I was in this identical situation about three weeks before you, here's my post: viewtopic.php?f=2&t=38590
Basically I wanted to build a 20" folding ebike that did 20mph/30kph using BMSBattery parts. I wound up going with two 24V 10AH frog batteries and two front Q85 24V 250W kits, laced into 20" wheels, all from BMS battery. I also picked up some extra throttles because they were so dirt cheap and shipping is barely anything if you are already buying a bigger kit. Everything was received in about 2 and a half weeks (a second order I recently placed came in only 1 week). Everything was well packed and the only annoying thing was DHL charged me an extra 21 bucks a week or two later. Weird.
Anyways, the first wheel had some lateral and radial untrueness. I put it in my truing stand and quickly saw that one of the spokes wasn't even tensioned, I could wiggle it around and move it up and down. I trued the wheel and then it was fine. The second wheel was much closer to true and had better spoke tension, i just did some fine tune adjustment to make it extra true.
I put the motors on two 20" folding bikes. My initial research led me to believe most folding bikes use an 85mm wide front fork dropout width, which is why I went with the q85 motor. When I installed the motor though, there seemed to be about a 1/4 inch extra on each side of the motor, which adds up to a total of about 100mm so perhaps this folding bike did use a 100mm front fork and I hadn't planned accordingly. No matter though because the motor kit came with a couple of what appeared to be spacers that fit over the axle of the motor. They were about 3/16 inch thick I'd guess so they didn't totally make up the gap, but they got close and allowed me to crank down the axle nuts and not bend the fork as much as it would have without the spacers. The slight bending of the fork seemed fine as it was only a few mm on each side. Next I put the 24V 10AH frog batteries on the seat posts because there wasn't enough room on the frame's actual seat tube to mount it. The annoying thing here is that the frog battery seems to be designed to clamp onto a thicker frame tube than the thin seat post I mounted it on. That meant tightening the bolts around the seat post basically turned the two metal arms into a triangle because I had to tighten the bolts down so freaking far. Then because I had tightened them down so far to force the metal arms around the seat post, they were now not so centered so the plastic housing for the lower part of the battery no longer fit since the bolt ends stuck out so far to one side. I replaced them with shorter bolts (which fit because now to the two metal arms were bent closer together) and everything then worked fine. If I do it again in the future I'd probably machine a bit of a spacer, such as a block of aluminum drilled with a hole slightly over the size of the seat post, cut in half to make two arch looking pieces and then clamp those in the battery's clamp arms around the seat post. Also of note: the battery comes without leads connected but includes the leads and connector. It helps to have a wire stripper/crimper to strip the wire and crimp the connector. In a pinch a knife and pair of pliers will work. (Now how many people cringed when I said that?) Next I taped the controller into the lower part of the battery holder that stays on the bike using electrical tape and it helped hide it nicely and also likely give a small amount of shock absorption for the controller, for what it's worth.
The battery takes about 6.5 hours to charge on a TOTALLY dead charge, though it only got to that point once. It's a bit long of a charge time, but hey, good/cheap/fast - pick two.
My fiance and I have ridden the bikes for about 100km each. So far I'm very satisfied with the whole BMSBattery kit and battery. The speed is just shy of 30 kph (we were in Israel so I had everything in SI units) though on even a tiny bit of a downhill it could get up to 33-34 kph. The acceleration leaves a lot to be desired, though I'm used to my two ebikes here in the states, one with a Xlyte 5303 behemoth doing 30 mph and acceleration that scares people and another with a 9C 2808 that does almost as good. The range of our little electric folders seemed to be just shy of 30 km with no pedaling, which was decent for us to toot around town, go to the beach and the park all in one trip. If I could change one thing, it would be to have gotten the 15 AH battery instead of the 10AH, which would have likely given us just over 45 km range.
Here is a pic of one of the two bikes: http://postimage.org/image/jm3l0993p/
And here are 5 or 6 pics of the other, currently for sale on a craigslist-type website in Israel. Hey, if you know anybody... haha http://www.yad2.co.il/Yad2/ViewImage.ph ... b02f051a82
I don't have enough data to suggest any long term reliability, but from what I've experienced so far I am very happy with BMSbattery and the parts I ordered. I will definitely order from BMSBattery again.