Building an ebike for commute in Cornwall

[niggle]

I am completely new to ebikes so would appreciate advice on all aspects relating specifically to building up an ebike for my beloved to commute on, though I do have a fair bit of experience building, repairing and renovating non assisted bicycles, up to and including building wheels.

My beloved's commute is about 13.5 miles for the round trip and 1000ft of ascent (22km, 315m ascent) according to Bikehike. The steepest gradient in a couple of places is around 12% and there is a 1.5mile hill setting off from home of around 5-8% gradient.

Definitely this will be a step through frame, but I would appreciate advice on all the following:

I am thinking along the lines of a mid drive kit by Bafang: but what power output would be best for a non cycling fit lady in her fifties with a 'comfortable' build, but a stated desire to get some gentle exercise out of the riding. i am aware of the legal implications if using a motor with more than 250W rated output.

I am thinking of using a SRAM P5 internal gear hub with hub brake that I have already 'in stock' built into a wheel: is this adequate, e.g. what sort of bottom end gearing should I be looking at for getting up the 12% bits mostly on motor power? Also what gearing suits the motor best at max speed on the flat? Plus will it shift OK with power assist, i.e. when my OH stops pedaling and/or releases the throttle lever will the motor quickly stop putting in the power- the hub does not like shifting under load.

The next question is the battery capacity: what would be a pretty much guaranteed capacity to cope with the above round trip commute, with recharge at home possible nightly? Also can I set up a charger to use Economy 7 at night? Bike will be in an integral garage with easy access to mains socket.

I am aware of the trend towards having the battery on the down tube but looks this will not work well with a step through frame that the user will definitely be stepping through, so will be looking for alternative battery placement: i imagine this would best be on a rear rack, so where can I get a rear rack battery, or can I just screw one of the bottle cage boss mounted ones commonly sold with the kits to a rear rack?

The front brake will also probably be a hub brake (Sturmey Archer 90mm) but are the brake levers with cut offs supplied with ebike kits compatible with these brakes that use 'standard' cable pull, as per canti brakes and caliper brakes, rather than the bigger cable pull of v-brakes? E.g. are they adjustable for cable pull like these are (shown in v-brake mode, changed to 'CR' cantiliver brake mode by moving the triangular widget in the top version, or moving the pivot point down in the the lower one):

Final question is re lighting: I use a dynamo hub for my own non assisted commuter bike and think it is great with German regulations approved LED lights, i.e. StVZO approved with K~xxx markings. I would use similar lights on the ebike but think it seems silly to have a dynohub powering the lights when there is a great big battery available. Non of the kits/batteries seem to have any kind of loom/cable to power lights so how to connect? I am happy to splice in some extra wiring if that is what is necessary but some guidance about how to would be much appreciated. Also do I need to use ebike specific lights or can I use any of the 6V dynamo LED lights I have in stock already, somehow powered from the battery?

 

[Deleted member 4366]

Let's start with the easy things. Forget the Dynamo. that just adds unnecessary weight. There's plenty of good cheap battery lights. You'll have to charge your bike every day, so it's nothing to charge your lights at the same time.
http://www.pedelecs.co.uk/forum/threads/the-new-best-headlight.25228/
These rear lights are very good too. They seem to make drivers be more aware. Maybe they get confused - who knows.
http://www.ebay.co.uk/itm/Laser-Beam-Waterproof-LED-Bike-Bicycle-Cycle-Rear-Back-Tail-Lights-Light-Lamp-G3-/122327259821?hash=item1c7b45daad:g:SuMAAOSwbdpWYnHC

Hydraulic disc brakes for the front are simpler, more maintenance free and basically, just better brakes. I can't see a reason for a hub brake, especially when you mention hills.

13.5 miles isn't very far. You should be able to do that with any battery over 10Ah.

It's difficult to know which motor to recommend without knowing your weight. You need nearly twice the power to get a 14 stone person up a hill compared with a 7 stone one. Crank motors and hub-gears isn't the best combination. Derailleur gears change much better, but if you were to have derailleur gears, that brings in all the hub-motor options too.

