Bikeon, "cassette drive" torque sensing motor

[Guerney]

The motor sounds awful - is there a muffler modification available? Some sort of sound absorbing woolly cap? This motor whine would very much get on my nerves.

https://endless-sphere.com/sphere/threads/bikeon-cassette-drive-torque-sensing-motor.123345/post-1802619

 

[neptronix]

I've watched both videos about the sound and it seems like it's a bit quieter than most mid drives and geared hub motors.

High frequency sound is the easiest to dampen with various kinds of acoustic materials, but you might negatively affect the cooling of the motor. It's unknown if the motor has a surplus of heat shedding capability, but if it does, some acoustic material slapped on it could help.

 

[Guerney]

I've watched both videos about the sound and it seems like it's a bit quieter than most mid drives and geared hub motors.

While riding, I can hardly hear my BBS01B. A horrible whine would be a downer. Total dealbreaker.

 

[rafalg]

I think this is an interesting option for carbon fiber bikes as the drive can be installed without modifying the frame in any way.

 

[lnanek]

I don't mean to be difficult or controversial here. My numbers are coming from measuring the various diameters on the BikeOn website pictures, assuming a red ring inside diameter of 175 mm from a picture that Aram graciously provided me.

I do not doubt that the BikeOn drive mounts without problem on a 36 teeth cog. That is the innermost cog in the cassette, and the cog that the red ring clamps onto with the black teeth.
But as far the maximum diameter of the cog driven by the chain is concerned, a 135 mm / 33 teeth cog seems the maximum that can clear that bearing, judging from the pictures available to me.
If the bearing rotates with the chain, 135 mm diameter or 33 teeth is ok. (I might be off by a mm or two.)
If the bearing (or bearing housing) is stationary, or rotates with the red ring (i.e. against the chain direction if the chain were to contact it from below), then the chain has to have a straight path (tangent) from the top of the largest possible chain driven cog, clearing that top bearing, to the torque sensor. I measure that to be a cog of 104 mm diameter or 26 teeth. Again, I might be off by a mm or two.

I acknowledge that I might be the only one who wants to preserve the slowest possible gear while using the BikeOn drive.
Maybe the continuous power of the BikeOn drive is so large that I wouldn't need that largest cog. I don't know.

What I do know is that I can do a 6.5% grade at about 5 mph with about 60rpm cadence and 34 front teeth and 34 rear teeth comfortably, with both the ebike.ca motor simulator and the An interactive model-based calculator of cycling power vs. speed bicycle simulator telling me I need about 150 W of human power. Clearly I don't want to pedal at 120 rpm and 9.5mph with an additional 150 W from the motor, so I do not need the 34 teeth rear cog, but I would like to know how much headroom I have. If the motor can do 150 W continuously, then a 22 teeth rear cog is fine, and gets me to 73 rpm, which is great.

Have you gone to the shop page on their site? There's a form with how many teeth your biggest gear has you have to fill out before putting it in your cart:


Therefore any images you are measuring may not be exactly what you get if you plug different things into the drop down when you order. The red ring size could differ, be mounted farther away, etc..

 

[spaceman]

But as far the maximum diameter of the cog driven by the chain is concerned

Oh, I see, I get it now.

As I said before: 2-3 sprockets will not be accessible. If you want to install your own cassette with your choice of sprockets, that will work. In that case 33T seems reasonable, but it has to be checked.
I have to check what is the max sprocket size you could fit in that case as a second or third sprocket. Will try to do that once I have more time for sure.

However, I think you don't need it:
we have been testing the device in the heat of Las Vegas Metro desert , running it continuously on a trainer with 2 fluid resistance units connected to the wheel for over a week non-stop, to check the wear and tear of the parts.
The unit can sustain over 180 W continuous power output at 45 degrees C ambient (about 115 Fahrenheit) with some minor airflow to the motor without overheating. With ambient temperature of 26 - 28 degrees C continuous power output without overheating is well over 500 W.
These tests are the worst of the worst cases: extreme heat and continuous power output. As I pointed out before, the motor follows the power applied to the pedals, which is some sort of pretty slow sine wave. That is a better situation for heat dissipation.

What also helps in these situations is the transmission ratio (relatively high rpm of the motor rotor, which creates some turbulence around it) and the fact that the motor is exposed to air.

I hope this helps.

 

[spaceman]

Is it possible to work with a belt drive?

Not with this model.

What about Shimano Alfine or Rohloff?

Not yet.

 

[spaceman]

why belt transmission is used instead of directly driving the big red sprocket from motor sprocket

Belt drive is one of the most suitable for this application.

 

[Gruesome]

Have you gone to the shop page on their site? There's a form with how many teeth your biggest gear has you have to fill out before putting it in your cart:
View attachment 354998

Therefore any images you are measuring may not be exactly what you get if you plug different things into the drop down when you order. The red ring size could differ, be mounted farther away, etc..

