Electric Bikes – odometer

7th February 2017 – 7631 kilometres

4th November 2016 – 7432 kilometres

18th October 2016 – 7245 kilometres

5th October 2016 – 7080 kilometres

20th September 2016 – 6910 kilometres

7th September 2016 – 6803 kilometres

22nd August 2016 – 6703 kilometres

12th August 2016 – 6610 kilometres

5th August 2016 – 6553 kilometres

22nd July 2016 – 6389 kilometres since June 2014

Posted in Electric Bikes

Electric Yuba – settling in

It seems like weeks since I made the last modification to the bike, other than some panniers, I think it is basically finished. The last mod was a new front brake cable to give a little more slack when handling the bike. I rode down to Pack and Pedal, our LBS to borrow some cable cutters to trim the inner cable, and gave Darryl a view of the bike. He seemed impressed, even if it is not his sort of bike. And that is the story of the Yuba, wherever it goes, people notice it, some smile, some laugh, some comment on some aspect of it but even school kids think it has a certain “coolness” about it.

I overtook another electric bike the other day while going over the ramp in Porirua, one of my computer customers in fact, which surprised me a little, as I know he likes to get a move on when he is riding his bike, which is a German brand with a Bosch motor system. Still felt good though!

I am now up to 330km, which is not a lot, but the weather was particularly foul for the first few weeks of ownership, and the last couple of weeks have been nicer, but I have been busy, and quite a few jobs involve picking up and dropping off fragile computers. However, I am getting the feel of the motor system and the bike. There are definitely tricks and wrinkles to getting the best out of the bike while making it fun to ride. The first is not to be afraid of upping the PAS level when riding hills, yes it uses a bit more power, but it does mean I can pull a higher gear without straining my aging body! The second is to use the gears and to change gear early (because of the gear sensor). A lot of time is spent in higher gears, at a high pedalling cadence with zero assistance, which is great. When the cadence drops, power gradually kicks in which is starting to feel very natural.  It is really difficult to describe all the different subtle things that one learns riding this type of system and bike.

I have taken to riding the local cycle paths to Porirua, through Bothamley park. On the long wheelbase, heavy bike this is so much fun. The bike is steady as a rock, corners so smoothly, rides the bumps on it’s 2.125″ tyres. Downhill is so much fun, completely powered by gravity! Uphill is where the bike comes into its own, with gears and power to spare it really is a fun ride back up to the top! The old ebike was excellent too, just in a different way.

The coffee cup holders built into the rear deck work really well, the sales assistants in Mega Mitre 10 really liked them as I rode through the drive through to pick up some galvanised bolts!

Posted in Electric Bikes, Yuba Mundo eV4

Electric Yuba – well it is a cargo bike!

The build of the Yuba is nearing completion, only one project to complete after the fitting of these bits and pieces.

So the Yuba is a cargo bike, and I bought it to serve as a business vehicle so that I can visit customers within a 10-15km range of the workshop, without spending $6-10 dollars on petrol. It is also a point of difference for the business which I will make more of in the future. You can buy a whole bunch of cargo carrying bits and pieces to fit a Yuba, which are all beautiful bits of kit, but with the prices to match. This was always going to be a budget build, I saved about $2500 to $3000 building it myself, so I am not going to spend another thousand bucks on flash Yuba branded gear that doesn’t quite do what I want.

Luckily, the Yuba comes with lugs, many many lugs, threaded in various sizes, and usually with the correct setscrews already fitted into them. This means that designing and making your own parts is relatively easy.

So phase one was the rear of the bike. The rear rack which is a substantial part of the bike comes without a deck, but has 8 lugs with bolts ready to attach one. I looked at what was available, and decided it was a relatively simple design job. So I measured carefully the position of all the lugs, the diameter of tubes etc, and designed a deck, which I cut out of some building ply I had lying around. As a bit of customization, I cut two cup holders into the deck, so that I can carry a long black (for me) and a large cappuccino for Lynn from our favourite coffee carts to Lynn’s work or to nice parks to drink them.

