ebike conversion - recommendations

[trailgumby]

I have a mate who is a heart attack survivor. He is looking to convert his Santa Cruz Tallboy XC dually to mid-motor electric. Currently it has a 3x9 SRAM drivetrain. I'm a bit wary of Bafang and other chinese conversions, and especially cheapo chinese LiPo batteries. 250W and australian rules compliant is a requirement. What reputable kits would you recommend?

[find_bruce]

Following the thread because I have a similar plan.

Are you thinking front hub, rear hub or mid drive ?

[trailgumby]

Following the thread because I have a similar plan.

Are you thinking front hub, rear hub or mid drive ?

'
I think my friend wants mid-drive. My view of front drive is that on a bike of any kind it is inappropriate - understeer on a bike is a recipe for broken collarbones.

[skyblot]

I'd go with a Bafang, no hesitation. I've done a lot of conversions over the past few years, and the motors have been good. I buy from Australian distributors for both motor kit and batteries, for local warranty, spares support, AU approved chargers and quality batteries.

A 250W kit is an easy install, and with a download cable the motor's operational settings can be tailored to suit the rider.

[Thoglette]

How do these mid motor conversions measure torque? I'm looking to convert an omafiets (or just get a Gazelle e-thing) but have yet to find the bloody obvious solution: a reasonably priced torque sensing hub motor.

[skyblot]

How do these mid motor conversions measure torque? I'm looking to convert an omafiets (or just get a Gazelle e-thing) but have yet to find the bloody obvious solution: a reasonably priced torque sensing hub motor.

The Bafang BBS series don't measure input torque, ie they are not torque sensing. They are merely cadence sensing, turn the cranks, and the motor turns on at whatever power setting is selected.

The Tong Sheng TSDZ2 mid drive is torque sensing, but from memory has an even wider "Q" factor than the Bafang. The TSDZ2 isn't as well supported for spares and knowledge, but has torque sensing advantage as well as open source software for those who like tinkering.

The Bafang has a "no load" motor speed of approx 80 cadence, if you habitually pedal faster than 80 you will receive little benefit from the e-assist, I believe the TSDZ2 has an option for faster cadences (100 +?) if you use the open source software. I have not used a TSDZ2 so have no personal experience with them.

[skyblot]

... priced torque sensing hub motor.

Torque sensing bottom bracket bearing/axle assemblies are available that will work with hub motors and controllers. Not readily available out here, but can be sourced from USA based shops for more reliable communications.

[redsonic]

I am on the waiting list for one of these:

https://www.lightest.bike/

I "invested" in their crowdfunding, then COVID hit, and they still haven't started production. Good option though, if you want mid drive, torque sensor, and not Chinese.

[Thoglette]

I am on the waiting list for one of these:

https://www.lightest.bike/

Looks interesting. I'd been a bit agin' middrive but that looks eminently sensible

[Gordonhooker]

I have ridden both rear hub drive (my bike) and a middrive a friend of mines bike. I prefer the rear hub drive because it has a thumb throttle if you need a little break while riding. The middrive requires you to peddle always to get any assistance from the motor when you need it. Of course there are lots of people out there who wouldn't see that as an issue, but age does weary some of us at times.

[redsonic]

I have ridden both rear hub drive (my bike) and a middrive a friend of mines bike. I prefer the rear hub drive because it has a thumb throttle if you need a little break while riding. The middrive requires you to peddle always to get any assistance from the motor when you need it. Of course there are lots of people out there who wouldn't see that as an issue, but age does weary some of us at times.

The throttle isn't specific to rear or mid drive. You can use one with mid drive motors, but it is actually illegal on a motor over 200watts; you are supposed to progress by pedaling your ebike. Most legal 250watt motors have a limp home function at 6kph, but otherwise, you need to pedal. The mid drive I linked to above has an option for a throttle, but you would then make it illegal to use (at least in QLD).

[Gordonhooker]

I have ridden both rear hub drive (my bike) and a middrive a friend of mines bike. I prefer the rear hub drive because it has a thumb throttle if you need a little break while riding. The middrive requires you to peddle always to get any assistance from the motor when you need it. Of course there are lots of people out there who wouldn't see that as an issue, but age does weary some of us at times.