A crank motor kit and battery will set you back about £650. There's some questions on the long-term reliability of the Bafang BBsxx motors, which is not so bad if you can fix them yourself. I don't think I've ever seen evidence of one going for thousands of miles without attention, compared with hub-motors, which are generally pretty reliable these days.

A few things to bear in mind when building an electric bike that I've learn't over the years from my many builds:

1. Think about weight. The lighter, the better.
2. Things that make a normal bike good are often not necessary on an electric bike. A cheap normal bike converted can become a very good electric bike
3. Hydraulic disc brakes are leaps ahead of anything else regarding reliability, maintenance and performance.
4. Choose a battery that can be replaced by another standard battery when it wears out after 2 to 3 years.
5. Battery weight and positioning is important. It should be as low-down and centralised as possible. If you can't get it low and centralised, then get the weight as low as possible, which means modern cells and higher price. Don't use a standard rack, which will position it too far back and too high. It needs to be as close to the seatpost and wheel as possible.

 

[Woosh]

I don't think I've ever seen evidence of one going for thousands of miles without attention, compared with hub-motors, which are generally pretty reliable these days.

There is one second hand CD bike for sale on the Woosh website this morning with 2632 miles on the clock.
Nothing done to it.

http://wooshbikes.co.uk/?secondhand

Sport CD with 10AH battery
36V 10AH battery, range about 20 miles
Good condition
Location: London
2632 miles on the clock
The newer version has larger battery, for other details, follow this link: /?sport-cd

Suggested offer: £349
New price: £899.
Please call.

 

[The Davis Bike]

Hello i have made a few step though bikes,
- i think the mid drive is the best overall package (the pic has a hub drive as a mid drive would not fit on this frame), you may need an internal gear sensor which will stop the motor, when changing gear.
- I am afraid I don't know about hills as I live in Cambridge.
- Battery 10ah 36v or more, I would think. The rear rack battery changes the weight distribution of the bike. i used Munsen Rings to put the battery down the seat post (may not work for your build), you can still step though, but a bottle battery maybe less intrusive. (there is a battery that goes behind the seat, maybe an option?)
- The brake cables that come with the kit, i think will work fine (but i would double-check before you order)
- Lights, just use the dynamo, the battery is 36v and the light is 6v you would need a resister to drop the volts (which will be ugly, heavy and a pain), you can get 36v lights which will work, if you really want to use the battery directly (i like the idea of the battery powering the wheels, which in turn power the lights, but that's just me).

hope this helps a little,

pictures please when you have finished you build

Thanks Tim

 

[Woosh]

Hello Niggle,

I realize that you want to convert one of your bikes but I thought it may help your decision to look at a few ready made step through bikes for comparison.
From my range, I would suggest: the £749 Woosh Crusa.
I reckon to build the same bike with new components, it would cost you £950.
If you need more acceleration, the Santana2 and the Big Bear LS.

 

[niggle]

Let's start with the easy things. Forget the Dynamo. that just adds unnecessary weight. There's plenty of good cheap battery lights. You'll have to charge your bike every day, so it's nothing to charge your lights at the same time.
http://www.pedelecs.co.uk/forum/threads/the-new-best-headlight.25228/
These rear lights are very good too. They seem to make drivers be more aware. Maybe they get confused - who knows.
http://www.ebay.co.uk/itm/Laser-Beam-Waterproof-LED-Bike-Bicycle-Cycle-Rear-Back-Tail-Lights-Light-Lamp-G3-/122327259821?hash=item1c7b45daad:g:SuMAAOSwbdpWYnHC