Phase 1a was the “footboards”. The frame for these is removable, and also comes with lugs. I was in two minds whether to put these on, and still am unsure about whether to continue using them. I am getting my foot caught under them when I set off using the throttle, and my feet trail behind the pedals. However, if they are on they need something to fill in the gaps. Again, fitting lugs were provided, however measuring their positions accurately was much harder, lots of trial and error making paper versions, foamboard versions, and finally ACM (aluminium composite material) versions. Even in the final versions I had to modify the hole positions as I fitted them to the frames! The ACM  is white, so I made some black vinyl graphics to fit.

Phase 2 is a little different, and I am quite lucky with how this worked out. From a source I cannot mention in a public space, but which is totally legal and above board, I acquired a front rack with a delivery box with a rather dilapidated lid. The rack is lightweight aluminium, and may be a prototype rack that was never put into production. However, it was designed to fit a completely different bike, with rack mounting points welded to the head tube. The whole thing is designed to carry about 15kg of weight, 250 days a year for 20km a day. The Yuba has its own front rack (Bread Basket) mounting system, which consists of threaded lugs behind the head tube, through the “boom tube” and the down tube. These are about 60mm further back than the mounts the rack is designed to fit, and a little narrower than the intended fit,

Luckily for me, 20,000km away, I have a son who is a qualified general technician, who has access to some sophisticated CAD/CAM equipment for cutting and bending some rather nice materials. So I again did some very careful measuring, and did a reasonably accurate rough design, which Richard interpreted into two absolutely superb brackets. The bike is not as accurate as the brackets, so I needed to relieve the bike attachment holes in the brackets by a total of 0.5mm to fit the slightly mismatched lugs, but the bolts between the rack and the brackets just slipped through all 6 holes – magic! When all was tightened up, the rack was as firm as could be, really rigidly fixed to the bike.

Pictures of the brackets

Pictures of the rack fitted to the brackets. The orange sections of tubing are covered in a 3M reflective vinyl, the same vinyl which is used for the sign writing at the rear, and around the edge of the footboard frame (covering the scrapes and damage that a shop soiled bike will have). Its a pretty good match for the metallic orange Yuba paint, until you shine headlights on it at night, then its like a big Christmas Yuba!

The lid on the delivery box was unsuitable for what I wanted, with wire supports, transparent panels and all sorts of clever stuff. I liked the way it fitted to the box, so I deconstructed the lid, and used just the part that is yellow, which has all the fitting poppers, eyelets and elastic draw cords. To that I attached a new flat lid panel, made of two layers of a cordura type nylon, with a panel of 10mm closed cell foam (sleeping mat material) sandwiched between them. I reused the bias binding off the original lid to tidy up the sewn edges. The delivery box is big enough for my large laptop case, in which I can carry two laptops, chargers, my eftpos terminal and a variety of cables and knick knacks that I may need at customers premises (the space for a second laptop is reserved for when I need to take a laptop to/from a customer). There is also room for spare waterproofs, hats and gloves etc

The front brake cable was a little short to go either way, around the outside (as in the pictures above) or down the middle like the rest of the cables, and was getting stressed when maneuvering the bike in and out of the garage and parking places. I bought an outer cable about 300mm longer, and a replacement inner cable, and routed the cable down between the rack mounting plates, and looping out to provide as gentle a path as is possible to the V-Brakes. The rear brake and gearchange cables go down the middle and back to the boom and downtubes with little extra stress. The smooth top tube of the rack provides a nice track for the cables to slide along when the wheel is turned. The electric system loom also goes along the handlebars and down the stem and around the head tube quite nicely.

The final project is a pannier, or set of panniers, tailored to fit the rear of the bike, at least one of which will be padded and of a size to carry a desktop computer without it getting damaged or wet. A tall order, but I am part way through the design now, and have all materials ready to go.

Posted in Electric Bikes, Yuba Mundo eV4

Electric Yuba – programming Bafang BBS01B

As I have described before, I am not particularly happy with the performance of the Lekkie 300W mid drive motor out of the box. It’s good, but it does not suit me.

The problem is, we are all different, ride different bikes in different ways, and have our own requirements. The Lekkie Summit 300W is the Bafang BBS01B 350W (I think) which is branded and labelled as a Lekkie, and has its own firmware version which may or may not de-tune it to 300w – whatever 300W means on an electric bike. Not sure who did this, I thought it would have been Paul at EM3EV, but it is different to what I have seen of his firmware, which makes me think it is uniquely Lekkie. Anyway, whoever did it did not know that I weigh 102kg, ride a Yuba cargo bike, and like to pedal fast and get assistance as I ride up hills and along the flat.

