Noise:

We are currently working on this topic. It has no influence on the motor’s performance or durability and seams to be no more than a peculiarity of one of the sprag clutches of our motor.

If the motor’s assist is very low (less than ~ 10W) it seams that the electric motors torque is not enough to rotate the clutch, but not fully engage it. This can lead to the weird rattling/grinding noise. The forces in such a scenario are however extremely low and do not put any mentionable wear on the internals of the motor.

From everything we know and all the 1000s of field testing kilometers we have already done this issue is nothing to worry about.

Nevertheless the low noise is one of our strongest USPs and we are working on a solution. We believe that some tweaks in the motor controller algorithm could reduce or even completely remove this noise. Our goal is to roll out a software update before the end of this year.

I think there is a typo and the first "not" should not be there. ....the electric motors torque is not enough to rotate the clutch, but not fully engage it. Here it is corrected, if I am correct.

..... If the motor’s assist is very low (less than ~ 10W) it seems that the electric motors torque is enough to rotate the clutch, but not fully engage it. This can lead to the weird rattling/grinding noise.

 

[DBSwiss]

I made a video. Comparison video between TQ and Fazua



An update I received today from TQ on Noise:

We are currently working on this topic. It has no influence on the motor’s performance or durability and seams to be no more than a peculiarity of one of the sprag clutches of our motor.

If the motor’s assist is very low (less than ~ 10W) it seams that the electric motors torque is not enough to rotate the clutch, but not fully engage it. This can lead to the weird rattling/grinding noise. The forces in such a scenario are however extremely low and do not put any mentionable wear on the internals of the motor.

From everything we know and all the 1000s of field testing kilometers we have already done this issue is nothing to worry about.

Nevertheless the low noise is one of our strongest USPs and we are working on a solution. We believe that some tweaks in the motor controller algorithm could reduce or even completely remove this noise. Our goal is to roll out a software update before the end of this year.

Thanks for getting that response from TQ. This is exactly what I was hoping for. It being a clutch issue makes sense and the explanation is reassuring.

 

[DBSwiss]

This is a really good video that explains the harmonic pinwheel motor principle that TQ is using. The author then designs, 3D prints, and assembles a motor which is pretty cool As well.

 

[prolix2]

Thanks for getting that response from TQ. This is exactly what I was hoping for. It being a clutch issue makes sense and the explanation is reassuring.

LBS swapped my noisy motor off with another bike with a brand new motor. It was wonderfully silent for 35 miles now the same grind clatter starting again. Still a wonderful bike. Maybe this new purported firmware algorithm will help. And I would guess that most people would not notice it.

 

[ZillaG]

This is a really good video that explains the harmonic pinwheel motor principle that TQ is using. The author then designs, 3D prints, and assembles a motor which is pretty cool As well.

WOW! This is inarguably the BEST post on the HPR design. Thanks!

 

[Bikenmike]

Do you think the noise is a fault, or is it just part of the motor design that causes it (like the bosch / shimano backlash rattle)?















Does the grinding noise cause any issues, or is it just an unpleasant sound?















I havent noticed it on mine, but can sometimes hear more of a slight ticking noise...



I've had my exe for a few months and have done more than 1300 k's the motor has had the same grinding noise since new and it's getting worse! I have noticed when the noise occurs the assistance shown on the display drops to zero this can happen whilst I'm pedaling uphill fairly hard.

I can't believe this can be classed as acceptable especially since not all owners are experiencing it.
Luckily my LBS is very sympathetic and is pushing Trek to replace the motor.

 

[prolix2]

I experienced it a lot on the first motor, but it’s strictly a sound thing no functional implications at all, just very annoying in that my expectations were so high and it was not present at all in the first 30 miles, 50 km. My local bike shop eventually swapped motors, and it is barely present on the second motor. A TQ representative says that it is a problem where a sprag clutch fails to fully engage with the motor at very low power. He said the forces are low enough that it should not have any consequence for wear , and that they are working on a software change of the algorithm to try to stop this sound. or lessen it , I believe he said. On my second motor I have to pay extremely close attention in order to detect it above the sound of the tires and leaves, and I’m choosing not to do this, so I am extremely happy with the bike.

 

[Bikenmike]

Great to hear your new motor is performing better hopefully I will have the same success. As I said in my previous post mine stops giving assistance when the noise happens, this can be whilst I'm going uphill putting in 80 to 90 W and the motor should be giving 40 to 50W, so more than just a noise with mine.
Most annoying but overall a great bike, I love the silent motor.

 

[DBSwiss]

Great to hear your new motor is performing better hopefully I will have the same success. As I said in my previous post mine stops giving assistance when the noise happens, this can be whilst I'm going uphill putting in 80 to 90 W and the motor should be giving 40 to 50W, so more than just a noise with mine.
Most annoying but overall a great bike, I love the silent motor.

Are you seeing this behavior when in the high (turbo) mode? I also have some strange motor support in the high mode. Sometimes I get quick support when I start out but it suddenly cuts out despite me putting in consistent 100+watts. This is not related to the noise in my case. I am wondering if this is a software issue or an actual motor issue. My guess would be software.

 

[prolix2]

Are you seeing this behavior when in the high (turbo) mode? I also have some strange motor support in the high mode. Sometimes I get quick support when I start out but it suddenly cuts out despite me putting in consistent 100+watts. This is not related to the noise in my case. I am wondering if this is a software issue or an actual motor issue. My guess would be software.