The throttle isn't specific to rear or mid drive. You can use one with mid drive motors, but it is actually illegal on a motor over 200watts; you are supposed to progress by pedaling your ebike. Most legal 250watt motors have a limp home function at 6kph, but otherwise, you need to pedal. The mid drive I linked to above has an option for a throttle, but you would then make it illegal to use (at least in QLD).

My ebike is legal and has the throttle to use for those slow 'limp home' as you put it features. So as I said the middrive - middrive in QLD doesn't have a throttle, which was the point I was making.

[skyblot]

I have ridden both rear hub drive (my bike) and a middrive a friend of mines bike. I prefer the rear hub drive because it has a thumb throttle if you need a little break while riding. The middrive requires you to peddle always to get any assistance from the motor when you need it. Of course there are lots of people out there who wouldn't see that as an issue, but age does weary some of us at times.

The throttle isn't specific to rear or mid drive. You can use one with mid drive motors, but it is actually illegal on a motor over 200watts; you are supposed to progress by pedaling your ebike. Most legal 250watt motors have a limp home function at 6kph, but otherwise, you need to pedal. The mid drive I linked to above has an option for a throttle, but you would then make it illegal to use (at least in QLD).

Slight correction here, a throttle on an e-bike is illegal if it can power the bike at more than 6kmh, irrespective of the power limits on the system.
Reference: 353BPower-assisted bicycles—Act, sch 4, definition power-assisted bicycle
(3)A vehicle mentioned in the Act, schedule 4, definition power-assisted bicycle, paragraph (a)(i) is not a power-assisted bicycle if—
(a) the vehicle has an internal-combustion engine; or
(b) either or both of the following apply to the vehicle—
(i) when propelled only by the motor or motors, the vehicle is capable of going faster than 6km/h;
(ii) the motor or motors of the vehicle are capable of operating when the vehicle is going faster than 25km/h.

[AUbicycles]

I would not go for a mid-drive conversion. I just don’t feel they are there.

A front-drive is not only easier, they have also come a long way. Bafang still present themselves poorly and for anything new.. like the eRoad they have a tendency of (appearing to) justing banging it together. But they are used by a number of brands and think that they can still get the balance in reliability verses cost.

Mahle is a conversion option… not sure if they will give you enough Dually power and with this in mind would look at rear hib drive options where you go for the rebuild of the rear wheel and I feel will be giving you power into the drivetrain

[louisfun]

I'd go with a Bafang, no hesitation. I've done a lot of conversions over the past few years, and the motors have been good. I buy from Australian distributors for both motor kit and batteries, for local warranty, spares support, AU approved chargers and quality batteries.

Sorry to resurrect this old thread, but I'm looking at DIY ebike conversion myself. @skyblot, can you tell me which Australian distributors you used?

My use case is recreational cycling for a foldable bike (20" Giant Expressway), so I just want a lightweight motor & battery for some uphill assist. I'm not intending to use it for speed or long commutes.

I'm thinking of a front hub motor conversion, but I'm having difficulty finding a conversion kit for 20" front wheels with a small 5.2Ah battery. 36V 10Ah batteries are 33cm long which are too long for me. I'd like to go with Bafang, but many online kits don't even list the motor used...

[skyblot]

Sorry to resurrect this old thread, but I'm looking at DIY ebike conversion myself. @skyblot, can you tell me which Australian distributors you used?

My use case is recreational cycling for a foldable bike (20" Giant Expressway), so I just want a lightweight motor & battery for some uphill assist. I'm not intending to use it for speed or long commutes.

I'm thinking of a front hub motor conversion, but I'm having difficulty finding a conversion kit for 20" front wheels with a small 5.2Ah battery. 36V 10Ah batteries are 33cm long which are too long for me. I'd like to go with Bafang, but many online kits don't even list the motor used...

I buy from Pirez in Melbourne, and Cap Rouge in Qld. Neither of them offer hub motors any more.
The only hub motor supplier I know is Electro Bikes at Capalaba, Brisbane. Barry's been in the game a long time and might be able to help you out.