I have done a bit of research, which nowadays is incredibly easy, all the hard work has been done and documented on places like Endless Sphere, UK pedelecs and many other places. Thanks guys, much appreciated. Even the home made cables are now available for $16 from suppliers in china.

So I now have a cable, which I got to work after a bit of fiddling – some connection somewhere was intermittent, possibly a dry solder joint on one of the pins on the USB serial adapter.

I will just give a single source for how I did this, a wonderful person called Penoff, who resides in Norway, but I don’t think he is Norwegian! Anyway, he did all the research, created a simple web page and a document that describes how to make a serial adapter, how to connect it and how to use it. Additionally he took the open source software used by provided by Bafang, and rewrote it so that it works, it is in readable, understandable English, and made it available for us all to use. Inside the program folder is a help document that explains how to use it.

However I did read a lot of other stuff, which may be worth while just as background knowledge. Just search for programming BBS01, and lots of stuff pops up.

So, the programming cable goes into the display connection from the motor (you have to unplug the display) and the other end goes into a USB port. Penoff’s program is a single click to get going, and the port being used by the serial adapter should already be in the drop down. If you don’t know which one to use, Penoff explains it all in his document. Switch on the battery, click on connect, and you know it is working when the hardware and software information is populated.

The first job is to Read Flash – which reads the settings from the controller into the program. At this point I save them to a file called Lekkie 300.el, in case I wanted to revert to them later.

At this point I was a little surprised by the values already programmed into the controller – they are already quite aggressive and not far off what I was going to change them too anyway. In particular, the Speed Limits on each assistance level were already all set to 100%. Not what I was expecting, but they are what I was eventually going to change them to. Images of the settings follow.

Next I changed the values I wanted to change, and used write flash to update the settings on the controller, then did a read flash to make sure they were right.

So what did I change and why?

On the basic screen, nothing. If the Current Limit had been 15 as I was expecting, I would have changed it to 18, but that’s what it was already. This would have allowed for more current and more torque. However, I think the C963 control panel may override this value, and the control panel is locked down so that I can’t get to this value.

If the speed limit values had been something other than 100% for each pedal assist I would have changed them (but may have gone for a spread from 75% to 100% over the 5 usable values). Changing the Speed Limits means that the drop off as the cadence rises is delayed until much later, as it will attempt to get to the full programmed speed limit in each setting.

On the Pedal Assist screen I changed a few values.

I left speed limit at 40kph, it will never get to it, but it means that the % of speed limit will be a percentage of 40kph, not a % of 32kph (20mph), so it will not cut out too early.

I changed the Start Degree from 4 to 10, as I like a little leeway when I start pedaling before it kicks in.

I changed the Current Delay to 8 from 6, 8 is the maximum, and it means that the current does not decay until the latest point on the cadence range.

I also changed Keep Current to 100% for the same reason.

On the throttle page, I reduced the Speed Limit to 32kph and I may decrease the designated assist later. 9 gives 100% current and 100% of the speed limit, but I am not too keen on an aggressive throttle, level 5 would suffice.

And that is it, I did 23k on it today, and while it will never be a racer, I can now ride comfortably both slowly and at a reasonable speed along the flats and uphills, without using any PAS level higher than 3. It seems to be more efficient using power, I get help when I need it at a reasonable level, which stops me winding on the throttle or kicking the PAS level up to 4 or 5 so that I get assistance when I am pedaling at a higher cadence. So a nice easy job, and great results.

The C963 display panel is also branded Lekkie, and is a King Meter KM5S model under the skin. However, there are aspects of this meter which can be programmed by the user normally using the Personalised Parameter Setting functions. Unfortunately this display appears to have been modified so that this function can’t be used. This means I cannot change the available PAS levels from 5 to 9, but it also means that the “Controller Over-Current Cut Setting” may be set to 15A or 300W rather than the 18A or 350W which the controller is set to. I might be totally wrong on this whole thing, but I feel this is how the kit is sold as a 300W system.

Maybe I will acquire a non branded controller and see what I can do.

