Mid drive motors with torque sensor?

[redsonic]

I have decided that my next bike is going to be electric. I need help with lugging around the shopping and towing a trailer. I am hoping that I will leave the car home more often if some pedal assist is available.

I plan to build up my next bike (I have all the components) and electrify it with a mid drive motor. So, it would be built from scratch as an electric bike. I am reasonably competent mechanically, but have no knowledge of electrics.

My research has led me to the mid drive option, and I was hoping to hear about people's experiences with either the Tongsheng TDSZ2, or the newer Lingbei MM28.250, both in 250watt form, used in pedal assist mode. Neither of them sound very reliable (typical Chinese manufacturing quality issues), but there seems to be a fair bit of information out there, and aftermarket parts (for the Tongsheng at least) seem to be readily available. I have discounted the more reliable Bafang as it doesn't have a torque sensor. I am happy to hear testimonials about the Bafang though.

I will likely buy from Aliexpress rather than from an Australian firm, as I don't really see any advantage with local warranty when it will likely take months for problems to be rectified (quicker to order parts online and fix myself?).

Anyway, if anyone has advice or links to information, it would be much appreciated. I am working my way through some very long threads on the endless sphere forum; if there are other good sources out there, send them my way please.

[eldavo]

My intro background having a couple newer generations/variants of Bosch and old BBS02 and couple gens of BSSHD...

I wouldn't prioritise my choice by torque sensor, when the alternatives have programmable ramp up, multiple assist levels etc.

I would instead say programmable by current limit in multiple assist stages with all other aspects of custom programming would be my priority for a non-OEM option.
Since they all pretty much do that, I guess price out of quality/parts/warranty concerns (e.g. dead on arrival or in first 3 months / 1000km). Higo connectors and internal controller for tidy packaging would be essentially assumed standard against Bafang as the defacto.

[BrianDamage]

About a month ago, I converted my son's 29er MTB using the Lingbei MM28.250 motor . I chose this model after doing some research, deciding on a torque sensing motor and talking to the local supplier (Perth Electric Bicycles in Fremantle).

The first kit I got worked fine for about 30 minutes, then the pedal assist failed without any error message on the display, though the throttle still worked fine, which was weird. The guys in the shop at PEB gave me a whole new kit, no questions asked, which justified my decision to buy locally rather than direct, since I also had some doubts about the quality. Paid more of course, but that was peace of mind for me, plus I didn't fancy waiting weeks (months?) for delivery.

Recently the top cover for the control button attached to the C800 display, which I had noticed was wobbly, "must have fallen off" when my son was riding the bike. Again, the shop replaced the whole display unit for brand new, no fuss.

So, aside from some initial quality concerns, I've found the motor to be really good. Does take a bit of getting used to get it in the goldilocks cadence zone, but once there it's flawless. It has 3 modes (Eco, Std and Pwr) and between 3-9 selectable support levels within each mode.

4/5 stars

[redsonic]

My intro background having a couple newer generations/variants of Bosch and old BBS02 and couple gens of BSSHD...

I wouldn't prioritise my choice by torque sensor, when the alternatives have programmable ramp up, multiple assist levels etc.

I would instead say programmable by current limit in multiple assist stages with all other aspects of custom programming would be my priority for a non-OEM option.
Since they all pretty much do that, I guess price out of quality/parts/warranty concerns (e.g. dead on arrival or in first 3 months / 1000km). Higo connectors and internal controller for tidy packaging would be essentially assumed standard against Bafang as the defacto.

Thanks for the quick response, Eldavo.
I had seen all the chat about programmability but, not having ridden many ebikes, didn't really understand the need. I gather it is an enormous help with ride-ability? Starting to rule out the Lingbei if that is the case.

Thanks for the Higo connectors tip. I am anticipating electrifying my mother's recumbent trike next, and will need trouble-free cabling extensions.

All the mid drives have internal controllers as far as I know.

[redsonic]

About a month ago, I converted my son's 29er MTB using the Lingbei MM28.250 motor . I chose this model after doing some research, deciding on a torque sensing motor and talking to the local supplier (Perth Electric Bicycles in Fremantle).

