Wisper Motor

[Phil the drill]

Hi,

Anybody know which version of the Bafang motor is the standard fitting to the 905se? I know it's a 36v 250w but its the rotation speed that I was wondering about. As the Wisper in de-restricted mode is capable of assistance up to approx 18-19mph I'm assuming that the version fitted is the 235rpm one - the one listed as designed to power a 24" wheel at up to 28kph. It seems that one fits the bill vis-a-vis the 18-19mph speed in a 26" wheel.
At some stage I may re motor the wheel to suit my hilly terrain a little better, but it would be nice to know where I am starting from. The motor has absolutely no external identifiying marks, serial number etc. on it, just a sticker saying Suzhou Bafang 200w - something I'm assured is not strictly correct anyhow (I'm told it is definitely a 250w motor).
Anybody able to confirm the motor spec. please?

Thanks, Phil

 

[frank9755]

Phil,
I looked into this a while back. I clocked mine at 292rpm. Discussed on this thread
Regards,
Frank

 

[Phil the drill]

Thanks Frank.

There is so much info around on this site it is easy to overlook or duplicate something that has been discussed before!
I was interested to see that the motor and wheel free rotation speed was clocked at 292 rpm. According to the Suzhou Bafang website (and assuming that the motor is is the SWXB or QSWXB model (the only ones it resembles in their pictures)) then the motor is either the 36v 250w 280+/-5 rpm model intended for 20" wheels or it really is the 36v 200w 290+/-5 rpm model stated as intended for 18" wheels. This appears to be curious unless there is some major dicrepancy in the measurement of unloaded wheel speed.
Although it would mean sacrificing speed on the flat (not an issue for me, I don't have much!) the hill climbing performance could be significantly improved by a move to a higher torque lower speed motor such as the 205rpm model designed for 26" wheels, or even the 185rpm model intended for the 28" wheels. Speed is not an issue for me. I've had nearly 40mph out of my Wisper downhill (measured on a sat nav., so no wheel measurement error!), with the motor off ! Going back up those same hills, fully loaded and into a 35-40mph head wind, taxes both the motor and me to the limit . Hence the question!
Would be nice to know exactly which version (model and rpm) was standard, in order for me to be able to make an informed judgement on a more suitable alternative, for my needs.

Cheers, Phil

 

[frank9755]

Phil,

I would guess that the Wisper motor is the 22 or 24 inch version. The 20" version is in the Ezee Torq, and that is faster. The Suzhou Bafang site doesn't make it clear, but I would assume that the revs figure is normal operating revs, rather than unloaded revs.

I would expect the one that they recommend for 26 inch wheels would give you a top speed of 15 mph and better hill climbing. If you put one in a Wisper you may find you have re-invented a Synergie Mistral!

Regards,
Frank

 

[Phil the drill]

Hi Frank,

Well there's a thought!
I'm sure I can't be alone finding it frustrating that this sort of information is so hard to get hold of! It's not really like asking for trade secrets after all. I'm guesssing you're right, but it would just be nice to find someone 'in the know' who could confirm the model for me! It shouldn't be too much to ask, surely?

Cheers, Phil

 

[flecc]

Judging from other Suzhou motors on differing bikes, I'm of the opinion that it's the 24" version. Of course this is all only relative to Europe, in much of the e-bike world where 20 mph is the norm, the 905se is undergeared and a touch slow.

Manufacturer specifications are usually for working conditions covering the optimum range of torque, power and efficiency, and all these motors free spin to revs well beyond that.
.

 

[Phil the drill]

Thanks Flecc.

I had guesssed it might be something like that, but as I said it was just a guess! For me, the ability to move the optimum torque down the speed range to improve it on steep hills would be very helpful. I carry some hefty loads up some very steep lanes and I don't have shower or changing facilites at the other end (in most cases. I actually commute on the bike to 3 different work places, but the topography of all the routes is broadly similar). Although I would not class myself as a powerful cyclist, I am reasonably fit for my age (49), and I can cycle up a 1:6 hill of 600+yds, without getting out the saddle on my hybrid (a Ridgeback Meteor), but that would be unloaded and slowly...I also have quite a few of those switchbacks on my route, some of them steeper in short sections. At the end of a route with several of those and no shower at the other end, I think my colleagues would be keeping to the other end of the room. Unfortunately I am one of those people who tends to sweat profusely even when I don't feel particularly tired, or haven't excercised heavily. When I do, it is fairly dramatic to the onlooker . I'm OK, I do excercise regularly and I'm used to it! The aim of this rambling missive is to explain my motive for looking at improved hill climbing on the Wisper. I have already re-geard it, and that has helped a lot, especially from the rider input side of things but I could do with a little more 'grunt' from the motor on these hills. I am perfectly happy to cycle unassisted on the flat, so long as the wind isn't too strong (although the top of one of these hills passes a large windfarm, where the wind direction is always in my face, whichever direction I am travelling in ).
Only question for me is whether to go for a 26" rated motor, or sacrifice more speed and go for the 28" motor. I suspect that the former may give enough of an improvement, but it's pretty hard to guess. Incidentally, I think that on the constantly changing gradients hub gears would drive me nuts and the isssue of that and the low pedal cadence would make the Panasonic powered units very frustrating for me. I'm not afraid of pedal input, hence the growing interest in the Cytronex bikes.

Cheers, Phil