Posted in Electric Bikes, Yuba Mundo eV4

Electric Yuba – gear sensor

I ordered a Lekkie Gear Sensor from Bicycle Junction, which arrived this morning, and also a splitter cable so that I can connect it in.

Because of the length of the cable (about 300mm), and the position of an appropriate place to plug it in, it is necessary to put it near the gear change, between the handlebars and the main tube of the frame.

Most installation guides recommending splitting an outer cable guide, and placing the sensor between the two cut pieces. I chose to use a brake sensor adapter I had spare to fit it between the change lever and the cable. This is just a piece of plastic with two male ends, one to fit into the gear change lever, and one to fit into the gear sensor.

So the first job is to completely remove the inner cable back as far as the lever. To do this you have to remove the end cap on the inner cable. Unfortunately, this leaves the inner cable slightly squashed, which causes problems threading through the gear sensor. I recommend completely removing and disposing of the old inner cable, and buying a new one.

With a new cable, I threaded it back through the change lever, the adapter I mentioned, the gear sensor and then all the various parts of the outer cable and lugs etc, until it is reconnected to the derailleur, and then adjusted it. It sounds easy, but having spent quite a long time trying to thread a cable that was starting to fray, and having to remove the damaged cable when it all went wrong, and then a trip to the LBS for a new cable, it all took a couple of hours!

Wiring it is is easy. Unplug the right hand brake sensor from the main loom, and plug in the Y adapter. Plug the brake sensor back into the Y cable, and the gear sensor into the other leg of the Y cable. Tidy up the cable runs, and it is all done, really simple.

Anyway, it is all on and working. First impressions – well it is definitely much smoother changing gears. The motor shuts down just as the gears engage taking all the pressure of the drive chain at just the right time. Somewhat disconcerting is the quite significant delay until the motor kicks in again, and of course the “soft” start effect. It’s probably not too long a time, but when you are changing down on a steep hill, you can lose a lot of momentum. Overall, I think it will be better for the bike, if not for me. I will just need to change gear earlier.

Incidentally, as I removed the old inner cable fron the gear sensor, the sensor came apart. Two things are instantly obvious. Firstly the main body of the device is aluminium extrusion, making it quite robust. Secondly, rather than a complicated mechanism which some sensors have, this one has a simple rectangular “carriage” that slides up and down a similarly shaped hole through the length of the device. Inside the carriage are two magnets. The carriage has a cable gripper through the middle of it, which makes the carriage move with the gear cable, but allows it to be positioned and removed etc. In the second cavity running the length of the device is a small circuit board, with an LED at one end, and a series of bumps down its length, covered with shrink wrap. These bumps are probably Hall sensors that will detect the moving carriage magnets, and hence the moving cable. I like the cleverness and simplicity of this design, it is really just a mores sophisticated version of the brake sensors I use on our other e-bikes. Hopefully it will give me many thousands of kilometres of hassle free gear changes. It went back together again easily, and works fine.

Posted in Electric Bikes, Yuba Mundo eV4

Electric Yuba – gearing

I have had a good couple of days with the Yuba. After 60 or so kilometres riding it two things were obvious. Firstly, the gearing needed work. Secondly – the “power profile” needed adjusting, i.e. the amount of assistance given at different road speeds and pedal cadence. This second point I will deal with when the programming cable arrives.

OK, when the Yuba was taken off the back of the car, it had a 38 tooth chain ring, riveted firmly to the crank. At the rear it had a somewhat rusty Shimano MF-TZ21 gear freewheel gear cluster, with cogs from 14 to 28 teeth (14,16,18,20,22,24,28). This bike has been a display model, and has spent its early life parked outside the shop.

When I fitted the Lekkie mid-drive motor it came with a 46 tooth Bafang chain ring that was attached to the motor with 5 set screws. This gave much higher ratios, making for nice fast cruising along the straights, but a real struggle up the steepest hills.

I didn’t want to revert to the super low original gearing, but I was struggling with the significantly higher geared new setup, even with the electric motor.

So I looked around at alternatives. Firstly suppliers – you can get different sized Bafang chain rings, and quite cheaply, but postage and the delay put me off this choice. Lekkie also supply a range of Bling Rings, in sizes and colours to suit everyone. However, I just needed black. Secondly – what size – half way between 38 and 46 is the magic number 42, and Lekkie make a Bling Ring in that size! So I ordered a new 42T Bling Ring from Bicycle Junction at the standard price, who delivered it in a few days, free of charge, so a tiny saving there!

