advice for newbie, crank or hub for first timer

[big_gems]

Hi,

I am considering a conversion to ebiking. I have done some reading and asked a few folk, for advice. Torn between crank and 350-500w hub,probably bafang 500w cst 36v

I am looking to go up to 20mph, weigh about 19st, using an old marin palisades trail (chrome alloy/steel frame), I would like it to do about 15-20miles, and i hope to do pedaling but have a few hills in the way,

What options are there for batteries, do they just go into a pannier if they are too big for an alloy case, are there any frame bags or any more discreet way of mounting them?

Happy to go up to 48v if worth it

Any idea when the 750w 8fun crank is coming out, would it be worth waiting for?

Quite keen for it to be as discreet as possible, I have seen the magic pie 3, it looks a little too large for me physically and probably too powerful?

thank you in advance

 

[103Alex1]

Hi,

I am considering a conversion to ebiking. I have done some reading and asked a few folk, for advice. Torn between crank and 350-500w hub,probably bafang 500w cst 36v

I am looking to go up to 20mph, weigh about 19st, using an old marin palisades trail (chrome alloy/steel frame), I would like it to do about 15-20miles, and i hope to do pedaling but have a few hills in the way,

What options are there for batteries, do they just go into a pannier if they are too big for an alloy case, are there any frame bags or any more discreet way of mounting them?

Happy to go up to 48v if worth it

Any idea when the 750w 8fun crank is coming out, would it be worth waiting for?

Quite keen for it to be as discreet as possible, I have seen the magic pie 3, it looks a little too large for me physically and probably too powerful?

thank you in advance

If you go crank then get a decent Bosch, Impulse or Panasonic one with a proper intuitive torque sensor etc.

The CST as a conversion option will be much cheaper than the above (about £500-£600 outlay as opposed to £1.5 - £2.5k since you already have the bike) .. unless you really go to town on the extras and features of your build and wind up buying a load of tools and accessories ! It's MUCH more powerful than one of the above as far as hill climbing is concerned. Unless you're really unfit and don't want to pedal then can't see 48V being necessary tbh.

Your mounting options for battery of that weight / dimensions will be rack bag or rack bag ... unless your frame triangle can accommodate a 20Ah Chinese battery. If it can then bikebags.co.uk will make you a bag for about £60. You could also get a Samsung battery made up for you in a bag for a few hundred quid more and that'll almost certainly fit in your frame triangle. You can also make your own box which looks a bit more 'finished' than a bag. Frame triangle bag or box is not as discreet as a rack bag. But it has the advantage of improving the handling and weight balance of the bike.

 

[big_gems]

Thank Alex,

Not looking to spend more than £800, so looks more like a hub on my shopping list then.

Thank you once again

 

[pn_day]

Interesting - I'm also interested in the 500w CST hub gear for my first build.
The sine wave controller that bstbattery do looks like it might work well with this - is that what you are going for as well?
Phil

 

[103Alex1]

Not sure how well those sine wave controllers work with such a powerful motor... I'd personally just fit a throttle (or preferably 2 two thumb throttles across a switch - one sprung and the other unsprung with a brake cutoff). Be interested to hear if someone's tried one.

Although the motor's got a hall sensor connector, I actually run the motor sensorless and it's just a bomb !

 

[Deleted member 4366]

For the small extra cost, I'd get both the S12S and S12P. The same LCD works with both of them. The S12S is smoother, but only 23 amps compared with 28 amps for the S12P. If you're not too heavy, the S12S would be OK, but heavier riders might prefer the S12P.

 

[big_gems]

Any news if the 750w hub motor is being released soon?

 

[trex]

re crank drive: are you talking about the 8-Fun BBS01? two versions: 250W and 350W, both are available from Aliexpress. The 350W is probably too powerful for your bike, you'd need better brakes and better suspension.

 

[big_gems]

My bike doesn't have suspension, would that be a good or bad thing? Is it the same engine with either 36 or 48v or a different motor?

Thanks

 

[trex]

lack of suspension does not matter much if you have a low power motor but that rules out mounting a biggish motor to the front. It's also very easy to ride too fast with a crank bike because of gearing. While a 250W 8-Fun front motor can get you to about 18mph on the flat, the 36V BBS01 can easily get you to 22mph. At that sort of speed, bumps are very unpleasant without good suspension.
The 48V BBS01 has same gearbox but bigger motor. The price is $10 more.
Another idea is to get a motor with built-in torque sensor:
http://www.aliexpress.com/item/24-36-48-E-Bike-Torque-sensor-Motor/594488064.html
The torque sensor replaces the throttle. I think it's a bit like a go faster Momentum Upstart and a better choice than CST motor for your bike. It sits between a 250W and a 350W motor and gives you better control, it encourages you to pedal hard like with a crank motor and you keep the front derailleur (crank motor loses the front derailleur).

 

[pn_day]

For the small extra cost, I'd get both the S12S and S12P. The same LCD works with both of them. The S12S is smoother, but only 23 amps compared with 28 amps for the S12P. If you're not too heavy, the S12S would be OK, but heavier riders might prefer the S12P.

That's interesting - unfortunately I think that both the OP and I classify as heavy so the sinewave controller might be out for a 36V setup. Would the S12S and S12P operate at 48V?

If running at 48V would that give slightly more speed, but probably about the same amount of torque? Or would you also get more torque as well?

 

[Deleted member 4366]

By increasing from 36v to 48v, you get more torque, but you also get more speed. The speed is not an advantage if the motor already goes at the speed you want with 36v. The 500w CST does about 22mph at 36v (270rpm), which would increase to about 30mph at 48v. This brings two problems: Firstly, it doesn't have the power to hold a heavyweight at any more than about 24 mph, so it'll be working very hard. Secondly, it'll work very inefficiently at speeds below 15mph at full throttle. Ideally, you'd want a 201 rpm 36v motor for 48v or a 270 rpm 48v one. Nothing is simple.

The price of the extra controller is only about £20, which you can get back when you sell the one you don't use.. The advantage of the sine-wave one isn't that much compared with the square wave one, so, if you have doubt about the power and don't want to spend the £20, get the square wave one.

 

[103Alex1]

Would the S12S and S12P operate at 48V?

Yes. S12P is to run sensorless according to specs sheet so presumably you just leave the Hall Sensors disconnected.

You can also still get the KU123 controller which although not compatible with the LCD from BMS Battery is good for 36/48V. Do you want to run on a throttle or try to use the PAS ?

You can always fit a standalone Cycle Analyst display or use Speedict. I use a Cycle Analyst with mine coupled with a KU123 controller.

d8veh, apart from the LCD compatibility what advantage is there in the S12P over the KU123 ?

A 36V 201RPM motor to run at 48V could be this one but it needs a freewheel :

http://www.bmsbattery.com/ebike-kits/585-bafang-350watts500watts-bpm-motor-e-bike-kit.html

 

[Deleted member 4366]

d8veh, apart from the LCD compatibility what advantage is there in the S12P over the KU123 ?

None, but that LCD is very handy, especially the switch.

I forgot that the S12P is sensorless. You're running your CST sensorless, so that should be OK, but I don't know about other motors. Some stutter a bit at startup, and others sound a bit rough.

 

[pn_day]

Thanks for the info on 36V vs 48v on this kit. I don't know about the OP but I found it very useful. 36V for this kit seems like it might be a better match to avoid over taxing the engine, particularly with my 15st frame on the bike plus a pannier or two.