Taken the plunge.

[kwackers]

The legality and getting caught are the same mentality as the "boy racer" who illegally modifies their Chavriolet

It is available, it can be done, and if you wish to take the risks of being caught then that is fine, don't bleat when you do get caught and the machine is confiscated

I've never been a bleater. I've never understood people who were.

E-bikes are the easiest thing in the world to hack. I doubt any policeman would go further than check the motor stamping and even then I suspect you'd need to be trailing traffic at 30mph before they stopped you plus they'd need to be on the ball regarding e-bike legislation.
The real risk is probably in a collision.

If I were to do it. I'd 'break' the controller so it shows all the right data but the speed limit doesn't work. Who's to say it wasn't like that when you bought it?

[bikes4two]

What an interesting thread - I'm a theoretical fan of ebikes (in that as yet I'm not considering getting one but the knees are starting to tell a different story ) - hopefully before I do need one, the situation of power vs legal limits etc will be more settled.

Youtube and searching 'bafang' is an education

[kwackers]

I bought one of those little bar extenders that allow you to fit the plethora of handlebar gadgets your modern cyclist needs.
It meant I could find room for some stuff, particularly the throttle.

So now I have a throttle and I've been out for a test ride and I must admit I'm not feeling the love for it. Without my input it's just too slow.
Acceleration also seems a bit poor - although whether it's genuinely any worse or whether it's just because I'm not pedalling and thus have more time to analyse I'm not sure.
About the only use I can think of for it is edging forward in traffic without pedaling since turning the pedals puts the max assist on whereas the throttle can be tweaked open for 'creeping' forward.

[hemo]

What an interesting thread - I'm a theoretical fan of ebikes (in that as yet I'm not considering getting one but the knees are starting to tell a different story ) - hopefully before I do need one, the situation of power vs legal limits etc will be more settled.

Youtube and searching 'bafang' is an education

The legality is already there to read.
The main points ;
Motor rating must not exceed 250w.
Assist speed 15.6mph, 17.1ph given 10% leeway.
Throttle pegged at 6km/h unless you are also pedalling.
Amp rating not defined or N/A.
Voltage nit defined AFAIK but have seen somewhere 48v nom stated as max.

[Bonefishblues]

What an interesting thread - I'm a theoretical fan of ebikes (in that as yet I'm not considering getting one but the knees are starting to tell a different story ) - hopefully before I do need one, the situation of power vs legal limits etc will be more settled.

Youtube and searching 'bafang' is an education

The legality is already there to read.
The main points ;
Motor rating must not exceed 250w.
Assist speed 15.6mph, 17.1ph given 10% leeway.
Throttle pegged at 6km/h unless you are also pedalling.
Amp rating not defined or N/A.
Voltage nit defined AFAIK but have seen somewhere 48v nom stated as max.

So not completely clear, or are these things not relevant?

[kwackers]

Amp rating not defined or N/A.
Voltage nit defined AFAIK but have seen somewhere 48v nom stated as max.

So not completely clear, or are these things not relevant?

TBH I've not seen any max ratings and it doesn't make a lot of sense for there to be any. Electric motors are pretty efficient, power output isn't a long way from power input and power input is given by V x A.
This was the basis of my comment further up, 36v @ 26A gives 676w which is obviously high.

In fact the current rating shown on most motors is the max they'll take (determined by the FETS), ditto the upper voltage limit and is purely technical rather than legislative.

So what's really happening depends on the motor design and it's associated electronics. If the motor could pull 26A then you have to assume that's internally limited by the controller. Hence hacking the controller to increase the current going through the motor will increase its power (I suspect a lot of these motors are the same, they're just programmed and power stamped to suit their purpose. Have you noticed the higher power versions cost pretty much the same as the lower ones? )

At some point regardless of programming the motor will flatten out current wise. They're inductive devices so as their speed increases the current naturally falls off, this is where "over-volting" comes into play.
By running the motor off a higher voltage you can increase the amount of current they draw at speed and because power is a function of time that means they make more power...