Lekkie 42T Bling ring

Fitting is reasonably straightforward, after all I had only just fitted the original one. Looks good on the bike too.

Bling Ring fitted.

I took it for a ride to a customer’s house, who lives half way up one of the steepest streets in Whitby, and the difference is noticeable and it is much better. Pedaling top speed is down to about 32kph pedaling comfortably, but downhill pedaling frantically I can get about 39kph. The 32kph will eventually match the assistance from the motor when I have worked some magic on that. The lower gears are great. The whole range of gears is basically one gear lower, so the new second gear matches the old first gear, and is very suitable for the steepest hills on most of my rides. However, the new first gear was still a bit of a struggle on the very steepest hills.

In my box of  bits from the build of the first bikes are two Shimano MF-TZ31 freewheel gear clusters, bought in error when I was quite naiave about the various types of gearing systems available on bikes, and they have been sitting gathering dust ever since. However, they have been kept carefully packet away, so they are as new, no rust etc.

These clusters are the same as the Shimano MF-TZ21 fitted to the Yuba, but the 28 tooth low gear has been replaced with a super low 34 tooth granny gear. So the gear set is 14,16,18,20,22,24,34. A quick bit of math shows that this cluster combined with the bling ring will give me a slightly faster top gear, and a slightly lower first gear than the original Yuba set up and a much lower first gear than either of the Bafang or Lekkie set ups. Perfect!

So this morning I made my second attempt to replace the gear cluster. Two major problems occurred.

1. Holding the axle still while releasing the nut on the drive side of the axle proved difficult. Eventually I found a combination of wheel nuts and spacers that allowed me to tighten up two wheel nuts against each other on the non drive side, tight enough to hold the axle while the nut on the other side was removed. This needed to be removed so that the freewheel removal tool could be put over the axle and into the freewheel splines.

2. The freewheel removal tool happens to be the same one you use to remove cassette locking nuts, and I already had one from building the original bikes. The original bikes had 12mm axles instead of 10, so I had had to drill out the tool to fit over the axle. The Yuba has even bigger axles, 14mm I think, so I had to manually file out the hole  in the tool to go over the axle. This took a while.

Finally, I used a deep 15/16″ socket over the axle and tool, onto which I put on my 600mm long socket bar, which made short work of removing the freewheel from the wheel. The rest of the installation was really easy.

So the gearing is now pretty good, I will take it for a ride soon to check it all out.

The gear range with the original cluster was 28/14 or 2:1. With the new cluster it is 34/14, or 2.43:1, a big improvement.

A table of the gearing changes follows.


Original Shimano MF-TZ21 14/28 cluster Shimano MF-TZ31 – 14/34 Megarange cluster
Chain Ring Yuba Bafang Lekkie Lekkie
Teeth 38 46 42 42
Rear cog Rear cog
14 2.714 3.286 3.000 14 3.000
16 2.375 2.875 2.625 16 2.625
18 2.111 2.556 2.333 18 2.333
20 1.900 2.300 2.100 20 2.100
22 1.727 2.091 1.909 22 1.909
24 1.583 1.917 1.750 24 1.750
28 1.357 1.643 1.500 34 1.235


Posted in Electric Bikes, Yuba Mundo eV4

Electric Yuba – just how far will it go?

Well, yesterday I found out. After 23km on Sunday, including about 200 metres of climb, I thought I would leave it without charging, and do a few short trips to see how far the battery went. So on Monday the first thing I did was a 26km trip with another 200 metres of climb, straight into a raging southerly for the first half. To give you an idea of how strong the wind was, pedaling into it, with assistance I was struggling at about 17kph. Riding with it on my back, I was doing over 30kph with zero watts on the watt meter. I got all the way home to Whitby, and about 600 metres from home, the battery warning started flashing, and then 100 metres up our street with about 300 metres to go, it cut out. I walked up the rest of the hill. Total distance on one charge of the 13aH battery – 49k. Not bad, even if it is killing me because the gearing is wrong and the controller settings need tweaking.

I just rode up the same hill again to home, and relaxed into it, just pedaling slowly and let the motor and the low gears do their job, and while I wasn’t going to break any speed records it was quite easy.

