Another new TQ motor: hpr40

[apctjb]

yes, and your math is right that it takes 300w to go up a 10% grade (200lb total) at 8mph. if your speed drops down to 4 or 5, there’s no way to get it back up other than increasing rider power to 225+ w, the X20 isn’t strong enough for that.

Thanks, very helpful. I am able to grind up 10% grades at 5mph which implies I am capable of putting out~200W. So sounds like with a X-20 bike like the Addict eRide I should be able to manage 10% grades no problem as long as I maintain some speed. That clears up a concern I had about getting a hub drive vs mid drive.

 

[mschwett]

Thanks, very helpful. I am able to grind up 10% grades at 5mph which implies I am capable of putting out~200W. So sounds like with a X-20 bike like the Addict eRide I should be able to manage 10% grades no problem as long as I maintain some speed. That clears up a concern I had about getting a hub drive vs mid drive.

yes, and even 150w of assist is really quite a lot on a road bike, that's the difference between a spirited amateur and a pro in a lot of cases. you won't go "fast" up a hill, but you'll go a lot faster than almost any human powered bike. beware though, with the small internal battery that sort of thing will drop the range very low. of course it's fairly rare to find hills that just keep going up at 10% for miles and miles, but if that's your jam....

an example climb here in san francisco might be mt diablo. to the top is around 10 miles and 3,200 feet of climbing, more or less without breaks, call it 6% the whole way. 150w from the bike and 150w from the rider would have you going 10mph the whole way (at which point you'd need to not be at 100% power on the x20, or you'd be drawing more than 150w), so it would take an hour and you'd use around 180wh of battery, which is 75% or so! of course you'd use none coming down, so the range in that scenario is around 25 miles.

i'd shoot for more like 75w from the bike and 150w from the rider and go 8mph. now it takes 1.25 hours, but you'll only use 120wh or so, and the climb only eats half the battery. now you've got enough juice to do a 40+ mile ride, depending on how much you use the battery on the flats. at 225w you're still going faster than almost anyone climbing on a road bike!

the problem with these bikes comes if the rider can't do 100-200w (the more the better), is very heavy, and/or the climbs get above 10% for any period of time. my last block on the way home is 14.5% and i really crawl up it on the addict if not feeling well. the HPR40 bikes would eat those climbs up, i'm sure, assuming gearing close to 1:1.

 

[apctjb]

Ran across the following video, helped me better understand how a Harmonic Drive works .https://www.youtube.com/watch?v=xlnNj9F37MA

 

[TRW]

Ran across the following video, helped me better understand how a Harmonic Drive works .https://www.youtube.com/watch?v=xlnNj9F37MA

That is indeed an interesting video but...
The strain wave drive is quite different to the TQ HPR, it has a flexible element, the HPR has all rigid elements
The cycloidal drive is also similar but different, but is more similar in that all elements are rigid
TQ's HPR (Harmonic Pin Drive) is unique to TQ I believe (they have a patent!)
At the end of my video you can see how the HPR works

 

[kevinmccune]

Just announced, and Canyon’s high end TQ hpr40 ebike weighs under 22 lbs. Interesting direction for TQ: lower power, smaller battery, no top tube ebike display, hidden assist level buttons, all but invisible. 200 Watts (nominal and peak) and 40nm torque. They’re going for the ultimate roadbike experience with a bit of help but not too much. It will be interesting to see if trek and the others go this direction or use the larger hpr60 in their next gen. bikes.

TQ HPR40 On Review: Stealth Motor for Drop-bar Bikes

TQ HPR40 motor on review: ultra-lightweight e-drive for road and gravel bikes with a natural ride feel, quiet performance and top-class integration

granfondo-cycling.com

nice torque numbers,restricted top speed by virtue of low wattage,perfect for roadies and veteran riders.

