Noob questions

[duncmac]

Hello All

I've been reading through posts on here and in general having a browse around whats available for building up an ebike.

My motivation for getting into ebikes is looking to save a few quid and having some fun.

At the moment I motorbike into work each day, its a short commute 9ish miles each way, through a not unpleasant route into london from the southeast.

"9 miles you say? why dont you bike it in you lazy tart" well I am a bit lazy and theres a hill or two in the way.

So I'm looking to put together an ebike kit to put on an old steel frame marin moutain bike.

I'm mechanically minded but not yet got my head round the electricity side of things.

Question I have are, based upon my route and my need to be able to make the whole distance with minimal/no pedaling and the really steep hill at the start/end, speeds of not more than 30-35mph what kind of motor/battery am I looking at?

I'd rather spend on something thats a bit more over-engineered than I need and have it reliable/upgradable.

Is something like crystalites the crown and a ping 72v 15ah battery going over the top, what kind of controller would be needed?

 

[bowlofsalad]

http://ebike.ca/simulator/ After you play with that some, check out what they have for sale.

Figure out the grade and put the grade into the simulator, you might want a slow winding motor. If the hill is a real monster, you might want to consider a mid drive or two motors, one in each wheel, with some holes drilled in each side of the hub and some boeshield t-9 or something similar sprayed on the appropriate locations. I also recommend any ebike have a solid job in relace, do not go cheap on the spokes, especially if you are going 30+mph with no suspension. Even with suspension though, don't scrimp on the spokes and relace, it's important unless you don't mind dragging home a busted ebike or getting a truck to pick you up or something. A wise person would carry some spare spokes just in case.

At those speeds, fat tires and full suspension don't seem optional. Order a voltmeter, plan to buy a watt meter (cycleanalyst is popular for a reason), and maybe a celllog (this requires balance leads, they are necessary in my opinion).

You'd need a controller that can handle 72v. I couldn't tell you if 72v was over kill or not, that really really depends, but frankly, I don't care. If you want 72v, go for it, there really isn't over kill for this, just so long as it does what you want it to do. Nothing ever broke from being made too strong.

Whatever battery you choose, find it's dimensions and make a cardboard box as a mock battery, maybe make it a bit larger for the container and foam that'll go with it. Then put it in the triangle of whatever bike you are going to use or looking to buy. If it doesn't fit, it is going to be an obvious no go for you. There are other battery mounting options like racks with a battery on top, seatpost mounts, and racks with panniers and a split battery or something like that. Most people on uprights prefer the triangle because it's strong, low center of gravity for good balance and generally not too difficult to setup.

A better subject for this thread would be "Need advice for picking battery/ebike kit."

"Noob questions" can mean anything and to me it means nothing.

Watch out for those garbage bins, I hear they have eyes.

 

[Anthony King]

Hello Duncmac,

I'm also new but I have one bit of advice since I also live at the top of a big hill (412ft. elevation gain).

I figured the average grade of my climb and plugged in into the simulator, but I didn't figure out the grade of the shorter, steep sections, which are in places just over twice the grade of the average grade.

It wasn't a terrible mistake, but a really dumb one in retrospect that I wouldn't want to see anyone repeating.

I'm carrying children and cargo up my big all and am happy to average 10mph on the way up. So I don't have motor/battery advice. Best of luck, you'll get lots of help on ES.

 

[duncmac]

I've seen plenty of 12g spokes talk, I'm liking the look of the 29er moutain bikes or at least something like Bontrager Hanks or BIG APPLE PLUS tyres.

Sound battery advise, regarding total elevation and size.

I've been playing around with the simulator, but still feel like I need to know more about batteries and controllers and how they interact.

I'll do some more reading to work out my questions on what battery capacity I need and what battery "power/discharge rate" I need for the motor and what I want it to do.

 

[parajared]

Spoke breakage comes when you have loose spokes but don't tighten them then go down a bumpy road, or overtighten and go down a bumpy road.
I used be on board with the whole "get fat spokes" thing, but after breaking just as many 12ga spokes as 14ga spokes, I think it's more of a tension/maintenance thing than anything.