Posted in Electric Bikes, Yuba Mundo eV4

Electric Bikes – Yuba Mundo eV4 – first rides

So, the build was finished at 6.00 on Friday, and Saturday morning I took it for a first ride, into Porirua to take my wife a coffee at work, and to buy some mudguards.

Obviously this was to be a shakedown trip, and a trial of the bikes performance. Despite choosing the Lekkie 300w kit, and knowing that it was probably programmed by Paul at EM3EV, I didn’t realise some of its features.

The ride over into Porirua didn’t seem too bad, a good 100+ metres of climb at first, followed by lots of downhill and another sharp climb. The Pedelec system seemed to work great, but at times I felt I was putting too much effort in. A coffee was bought, delivered and shared, and I set off for the local bike shop (Pack and Pedal in Porirua) to look for some fat mudguards to cover the 26 by 2.125 tyres. On the way there some peculiar things started to be felt, and it appeared the left crank wanted to get off! Fortunately, I could throttle my way the last 500m to the LBS. I found some ludicrously expensive mudguards, and borrowed an 8mm allan key to tighten up the cranks – good and proper!

On the way home I started to get very frustrated with the bike, some very unusual things were happening. I am used to a 350w hub motor, which is a little under powered, so I have developed quite a high cadence in order to help it out up the hills. The Lekkie system came with a 46tooth chain ring, which is possibly a little big for the bike.

Anyway, the main issue was that it seemed to be easier to pedal in high gears than low gears. Whenever I changed down a gear to go up hills etc, it got harder to pedal up the hill. When going along straight flat roads in 7th gear, changing down to 6th gear felt like I had thrown an anchor off the back! This is a summary based on what I know now, but at the time I was frustrated and annoyed that getting home was very hard on me and the battery (I used the throttle to overcome some of the hills and head winds etc).

A bit despondent, I fitted the mudguards. By chance I had picked up a set for an ATB, which fitted using rubber bungees and cable ties – no bolts, nuts or anything else mechanical. At first I found this annoying, and while I got the front guard to fit as per the instructions, the back was not going anywhere near it. A quick rethink at the back and I realised that the Yuba has so many supports, cross bars and stays, that the whole mudguard could be attached to the stays and frame directly. When I looked closer at the front forks I realised that if it had needed lugs to bolt to, I would have been in trouble as there are no lugs other than for disc brakes on the front forks. I need to look for some normal stays to replace the bungee attached ones that came with the front guards, there are threaded mounting holes at the bottom of the forks.  Anyway, the guards are fitted and look great.

I also changed the height and angle of the handlebars, using the adjustable angle thing between the stem and the bars. The bike now fits a lot better! I did a retighten of everything I had fitted just to make sure.

So – what about the main issue? At first I thought something was faulty, so I started looking on the web for the same symptoms, searching for “bbs01 bafang low power in low gears”. A fortunate search choice, nothing that matched my problem came up, but a lot of links to pages about programming the Bafang mid drive hubs, including this one on Electricbike-blog.com.

Without reading too deeply I realised that the Bafang cuts off the power gradually as your cadence increases, so low gears and fast cadence means little assistance. While I didn’t think my cadence was high, the description matched my experience exactly.

So on Sunday we did another bike ride to our favourite cafe (a 23km circular route) and I changed my riding style to suit what I had read. What a change, I went from hating the damn bike to loving it in about 5km! I explored exactly what was happening in various power settings, gears and amounts of effort, and it all started to make sense. I was still working hard going up hill, but 103kg on a 30kg fat wheeled bike is always going to be hard work even with 300 watts of assist.

I am now using the watt meter to learn how and when to change gear. When the watts starts to rise over the norm for the PAS setting, change down a gear. When the watts drop down below about half of that change up a gear, and feel the push of that motor!

I checked out the settings in the above article for the EM3EV version of the motor, and found the offending item. The current decay setting which controls how high the cadence is allowed to get before power is reduced is in a range of 1-8, and of the 5 example of settings, the setting on my motor is the lowest, a 4 where others are at least 6 and usually an 8. This explains a lot. A programming cable is not expensive, so I have one on order, and when it comes I will check out the motors parameters, and fiddle just one or two of them. Hopefully I will be able to retain my faster cadence, because slogging up hills with a cadence of 60 or so is killing my old knees!

