UK newbie needs advice on 1st Ebike Build.

[footloose]

Mac 10T with 50V battery is a nice setup.

One thought. The setup is going to be a bit beyond strictly street legal, so building for stealth might be good idea.
The triangle battery options are great, but they are not stealthy.
You might look at the EM3ev 50V / 10.25Ah rectangular pack?
It is small and light (3.5kg), could easily slide invisibly into a pannier on rear of bike...
and the pannier would serve the dual purpose of making the motor less visible.

I have the same battery, but a 12.3 Ah rectangular version (not currently available from EM3ev).
It happily supplies 30A of current... which I decided was too much really, so bike is currently set up to draw 25A max.
Based on that, it would seem the 10.25Ah battery could readily give you 20-25A...
which will give you 25-30 mph top speed, and ample acceleration.

I took a "moderate" ride last weekend... cruising rather than hot-rodding, flat, no wind, with me doing moderate pedaling.
12.3 Ah battery give me nearly 50 mile range in those conditions.
So 10.25 Ah would likely give you ~40 mile range in ideal conditions.
Probably 20-30 miles with some headwind or moderate hills?

 

[loxster]

Thanks Footloose for your reply, I know it won't look stealthy with the triangle frame bag but I'd like to keep the weight in the frame so as not too effect the handling too much.

I've emailed Em3ev regarding recommending me a set up and Paul as got back to me with a shopping list of items...one thing though, He lists a Cycle analyst on there, What is one? And do I need one?

All help appreciated here please.

 

[footloose]

Hi Loxster,

I hear you about keeping the weight in the triangle.
Weight distribution makes a huge difference in handling.
Off topic a bit, I took a couple flying lessons a few years ago.
One thing I thought was pretty interesting... once up in the air and
actually flying, at least on small planes there is a mechanism to
adjust front/rear weight distribution by moving a small weight
back and forth slightly on a longitudinal track (at least, that's what I understood
from the instructor's explanation). Amazing how much difference
getting it "right" made. A tiny bit out one way or the other and
you could feel it. Hit the sweet spot of balance, and it just felt "right".
Like tuning a guitar... you can feel it.

Anyway, about the CycleAnalyst (CA).
It is a handlebar mounted computer system that both displays key info
and lets you control key system values.
You don't actually *need* it to make the basic ebike system run...
but if you can afford it, I recommend it highly.

What does it do?

Tells you things like current speed, Ah expended since last charge,
current watt/hours or amp draw (you might say current current, but jeez
that is an awful pun), w/h per mile, etc. In other words, a bit like a
car dashboard with odometer, gas level, tachometer, etc. You don't
100% need those things to drive, but they are pretty nice to know.

Maybe more important, it also lets you manage key inputs.
For example, peak amp draw.
Phenomenal what a difference being able to "tune" this makes in riding.
Originally, I had my main bike set up to draw 30 amps via CA.
Changed the value to 25 amps.
Doesn't sound like much, but it changes the character of the ride pretty substantially.
Then progressively "marched" the amps down via CA ... 20... 15... 10... 5... just for grins
and to better understand how motor/battery would perform.

So, I like CA big time.
One word of advice.
I have the 2.3 version.
There is a new 3.0 version available.
The 3.0 version is *much* more capable as a computerized control system...
but also is much more complex. (A few apparently pretty smart people have thrashed
a bit on getting the 3.0 version set up correctly for their bikes.)
So all in all, if I were ordering a new CA and didn't truly need the 3.0 functionality...
I might order one of the older versions.

Link: http://ebikes.ca/drainbrain.shtml

 

[NeilP]

Hi Loxster.

I have not read all this thread...yep to f ing lazy..and fed up with the net tnigh...bu

i am n UK also...well Jersey.

A few things I have seen in my e-bike building over the last few years.

Paul..UK chap...has a Chinea store...Emissions free...can supply stuff very quick if yu want to pay the postage..have had stuff from him n less than 10 days.
http://www.emissions-free.com/store/

I was out on my bike the other day. with power limited via a Cycle analyst ..I was checking out power levels..I wanted to see what the minimum I would need to pull reasonable speeds up some local Jersey hills.

I weigh 11st 6 and pulling up some small local roads at 15 mph. not stupid steep hills, but not easy climbs either...so with speed limited to 16 mph, unlimited current and power levels, I was pullign about 1500-2000W.

If you want to do any pedalling without drag, it MUST be a a geared motor DD is just too heavy for long term pedalling.

 

[loxster]

Hi,

So would I be correct in thinking that if you drop the Amps down this will slow the bike down aswell?

So 30A is the most powerful setting then stepping down the Amps reduces the power supplied thus reducing speed?, Why would you do this? Is it to save the battery power?
What would happen if I didn't purchase a CA? Would I be getting full power only, all the time?

Thanks J.

 

[footloose]

Ah, hard to give a black/white answer to your question.

The construct that works best for me in understanding e-bike power is:
Volts = Horsepower = Top Speed.... Amps = Torque = Acceleration.