That's the technical nonsense.
From a legislative point of view enforcing anything other than power is nonsensical. Voltage *could* be regulated from a safety perspective though but I think that's about it.

[reohn2]

IMO as a non techy user all that matters is power in the form of top speed and acceleration,pulling power is a definete plus and shouldn't be a limiting factor IMO after all its inclines and wind that matter most to a responsible e-bike user.

Someone mentioned either on this thread or another (?) they think there'll be more collisions/incidents involving ebikes.
IMO if the ebike in question complies with the law ie;250w 15.6mph max,I can't see that being the case TBH.The problems begin with 500>watt 25>mph powered machines with acceleration to match in the hands of idiots or the inexperienced,with the present state of law enforcement how you stop that happening is anyone's guess.

[hemo]

The wattage rating is defined by the copper motor windings.
Drive units to have 250w continuous rating without over heating.
UNECE regulation No85 defines that said motor will have a higher wattage output however the output must only have a max 30 min duration. Obviously a 250w rated drive would start to over heat after continuous high output.
A 350/500/750W drive would not over heat in the same tests to define wattage/power.
Each manufacturer has a certificate of conformity to document each individual drives characteristics if called upon.
The legality of ratings is a mine field though a stamped/marked drive unit from a manufacturer should be enough to suffice any doubts about its rating ability.

[kwackers]

The wattage rating is defined by the copper motor windings.
Drive units to have 250w continuous rating without over heating.
UNECE regulation No85 defines that said motor will have a higher wattage output however the output must only have a max 30 min duration. Obviously a 250w rated drive would start to over heat after continuous high output.
A 350/500/750W drive would not over heat in the same tests to define wattage/power.
Each manufacturer has a certificate of conformity to document each individual drives characteristics if called upon.
The legality of ratings is a mine field though a stamped/marked drive unit from a manufacturer should be enough to suffice any doubts about its rating ability.

That's a bizarre set of standards.

What constitutes overheating? The melting point of copper? The insulation?
What about the cooling fins on the motor?

As far as I can tell the copper windings are no different between the motors. In theory the lower power motors would have a higher gauge of wiring but that doesn't seem to be the case.
Even if it were, the risk of overheating is entirely down to power input and cooling efficiency. The case is the same so cooling efficiency is the same, lower power motors aren't implicitly less efficient which raises the question why would they overheat with 500w when a 500w motor doesn't?

I doubt there's anything in the standard that says the motor should overheat after 30 minutes. Even if it did it some enterprising wag would start to fit bigger cooling fins etc and a quick look on youtube at some of the seriously over powered units suggests nobody is that worried.
Swap out the fets and run a kw or more through them without issues.
FWIW, the case on mine is barely warm after an hours use, even into the wind when it's giving me its all!

(Obv lifetime is reduced, but that's a given. More work equals shorter life. Same as people...)

[kwackers]

Found a use for the throttle.

Coming through Widnes, one of the companies there had obviously decided to burn stuff rather than pay to have it removed with the resultant thick lung filling smoke that accompanies industrial level burning.

IME it's impossible to hold your breath for long whilst cycling, certainly not long enough to cycle 4 or 5 hundred yards to the other side.
So it was throttle FTW! Stop peddling, press the throttle and hold ones breath...

[kwackers]

Major failure last night!

14 miles from home and sudden power loss. Bit of fiddling, removing the battery, putting it back and checking stuff couldn't find anything (and the battery was fully charged).

So cycled the rest of the way in muggle mode (which should please Horizon). Can't say it felt difficult although my brain insisted there was something odd about the bike. When you stop peddling the bike feels as though it speeds up!

Anyway, turns out when I fitted the battery I drilled an hole in the aluminium base plate to lift it up. That was fine but it meant the top hole supporting the battery was a lot lower and that in turn meant the battery could flex by 'hinging' around that hole.
Eventually a lug on the battery snapped allowing the battery to move around a lot which in turn damaged the connector by opening up the terminals, a few sparks later and the connection is duff...