OK well we are just going to have to politely disagree on the lighting issue as I have long since moved away from using inappropriate and dangerous front lights that do not have a beam cut off, I have used a Magicshine XTML T6 in the past and it was a PITA trying to avoid blinding oncoming drivers fiddling about with it every few seconds, either the power level or swiveling it down and back up, then having having to re-charge 2-3 times per week, then having the batteries fail after a couple of years, then have the cables fail due to having to remove, replace etc every time you stop in town or at work etc. Now I use an always ready, utterly reliable dynamo system with a Shimano DH-3N80 dynamo hub and German standards approved bolt fitted front and rear lights on my all year commuting non-electric bike. The front light (I have used an Axa Luxx 70 and currently trying out a 90 lux Hermanns H-One S) throws all it's light towards the road surface where you need it to go, it has a beam cut off which prevents nearly all of the light going in to driver's eyes and I can maintain speeds up to 30mph on twisty country lanes with it (down hill I hasten to add!)

Really there is naff all weight gain when you compare with battery powered lights that you can actually see with on an unlit country road, e.g. the DH-3N80 hub weighs 481g, an equivalent XT front hub weighs 153g and the 4x18650 battery pack for the Magicshine weighs 250g, my rear rack dynamo lamp, a Spanninga Solo, weighs 32g, the battery version weighs about 30g more with 2xAAA batteries in, so we are talking about less than 50g difference.

Also yes, plugging in the main battery will be necessary but why add to that with recharging lights when you can have zero faff lighting either from the main battery or a dynamo hub? If i was to go for battery lighting it would also be decent approved stuff, but I would very much like to avoid it as I know the rider will not like the extra fuss.

Hydraulic disc brakes for the front are simpler, more maintenance free and basically, just better brakes. I can't see a reason for a hub brake, especially when you mention hills.

Good points, but how do you solve the problem re the motor cut-off switch thing? Also you should really try a 90mm Sturmey Archer front brake, they were originally designed for tandems and some guy on the net managed to bend his roadster's front forks with one; they are very low maintenance, the brake shoes last for decades, they are virtually impervious to the weather and will outlast any hydraulic disc brake by a factor of about 50 to 1: my friend who does 15000 miles a year on his Rohloff geared full sus MTB gets through a set of hydraulic disc brakes annually, just buys another set when they have seized up beyond redemption. However as predicted mileage for this build is very much lower I will give this some more thought, particularly as the drum brake option does come with a bit of a weight penalty.

13.5 miles isn't very far. You should be able to do that with any battery over 10Ah.

Good to know, I just want to be sure of getting the right one due to the cost involved, also see below re weight of the rider...

It's difficult to know which motor to recommend without knowing your weight. You need nearly twice the power to get a 14 stone person up a hill compared with a 7 stone one.

As I said it is for my beloved and she is definitely 'cuddly' but I am not going to take the risk of asking her how much she weighs my best guess is somewhere between the 7 and 14 Stone examples, but a lot closer to the latter (hope she never reads this forum...)

Crank motors and hub-gears isn't the best combination. Derailleur gears change much better, but if you were to have derailleur gears, that brings in all the hub-motor options too.

Shame, I hate derailleurs for all year commuting, I used a Nexus 8-speed hub bike for 8 years and it was so easy to live with that when I replaced it I went with a nicer build with an Alfine 11.

A crank motor kit and battery will set you back about £650. There's some questions on the long-term reliability of the Bafang BBsxx motors, which is not so bad if you can fix them yourself. I don't think I've ever seen evidence of one going for thousands of miles without attention, compared with hub-motors, which are generally pretty reliable these days.

What are the disadvantages of front hub motors, as presumably they are fine with hub gears? Can you fit a disc brake on any of them? Also what are the problems with the Bafang mid drives and are there any alternatives out there that are any better?

A few things to bear in mind when building an electric bike that I've learn't over the years from my many builds:

1. Think about weight. The lighter, the better.
2. Things that make a normal bike good are often not necessary on an electric bike. A cheap normal bike converted can become a very good electric bike
3. Hydraulic disc brakes are leaps ahead of anything else regarding reliability, maintenance and performance.
4. Choose a battery that can be replaced by another standard battery when it wears out after 2 to 3 years.
5. Battery weight and positioning is important. It should be as low-down and centralised as possible. If you can't get it low and centralised, then get the weight as low as possible, which means modern cells and higher price. Don't use a standard rack, which will position it too far back and too high. It needs to be as close to the seatpost and wheel as possible.

