250W PAS build recommendation

[harrisonh]

Looking to build a 26" wheel, 250W PAS ebike for my girlfriend rim brake mountain bike.

My rides are usually 1-2 hours at 17-20mph on paved/gravel/dirt roads.
She can ride at about 10-12mph. This is just a bit too slow for me to enjoy. I tried my ebike with regen drag of ~100W, and that worked...but tossing my 50lb ebike into the car is a pita...

She wants to still get exercise when biking.
Thus, hoping a 250W PAS would bring her up to 14-18mph.

I have these parts on hand:
1) 35A grinfineon controller, which I can reverse shunt modifiy to reduce power
2) 44V 5.2Ah (200Wh) lipos (4x 6s 2.6Ah)
3) parts for a Lebowski controller. Prefer not to use this, since building it will take me a bunch of time.

What options are there?

I checked out Grin, but it seems too expensive for my needs
G311, PAS sensor, cycle analyst = ~$600
Use one of my controllers and Lipo.

BMSBattery:
Q75/Q100, S06P controller? = ~$200
Not sure how PAS and this controller would work though.

Topbikekit:
Q75 similar motor?
The LCD options for the controller is very confusing...

There also seems to be many kits on ebay, aliexpress, etc. Would love some suggestions.

 

[motomech]

14 to 18 mph is too slow. Surely you must know that under 20 mph is boring, I mean, do you go 17 mph on pavement when you can go 20 mph?
I'm not abreast of what kits are out right now, but it seems like they (like everything else)have gotten kinda expensive. The least expensive way to go is with a used Jump (Uber) frt wheel/motor asm(with tire) that Jag35 sells for $60 shipped. The one I got was like new, but the Bafang SWXO2 would be kind of fast on 12S lipoly (that's what you mean by lipo, right?). On 36V (Which probably is the way the system was originaly), The Jump motor would do 20 -22 mph w/ a 26" whl.
Rear mount would be better of course, but @ 20 mph(approx 700 Watts), it doesn't matter that much anf a frt. mount is easier to install and less expensive..
If you want a rear hubbie, any mini like a Cute(Q100) should be a low-speed range motor (201) to keep the top speed near 20 Mph on 12S. I would just use a free hub unless the bike came with a decent cassette (w/ a 11T sm. gear). It sucks to shell out $$$ for a DNP free whl., but they work well enough and last a long time.
Speaking of LiPoly, those "torque imitation" controllers like the SO6P(forget the 35 amp job, too big)w/ the lcd displays didn't like the Voltage on my 12S packs(Which is more than 44V, BTW) and couldn't read the initial value right. I thin k it has to be a "just right" value the first time to fool the controller into thinking it's a Li-Ion pack, but it's a gd. controller (just a little weak) when it's working. Anyhow, I didn't try that and I just use simple square wave controllers w/ 3-speed range adjustment(3 leds). That's all I need at those low speeds. I don't even have a pas. I just set the cruise a little slower than I want to go an pedal on top of that. Plenty of long, straight streachs on my routes for me to get a workout.
Q75 is too sm. to mess about with,...unless she wears lycra
5.2 Ah of 12S LiPoly will get her about 10 miles max. I ride around town on a single 14S pack of 5.2Ah, but if I'm going any distance, I carry an extra.

 

[harrisonh]

I noticed just now that Topbikekit.com is not secure (does not use https)
Do people actually trust to send payment info, address, etc over to them this way? I saw on aliexpress/ebay, it costs significantly more, even after accounting for shipping costs.

 

[Freddy1]

My thoughts, forget the parts you already have (displays and controllers are dirt cheap). Just buy a suitable package of AliExpress that is built around a KT display and controller of about 25A.
A rear hub 750w or 500w motor weights no more than a 250w motor. So if it were me I'd go 750W.
A KT controller is VERY easy to scale back the power to whatever you want (% of controller output, link throttle to PAS display level). So over engineer it as the extra cost is next to nothing, and then program it back to the required power.

 

[E-HP]

1) 35A grinfineon controller, which I can reverse shunt modifiy to reduce power
2) 44V 5.2Ah (200Wh) lipos (4x 6s 2.6Ah)
3) Cycle Analyst + PAS
4) 250W Bafang 26" front hub - $65 delivered
https://www.ebay.com/itm/364033884587?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=364033884587&targetid=1264870805984&device=c&mktype=&googleloc=1014187&poi=&campaignid=14859008593&mkgroupid=130497710760&rlsatarget=pla-1264870805984&abcId=9300678&merchantid=8458744&gclid=Cj0KCQiAtvSdBhD0ARIsAPf8oNnDis5OSt8eI9fjAVOwlOTWGvKK9qg4LKokCtdTmB7KsiwAPoqLQZ4aAtirEALw_wcB
(can't tell from the pic whether the rim works with rim brakes)

The grinfineon has a lot of flexibility on voltages, so you can upgrade the battery after she sees if she likes it, and the CA will allow you to cap the current without having to undo the shunt mod.