Conversion kit opinions

[derf]

he

The BPM motor is much bigger and provides more torque in every gear except maybe first. The BPM will run typically with 20A to 22A compared with the BBS01s 15A, so it'll provide over 30% more power too.

Low powered crank motors can get you up steep hills, but you have to do a lot of pedalling whilst going slowly in first gear. The hub-motors don't care what gear you're in. They give their torque regardless, which makes them much more relaxing and comfortable to ride.

Obviously, low powered crank motors can climb better than low powered hub-motors, but there's 250w hub motors that can give a lot of power and torque.

here's where I get confused - I know electric motors provide the same amount of torque at any revs (i.e. they don't have a torque curve like a combustion engine - it's a flat line) - but still, using gears must multiply the torque? i.e. a 250 watt crank motor running at a three to one ratio will produce three times more torque than the same hub motor running directly as far as I understand or is this too simplistic?

 

[Deleted member 4366]

Ok, thanks. I've had another look at the BPM and see it's 350W. So, staying road legal at 250W, what hub motor(s) would you recommend might be best suited to hauling my 14 stone self and dodgy legs around Welsh/Derbyshire countryside?

There's a 250w version of the BPM, which is virtually the same as the 350w one. The main difference is the writing on it.. Check with Woosh what's written on theirs kits.

The Ezee motor is very similar to the BPM in size, weight and power. It's definitely rated at 250W, but Ezee kits are a little more expensive than Woosh's BPM kits.

 

[Deleted member 4366]

he

here's where I get confused - I know electric motors provide the same amount of torque at any revs (i.e. they don't have a torque curve like a combustion engine - it's a flat line) - but still, using gears must multiply the torque? i.e. a 250 watt crank motor running at a three to one ratio will produce three times more torque than the same hub motor running directly as far as I understand or is this too simplistic?

That's true. I turned a 250w hub-motor into a crank-drive to test that, and it could pull me up some pretty steep hills without pedalling, which it couldn't do when it was in the hub; however, the motors used in most 250w crank-drives are fairly small compared with a hub-motor and often run with lower current. Therefore, they have less power, which is why they can only make higher torque at low speed:

 

[derf]

That's true. I turned a 250w hub-motor into a crank-drive to test that, and it could pull me up some pretty steep hills without pedalling, which it couldn't do when it was in the hub; however, the motors used in most 250w crank-drives are fairly small compared with a hub-motor and often run with lower current. Therefore, they have less power, which is why they can only make higher torque at low speed:

pretty cool conversion (somewhat post apocalyptic look), i will have to try a hub motor I think to get beyond theory of torque and current and ratios..

 

[rusky]

Thanks for all the replies. I've had a look at the BPM too & as is the norm with these threads, I'm none the wiser

I'm undecided between a rear hub drive & the BBS01.

 

[trex]

That's true. I turned a 250w hub-motor into a crank-drive to test that, and it could pull me up some pretty steep hills without pedalling, which it couldn't do when it was in the hub; however, the motors used in most 250w crank-drives are fairly small compared with a hub-motor and often run with lower current...

that's why I thought the BBS01 36V 18A 350W is just right. It gives about 85% of the pulling power of the BPM but whisperingly quiet. Civilized and cheap transport.

 

[Deleted member 4366]

Thanks for all the replies. I've had a look at the BPM too & as is the norm with these threads, I'm none the wiser

I'm undecided between a rear hub drive & the BBS01.

You have to t try them to see the difference. Can you get to Redbridge (Romford) on Sunday afternoon? You will be able to try just about every type of bike there.

 

[Nealh]

I am planning on going on Sunday as I haven't totally decided on a cd conversion yet. Looking fwd to trying cd and bpm. Have woosh got a 18a cd on a test bike and if so will this be there ?

 

[trex]

yes, Hatti confirmed that she'll take the blue Rascal test bike with the BBS01 18A 350W motor to Redbridge but it will have to be restricted because of public tracks.

