E-assit for a Bacchetta Giro ATT 20

[Aushiker]

Hi

I am throwing around some ideas on e-bikes and one of the options is trying to re-try my Bacchetta Giro ATT 20 but with e-assist. The alternative is get a diamond frame e-bike off the shelf, e.g., something like a Bergamont E-line CMGN which I can purchase locally for AU$4,500.

The bike will be used as a dedicated commuter, my commute is 84 km round trip with around 300 metres of climbing each way but the big killer is that the ride home is into coastal headwinds which are often around the 50 km/h range.  Also the ride to work is often into a strong cross wind so not to many goals kicked most days.

Anyway I am considering a Bafang BBS02 kit based on comments at Endless Sphere but what I would like is any feedback from owners who had done a conversion on a Bacchetta Giro 20 or other SWB bikes. I am aware of the various threads on trikes but I haven't found much on SWB conversions.

One thing that is worrying me or two things are and they are:

(1) Mounting the battery idea. Not keen on the rack approach as I don't want to add more weight to the rear wheel;
(2) Single crank sufficient or can these be run with a triple?

Oh one last thing is I am in Australia where we are legally restricted to 250 w motors but I think I would be okay with a 350 w motor .

Also if anyone has recommendations on a supplier that would be appreciated.

Thanks
Andrew

[jsabine]

Battery mount under the seat? Likely to involve some fabrication and possibly two small batteries, one on each side, rather than one big one, but I'd have thought it would be good for weight distribution and give easy cable runs.

[oddball]

My recumbent commute is a similar distance to yours but with 1000m more climbing and around half your  headwind on a typical day. I've been considering a crank drive e-assist for next winter and I'm drawn towards the Sunstar Kit. There are some examples of mounting their batteries here:

http://www.sunstaribike.com/en/gallery/recumbent-pedelec/

[Aushiker]

My recumbent commute is a similar distance to yours but with 1000m more climbing and around half your  headwind on a typical day. I've been considering a crank drive e-assist for next winter and I'm drawn towards the Sunstar Kit. There are some examples of mounting their batteries here:

http://www.sunstaribike.com/en/gallery/recumbent-pedelec/

Thanks. I did look at Sunstar but couldn't find anyone selling them online so move on from them. Any suggestions?

Regards
Andrew

[Kim]

Yeah, under the seat is the place to put weight on a SWB 'bent.  Building the battery in two halves isn't difficult, but make sure the connection between the two is robust if there's a BMS involved.  Could be as simple as hanging it in Banana Bags, though I'd prefer something more robust.

[Aushiker]

Yeah, under the seat is the place to put weight on a SWB 'bent.  Building the battery in two halves isn't difficult, but make sure the connection between the two is robust if there's a BMS involved.  Could be as simple as hanging it in Banana Bags, though I'd prefer something more robust.

If I have to start playing with batteries I will give this idea a miss. I am getting way outside of my technical understanding and really want this process, if I go this way, to be as simple as possible. Others seem to be able to do it okay, so it shouldn't be too hard should it? I have seen one photo which I cannot find now of the battery behind the seat, it was a BionX build and in the photo below it is under the stick but further back. Maybe that is an option.



Regards
Andrew

[Kim]

If I have to start playing with batteries I will give this idea a miss. I am getting way outside of my technical understanding and really want this process, if I go this way, to be as simple as possible. Others seem to be able to do it okay, so it shouldn't be too hard should it?

It all comes down to range and power.  Most people, especially those using electric assist, don't ride bicycles very far, so manufacturers build modest battery packs in shapes and weights that can easily be fitted to bikes.  84km is at the top end of what you can expect from an off-the-shelf enclosed battery, though you're likely to gain a bit from the efficiency of a recumbent^[1].  If you want to increase the power/speed beyond the legal limits, you lose exponentially more power to pushing air out of the way.

Barakta's trike will do that sort of distance on a little over 500Wh (that's at the 250W/25kph legal limit, with a decent amount of rider input), so you should be able to manage it on a standard battery - at that power limit.  With a 350W motor you're going to fall short.


ETA: Oh, hang on, you said round trip.  If that means you can recharge the battery at work, you should be fine.


_{[1] Unlike humans, electric motors work just fine lying down.}

[Aushiker]

ETA: Oh, hang on, you said round trip.  If that means you can recharge the battery at work, you should be fine.

Yep, should be a simple task to setup a charging station at work. Either buy a second charger or take one with me. The bike comes into my office anyway.

Andrew

[Aushiker]

Progress is slowing occurring. I now have the Bafang BBS01 36v 350W motor and all the other bits and pieces I wanted for the conversion (e.g., rack) bar the battery. The battery was coming via FedEx in a separate parcel and FedEx flew it into Perth where I am and then promptly sent it over to the other-side of the country. Hopefully it will turn up next week.









More photos at Google+ Photos if interested.

Regards
Andrew