Inanek, I thought about that (red ring size being variable), but concluded (maybe wrongly; spaceman should tell us) that would make manufacturing and stockkeeping unnecessarily complicated. I'm assuming what changes are just the two black clamps with inward facing teeth that trap the cog driven by the red ring. But maybe I am wrong.

If, from Aram's earlier post about testing in Las Vegas, the motor can put out up to 500W continuous at temperatures I would want to bike at (28°C is 82°F), then there should be no problem even going up extended 10% grades at about 10 mph:

An interactive model-based calculator of cycling power vs. speed

Total power needed would be close to 500W, if the rider supplies between 100 W to 150 W, everything should be fine with a 700c rear wheel and a 34T chainring and 23T cog, at 84 rpm cadence (at 10 mph a 700c wheel spins 2.1 times per second). No changes to my cassette needed, since the 23T cog should be usable (motor drives 34T cog, 30-27-25 are lost to get the 11 mm clearance needed to get the chain past the baseplate of the kit), the smallest 7 cogs are accessible.

My earlier question about whether a 33T cog or only a 26T cog can be chain driven is then also irrelevant, unless somebody wanted to tackle grades significantly steeper than 10%.

 

[Epithemeus]

The unit can sustain over 180 W continuous power output at 45 degrees C ambient (about 115 Fahrenheit) with some minor airflow to the motor without overheatin

Good data! What rpm is the motor being driven at for the tests?

 

[Gruesome]

So, where are the users of the prototypes and of the first production units posting their experiences? Not here, it seems. I looked on pedelecforum.de, but there is nothing there either (there is an unrelated user 'bikeon'; same on forums.electricbikereview.com).

Secondly, I downloaded the BikeOn android app, but there is no demo mode to look at the different screens. The app download page on the google play store shows a few screen shots, but those look pretty minimal.
I'd be very interested to find out whether I can configure a page to show human and motor power, and battery voltage and current. Alternatively, sharing those parameters to another program would also be great. I like the Jepster app, because it allows configuring a combined data & map view.

I don't know whether the link has been posted here yet, but the BikeOn project story on Hackaday.io is very interesting; talk about tenacity! Unfortunately it stops in 2020.

 

[Gruesome]

Have you gone to the shop page on their site? There's a form with how many teeth your biggest gear has you have to fill out before putting it in your cart:
View attachment 354998

Therefore any images you are measuring may not be exactly what you get if you plug different things into the drop down when you order. The red ring size could differ, be mounted farther away, etc..

Checking the video on red ring exchange, it seems pretty clear that the red ring does not change with sprocket size, otherwise it would not fit into the support bracket:

 

[Guerney]

Is that some sort of ickle off-the-shelf high pitched annoyingly whiney drone motor?

 

[lnanek]

Checking the video on red ring exchange, it seems pretty clear that the red ring does not change with sprocket size, otherwise it would not fit into the support bracket:

That's exactly what I said. You get shipped a different size ring depending on what you enter in the form when you add to your cart on the store page.

The guy I was replying to was measuring the ring in all the photos and claiming supporting certain tooth sizes was impossible. I was pointing out he wasn't measuring what he would receive depending on what he entered in the form. He thought there was only one size ring for all models/skus.

 

[Gruesome]

Well, maybe we all need to become better at reading; writing doesn't seem the problem.

What I am trying to point out is not exactly what you said; you are actually repeating what you said, namely that the red ring is different for different sprocket sizes. I do not believe that is true.
Spaceman should really answer this, but from the video I just linked to it seems pretty clear (maybe to me only) that when ordering a kit or ring for a different sprocket size the red ring itself does not change size (since it fits into the same support roller bracket); what changes are the two black sprocket attachment clamps that are bolted to the red ring.

Aram/spaceman, can you please sort this out?

 

[spaceman]

Good data! What rpm is the motor being driven at for the tests?

The wheel speed was between 12 to 18 mph during hot part of the day and higher at night.

 

[spaceman]

where are the users of the prototypes and of the first production units posting their experiences?

We've sold several tenths of units so far. Most of our users are not youngsters and online presence is often minimal. We have some videos on our website with user feedback.

I downloaded the BikeOn android app, but there is no demo mode to look at the different screens.

We are very small team with limited resources and have to pick our battles wisely. We are constantly improving the product. Just yesterday we've pushed a software update: it is now possible to set the assist mode levels in setting screen, for example.

Alternatively, sharing those parameters to another program would also be great.

We have it on our to do list.

but the BikeOn project story on Hackaday.io is very interesting; talk about tenacity! Unfortunately it stops in 2020.

We have been developing BikeOn for several years now and have never taken any investment; these are our own savings.
With a small team of 2 (now we have a third part-time member), we have developed everything you see now: the hardware, the software, the firmware, the electronics, the custom motor, the IP, and more. We've also spent pretty significant effort to build a reliable over-the-air firmware update mechanism (similar to what Tesla has done) in order to keep all the devices up to date with the latest firmware.

 

[spaceman]

Checking the video on red ring exchange, it seems pretty clear that the red ring does not change with sprocket size

That is correct.