29ers are neat bikes, they plow over rough terrain with ease, and the racing non-motor types seem to think that they are more efficient. but they aren't very good with hub motors. I'm not sure what the science is behind it is, but taller wheels run less efficiently than short wheels. I base this on the fact that my MXUS 20" always runs more efficiently than my 9C 26" at the given speed it's going.

A number of the more zealos members on the sphere run 20s or 24" setups for this reason.

 

[d8veh]

You're taking a big risk commuting in London at that speed. Doing it once or twice is one thing, but you're going to get noticed doing it regularly. It only takes one frustrated motorist to report you, then the next day the police will be waiting for you and you'll lose everything. With a 30mph bike, massive pancake motor and batteries hanging off everywhere, you won't be able to kid them that it's 250w. I think that you'd have a much better chance if you built a stealth bike, kept the speed down to about 23 mph and rotate your legs like you're pedalling. You need to think this through a bit.

 

[shenzhen_ex]

It only takes one frustrated motorist to report you, then the next day the police will be waiting for you and you'll lose everything.

Now that is freedom!

 

[shenzhen_ex]

A number of the more zealos members on the sphere run 20s or 24" setups for this reason.

I went with a 24" setup so my bike will fit in the elevator
2" wide rims were $ 9 USD each direct from the factory.

 

[Tommy L]

Welcome to the forum!

One thing to get your head around on the electric side is the electric motor and how it's wound.
For instance, 9c makes a 2805, 2806, 2807, 2810, 2812. They may make others, but these are the
ones I've seen most.

Each one will spin so many RPM per volt. They call this the motor KV.
The 2805 will spin approx 10rpm per volt, and
the 2810 will spin approx 5 rpm per volt.

You get a sense that at 36v the 2805 will spin at 360rpm, and
at 72v the 2810 will spin at 360rpm.

Some here on the forum have tested a similar to a 2805 motor in a 20" wheel at 72v (approx 720rpm),
but being in a smaller wheel, its like gearing it down. It will take off like lightning and get into
it's sweet spot (higher efficiency).
The 2810 will do the same thing, take off quick and get into a sweet spot.

The geared hub motors in a 26" wheel have a smaller motor inside the hub with a little gear(on motor) to a bigger gear(on hub)
so the motor might spin at 3 or 5,000rpm, getting the motor into it's efficiency range quickly, and has good hill climbing too.

How long the hill is, plus is there a headwind? These are things that make designing an ebike interesting and there is no one "Best way"
for an ebike. Most here build several ebikes and use them for different purposes. Speed bikes on flats on a track. Hill climbers for hill
climbing competitions, etc....

Some here that have lots of hills to deal with use 2 wheel drive. Yes, one on the front and one on the rear
This 2wd setup splits the "Load" between the two motors. Some here will tell you not to do it, others will tell you they love it!

Corban enjoys 2wd

[youtube]QgOyDKrFZdc[/youtube]


So selecting battery voltage and motor winding to do a certain thing is something to consider.

Geared motors are more stealth as then tend to be in a smaller hub. They also come in different motor winds.

Everything has it's limitations. Using a CA v3 Cycle Analyst Version 3, has the option of reading the heat inside your motor
and will automatically reduce power to the motor, saving it from burning up

Tommy L sends.....

 

[arkmundi]

You always have the option of building an ebike that will travel the speed/distance you want and then getting it registered as a "moped", so its street legal. Just one suggestion regarding the motor: definitely get a geared motor, for the torque. The reason I went for the Heinzmann 500 watt motor - high quality and geared. Good luck!

 

[Kinni420]

Despite the more recent EU directive and standard, the UK’s[25] Electrically Assisted Pedal Cycle Regulations 1983 (SI 1983/1168) have not been rescinded and still apply. These require that the motor has an average power output limited to 200 W (250 W for tricycles and tandems), weight limited to 40 kg (60 kg for tricycles and tandems), and a maximum speed when power-assisted of 15 mph. For electric cycles meeting these requirements, the vehicle does not require registration or periodic road worthiness assessment, and operators do not require a licence or insurance. (Operators must be at least 14 years of age.) However, since 2006, when Statutory Instrument 2935 brought EU Directive 2002/24/EC into UK law, vehicles that don't meet the EU definition of an electric cycle have required type approval. This overlap of requirements has certain effects, as described below.