The first kit I got worked fine for about 30 minutes, then the pedal assist failed without any error message on the display, though the throttle still worked fine, which was weird. The guys in the shop at PEB gave me a whole new kit, no questions asked, which justified my decision to buy locally rather than direct, since I also had some doubts about the quality. Paid more of course, but that was peace of mind for me, plus I didn't fancy waiting weeks (months?) for delivery.

Recently the top cover for the control button attached to the C800 display, which I had noticed was wobbly, "must have fallen off" when my son was riding the bike. Again, the shop replaced the whole display unit for brand new, no fuss.

So, aside from some initial quality concerns, I've found the motor to be really good. Does take a bit of getting used to get it in the goldilocks cadence zone, but once there it's flawless. It has 3 modes (Eco, Std and Pwr) and between 3-9 selectable support levels within each mode.

4/5 stars

Thanks for that BD. I was hoping to hear from someone who has used the Lingbei. As far as I know, there is no-one in Brisbane who supplies them; I would have to go through Solarbike (who will have more in stock in 4 weeks). Their closest retailers are in NSW, so it would be an online purchase, and probably come from WA. Not just a matter of visiting the shop in the event of a failure like you had.
When you say there is a goldilocks zone for cadence, do you think that the pedal assist is based more on pedal speed than pedal pressure? I have heard that the torque assist is not as intuitive as the Tongsheng one. What is your experience with the Lingbei when you really stand on the pedals?

[Calvin27]

I've gone through a fair few between me and my mate. Currently running a 350 mid drive that has done about 5000km through some laborious terrain (it's a mtb adventure ebike). They are quite reliable and have better efficiency (probably 30% more efficient than the equivalent bbs02) and natural feel than a lot of the bafangs - no doubt. Where they fall down is the top end speed is lacking due to gearing - at above 30kph the motor is not doing much and you kind of need to grind to get it going, not a problem most of the time but it takes time to teach yourself to grind instead of spinning. The only other major issue is the spur gear is plastic and notorious for failing. Easy fix with a brass one but it does make it louder.

[BrianDamage]

When you say there is a goldilocks zone for cadence, do you think that the pedal assist is based more on pedal speed than pedal pressure?

Well, I say cadence but in reality obviously torque is a factor. The temptation to mash the pedals is sometimes there, but doesn't really yield the same linear benefit. Instead, it's more of case of keeping the pedals spinning, with some force, but not too much.

The only other major issue is the spur gear is plastic and notorious for failing

If I remember correctly, the Lingbei is better regarded because it has a metal gear (though I could be mistaken).

At the end of the day, when comparing it to my wife's $4k Specialized Turbo Levo the feel and performance is absolutely night and day, but then this build was over two grand less, even when including the donor bike.

[redsonic]

I've gone through a fair few ...

I assume you are talking about the Tongsheng, Calvin?

[redsonic]

If I remember correctly, the Lingbei is better regarded because it has a metal gear (though I could be mistaken).

I believe the Lingbei has a larger nylon gear, which takes longer to wear out. I like the idea that the Tongsheng gear can be replaced with a brass one.

At the end of the day, when comparing it to my wife's $4k Specialized Turbo Levo the feel and performance is absolutely night and day

Some of the purpose built ebikes look really slick. I would be happy to spend a bit more on the motor to get performance like you describe, but the proprietary ones aren't made for normal bottom brackets. The only after market ones I could find are the Chinese brands I have mentioned. Feel free to pipe up anyone who knows of others!

I have decided to build my own mainly because I have the bike ready to build up, but also because it would be a shame to buy a dedicated ebike with integrated motor and battery only to end up with a useless frame when battery or motor fail and replacement is no longer supported by the manufacturer. I also have fairly picky requirements re geometry and set up, and the dedicated ebikes I have looked at seem to be more upright than I need, with fewer sizes to choose from too.

[Calvin27]

I've gone through a fair few ...

I assume you are talking about the Tongsheng, Calvin?

Yep I've had 250, 350 and 500w tongshengs.

[redsonic]

A plethora of choices! After much research, I decided that I didn't really want to become an electronics whizz or fettle and replace unreliable Chinese parts.
So, I went Italian. BikeeBike (https://www.bikeebike.com), the makers of another mid drive kit (discounted by me because of large Q-factor) are crowd sourcing their next project called the Lightest ebike kit.

https://www.lightest.bike/#Subscribe



It directly drives the chain, is torque sensing, and can be readily removed to convert the bike back to manual. I will post updates on this thread, but it will likely be the end of the year before I get the unit.