[redsonic]

I second the recommendation of Electro Bikes at Capalaba. They've always been super helpful to me.

[louisfun]

Thanks for the pointers. I’ll ask Barry for help.

[Duck!]

I reckon you'll have a hard time getting a hub drive in a 20" rim; they're big hubs that won't leave much room to get spokes in, especially if the smaller 406mm rims (the stupidity of describing wheel size based on tyre diameter; there are two different rim diameters for so-called 20" wheels. 406mm is standard BMX size, but race BMX and many recumbents and folders use 451mm rims. I can't recall for sure, but I think the Expressway uses 406mm....)

[Thoglette]

I reckon you'll have a hard time getting a hub drive in a 20" rim; they're big hubs ....

I agree on the common "pie plate" jobbies that are common (and often over 1kW), but I've seen some much more sensibly sized ones recently (c. 200mm).

Frankly I don't know why you need anything more for 250W

[Duck!]

Even a 200-ish mm diameter hub is going to be pushing for space in a small rim. A shallow-section 406mm -measured at the tyre bead seat - rim is going to have a spoke bed diameter of around 390mm. That doesn't leave much room for spokes, only about 100-110mm depending on lacing, and the width of the hub relative to the rim diameter is going to bring some pretty extreme spoke angles which will compromise component strength. As an experienced wheelbuilder, I'd be very reluctant to take on such a build.

[skyblot]

Even a 200-ish mm diameter hub is going to be pushing for space in a small rim. A shallow-section 406mm -measured at the tyre bead seat - rim is going to have a spoke bed diameter of around 390mm. That doesn't leave much room for spokes, only about 100-110mm depending on lacing, and the width of the hub relative to the rim diameter is going to bring some pretty extreme spoke angles which will compromise component strength. As an experienced wheelbuilder, I'd be very reluctant to take on such a build.

Mmmm, I had one wheel (406 with a rear hub motor) from a "kit" returned only weeks after it went into use. The lady said a few spokes were loose. Slight understatement - 7 were missing entirely, another fell out as I turned the wheel over, and the rest were very loose.
Rebuilt with good spokes by a man knowing his trade, as far as I know it's still going years later.

[redsonic]

I bought a kit to convert my Mum's recumbent trike with a 20' rear. The spoke angles are extreme, and I thought we'd have trouble, but it's been fine so far. Probably helps that Mum is light and on 3 wheels.
Another rear conversion I did from a kit (700c) kept popping spokes until I re-laced it.

[ozfoz]

Hi, I recently posted here about my Tong-Sheng conversion and using Ozito PXC batteries as a power source.
Somebody commented and asked for more details on the battery set-up, but I can't find the thread. Apologies for the delayed reply.
I am happy to show how I connected the batteries, but I would hesitate to recommend the method to anyone without basic electrical or electronics knowledge, since there is always the danger of fire with any kind of lipo battery. I believe, after dismantling the Ozito batteries, that they are robust and well made. I have an electronics background and visually, the battery construction and circuit board construction is high quality. They appear to have full battery-management circuitry, with protection for overcharge, over-discharge, and thermal protection, but if you make a mistake connecting them up, I guess sparks could fly.
I did have to fabricate some connecting leads and fit terminals to the leads that fitted into the battery connections, so you would need to understand how to choose the appropriate wire gauge and be confident that you can judge the quality of your work. These batteries are capable of a high discharge rate so if you do get it wrong, it could be quite spectacular.
I used four standard ozito PXC 18V 4Ah batteries in series- parallel to get an 8Ah 36V power source. If you're not sure what series-parallel is this may not be a project for you. I have them mounted in a watertight tupperware-style box on a rear rack. My first version used two batteries mounted on the downtube, much more aesthetically pleasing and lighter but very limited range.
I am experimenting with 3D printed connectors to speed up battery removal and installation, since they need to be removed for charging.
Hope this helps, and gets to the person that asked for more details!

[Andy01]

Hi, I recently posted here about my Tong-Sheng conversion and using Ozito PXC batteries as a power source.
Somebody commented and asked for more details on the battery set-up, but I can't find the thread.

Just search for your own posts;

search.php?author_id=51121&sr=posts - pick the second one