Advice Needed for Conversion Kit

Benjahmin · May 12, 2020

A hub motor and battery will add around 7-8kg, as a percentage of overall weight I wouldn't worry. If the bike's handleing it any way I don't think it's going to make much difference.
I think you should be able to get a frame battery on the down tube with a motor in the rear wheel for better distribution.
I would not recommend the 'switchable' motor, it is likely to be a direct drive. They are crap on hills, are inefficient and are notorious for eating batteries.
Rear hubs are a less technical ride than mid/crank drives. You don't have to worry about what gear you are in and gear changing is not crunchy. Also you can keep the front deraileur.
A self conversion would be straight forward on that machine and would cost you well less that your £800 budget. Have a look at the kits Woosh bikes have, they're all plug and play. You may need to look at their BPM motor which is high torque for the larger person. They will offer all the support you need in parallel to the help you can get here.

sjpt · May 13, 2020

chrisb1357 said:
When u say "Switchable Motor" what do you exactly mean by this.

Some motors have a switch that permits for example a nominal 1000w motor to be limited to 250w. They are often direct drive hub motors as mentioned above and are very inefficient running at lower power. Even when switched to 250w they remain illegal as a pedalec; the rules are fairly clear on that. A lot of advertisers are far from clear, even totally incorrect in saying things like 'can be switched to 250w to be legal on UK roads' https://www.amazon.co.uk/Voilamart-Electric-Bicycle-Conversion-Brushless/dp/B07BDGVSQ1

The switchable mid-drive you mentioned at the start of the thread (? http://driveconversionkit.com/2019/06/21/pcc-lb-01-switchable-36-volt-250-500-watt-e-bike-mid-drive-motor-kit/) is almost certainly not that very inefficient direct drive type, but I'm not quite sure on what basis they can claim it as legal. I'd be interested to hear comments from others on that.

Woosh · May 13, 2020

you can fit an XF08C rear hub kit to your wife's bike.

Woosh hub kits | Electric Bike Conversion Kits from Woosh

Woosh range of hub kits with choice of front or rear hub motors. Convert your bike into an electric bike.

wooshbikes.co.uk

I am out of stock at the moment, next shipment arrives in a couple of weeks, 25-May if you can wait.

Gavin · May 21, 2020

Chris- I feel your pain and empathise with your confusion around ebikes, however don’t despair. I started planning my ebike project a year ago, and having spent all my life riding and racing motorbikes I thought it would be an easy cross-over. It isn’t. Pushbike manufacturers seem to enjoy making things difficult, and the number of different component options is truly staggering.

I spent 6 months lurking on this forum and Endless Sphere, just gathering opinions and gaining an understanding of the technology and the relative pro’s and con’s of each drive type and the different brands out there.

The end result was I built a conversion that is so much fun and suits my needs perfectly, for a fraction of the price of an equivalent specced bike off the shelf. And much more importantly (to me anyway) it’s all my own work.

We’re living in a golden age of ebike technology at the moment, where people like us can build cool creations in our sheds and go out and enjoy them without interference. However pretty soon the government are going to strangle the ebike industry (and particularly conversions) to death.

So make hay while the sun shines!

Best of luck

Gavin

RobN · May 21, 2020

Hi Gavin,
as a newbie to the ebike world I would be interested to hear more on your build.
I am torn between which would be best for me. I like offroad but I would also like it on road as well.More power the better, legality hampers this but is not a deal breaker. I have a Cube attention mountain bike that im happy with and would be happy to turn into an ebike but which motor, where to put the motor etc etc.
Then I look at the new stuff coming out and wince at the prices of the new ebikes but they do look great..!
And info on yours may help me decide.
Many Thanks
Regards
Rob.

Woosh · May 21, 2020

chrisb1357 said:
Hi,

How does this compare to DWG22C-48V

Chris

The XF08C gives 45NM maximum torque.
The DWG22C 48V 60NM maximum torque.
I usually recommend the 48V DWG22C (60NM) to those who weigh over 100kgs and live in a very hilly area, SWX02 (50NM) for between 80kgs and 100kgs, XF08C (45NM) for the rest.
The XF08C is OK for even 100kgs if the area is not very hilly.

Gavin · May 21, 2020

Hi Rob

I should preface my answer to your question by saying that even having built mine from the ground up (with the exception of the motor) and now planning my second kit build, I still know very little about bikes and converting them. There are some seriously knowledgeable people on here and I’m definitely not one of them. However, I’m very much the “guy in the street” who can hopefully lend some pragmatism to the debate.

My conversion was spawned out of a combination of envy and irritation in December 2018, when my boss decided to spend £4.5K on a LaPierre AM700 ebike, instead of giving it to me as a Christmas bonus. I told him that a fool and their money are easily parted, and declared that I could build an equivalent bike in my shed (quite a bold statement, it turns out)!