OK thanks for all the above, I always think about weight when building a bike, e.g suspension front forks, as seen on many ebikes, are a major weight problem compared to even a cheap steel rigid fork (plus they soak up energy when they bounce up and down as you pedal, do nothing for on road ride quality, need maintenance and still wear out and need replacing). weight does also matter quite a lot when you are riding up a hill entirely under your own steam...

Sorry if I come across as a bit 'know it all' when I have asked for advice, but I do have a decade's experience of daily commuting by bicycle plus many more years of mechanical tinkering and maintenance with bicycles and motorcycles, i just know virtually nothing about ebikes.

 

[niggle]

Hello Niggle,

I realize that you want to convert one of your bikes but I thought it may help your decision to look at a few ready made step through bikes for comparison.
From my range, I would suggest: the £749 Woosh Crusa.
I reckon to build the same bike with new components, it would cost you £950.
If you need more acceleration, the Santana2 and the Big Bear LS.

Hi Mr Woosh, I have already perused your website, mainly looking at the mid drive kits. The used bike you posted previously is no doubt good value but is not what my OH is looking for, a step-through frame is a must. The Woosh Cruiser is a lot close as you say, but still has the hated derailleur gears. A mid drive version with e.g a Nexus 8 spd hub would be very attractive, but I understand that, as previously mentioned up thread, crank drives can be an issue with hub gears? I know that building a bike from parts is nearly always more expensive but you do get the opportunity to spec it just the way you want and spend money on what is important to you, plus as a typical cycling enthusiast I already have a lot of usable bits hoarded away in the garage.

 

[Woosh]

Niggle, the Sport CD is with reference to d8veh's post, re. 'evidence of one going for thousands of miles without attention' That one did just that, 2,6xx miles without special attention.
For your wife, there is also a second hand Woosh Santana CD currently for sale.
That bike has a 15AH battery and only ridden 569 miles. The previous lady owner is looking for offers around £499. I think it's an excellent bike for the money. http://wooshbikes.co.uk/?secondhand

There is nothing special with the rear wheel.
You can easily replace it with another 700C wheel and a hub gear if you like.

 

[niggle]

Hello i have made a few step though bikes,
- i think the mid drive is the best overall package (the pic has a hub drive as a mid drive would not fit on this frame), you may need an internal gear sensor which will stop the motor, when changing gear.
- I am afraid I don't know about hills as I live in Cambridge.
- Battery 10ah 36v or more, I would think. The rear rack battery changes the weight distribution of the bike. i used Munsen Rings to put the battery down the seat post (may not work for your build), you can still step though, but a bottle battery maybe less intrusive. (there is a battery that goes behind the seat, maybe an option?)
- The brake cables that come with the kit, i think will work fine (but i would double-check before you order)
- Lights, just use the dynamo, the battery is 36v and the light is 6v you would need a resister to drop the volts (which will be ugly, heavy and a pain), you can get 36v lights which will work, if you really want to use the battery directly (i like the idea of the battery powering the wheels, which in turn power the lights, but that's just me).

hope this helps a little,

pictures please when you have finished you build

Thanks Tim

View attachment 17557

Now that is the kind of thing SWMBO has in mind, but I am interested in what the problem was with fitting the mid drive to the frame. The frame I was proposing to use has already been purchased from Ebay, not a bad price and it can always be used for something else if it does not work out:

In all my searching about I did see the internal gear sensor listed somewhere, but cannot remember where... can anyone confirm this will cure the issue with mid drive and hub gears?

I have thought of a 'dodge' if the brake levers do not work with canti/caliper/drum brake cable pull, will update if this comes off.

As for lighting I will 'weigh up' the options, but I am definitely keen to avoid battery lights, especially for the front.