The following features of an EU-definition electric cycle are not legally available in the UK:

upper power outputs between 201 W and 250 W on bicycles
maximum speeds between 15.01 mph and 15.53 mph'
weights above 40 kg for bicycles and 60 kg for tricycles and tandems

The following features of a UK-definition electric cycle make a vehicle subject to type approval:

the application of motor power without use of the pedals
the application of motor power without progressive reduction to zero at 15.53 mph (meaning that at the maximum UK speed of 15 mph some residual supply of power is permitted)

There are no known cases of enforcement of the requirement for type approval. This could be because compliance with type approval is declared when a vehicle is first registered for use on the road, and UK-definition electric cycles are exempt from such registration by the 1983 UK regulations.

 

[majornelson]

Check out a Mac 500w motor with a Cycle Analyst v3 from em3ev.com (cell_man). Add a 48v triangle battery...

It comes with a 3 position switch that allows you to limit the power. You can set it to be legal/almost legal/not legal depending on where you are riding. I use a thumb throttle and always assist with some pedaling. Great kit, matched wires and plenty of torque for the hills...

For the record, this setup will give me up to 60 miles range at 20 mph. And top speed is 35+ mph. It *will* pull strongly up hills. I use the Mac 500w 8T with a 9 FET controller.

Good luck.

 

[d8veh]

You always have the option of building an ebike that will travel the speed/distance you want and then getting it registered as a "moped", so its street legal. Just one suggestion regarding the motor: definitely get a geared motor, for the torque. The reason I went for the Heinzmann 500 watt motor - high quality and geared. Good luck!

Good idea, but virtually impossible in the UK. I only know of one guy that achieved it. There's too many complicated regulations you must comply with. Some are impossible, but if you're lucky the test guy might be sympathetic and allow compliance. If you wanted to go that route, it would be better to get a 50cc scooter or ready-made and registered electric scooters because, even if you could pass all the tests and get your registration, you wouldn't be able to use it on cycle paths, nor would you have any of the other privileges cyclists have.

 

[arkmundi]

Well, I'm not in the UK, so don't have the problem. If I were, I'd be building a coalition of ebikers to get the laws changed. I'd want my pedal bicycle, with an electric assist, to be legal. I'd work to get the upper limit up to 750 watts and 25 mph. What preceded your restrictive laws? Why so low?

 

[duncmac]

Thanks for the replies.

I'm not intending to burn in at 35 mph with my feet up on the handle bars.

I just want something that will pull v. well up steep hills and long inclines. I intend to pedal too, but would prefer to buy the one motor and have it be more than I need and not overheat on the hill of death on the way back home.

If this is a bad idea (over spec'd motor) for specific reasons let me know.

Obviously stealth is the way to go, so rear saddle bags will be used to cover things up and for storage. I'll ditch my plan to get one of these http://www.turbospoke.com/

Thanks for the info on KV's Tommy I'd grasped the idea that you could get a motor with high torque but low speed, didnt know the specifics though.

 

[Tommy L]

Obviously stealth is the way to go, so rear saddle bags will be used to cover things up and for storage. I'll ditch my plan to get one of these http://www.turbospoke.com/

Thanks for the info on KV's Tommy I'd grasped the idea that you could get a motor with high torque but low speed, didnt know the specifics though.

You are most welcome. I might have not been 100% accurate, but I'm glad you get the point. A good concept to understand. I knew this concept
a little for my first few builds. That's why I went for a 2810 and 140volts A fairly Efficient combo

TURBOSPOKE..... lol......when a hockey/baseball card and a clothes line peg isn't good enough lmao!

Tommy L sends.....

 

[d8veh]

I just want something that will pull v. well up steep hills and long inclines. I intend to pedal too, but would prefer to buy the one motor and have it be more than I need and not overheat on the hill of death on the way back home.

If this is a bad idea (over spec'd motor) for specific reasons let me know.

Obviously stealth is the way to go, so rear saddle bags will be used to cover things up and for storage.

What about something like this Carera Kraken (£90 used) with Bafank 500w CST and 20aH 36v battery (£500). Top speed is about 23 mph, and it'll climb any hill.

