Getting an electric road bike

[cwah]

Hello all,

My previous BPM has died and now I'm without any decent way to travel now. I feel handicapped

I'm thinking to get a spare electric fast road bike I could easily carry with me. And that could also work when electronic fail...

Here's the bike I'm thinking to get:

http://www.evanscycles.com/products/specialized/sirrus-sport-2013-hybrid-bike-ec042533#answers

It has good reviews and seems quite efficient for road bike.


Now, I need a motor. Which one would be best for a road bike at 25-30mph?
- A Cute100 260rpm?? I fear it may not be strong enough
- Bafang BBS02? benefits would be to have perfect freewheeling. Because geared motor still have a bit of friction...
- Xionga motor?


Any suggestion?

Thanks

 

[Deleted member 4366]

I sent you a PM about a folding bike.

 

[cwah]

Yeah thanks I answered. And no I'm not confident abour his bike or his motor.

He's also selling it at full price so it would cost me the same to get it imported from china

 

[trex]

I'd fit a BBS kit to this one. Quick, cheap, fast, no messing about with wheels and brakes.

 

[cwah]

Yeah, the BBS almost look like the right one.

However, I'm hesitating with the new xionga dual gear motor.... D8veh had very good feedback on it....

I just wonder if the perfect freewheel of the BBS would be better than a xionga?

 

[Geebee]

My experience is that all hub motors have more resistance than a normal bike hubs.
Plus the weight of the BbS is in the right place and a puncture is the same as a normal un-assisted bike.

 

[trex]

perhaps d8veh has tried the xiongda XD at 48V but at 36V it can only reach 20mph, I tried one at Woosh last week.

 

[cwah]

Yeah, don't forget it's going to be on a road bike with 700cc wheels! So even at 36v it should be a bit faster. And I can probably upgrade it to 48V...

It would be a really lightweight and stealthy complete set up. Issues would be the noise and small drag. But better torque at start and no need to change gear at every lights...


The BBS02 looks like a decent candidate too... apparently the 25A controller model is coming out with the 750W model!

 

[Deleted member 4366]

I don't think that the Xiongda would be good for a road bike. You can make it go faster by over-volting it, but that seems to defeat the whole idea behind it.

Trex, tell us about the Xiongda at Woosh. Is it a new model?

 

[trex]

Woosh got it about 3 weeks ago, can't be newer than yours. They put it on an old Elios, it climbed Pier hill OK, about 13mph at the bottom dropping down to 9mph at the top on throttle.
I left the setting on automatic all the time, noticed that it's not very smooth on PAS, the power seems to surge when PAS kicks in, motor must have been on high torque, quickly ramps up, then switches over to high speed, then hits 15mph speed limit, the LCD then cuts it out, makes it a bit unpleasant but very smooth on throttle. I can see it as a kit, Hatti does not say anything about new models. There was one picture on the wall but it looks like a crank drive.
May be 48V is the natural next step? 48V crank drive?

 

[awol]

My experience is that all hub motors have more resistance than a normal bike hubs.
Plus the weight of the BbS is in the right place and a puncture is the same as a normal un-assisted bike.

Do the BBS motors have any notable resistance against pedaling when not using the motor?

 

[Deleted member 4366]

Do the BBS motors have any notable resistance against pedaling when not using the motor?

Minimal, like any crank-drive.

Trex, tell us more. Why the secrecy?

 

[cwah]

Awol, the BBS is a crank motor, so no drag at all because the motor is located in the crank

 

[cwah]

I don't think that the Xiongda would be good for a road bike. You can make it go faster by over-volting it, but that seems to defeat the whole idea behind it.

Trex, tell us about the Xiongda at Woosh. Is it a new model?

I want to have something like the BH neo road bike lines:

Kepler did something similar with a SWX motor overvolted to 80V:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=47139


I'd like to do the same thing. Get a super light/stiff road bike. Add a small motor. Get the motor to help a bit + pedaling.

After all, cyclists in Tour de France only average around 350W to do 25mph average. Can't we replicate that with a motor? Low power, high efficience?


ps: I was thinking of the Xionga at 48V on a 700cc wheel. It would probably reach 25mph max speed. That should be enough

 

[trex]

your problem with the xiongda XD is the controller. The motor will run happily at 48V (I was told) but until you can get a 48V controller with 9 FET or 12 FET, you will be stuck with the 6 FET 36V. Also, I'd use the front motor XD on a 26" folding bike, that'll go in the lift and no need to stretch the frame.

 

[cwah]

The good point of the Xionga is that I don't need to bother with the gears... And it will lift me to speed.. From 20mph it should be ok anyway.

I was thinking to overvolt the controller to 48V. They surely have 60V fet inside?

 

[trex]

you can overvolt the controller, they've tried it at 48V, 24 mph on 26" wheels so you should get 25mph easily on 700C but the controller got hot, motor stays barely warm. Climbing speed stays same, seems to be limited by controller. In my view, don't bother fitting PAS.

 

[Deleted member 4366]

Those controllers that I was selling a while ago have a pair of brown wires, which reverse the direction of the motor. I've seen other controllers that have these wires too, so you only need to find a 48v one. You can then change speed manually with a switch.

The PAS can be a bit intermittent. I think that when it gets to the change speed point, it has a little think about whether it should change gear even if you have it fixed by the switch on high or low, so throttle is a must and PAS is optional. You don't need brake switches because the motor cuts very quickly when you stop pedalling using PAS. Brake switches are always good for safety though.

When I had mine on 44v, the power round about 20mph was quite good. I think with Cwah's lower weight, 48v should give about 25mph on the road without over-stressing it.