 

[spaceman]

The guy I was replying to was measuring the ring in all the photos and claiming supporting certain tooth sizes was impossible. I was pointing out he wasn't measuring what he would receive depending on what he entered in the form. He thought there was only one size ring for all models/skus.

I think Gruesome was trying to understand if he could use BikeOn with a custom cassette and what the largest size of the first usable sprocket would be. As for the red ring (we call it a rotor): there is one size rotor, on which we assemble the black sprocket holders of different sizes.

I hope this clears things up.

 

[spaceman]

the red ring itself does not change size (since it fits into the same support roller bracket); what changes are the two black sprocket attachment clamps that are bolted to the red ring.

Correct.

 

[spaceman]

Is that some sort of ickle off-the-shelf high pitched annoyingly whiney drone motor?

It is not. We use custom motor, which is made specifically for this device.
For example:
it has custom made magnets which improve the efficiency,
enclosed rotor-stator design which prevents mud and dust from penetrating the air gap,
beefed up bearings plus one additional 608 size bearing to make sure it will last for many years,
low profile which does not interfere with bicycle Q-factor,
cooling grooves,
and much more, this is not a complete list.

Here is a video of the device performance under load, I've posted it before:

Tom is very talented engineer indeed and has very interesting videos, btw.

 

[spaceman]

I would be happy to arrange an online zoom meeting to meet all of you, guys, answer all your questions and concerns in real time, show you the device and the app.
What do you think?

 

[Gruesome]

We've sold several tenths of units so far. Most of our users are not youngsters and online presence is often minimal. We have some videos on our website with user feedback.

We are very small team with limited resources and have to pick our battles wisely. We are constantly improving the product. Just yesterday we've pushed a software update: it is now possible to set the assist mode levels in setting screen, for example.

We have it on our to do list.

We have been developing BikeOn for several years now and have never taken any investment; these are our own savings.
With a small team of 2 (now we have a third part-time member), we have developed everything you see now: the hardware, the software, the firmware, the electronics, the custom motor, the IP, and more.

That's kind of what I guessed, that it is just the two of you. Pretty amazing what you have put together over the last ten years!
I hope you are able to get the sales going now. I'm very new on this forum, but I'd like to believe your presence here should help.

I found one user review youtube video, it's titled 'what users say', but there is just a single user. It could be worse, but it could also be a lot better.
The video 'bike performance under load' that you just linked to is very low on information content. There are no numbers, grade, speed, load, nothing. Also, the freewheeling noise is a function of the bike, not of the drive, isn't it?

A second observation: Your website comes across as a bit cagey about technical information, which is odd given it's coming directly from you (the inventor/engineer) and not some giant marketing department. I'm not saying you should put the technical stuff right up front, but it should be discoverable, like the 11 mm clearance requirement (instead of the vague 'you lose 2-3 sprockets'), and your heat shedding tests in Las Vegas. That is good advertisement! Do you have a video or some cell phone pics of the 45°C test run? I would make a page with that.

I'd also add a page that answers the question 'how much power do I need'? I think answering that question upfront is very important for small motors (or motors that just appear small), because that would assure your target customers that they can get meaningful improvement without needing 500 W. It takes a while to figure that out by oneself. The simulators are out there, but not everybody looking at your web site is aware of them. Some statement like 'adding 100 W motor power to your 100 W human power gets your flat speed from 25 km/h to 32 km/h (15 mph to 20 mph)' or 'below 10 mph, doubling your power doubles your speed up a grade' would be very helpful, I believe.

 

[spaceman]

I found one user review youtube video, it's titled 'what users say', but there is just a single user. It could be worse, but it could also be a lot better.

You can find more on our website: BikeOn Reviews

There are no numbers, grade, speed, load, nothing.

I log all my rides, should be able to find that one and post some data. It may take a while though.

A second observation: Your website comes across as a bit cagey about technical information, which is odd given it's coming directly from you (the inventor/engineer) and not some giant marketing department.

Agree. Our thought there was that most of our potential users are non-technical, however you are correct, we should publish more info and data.

Do you have a video or some cell phone pics of the 45°C test run? I would make a page with that.

Good idea. Here is that video, by the way:

I'd also add a page that answers the question 'how much power do I need'? I think answering that question upfront is very important for small motors (or motors that just appear small), because that would assure your target customers that they can get meaningful improvement without needing 500 W. It takes a while to figure that out by oneself. The simulators are out there, but not everybody looking at your web site is aware of them. Some statement like 'adding 100 W motor power to your 100 W human power gets your flat speed from 25 km/h to 32 km/h (15 mph to 20 mph)' or 'below 10 mph, doubling your power doubles your speed up a grade' would be very helpful, I believe.

These are all good suggestions, I really like all of them. We are going to make necessary changes in the near future.

I really appreciate all the comments and opinions, thank you!

 

[Gruesome]

Maybe it has been discussed and I overlooked it: what is the torque (in Nm) that the BikeOn motor puts out at the sprocket?
Sorry, found it, post #8: 55 Nm max (I assume limited by the assist level, and until it runs into the power limit or heat dissipation limit).