Ebike Conversion

[Blue Hills]

I signed up on Pedelecs and have been asking ebike questions over there.

I quite like the look of the Whoosh Aikema hub kit for my friend's bike. If I were doing a conversion for myself I would go for something like the Bafang BBS01B crank drive kit because I prefer a high cadence and am happy changing gear to suit. My friend always seems to choose too high a gear and then struggles. I think the extra oomph from the hub motor should get her up most of the hills she currently walks up.

Maybe being thick, but am confused - specs for second seem to say max rpm of 78.

That strikes me as quite low.

Had never even considered the RPM as a factor before I saw your post though - clearly a field best entered with care - luckily I think I have a few years before I make my entry into the world of electric assist.

 

[CXRAndy]

I signed up on Pedelecs and have been asking ebike questions over there.

I quite like the look of the Whoosh Aikema hub kit for my friend's bike. If I were doing a conversion for myself I would go for something like the Bafang BBS01B crank drive kit because I prefer a high cadence and am happy changing gear to suit. My friend always seems to choose too high a gear and then struggles. I think the extra oomph from the hub motor should get her up most of the hills she currently walks up.

The latest version of open software for the TSdZ2 allows for upto 130rpm without too much tail -off in power delivery. Endless sphere is the website for all things electric bikes, vehicles solar etc.

I challenge anyone to maintain that kind of rpm. On my normal road bike for training I will spin at 100rpm and sprint upto 170rpm, but dont reach those numbers on the road, more 80-95rpm

 

[CXRAndy]

Here is a link to files for those who like to do their own installation of firmware on the TSDZ2 https://github.com/OpenSource-EBike-firmware/TSDZ2-Smart-EBike

 

[ColinJ]

Maybe being thick, but am confused - specs for second seem to say max rpm of 78.

That strikes me as quite low.

Had never even considered the RPM as a factor before I saw your post though - clearly a field best entered with care - luckily I think I have a few years before I make my entry into the world of electric assist.

Oh, well spotted... I normally prefer more like 85-95 rpm. Still, like you, I don't need a motor... yet!

 

[CXRAndy]

My 2nd kit will be for my first MTB bike, when I just want to ride around uphills and a bit further a little faster with less effort- sort of recovery type riding.

 

[ColinJ]

Maybe being thick, but am confused - specs for second seem to say max rpm of 78.

I found a thread on Pedelecs discussing that. Somebody actually rebuilt his motor to work around it. There is no way that I would buy a new kit and then immediately gut it because it didn't do what I wanted it to do - I would buy something else in the first place! Still, it confirmed that the rpm limit would be a real problem for me. By the time I might need a motor (aged 70+?) then technology will have moved on so I'd see what is available then.

 

[plustwos]

Well, you are a Guru, but have you drilled two holes through the down tube to bolt on a plastic battery mount? Was that wise? I have been thinking of changing my wife's thirty years or so Dawes so that she can keep up with me on my new E-bike but was thinking in terms of mounting the battery on her rear pannier frame.
Ken

 

[Blue Hills]

Agree.
Assuming neither of us gets hit by a bus I think we are timing our electric entry pretty well. Tech will get better, more choice, more competion. And I may well go the convert route.
Do folk have ideas on what sort of frames are best for conversion platforms? I have in mind some good solid steel hybrid or rigid MTB.

 

[ColinJ]

Do folk have ideas on what sort of frames are best for conversion platforms? I have in mind some good solid steel hybrid or rigid MTB.

The bike that I plan to convert is my old Orange Prestige rigid (steel) MTB. It was always a bit small for me so I donated it to my friend who is pretty tall for a woman; it just about fits her. With riser bars to replace the current flat ones I think it would be a perfect fit.

It looks like the converted weight should be sub-20 kg which isn't bad for what would be a cheapish ebike.

 

[Ananda]

Agree.
Assuming neither of us gets hit by a bus I think we are timing our electric entry pretty well. Tech will get better, more choice, more competion. And I may well go the convert route.
Do folk have ideas on what sort of frames are best for conversion platforms? I have in mind some good solid steel hybrid or rigid MTB.

A steel frame with the longest chainstays you can find!
Steel carries gracefully the extra load and the long chainstays make for a better functioning chainline. Unless you use an IGH of course.
Unfortunately modern mtb frames are designed with short chainstays.

 

[Blue Hills]

A steel frame with the longest chainstays you can find!
Steel carries gracefully the extra load and the long chainstays make for a better functioning chainline. Unless you use an IGH of course.
Unfortunately modern mtb frames are designed with short chainstays.