 

[chas58]

I think you are right on with the spoke thing.

29” wheels are fine if you match the motor wind to size of the wheel. Shoot, I have a 700c (i.e. 29”) wheel that runs 30% farther than the same motor in a 26” wheel, although that has more to do with the bike/tires than the size of the wheel. The wheel size isn’t hurting anything. Efficiency comes from running the motor at the speed it is efficient at.
You just need a motor that runs at a lower RPM with a larger wheel. And in general, the larger wheel (with larger moment of inertia) is going to take more energy to spin up, while the larger wheel will be more efficient once it is spun up and cruising.

I'm happy with larger wheels, but I'm not climbing a lot of hills with that setup.

Spoke breakage comes when you have loose spokes but don't tighten them then go down a bumpy road, or overtighten and go down a bumpy road.
I used be on board with the whole "get fat spokes" thing, but after breaking just as many 12ga spokes as 14ga spokes, I think it's more of a tension/maintenance thing than anything.

29ers are neat bikes, they plow over rough terrain with ease, and the racing non-motor types seem to think that they are more efficient. but they aren't very good with hub motors. I'm not sure what the science is behind it is, but taller wheels run less efficiently than short wheels. I base this on the fact that my MXUS 20" always runs more efficiently than my 9C 26" at the given speed it's going.

A number of the more zealos members on the sphere run 20s or 24" setups for this reason.

 

[Bike Xing]

The hill you've got detailed doesn't seem to be too big of a threat (though resolution on the graph is a bit poor, as someone else mentioned, if there's one section that's .1 km long at 45% grade that could be a big factor).
This thread here includes data on what some bikes can do:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=51114&hilit=What+can+your+ride+climb%3F

 

[Kinni420]

Spoke breakage comes when you have loose spokes but don't tighten them then go down a bumpy road, or overtighten and go down a bumpy road.
I used be on board with the whole "get fat spokes" thing, but after breaking just as many 12ga spokes as 14ga spokes, I think it's more of a tension/maintenance thing than anything.

ACTUALLY, from my experience in building wheels for 25 years, spoke breakage comes from rim design not "tight/loose" etc. Ive been riding bikes all my life and working on them. I figure Ive got nearly 50k miles in the saddle (4k on electrics) and NEVER EVER ONCE broke a spoke from hard bumps. Ive broken a few by getting sticks stuck in them or crashing or getting hit by cars and getting the wheel "Taco'd"

I got my brand new kit from someone and the wheel came loose with 12g spokes. I tightened them down and threw it on the true stand and after I was done I got this.

Notice the way the spokes are actually bending? this is due to the fact that the rim was designed around a MUCH smaller hub flange diameter. The nipple coming out of the rim can only bend so far and the spoke has to bend to make up for this. This causes significant strain on the spoke where it meets the nipple. EVERY SINGLE SPOKE Ive ever broken on my ebike ALWAYS snaps right at the nipple. EVERY spoke Ive broken on a regular MTB usually breaks at the hub (or in the case of a stick in the spokes, wherever the stick hit the frame). Im still looking for a good rear rim for my bike that can cure this problem. Maybe someone whos in this industry can look into this? Id like to go with a motorcycle rim but dont have the frame clearance for a tire of this width.

going on. I dont have a 20", 24" or a 29er to measure. But I do have a 700c and a 26". I barely remember high school but diameter x Pi = circumference. 81.65 inches for my MTB. 84.75 inches for my 700c (the 700c with a 32 on it measures a little bigger than 27"). thats ONLY 3 inches difference for a full wheel turn. A mile is about 63360 inches, doing the math, a 26" wheel has to turn 28.4 times more than my 700c. that's ONLY 193.3 feet or 3.67% distance. Now Im no math major but this doesnt seem like much of an decrease in torque to me. It does make sense that larger/ smaller wheels will make a difference but I REALLY dont think its that much unless youre looking at running 3" MTB tires on a 29er compared to street tires on a 20".

Unfortunately a lot of us run rim brakes and dont have disc mounts so the ability to change wheel sizes is dang near impossible without buying a new frame. Wheel building on an electric hub is expensive and requires a lot of thought or a fat wallet before even considering it.