The base bike was an early-nineties Specialized Hardrock that I was attached to. The spec was as follows:

It needed to be quicker than my bosses bike (obviously).
It needed suspension forks, hydraulic brakes and decent wheels.
It needed to work as an off-roader, a commuter and a “pootle in the park with my girlfriend” bike
It couldn’t look even slightly blingy
It needed to cost hundreds rather than thousands to build

I bought all the stuff I thought I’d need, second-hand off ebay in various stages over a few months (Marzzochi Bomber forks, Mavic wheels with Hope hubs, Shimano hydraulic callipers, levers and discs) then at the end I bought the new stuff (Shimano rear mech, 8-speed cassette and shifter). Whilst I was assembling all that, I’d been lurking on here and Endless Sphere getting ideas about the conversion kit. I settled quite quickly on a crank drive with a throttle for the following reasons:

I’m a biker, and the idea of having a little 8-speed electric pushbike seemed really cool.
The choice of gears would (in theory) allow me a wider range of ratios so I could go off road, but also cruise at a higher road speed.
I could get a higher power motor without advertising to any passing copper that I was breaking the law

More research and a weekend spent working at the “Fully Charged Live” event at Silverstone led me to understand a fundamental difference that seems to run through ebike discussions- torque sensing Vs cadence sensing pedal assist. I rode a few different bikes at Silverstone and the difference is obvious. With a powerful cadence bike you don’t need to put any effort on the pedals and the bike accelerates, whereas with torque sensing you need to put the effort in and the motor multiplies it.

I much prefer the torque-sensing feel- it’s much more controllable and it keeps you fit. With that decided, I bought a 750w Tongsheng TSDZ2 kit from PSW Power in Germany and it turned up in a week.

I’ll spare you the details of the bike assembly, other than to say I couldn’t have picked a worse choice of base bike if I tried! However, the TSDZ2 kit is great. I reckon if you started with a decent bike with the bottom bracket already removed, you’d fit this kit in half an hour. I fitted mine without speed sensor and brake cut-outs (although I’ve subsequently learned that brake cut-outs can stop you frying your motor so I need to sort that) to keep the wiring down and it’s worked perfectly for the last 3-400 miles.

Early impressions are mixed, as follows:

Pro’s

The torque sensing is great- you still have to work for the power so you still keep fit, but you can go a lot further.
The bike is beautifully balanced, with great mass centralization.
It’s quite quick on the road (even with knobbly tyres it’ll do approx 30-35mph.
The throttle is really useful if you’re riding in deep ruts- just stand up on the pedals and pin the throttle (Like you would on an a motocrosser).
The TSDZ kit is part of a project by a load of techy guys who are improving it, with uprated (free) firmware available on the web. (This is on my to-do list)

Con’s

With the bike in higher pedal assist, you can really feel how much load the drive-train is under. If you change gear (especially uphill) in high pedal assist you have to back off the pedals briefly or the gears really crunch.
The TSDZ motor has a questionable reliability record. Looking on the web can bring up horror stories of stripped internal gears and the occasional fried controller.
If you buy from overseas (like I did) and it craps the bed then you’re fixing it yourself (or shipping it back to China for repair).

There’s also one final downside that I’ll list separately. As far as I’m aware, anything over 250w (and especially with a throttle) is illegal on anything other than private land. My choice of kit tells you which side of the debate I come down on, but I would make the following plea to anyone thinking of buying an “illegal” kit…..DON’T DRIVE IT LIKE AN IDIOT!
Bicycle/ pedestrian collisions are increasingly finding their way into mainstream media (there was one in Oxford yesterday, reported on TV) and it’s only a matter of time before MP’s are debating it in the house. Once that happens, regulation will be sure to follow (just look at how hard it is to buy a big drone now, compared to 5 years ago).

So in summary Rob I’d say get a rough idea of what you want the bike to do, read some posts/ ask some questions on here to get a feel for the different kits then get stuck in- they’re great fun!

Regards

Gavin

P.S- Sadly the head-to-head between my bike and my Bosses LaPierre has been postponed due to the virus….Place your bets now and I’ll keep you posted!

Electric Dream · May 21, 2020

I would agree with Gavin on the Tongsheng TSZDZ as a great kit. I too chose this kit for the torque controlled pedal assist and the natural feeling it provides. The reliability has yet to be proven as I’ve covered only a hundred or so miles.
As stated by others, fitment is hit or miss depending on the size and style of the bikes chain stays.
I took a chance and was lucky.
Details of my build can be seen @

Good luck with the build.

Regards

Iain

RobN · May 21, 2020

Hi Gavin ,
many thanks for your reply. It has answered many of my questions to be honest and was very informative.
I have much the same requirements as you had for your build by the looks of it and it looks like I will go the same way now.
Can I just ask why the base bike was deemed the worst choice by you? What made it not so good for converting?
I have a cube attention which may not be too dissimilar to your Specialized so I just need to know what may not be compatible with the build. I also intend converting my wifes bike (as it would not be fair to saunter off into the distance while shes blowing like a steam train up the hills ..!) which is a specialized Rockhopper so your thoughts on both will be very helpful.
OP I hope you don't mind me hijacking your thread if your still watching it but hopefully it has given you some thoughts on what is best for you as well.
Again many thanks Gavin for your in depth reply.
Regards
Rob

RobN · May 21, 2020

Electric Dream said:
I would agree with Gavin on the Tongsheng TSZDZ as a great kit. I too chose this kit for the torque controlled pedal assist and the natural feeling it provides. The reliability has yet to be proven as I’ve covered only a hundred or so miles.
As stated by others, fitment is hit or miss depending on the size and style of the bikes chain stays.
I took a chance and was lucky.
Details of my build can be seen @

Good luck with the build.