 

[apctjb]

The strain wave drive is quite different to the TQ HPR, it has a flexible element, the HPR has all rigid elements
The cycloidal drive is also similar but different, but is more similar in that all elements are rigid
TQ's HPR (Harmonic Pin Drive) is unique to TQ I believe (they have a patent!)
At the end of my video you can see how the HPR works

Thanks, I was wondering if there was a flexible element and if so the long term durability of that.

 

[Jeremy McCreary]

Ran across the following video, helped me better understand how a Harmonic Drive works .https://www.youtube.com/watch?v=xlnNj9F37MA

Wow, that guy's got skills — including video-making.

 

[stompandgo]

yes, and even 150w of assist is really quite a lot on a road bike, that's the difference between a spirited amateur and a pro in a lot of cases. you won't go "fast" up a hill, but you'll go a lot faster than almost any human powered bike. beware though, with the small internal battery that sort of thing will drop the range very low. of course it's fairly rare to find hills that just keep going up at 10% for miles and miles, but if that's your jam....

an example climb here in san francisco might be mt diablo. to the top is around 10 miles and 3,200 feet of climbing, more or less without breaks, call it 6% the whole way. 150w from the bike and 150w from the rider would have you going 10mph the whole way (at which point you'd need to not be at 100% power on the x20, or you'd be drawing more than 150w), so it would take an hour and you'd use around 180wh of battery, which is 75% or so! of course you'd use none coming down, so the range in that scenario is around 25 miles.

i'd shoot for more like 75w from the bike and 150w from the rider and go 8mph. now it takes 1.25 hours, but you'll only use 120wh or so, and the climb only eats half the battery. now you've got enough juice to do a 40+ mile ride, depending on how much you use the battery on the flats. at 225w you're still going faster than almost anyone climbing on a road bike!

the problem with these bikes comes if the rider can't do 100-200w (the more the better), is very heavy, and/or the climbs get above 10% for any period of time. my last block on the way home is 14.5% and i really crawl up it on the addict if not feeling well. the HPR40 bikes would eat those climbs up, i'm sure, assuming gearing close to 1:1.

Your numbers are ok for spitballing, but you are making a lot of assumptions about bike weight, rider weight, rider pedaling efficiency, cadence, and with the e-bike, drive unit efficiency. You can't just mash power numbers.

 

[Jeremy McCreary]

Hopefully this is will be more enjoyable after that fiasco

Excellent! Always wonder how the drawings and technical details needed for a video like this are obtained — e.g., CAD files and the 17.5 reduction. Are you connected with TQ somehow?

 

[Jeremy McCreary]

Hopefully this is will be more enjoyable after that fiasco

Excellent! Always wonder how the drawings and technical details needed for a video like this are obtained — e.g., CAD files and the 17.5 reduction. Are you connected with TQ somehow?

 

[mschwett]

Your numbers are ok for spitballing, but you are making a lot of assumptions about bike weight, rider weight, rider pedaling efficiency, cadence, and with the e-bike, drive unit efficiency. You can't just mash power numbers.

well, not really. we're talking about a specific bike - or at least a specific motor system which in a road bike means 23-30lb. not significant. i specifically mentioned rider weight, and 160-190lb probably covers most riders of this type of bicycle. a small difference, for sure, but in the previous message in the thread i stated 200lb. 25lb bike 175lb rider. pedaling "efficiency" is meaningless here, since i specifically referenced the rider's output power. how much energy it takes them to make 100w or 150w is only relevant to how tired it makes them, how much they have to refuel, etc. cadence is irrelevant, it's a hub motor. that's kind of the whole point of the discussion. of course you'll need appropriate gearing to make decent power down at 6-10mph, but again, if you aren't making the power, you aren't making the power.

drive unit efficiency is an interesting variable and one we don't definitively know about these small motors, but given the real-world results it would be pretty surprising for it be anything other than 70-80 percent in the ranges of speeds we're talking about.

i've owned and ridden an x20 bike for quite some time, thousands of miles, and it has a dual sided 4iiii power meter on it. i'm not speculating here, this is how the x20 system performs in the real world with a 200lb total load going up hills that range from 6 to 15 percent with rider outputs in the 100-200w range. i also had a 27lb creo before this, which i rode for many many more thousands of miles, and we know the performance characteristics of the SL system extremely well.

i wasn't just "mashing" power numbers, i pretty clearly stated the scenario and variables and the physics/math is pretty simple at these low speeds and steep grades. start going faster, and it becomes a real crapshoot with aero and friction and efficiency of a hub drive.