Thanks everyone for their advice.

[Comedian]

A plethora of choices! After much research, I decided that I didn't really want to become an electronics whizz or fettle and replace unreliable Chinese parts.
So, I went Italian. BikeeBike (https://www.bikeebike.com), the makers of another mid drive kit (discounted by me because of large Q-factor) are crowd sourcing their next project called the Lightest ebike kit.

https://www.lightest.bike/#Subscribe



It directly drives the chain, is torque sensing, and can be readily removed to convert the bike back to manual. I will post updates on this thread, but it will likely be the end of the year before I get the unit.

Thanks everyone for their advice.

Wow please update when you get it.

[AUbicycles]

Some further input - on local warranty I agree. Shimano and Bosch are the only brands that formerly have a dealer service and 'qualified' support for maintenance and repair. Other brands 'wing it'.

My take on the torque sensor, the more torque measurements you get per pedal revolution, the better.

On / Off pedal assist is nasty and the most crucial situations are when starting to pedal or with very slow cadence - this is the point when cheap / poor systems struggle to work out what the the rider wants to do and can behave badly (like suddenly accelerating or suddenly stopping).

The ramping (up / down) of the power assistance is the second crucial aspect and in the best case you can modify the controller software to optimise this - so the more datapoints you are collecting from the torque sensor per crank revolution, the more natural and predictable the pedalling and power assist.

--

Bafang is a funny one - the brand have made the biggest entry as a named Chinese brand into the western market - but they are so sloppy. With the e-roadbike trend, last year I saw a bike where they hacked one of their motors onto it and to present that botch-job at a bike show... and not even to have any staff at the stand is questionable.

[Comedian]

A plethora of choices! After much research, I decided that I didn't really want to become an electronics whizz or fettle and replace unreliable Chinese parts.
So, I went Italian. BikeeBike (https://www.bikeebike.com), the makers of another mid drive kit (discounted by me because of large Q-factor) are crowd sourcing their next project called the Lightest ebike kit.

https://www.lightest.bike/#Subscribe



It directly drives the chain, is torque sensing, and can be readily removed to convert the bike back to manual. I will post updates on this thread, but it will likely be the end of the year before I get the unit.

Thanks everyone for their advice.

Looking at the picture. What happens if the rider stops pedalling quickly or even backpedals from causing a giant chain-a-geddon? Would the motor drive slack between into the chain ring?

The first e-bike kit I had was an "elation". They had a unique design where they had a second chain ring on the other side which the motor drove. Unfortunately I had a hub bike with an eccentric BB. This layout was completely unsuited to this arrangement. That's probably a wasted story.. but what did impress me was I've never seen chain disasters like I had on the bike. Chains would be screwed up and twisted so bad you wouldn't even know where to start.

[redsonic]

Looking at the picture. What happens if the rider stops pedalling quickly or even backpedals from causing a giant chain-a-geddon? Would the motor drive slack between into the chain ring?

Good question. Apparently there is a freewheel within the crank spider, but I don't know how that would work.
Rocky Mountain eBikes have had a similar system for years, so there must be a way around it.

[John_Doh]

Did you finally get this kit? Update: Just saw, its due an April release. But that 1.7KG weight is tempting!

[redsonic]

Hi JD. It has gone way over the original estimate of last October! They found issues with a couple of components on the endurance testing, which led to a redesign of the electronics. Then, a couple of ebike manufacturers came on board with orders, and a request to improve the waterproofing, so they had to redesign the casing. Bikee Bike have communicated well all the way, and I would rather have a reliable unit after a delay than them rushing something to market. I will post on here when I finally get mine and install it.

[Janice]

I thought about Tongsheng but went with Bafang. Apart from having issues when everything got wet in the rain, it has been good.