Regards

Iain

Thanks Iain,
I had seen this on youtube previously and it was good to see how it is done.
Whats the hit or miss depending on chain stays bit mean though?
Regards
Rob.

Electric Dream · May 21, 2020

You require sufficient clearance around the bottom bracket and chain stays or the motor casing will foul. I had to file away a small area of of the motor casing (1-2 mm In one of the locations where it is raised for the casing screw threads)for it to to fit flush against the frame. It’s possible to fit spacers, but this can affect the chain line, making some gears unusable. Its also possible that the chain ring could foul the chain stays if they flare out soon after leaving the bottom bracket. I studied my possible choices of mountain bike and chose one that had a lot of clearance for the chain ring.
Like a lot of people who take on these projects I’m no bike mechanic, but figured how hard can it be. Forums such as this are a great source of help and inspiration.

Gavin · May 21, 2020

Rob- glad to be of assistance.

Most of the challenges I faced were caused by the fact that I knew nothing about pushbikes, so I was trying to build a pushbike from scratch as well as adding an electric motor to it. The main challenges were:

I thought it would be a simple thing to put modern forks in an older frame, unaware that the industry standard in bicycles had moved from 1” fork steerer tubes to 1 1/8th. As a result I had to turn up a new headtube to accommodate larger head bearings, cut the old one out of the frame then weld the new one in.

The bike originally had solid forks and frame geometry to suit. The new longer suspension forks mean that the head angle is more relaxed and the steering is noticeably slower. With hindsight I’d have steepened the head angle when I welded the new head tube in but I’ve just got used to it. This is also noticeable by the angle of the crossbar and how low I now have to have the seat.

The bike left the factory with cantilever cable brakes, so I fabricated a caliper mount and welded it on the rear of the frame to allow the hydraulic conversion.

Ironically the most visual part of my conversion (the cut downtube and rotated motor) was actually the easiest bit. Brace the frame, hack 120mm off the bottom of the downtube, fab up the ally brace plates then mount the motor. This left a perfect little cubby-hole to hide the wiring.

As I said, all of the above were self-inflicted challenges, however there’s a couple that you may face regardless of bike choice:

The battery is a heavy old lump and a lot of people complain that the plastic tags on the battery mounts break over time, resulting in the battery falling off. Most people drill the downtube and use riv-nuts to hold the battery however I’ve got an engineer’s distrust of riv-nuts so I welded M6 threaded inserts through the downtube. I used the top of the insert to mount the battery and the underside to mount the motor splash-guard. As a belt-and-braces I also welded a 25mm cross-piece to support the battery cradle laterally, and hooked a rubber strap over the battery from side to side. Now it’s rock solid.

The rear mech cable originally ran under the bottom bracket through a plastic guide, but obviously the motor is in the way. I just ran the cable along the original rear brake cable route and then used an outer and inner cable down to the rear mech. Seems to work OK so far.

Don’t let the above put you off though. Most mid-drive conversions are done on bikes that already have decent brakes and suspension forks and most people are happy to let the motor hang out of the bottom of the bike. I just like a challenge. Like I said earlier, with the right bike and no seized fasteners/ bottom bracket/ crank arms I reckon you’d do one of these conversions in half an hour.

With regards your wife- you make a good point. I went out last weekend and within 5 minutes my girlfriend had stolen my ebike and I was back to human power on her bike! Hence me now planning a second ebike build...

Good luck

Gavin

P.S- With regards your choice of bike, I haven’t got a clue. I don’t know the difference between a cube attention and a Rubix cube!

RobN · May 22, 2020

Excellent Gavin, much appreciated for the info you have provided.
Looks like ive got 2 bikes to convert....!
Thanks again
Regards
Rob.

RobN · May 22, 2020

Electric Dream said:
You require sufficient clearance around the bottom bracket and chain stays or the motor casing will foul. I had to file away a small area of of the motor casing (1-2 mm In one of the locations where it is raised for the casing screw threads)for it to to fit flush against the frame. It’s possible to fit spacers, but this can affect the chain line, making some gears unusable. Its also possible that the chain ring could foul the chain stays if they flare out soon after leaving the bottom bracket. I studied my possible choices of mountain bike and chose one that had a lot of clearance for the chain ring.
Like a lot of people who take on these projects I’m no bike mechanic, but figured how hard can it be. Forums such as this are a great source of help and inspiration.

Ahh right, thanks Iain
Regards
Rob.

Advice Needed for Conversion Kit

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