Sounds like a fair few from my current bunch will be ideal.
Which will save me from an old age having to ride some desperate clunker or something trying to look ultra cool and modern with "innovative" tube and frame flourishes.

 

[CXRAndy]

Well, you are a Guru, but have you drilled two holes through the down tube to bolt on a plastic battery mount? Was that wise? I have been thinking of changing my wife's thirty years or so Dawes so that she can keep up with me on my new E-bike but was thinking in terms of mounting the battery on her rear pannier frame.
Ken

There is a metal spine to the battery mount, encased with plastic. The plastic is for the mount key-ways for the battery to slip onto. The lock pin enters the metal spine, preventing easy theft attempts.

With regards to drilling holes. I don't see it as problem. Firstly its steel material, holes by there very nature aren't stress points. Metal fabricators use radius cuts or drill holes in corners of metal work to relieve stress fractures. When repairing metal that has cracked you're supposed to drill a hole at the end to help stop the crack extending beyond. By having four hole actually reduces loading on all points by sharing the battery weights lateral movement.

The only obvious disadvantage to mounting the battery on the pannier rack is, centre of gravity is increased in height, potentially giving a weird sensation of the bike pulling left or right in critical balance moments. These batteries weigh 3-5kg.

I experience this with panniers when I load them up with shopping. the added weight is like a pendulum moving you around and if not careful could topple you off if a little inexperienced.

If you do get your wife an ebike or convert one, you will find she will possibly out ride you into headwinds especially with a slight gradient. Steeper hills, she will destroy you. She will looked refreshed at the top of a climb as you arrive gasping, sweat dripping off your brow.

My wife having spent years not enjoying riding, because she always thought she was slowing me down. Bit now, we have giggle at the fact I put her on the front to pace me into wind. I can then sit in her draft and hang on

 

[CXRAndy]

Do folk have ideas on what sort of frames are best for conversion platforms? I have in mind some good solid steel hybrid or rigid MTB.

Steel or aluminium, but steel first.. Its the brackets that prevent rotation of the motor are tightened against the frame. Softer materials are prone to damage. I use 3mm rubber sheet between the bracket and frame to help protect the frame against rubbing.

To be honest it really doesn't matter about bike weight, a heavy old frame is usually ideal. The added motor and battery are nothing compared to the 250W constant power available. Do remember all these e-bike motors from Bosch thru to TSDZ2 can and do produce a lot more power in short bursts. 250W is rating for continuous output.

 

[Blue Hills]

Sounds like it's a conversion for me then, and i rather like fettling and going my own way. No need to impress anyone.
Any disadvantages to a conversion compared to a dedicated ebike?

 

[CXRAndy]

Sounds like it's a conversion for me then, and i rather like fettling and going my own way. No need to impress anyone.
Any disadvantages to a conversion compared to a dedicated ebike?

The only comments I tend to see are they kits aren't built to the same quality as the Bosch, Yamaha, Brose etc. Like you I like tinkering and making things work they way I want them. There are two obvious ways either wheel hub motor or crank based motor. Both have advantages over each other. The crank motors are usually quite small, extremely torque strong when coupled with gearing.

The two common crank motors are Bafang and Tongscheng (TSDZ2) Spares are plentiful and usually very cheap- not tied to sending it back to dealer for minor repairs/service.

Bafang have good reputation for building reliable strong motors with some being extremely powerful 1000W Bafang is what I call the traditional pedal assist- you turn the pedals, power will be delivered at whatever level you have it set on. As long as the pedals are turning, even with little effort you will get assistance. You will see folk just slowly rotating whilst travelling quite quickly, that's pedal assist.

TSDZ2 is a torque assist motor, It reads the level of effort the rider is putting in and then multiplies that effort depending on what level of assist you choose.

Example a rider is producing 100 watts of pedalling power, the motor is set on level 1 with 75% assist equates to 75 Watts, so total pedalling force is 175W. Now said rider still pedals at 100W but this time has max setting of 300%, a total of 300w+100W=400W pedalling force, that is a lot.

The rider still has to put in a 100W, but if they drop down to 50W, max assist will be reduced to 150W total of 200W. The rider still needs to pedal to get the best out of themselves and the bike. My wife wanted to have a workout from riding not a freewheel effort the pedal assist versions offer.

I chose the TSDZ2 with open firmware because the developer (Cassinho) has beautifully tweaked the motor response to make it super smooth in the way it accelerates from zero and added many features to help tweak the way you want the bike to perform. It rides just like a normal bike except with a whirr. The pickup from a standstill is nice and smooth but with a little bit of pep to it. Its not jerky. The power when riding cuts in and out smoothly.

I hope that helps. Im by no means an expert, this being my own experience of this kit. But boy