Why did I reduce Amps? Because front wheel kept wanting to lift off
ground when I took off from stop. Too much torque. So I dropped
the amps a little.

That *did not* reduce top speed... Just meant it took a bit longer to reach top speed.
The voltage... think horsepower, eg top speed... remained the same.

Without a CA, your controller and batteries will determine amps passed to motor.
Whichever has the lower capability will determine max current delivered.
With a CA, you can set arbitrary limits to "tune" your bike.

Make sense?

If anyone can explain better, please chime in!

 

[NeilP]

That is it really.

Amps can limit top speed, but that is not a hard speed limit.
It is limiting the top speed because power is being limited. So top speed will be different when on flat, or going up or down hill.

If your current was totally unlimited and top speed was 30mph,you would go 30 up hill or on the flat,
While going uphill you might be drawing 50amps,while on the flat only 18 amps. So if you limited current to 30,you would never reach that top speed going up that same hill without a lot of extra leg power, but on flat,top would remain the same.
Now limit current to 15, and top on the flat would limit too.

My bike could pull up to about 160 peak, but I limit to 120 via controller programming, and have the CA set via a 3 posn switch to give max,40,15amps.

 

[heavymetalthunder]

Too bad they limit you to 250w in the UK. If the governments of the world want people to stop using more oil then they should set the limit to 750w. In California we are limited to 1000 watt units, but is limited to 20 MPH. As far as I've seen, cops out here are fairly easy on E-bikers, even when traveling at about 30 MPH, as long as I'm not getting in the way of traffic or ding something stupid, they don't even give me a second look .

 

[NeilP]

I feel the same, but reckon 1500W. Speed of 20 is about right, a bit quicker than average person generally cycles, without being too quick.

 

[alsmith]

I feel the same, but reckon 1500W. Speed of 20 is about right, a bit quicker than average person generally cycles, without being too quick.

My thoughts are fairly similar. I tend to hold the throttle at around 20 normally, but could a bit faster if needed. Traffic lights, junctions, pedestrians, crash test dummies leaving school in gangs are all reasons to slow down. And dogs. I feel safer with that bit extra at 20 too.
The next natural step up seems to be around 35mph or so, keeping up with cars in built up areas but also getting attention from most people- best to avoid. And you always get a young lad or angry older male in his 20's or 30's who looks like he lives in a caravan and seems to take it as a personal challenge and must pass you causing problems like being far too close, or cutting in front of you too close.

Ah, hard to give a black/white answer to your question.

The construct that works best for me in understanding e-bike power is:
Volts = Horsepower = Top Speed.... Amps = Torque = Acceleration.

Why did I reduce Amps? Because front wheel kept wanting to lift off
ground when I took off from stop. Too much torque. So I dropped
the amps a little.

That *did not* reduce top speed... Just meant it took a bit longer to reach top speed.
The voltage... think horsepower, eg top speed... remained the same.

Without a CA, your controller and batteries will determine amps passed to motor.
Whichever has the lower capability will determine max current delivered.
With a CA, you can set arbitrary limits to "tune" your bike.

Make sense?

If anyone can explain better, please chime in!

But remember there *is* a point where reducing Amps *will* reduce speed.
It will be different for different motors and different batteries. As an example for my Crystalyte front hub 5303 (my motor, direct drive, not available now):
38V 27A shows top speed of 26.6mph, as does 28A, 30A, 50A and more.
at 26A it is 26.2mph, and starting to reduce.
25A is 25.9mph, 20A is 24.1mph 15A is 21.8mph

Go play with the simulator at ebikes.ca with you proposed/planned controller, motor and battery and see what you get for the various combinations available to you.

 

[loxster]

Hi,

Just out of curiosity can any one tell me if the Mac will stand up to a bit of off roading , ie Sherwood pines etc ( trail centres).
I know Boost bikes uses a BMC motor and he does nearly 40 mph and hammers it off road, Are BMC stronger than Mac's?

Thanks J.

 

[d8veh]

Riding round forest trails would be no problem, but you need to mindful of impact forces on the gears. I ride my Bafang BPMs and CST on off-road trails, and never had a problem, so the MAC should be OK, but don't go nuts doing big jumps etc.

 

[loxster]

There's no worries about me doing big jumps lol, Last time I tried a jump it went tits up and I nearly knocked myself out and I learned when your in your 40's you don't bounce like you did when you were a teenager

So if I stick to the blue routes I should be fine.

Thanks for the info D8veh.

 

[MadRhino]

Last time I tried a jump it went tits up and I nearly knocked myself out and I learned when your in your 40's you don't bounce like you did when you were a teenager

That is because you stopped jumping, then you lost the abilities over the years, ability to jump nicely and to stand the bruises. I am 66, never stopped jumping and hard off road riding, now I do it better than most of the kids.

 

[loxster]

66 yrs old!
Respect where it's due MadRhino.

I still remember fondly back to the days of my BMX (Raleigh super tough burner) when we built ramps and got people to lay down and jumped them. But my jumping days are long gone i'm afraid.

I'ts good to know the bike should hold up to some trail riding.

Thanks J.