 

[rusky]

I doubt I can get there as the Mrs wants to book a trip to France since it's a BH weekend

 

[rusky]

OK, due to extortionate ferry fares, it looks highly likely that I'll be at Redbridge Sunday

AFter more reading, the 350w BBS01 is now top of my list so looking forward to trying some bikes & hopefully coming home with a conversion kit

 

[1boris]

Is 350w legal? If not you sould go for the 48v 500w or 750w.They are not so powerfull.It took me a while understand that the cranks are only good for slow steep hill climbing and good speed on the flat.So I am changing my 48 bbs 500w (20a) with a "powerfull" hub motor.
An example:
I have a hill about 5%.With my legal neo cross (hub).I can pedal at 25 kmh.I can also do it with my bbs 500w for short periods.But I need to be in second or third gear to do it.And then I need a very high cadence to keep the speed up.If I shift to the fourth gear there is not enough torque to keep the speed up.But at slow climbing in 1,gear nothing stops it when pedalling.I will fall of the bike before it stops.
I have recently ordered a Bafang Cst 250w (big diameter) 205 rpm.I will run it at 48v 20-23 amp.I belive it will give speed up to 35kmh and Good climbing.
There is only one place to get this motor as far as I know. elifebike.com
But then again the bbs is easy to install and nice clean look.Not easy to choose

 

[trex]

boris, there may be a problem with your 48V battery. I tested the 36V 18A 350W motor, it has no problem blitzing 5% hill on throttle alone, even on 18T or 22T rear cog. You need a battery that can deliver at least 20A continously, or more.

 

[1boris]

I have tried it with a wattmeter,it draws 20 amp.Motor is ok.very strong on steep hills at slow speed.Speed on flat is about 45 kmh with hard pedalling.front cog 46 rear cog 32-11.On throttle alone I can get maybe 20 kmh in first gear.on that hill.but it loses torque/power with each gear.the hill is maybe more than 5%,but less than 8%.I know,because there is a marked 8% prosent hill very close to this hill
I am 100 kg+
The main point is that the 720w hub motor is faster than the 960w crank motor in that hill

 

[trex]

do you run the 720W hub with the same 48V battery?

 

[Nothing2SeeHere]

AFter more reading, the 350w BBS01 is now top of my list so looking forward to trying some bikes & hopefully coming home with a conversion kit

Interested to hear what you think. I'm in almost exactly the same situation (same exact bikes - though my Muirwoods is vbrake not disc) and I'm also coming to the same preferred option (as much because I can't decide which bike to convert). I'm also keen as Woosh mention stocking hydraulic brake sensors as an option on the website.

My decision now is for the battery options. I'd ideally like a backpack battery but this has its own logistical challenges (what happens if I fall off etc)

Let us know what you think after the weekend.

 

[trex]

...

I'm also keen as Woosh mention stocking hydraulic brake sensors as an option on the website.
...

they bought 100 sets of these:
http://www.alibaba.com/product-detail/BTN-electric-bike-hydralic-bike-brake_1471781843/showimage.html
which they've prompty lost.
They currently have no stock of hydraulic brake sensors.

 

[Nothing2SeeHere]

they bought 100 sets of these:
http://www.alibaba.com/product-detail/BTN-electric-bike-hydralic-bike-brake_1471781843/showimage.html
which they've prompty lost.
They currently have no stock of hydraulic brake sensors.

Useful to know. Will have to see if I can get my own then.

 

[Nealh]

Useful to know. Will have to see if I can get my own then.

From reading previous threads and on looking on ES it appears that the brake sensors that come with the BBS kits can be adapted (with some ingenuity) to be used with Hydraulic brakes. d8veh and others have posted pics of various means along with a brief description of how to do it.

 

[1boris]

do you run the 720W hub with the same 48V battery?

No,as I wrote before the Neo cross is orginal.But I have tried the neo with the same 48 volt battery before.It increased the speed and climbing a lot.So If I had used the same battery,the difference would be much bigger.I think I could pedal the Neo easily 30 kmh on the same hill with the battery I use on the bafang bbs 500w