[redsonic]

Reviving a very old thread. I received an sms from DHL out of the blue about a shipment, and disregarded it as a scam (I'm not expecting anything from overseas), but also had an email waiting and now realise my eBike conversion kit is finally on it's way from Bikee Bike in Italy. No notification from the sender but, if I am lucky, I should have the kit by Monday. Not sure if the battery is going to be a separate delivery but, judging from the customs taxes , I'd say the battery is with it.
It has taken over 3 years to arrive, but I'm glad to be finally getting something. I'll think long and hard before using crowd sourcing to buy something expensive again.
Will keep you posted on first impressions.

[Aushiker]

. I'll think long and hard before using crowd sourcing to buy something expensive again.

I learned that lesson a few years ago. Now, I would only do it with an established business such as Peak Designs (camera equipment).

Anyway will be interested to hear how you go with the conversion.

[redsonic]

. I'll think long and hard before using crowd sourcing to buy something expensive again.

I learned that lesson a few years ago. Now, I would only do it with an established business such as Peak Designs (camera equipment).

Anyway will be interested to hear how you go with the conversion.

Bikee Bike was an established business. They were already making and selling a mid-drive kit. I think COVID, plus some unanticipated redesigns was mostly responsible for the delay. Kit arrives today; looking forward to the unboxing.

[ozfoz]

I know this is an old thread, but I thought I would share my experience, since it is directly relevant to the original question.
I have a heart condition, so being able to control the effort required was paramount.
I have fitted and use a Tong Sheng TDSZ2 36 volt 250 Watt mid-drive motor.
I have fully researched this motor and parts availability, and am confident that I will be able to carry out most repairs and maintenance myself if and when needed.
Here's what I like from my experience with this motor:
Mid-drive as opposed to a hub motor makes use of the rear derailleur gearing. A front hub motor is ill-advised in a hilly city, because it puts undue strain on the fork and headset.
The torque-sensing is nothing less than brilliant- you feel as though you have bionic legs. People frequently describe this as a "natural" pedalling sensation. I agree with this description. The harder you pedal, the more assistance you get. You can choose the level of assistance applied in four ranges. I use a heart rate monitor to choose my assist level. I start riding at maximum assist to create a "warm-up" situation for the first ten minutes. Once I'm warmed up, I reduce the level to "eco" (the lowest level). This level compensates for the extra weight of the bike and just basically makes moderate riding pleasant- maybe the equivalent of having a couple of extra lower gears when you hit hills.
If I'm feeling tired or stale or my heart rate starts to go a bit high on the hills, I step up the level of assistance to bring my heart rate back down.
Contrary to some opinions, the motor has not stopped me becoming fit. I live in a hilly area, and the main effect has been to allow me to enjoy my rides right from the start, even when unfit.You can choose the level of effort you want to expend. In my experience you tend to ride a bit faster than you would without the motor, and have the confidence to tackle longer rides and steeper hills.
As I became fitter, I began turning the motor off for increasingly longer periods, and reserving the assistance for steep hills or when tired at the end of a long ride. One effect of this is that your range increases as you get fitter. I alternate my ebike rides with an un-powered road bike.
I chose to set up a DIY battery arrangement for my 36volts.
I use four Ozito 18volt 4 Ah batteries in a series-parallel arrangement. This is mildly inconvenient in that I have to remove the batteries from the bike for charging, but the removal/refitting actually takes less than five minutes in total. If anyone is interested, I am happy to share details of my set-up. I saved considerable money by avoiding proper ebike batteries, but it's a personal choice. I get double use out of the batteries because I have a few tools, including an electric mower.
I have a VLCD5 interface, and this alliws a few adjustnents to made without resorting to complicated "tuning" devices or software. I can adjust maximum speed, for instance.
The kit did come with a throttle, but this is more of a novelty than something useful, although I have occasionally used it on the flat to get my breath back quickly.
I hope these comments are helpful for anyone considering an e bike conversion.
Cheers

[Thoglette]

A front hub motor is ill-advised in a hilly city, because it puts undue strain on the fork and headset.

A bit like disk brakes (sorry)

I chose to set up a DIY battery arrangement for my 36volts.
I use four Ozito 18volt 4 Ah batteries in a series-parallel arrangement. This is mildly inconvenient in that I have to remove the batteries from the bike for charging, but the removal/refitting actually takes less than five minutes in total. If anyone is interested, I am happy to share details of my set-up.

That’s clever. Any traps for young players? What did you do for connectors & mounting? Fuses?