So I spent a couple of hours tracking this down and fixing it (confusing because the connection wasn't completely dead so you could turn it on but it would turn off a second later).
Was easy enough to repair the connections, also there are four connections but the battery only uses two so I paired those up for redundancy.

I made up a temporary bracket for the top hole on the battery too so it can no longer slop around, I'll make a proper one this weekend.

I guess the lesson here is batteries are heavy. Make sure they're well fitted!

I also discovered the throttle when applied removes the speed limit.

[Ruadh495]

I also discovered the throttle when applied removes the speed limit.

Mine doesn't. Different controller programming perhaps?

On uses for the "throttle"; I find it most useful for pulling away from a stop, especially up hill (maybe my bottom gear is a touch high). Throttle is much more intuitive for that than changing the assist up two or three stops and then back down again.

If you have a front hub motor throttle can be useful on slippery surfaces, a stab of throttle will pull the bike straight. You can also ride on throttle with one foot on the ground, on ice for example.

Throttle also makes a far better "walk assist" than the one provided, but I've yet to find a real use for walk assist. I suppose it could by handy for steps with a bike gutter, but I've never used those.

Lastly it can get you home if your pedal drive breaks (I've had a rear hub and a bottom bracket fail), providing you haven't too far to go and don't mind going slowly.

[kwackers]

Mine doesn't. Different controller programming perhaps?

C961?

Definitely is on mine.

On uses for the "throttle"; I find it most useful for pulling away from a stop, especially up hill (maybe my bottom gear is a touch high). Throttle is much more intuitive for that than changing the assist up two or three stops and then back down again.

Tried that and it's not happening for me. I think my bearlike bulk pressing on the pedals has just too much mechanical advantage for the motor to compete.

If you have a front hub motor throttle can be useful on slippery surfaces, a stab of throttle will pull the bike straight. You can also ride on throttle with one foot on the ground, on ice for example.

I can see that. Just need to remember.

Lastly it can get you home if your pedal drive breaks (I've had a rear hub and a bottom bracket fail), providing you haven't too far to go and don't mind going slowly.

Indeed, one of the first things I had go wrong was a crank came loose. Past experience says if you try to pedal with a loose crank you just end up knackering it. So I tightened it best I could with my emergency bike multi-tool and then proceeded to 'peddle' home by slowly rotating the pedals without actually pressing them. A throttle would have been more civilised.

[MikeF]

Kwackers - A very interesting thread (complete with red herrings by some posters ) thanks for posting. I've been looking at a Bafang conversion myself. It seems to me mid mounting motors are the best because the gears on the bike can be used and presumably reduce the current drain on the battery? Also with mid mounting conversion kits such as Bafang the bike remains a conventional bike and installation looks comparatively easy. Ready made electric bikes always look clunky to me and look as though they have extra weight because they have an electric motor.

Does your tourer have drop or straight handlebars?

[kwackers]

Does your tourer have drop or straight handlebars?

Drops.
I have been thinking about the ideal bike for conversion, but that's probably another thread.

Some more information that may be of interest with regards behaviour.

I guess we all have a level of effort we put in when cycling.
So because the unit has a cadence sensor and a maximum cadence set in the controller then as you approach that the assist drops off. So at say; 60 rpm you get max assist, but at 70rpm you get none.
So for a given amount of effort you'll probably get over 60rpm (because you're at max assist) add in your effort and you might make say 65rpm.
So you decide to go a bit faster, cadence goes up, motor goes down and for the extra effort you don't really go much quicker and the opposite happens if you try to slow down.
It's an odd feeling although you quickly get used to it but the upshot seems to be that for a given gear the bike tends to hang around a set speed (conditions dependent).

What this means is to some degree you end up controlling speed by choice of gear and assist level rather than with effort.

(Changing the assist level alters the cadence before cut off. Low assist levels have low cadence levels. I've set mine to have 5 assist levels, level 3 gives me a comfortable cadence but bizarrely I get much more of a sweat on using level 4 or higher because the cadence goes up and because I still put the effort in! The speed inhibitor skews this somewhat though.)

Worth pointing out these numbers can all be configured in by plugging a programming lead into the motor.