 

[stompandgo]

I don't know how your X20 would behave against the topic of this thread, the HPR40. I'll give you that. However, we will just have to agree to disagree about the rider stuff. You may not be spitballing, but you are drawing conclusions for others based on your one bike and your one power meter. I would never do that. If you've ever trained, raced, and coached with power, you'd understand that. It's not just "math". It never is.

Carry on.

 

[mschwett]

I don't know how your X20 would behave against the topic of this thread, the HPR40. I'll give you that. However, we will just have to agree to disagree about the rider stuff. You may not be spitballing, but you are drawing conclusions for others based on your one bike and your one power meter. I would never do that. If you've ever trained, raced, and coached with power, you'd understand that. It's not just "math". It never is.

Carry on.

i've had several different power meters on several different bikes - front hub, rear hub, mid-drive, acoustic - and we're not talking about training. we're talking about riding up hills on an ebike. going uphill at slow speeds is not racing, training, nor does it require coaching. of course training is not just math, and i never said it was. this is an e-bike forum, not slowtwitch or something...

 

[TRW]

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Excellent! Always wonder how the drawings and technical details needed for a video like this are obtained — e.g., CAD files and the 17.5 reduction. Are you connected with TQ somehow?

Thanks. Not connected to TQ. I just look at photos and figure it out from there.
TQ have some exploded models that they display at various bike shows so the media tends to take plenty of photos of those which is helpful
It took me a long time to get the HPR50 right, but HPR40 was fairly easy because of the similarities. Also and the EuroBike show was shortly after the release so I found enough photos from that

 

[TRW]

I'm a retired engineer, and I had to watch those videos twice to figure out how it all works. It is an absolutely ingenious design that relies heavily on precision machining. I bet that any grit or dirt inside would wreck it in no time.

Likewise, retired engineer (electronics), plenty of spare time to dabble with things of interest.
Probably if I was a mechanical engineer I wouldn't have been so intrigued by these motors and these videos would never have happened.
I like that you mention the precision machining, it is something I have heard TQ say that it one of their strengths.

 

[stompandgo]

i've had several different power meters on several different bikes - front hub, rear hub, mid-drive, acoustic - and we're not talking about training. we're talking about riding up hills on an ebike. going uphill at slow speeds is not racing, training, nor does it require coaching. of course training is not just math, and i never said it was. this is an e-bike forum, not slowtwitch or something...

But a human rides them. They don't ride themselves. You are using empirical data to draw conclusions using "math". If you've ever done any of those horrible, despicable things I've mentioned on an analog bike, you'd understand my point. I politely called you out on it, then you got nasty. See ya.

 

[apctjb]

Anyone know the ballpark efficiency (Power out/Power in) of the TQ40. I read that the downside of the Harmonic Drive is efficiency at the lower end of the range. Thanks to TRW I understand the TQ motor is unique and curious to learn if the benefits of the TQ come with a cost of lower efficiency and range?

 

[Jeremy McCreary]

I politely called you out on it, then you got nasty.

FWIW, your call out didn't read polite to me.

 

[mschwett]

FWIW, your call out didn't read polite to me.

no, it wasn’t, and as most who have been around here for a while know, i’ve done plenty of “those things” on an analog bike. no matter, there’s an ignore list for a reason.

 

[apctjb]

I am guilty of gross oversimplification when I asked the question about power requirements and was hoping for a simple ball park answer. I greatly appreciate the responses I received.