I also need a lower gear, 1st gear is just a bit hard on the hills I ride regularly, but there are some tougher hills in the area which will need something a bit lower. The 38tooth ring that came with the bike is probably a little low, so I thought I would swap the 46 tooth ring for a 42 tooth. What I lose in top speed will be made up for in hill climbing ability!

Posted in Electric Bikes, Yuba Mundo eV4

Electric Bikes – Yuba Mundo eV4 – delivery and build


OK, it all happened today! I rang Bicycle Junction just before midday, and was told that my motor kit had just arrived, and I could pick up the bike!

At just after 12, I drove into Wellington to the bike shop, and took delivery of bike and Lekkie motor kit. I hung the bike off the back of the Honda. It wasn’t as bad as it looks in the photo, it only stuck out about 200mm each side!

I got home about 1.10, and spent a happy 30-40 minutes unboxing the motor and battery, and trying things against the bike to see if there were any show stopping problems. Only one definite problem popped up, the speed sensor wire was designed for a normal bike, so was 30cm short to reach the back wheel of the cargo bike. The rest of the wiring looked a bit short, but until I actually put everything on the bike, it was hard to be definite. I attached the battery bracket to the downtube, and put the battery on charge.

Lynn cam home and I made lunch, and rushed back downstairs about 2:45 and started work.

First, remove the original cranks, chain wheel and bottom bracket, and remove the pedals from the cranks.

Check the bottom bracket tube for interferences inside, and then slide the motor through the tube. Add the left hand side bracket, which sort of completes the construction of the motor, gearbox and bottom bracket. Lift motor into position, and tighten up bottom bracket nut and two setscrews. Add the pretty locknut to finish the job off.

Around the other side, attach the supplied chain ring (46 teeth), as the original chainring (38 teeth) had a different mounting hole pattern. Add the chain guard, cranks and the original pedals.

I connected the motor to the battery bracket, and the wiring harness for the rest of the peripherals to the motor, and roughly cable tied it all in place.

In the end I had to remove both handgrips from the handlebars so that I could fit the front brake lever on the right, and the control panel, thumb throttle and rear brake lever on the left. These 4 items all connected into the harness with waterproof plugs and sockets, and all the wiring was just long enough!

At this point I replaced the battery on the bracket, powered up using the battery switch, and pressed the Mode switch for 2 seconds on the controller, and the control panel lit up! I did some simple tests on the motor, throttle etc. and adjusted the brakes, and took it for its first test ride at about 5.00!

And that just left the speed sensor. As this is a long tail cargo bike, the wheel is another 30cms or so back from the bottom bracket, so the normal sensor cable is about 30cms short! There are extension cables available for a few dollars, which are exactly 30cms long, but all the suppliers I checked out were out of stock, so I found some matching 3 core cable, grabbed my soldering iron, and spliced a 30cm extension into the existing cable, fitted the speed sensor and connected it all up. An LED on the speed sensor lights up when the unit is powered on, and flashes each time the magnet passes, so testing was quite simple, and when the rear was lifted and the throttle used to make the wheel turn, the speedometer registered.

By now it was 6.00, and dark, so no more test rides for today.

Tomorrow I will find some mudguards and fit them, and at the same time take it for a long test ride, which I will report on tomorrow.

I have found some reflective vinyl from one of my suppliers which almost exactly matches the colour of the bike, so I will order some of that to do the signwriting in.

Now the real fun starts – tuning to my needs and customising it to look good for the business!


Posted in Electric Bikes, Yuba Mundo eV4

Electric Bikes – a new addition to the stable.

After 3 years of building and maintaining our two Giant Elwoods with Bafang 8Fun rear hub motors, I have decided to purchase a new e-bike to act as a company vehicle for my computer repair business. My existing e-bike is having a few issues with rear wheels, mainly caused by the rider being tall and wide (183cm tall and 103kg). Add to this all the paraphernalia and gear I carry to keep warm, dry and to maintain the bike, then add on the battery and panniers for the electric motor, and then the electric motor itself, and I am overloading the rear wheel by at least 30kg.