I have also experienced some funky behavior in the high mode, only in the high mode. Sometimes variable support, sometimes more rapid cut off when slowing pedal effort. I assumed it was a software thing, where the program can’t always handle perfectly well all possible scenarios of all parameters. Sometimes my car automatic transmission will have a hiccup which I attribute to the same problem faced by its computer and hardware.

 

[Bikenmike]

Yes I had the same inconsistent support issue where the power cut out if I backed off my pedaling effort slightly, then it would take a couple of pedal strokes to come back on.

My local bike shop updated the firmware and that problem is now resolved . The grinding remained sadly.

 

[DBSwiss]

Yes I had the same inconsistent support issue where the power cut out if I backed off my pedaling effort slightly, then it would take a couple of pedal strokes to come back on.

My local bike shop updated the firmware and that problem is now resolved . The grinding remained sadly.

I will ask my shop to update the firmware then. Thank you!

 

[seamarsh]

My 9.8 XT has a serious crack / tick when pedalling, especially standing up and really cranking in it.
Checked crank tightness - Nope
Checked lock ring / chainring torque - Nope
Checked all bearings on the bike (cleaned and greased and torqued) - Nope
Dropped the motor and checked mounting bolts - Ah Ha!

No grease on the mounting bolts. (Cleaned / Greased / Torqued)
Absolutely perfect now.

Jsyk.

If you torque after apply grease your torque rate will be off.. you will apply more force. bolts should be clean and dry if using a torque wrench.

i was worried about teething issues with these motors… they look beautiful but also look complex and machining would have to be top notch to work right… hopefully they get this worked out for you all.. the sprag clutch not fully engaging at low rpm’s makes sense

 

[Bikenmike]

Sorry seamarsh but I have to disagree with your suggestion of tightening bolts dry the opposite is correct they should be greased otherwise they will NOT be torqued correctly.

 

[seamarsh]

Sorry seamarsh but I have to disagree with your suggestion of tightening bolts dry the opposite is correct they should be greased otherwise they will NOT be torqued correctly.

I can see how logically you would assume that but it's not the case. It's not an agree/disagree it's just the way it is.

Unless a bolt specifically calls for lubricant or thread locker all torques given by manufacturers are assuming bolts are clean and dry.

If you use lube the torques will be off. Also dry friction helps the bolt stay at the specified torque, if you lube it there a chance they will loosen.

You can also snap a bolt or strip threads if you lube it.. depending on material etc

I grew up with a mechanic as a father

 

[Bikenmike]

Wow seamarsh we have a lot in common my father also was a mechanic and I worked with him, if I had tightened down head bolts without lubing them I would have been in trouble.
I now use anti- size grease on all my bolts except when using thread locker. I know it sounds wrong but they definitely don't come loose.
But don't take my word do an Internet search. Or ask a bike mechanic I'm sure they will do as I do.

 

[seamarsh]

Wow seamarsh we have a lot in common my father also was a mechanic and I worked with him, if I had tightened down head bolts without lubing them I would have been in trouble.
I now use anti- size grease on all my bolts except when using thread locker. I know it sounds wrong but they definitely don't come loose.
But don't take my word do an Internet search. Or ask a bike mechanic I'm sure they will do as it will give you improper torque readings and is not necessary or factored into how torque specs are calculated. If th

As I said it's not wrong if the manufacturer calls for lube, like with head bolts.. but if it's not specifically called out you will go beyond the torque spec.

Unless it's specified the torque spec is for a clean dry bolt. It's especially true on high end bikes because torque specs are so low.. or motorcycles where its aluminum cases etc anyway peace.

 

[ebsocalmtb]

you're both right, but semantics are creating the gap. Anti-seize is technically classified as a grease, but really it's not quite the same in that regard. From my anecdotal experience, anti-seize does not seem to cause torque inaccuracies the same way that a moly, petroleum or synthetic (traditional) lubricant would cause.

So the way I see it, if you're using anti-seize, then carry on, use the same torque as stated. If you're using grease on the threads of a bolt, beware of what you are doing due to torque to yield, thread deformation, stretch etc.

That being said, I am both an experienced car mechanic and bike mechanic. I do not use anti-seize on my bike unless I am up against mixed metals such as an alu-alloy bolt and a steel insert or vice-versa. I generally, do not ever grease the threads of any of the bolts on my bicycles. I torque them, check them regularly and almost never find them loose.

 

[seamarsh]

you're both right, but semantics are creating the gap. Anti-seize is technically classified as a grease, but really it's not quite the same in that regard. From my anecdotal experience, anti-seize does not seem to cause torque inaccuracies the same way that a moly, petroleum or synthetic (traditional) lubricant would cause.

So the way I see it, if you're using anti-seize, then carry on, use the same torque as stated. If you're using grease on the threads of a bolt, beware of what you are doing due to torque to yield, thread deformation, stretch etc.

That being said, I am both an experienced car mechanic and bike mechanic. I do not use anti-seize on my bike unless I am up against mixed metals such as an alu-alloy bolt and a steel insert or vice-versa. I generally, do not ever grease the threads of any of the bolts on my bicycles. I torque them, check them regularly and almost never find them loose.

Exactly what I was going to say but didn't want to bother.. well said.

His original post said he "lubed" which is why I responded in the first place.. but lots of mechanics have their own methods that work for them so.. whatever works for you!