 

[Woosh]

In all my searching about I did see the internal gear sensor listed somewhere, but cannot remember where... can anyone confirm this will cure the issue with mid drive and hub gears?

http://gearsensor.com/products

After you have selected the motor, email them for the list of dealers.
Their gear sensor for BBS01/BBS02 retails at £50.

 

[niggle]

Thanks for this

 

[niggle]

That bike has a 15AH battery and only ridden 569 miles. The previous lady owner is looking for offers around £499. I think it's an excellent bike for the money. http://wooshbikes.co.uk/?secondhand

There is nothing special with the rear wheel.
You can easily replace it with another 700C wheel and a hub gear if you like.

Good value again, but vertical dropouts which mean a chain tensioner is needed to fit a hub gear- see the pic of the frame I have picked up for £40 inc postage from Germany, it has horizontal dropouts.

 

[Steve UKLSRA]

http://www.ebay.co.uk/itm/172488694852?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Cheaper Chinese copy

 

[Benjahmin]

What are the disadvantages of front hub motors, as presumably they are fine with hub gears?

I have an Ezee front hub and can confirm it takes a disc

and it climbs hills like you've got Bradley Wiggins as a stoker. However the control is not subtle, there is a strong surge as the pas kicks in. I like it but it spooks people who aren't used to it. One solution would be to start off in power setting 1 and move up once going. Notice the torque bracket to stop it spinning out of the dropouts. These motors/kits are not cheap but I've found it to be reliable and a prodigious hill climber. Front hubs can be skitty on the steepest of hills if the road surface is loose, I counter it by standing up and putting weight over the bars. I also have a Carradice C fitted(tools, gloves, keys etc.). The Ezee controller has an output for lighting and 36v lights are available. Or you can fit a step down and fit lights of your choice.

The Woosh 8fun BPM kit (as fitted to the Big Bear) is equally capable and somewhat cheaper, also takes a disc. My wife has the Big Bear LS and is no athlete. Even on this dutch style sit up and beg bike she's getting around our west Wales hills with only a mild glow. Much to the disgust of the local lycras.
So yes, all the power through the front wheel so no additional strain on your igh.

 

[The Davis Bike]

Now that is the kind of thing SWMBO has in mind, but I am interested in what the problem was with fitting the mid drive to the frame. The frame I was proposing to use has already been purchased from Ebay, not a bad price and it can always be used for something else if it does not work out:

In all my searching about I did see the internal gear sensor listed somewhere, but cannot remember where... can anyone confirm this will cure the issue with mid drive and hub gears?

I have thought of a 'dodge' if the brake levers do not work with canti/caliper/drum brake cable pull, will update if this comes off.

As for lighting I will 'weigh up' the options, but I am definitely keen to avoid battery lights, especially for the front.

hi,
the first bike i made i wanted to fit in the lights as well, but i couldn't figure out how (if you do, let me know).
The problem with that frame was the motor hanged down to low and was in danger of hitting curbs and sleeping policeman etc.
The frame that you bought looks great, i not think you will have a problem.

http://dillengerelectricbikes.co.uk/electric-bike-kits/8fun-mid-drive-kit-bbs01-by-bafang.html

This company has the option to buy a internal gear sensor for £63, but its quite expensive (i would think if you email them they would sell you one). i've only made single speed electric bikes so i never needed one.

one thing about the bafang mid drive kit the cranks are rubbish

 

[Deleted member 4366]

However the control is not subtle, there is a strong surge as the pas kicks in. I like it but it spooks people who aren't used to it. One solution would be to start off in power setting 1 and move up once going.

Another solution would be to change the controller to one of these with a LCD. They use current control:
https://www.aliexpress.com/store/product/36V-48V-500W-Brushless-DC-Sine-Wave-sensor-Controller-ebike-Electric-Bicycle-Hub-Motor-Controller-with/1314442_32759790640.html?spm=2114.12010608.0.0.Tcfs4M