The first cheap Chinese wheel that came with the motor broke a few spoke nipples, mainly because of the two cross pattern of spokes and the bigger diameter hub causing the angle of the spokes to stress said nipple, and also because the spokes were a couple of mm short, leaving the head of the spoke nipple without the spoke through it. The rim also wore thin because of heavy breaking, and got damaged when I hit a pothole.

So I decided to replace the rim with the original rim that came with the bike, and laced it to the motor. To avoid stressing the rim and nipples too much, I went for a one cross spoke pattern. However, as yet I have not had the wheel professionally trued, and I am breaking spokes at the hub end when I ride the bike. I am not giving up on it, and the rear wheel will become a project! I intend to use this bike for cycling holidays etc.

To avoid the weight problems, I decided I needed some thing a bit beefy. As it was also going to be used for my newly relocated business, I decided it also needed some carrying capacity. The answer is a cargo bike of some sort. Not wanting to look any more of a dork than I do already, I decided a long tail would suit best, which are specifically designed to carry 180kg or more on the rear wheel.

I looked around for a ready built electric cargo bike, and while there are some great bikes out there by Surly, Felt, Pedego and Yuba, here in NZ they are all exceedingly expensive, in the $5000 to $6500 range.

A lot of self built electric cargo bikes are based on the Yuba Mundo, which seems to be a really easy bike to work on, so I looked around for one. Bicycle Junction in Newtown, Wellington NZ sell two Mundo versions, the V4 and the V5. The V4 is the budget entry model, with 7 speed freewheel derailleurs,and V brakes, whereas the V5 has all the bells and whistles, 24 speed shimano cassette  gears, hydraulic discs, hub dynamo, but costs $1000 more! As I was considering a Bafang mid drive motor, it seemed a bit pointless to pay for the front derailleur and three chain rings, and a hub dynamo on an electric bike really is a ridiculous idea! Both bikes use a 48 spoke rear wheel, have a 120kg weight limit for the rider, and can carry vast amounts of cargo. The V4 forks have attachment points for discs front and rear, so I can upgrade in the future if I need to.

So, Lynn and I went into Wellington, and visited the cutest little bike shop in the world, and had a test ride of the Yuba Mundo V4. I found it comfortable, Lynn could ride it at a push – if she was careful of the cross bar! Bicycle Junction were having a 10% off sale, and upped it to 15% as an incentive, so after an hours walk and talk we decided to go for it.

I was going to order a Bafang Mid Drive motor directly from Chine and use my battery off my old bike, but Bicycle Junction sell the Lekkie Summit kits, and while they sound expensive at at $1790, when you add in the risk of ordering from China, the hassle of sorting out all the parts required and you factor in a new battery and charger, it is not a bad deal. And if it is costing a couple of hundred more, the convenience probably makes it worth it. So we negotiated another $90 off, and purchased a complete electric cargo bike for NZ$3400. I have some assembly to do when it arrives, so will document the arrival and conversion in detail in the next post or two.

I have some plans for upgrades and customisation, the bike needs mudguards and I would like the centre stand rather than the side stand, and I will sign write the wheel protector boards for the business. On the electric side, I prefer left hand half grip twist grips for the throttle as we use on our existing bikes, so one of those will be ordered, and I also want to try the Gearsensor, which detects when the gear shift is being operated, and switches the motor off briefly. This saves excessive damage to the gears.

Everything I have learned during the build and use of our existing bikes will help to make the build smooth and slick (hopefully).

Here is an artists impression of the signwriting, but my bike will be orange, not black.

Posted in Electric Bikes, Yuba Mundo eV4

Electric Bikes – hub motor torque/spacer washers

I originally posted this for someone who called asking for advice, but I am leaving it here in case it helps anyone else.

When you get a bafang hub  motor, it comes with two “torque” washers, which fit over the axle and have a tab that slots into the drop out. They firstly help to stop the axle turning, and secondly act as a spacer to bring the wheel width up to the width between the drop outs.

The following photographs show the location of the washers before putting the wheel into the frame, and in situ in the bike. See how the washers are between the frame and the wheel, and how the tab goes into the drop out AFTER the axle. This ensures the axle straight sides get maximum purchase inb the drop out to stop axle rotation, and the torque washers add their bit of anti rotation.

If you put them on the outside, the freewheel will jam against the frame, and will stop the wheel aligning in the dropouts and brakes properly.

Posted in Electric Bikes