You can buy it from ebay too, in case you worry about warranty.

http://www.ebay.co.uk/itm/Electric-Bike-Battery-Bike-E-Bike-36v-9ah-lithium-battery-Folding-Bike-/310870656937

Not that one. It has a low discharge rate, so probably crap cells. It's also very expensive for what it is. The one I linked to has high discharge high capacity Panasonic cells and only weighs 2.5kg.

And so it begins. Finally got the bike (woop!). Needs a clean up. Rode it home. Very responsive and fun. I've also ordered my parts from BMS. Slightly concerned though, and this is probably really dumb of me. The wheels are not 20" as far as I can tell (pic below). Nor are they 16". Is it because the tyres are so thin? Have I ordered the wrong wheel size :|

 

That looks OK - the same as BMSB 20" rims. There should be a size written on the tyre, like 37-406. It's the 406 that's important.

28-406

The BMSB one will go straight on once you've squeezed it in and centralised the rim. Start mugging up on how to dish a wheel if you don't already know. There's videos on Youtube, I believe.

So after months of waiting my parts have arrived! Still not chosen a battery but have plenty to be getting on with. I changed the cassette out and squeezed the wheel in, just to see what it would look like. Just like you said d8veh, it fits (JUST!) but man it looks wonky. I'm hoping the dishing will sort that out. I'm keen to get moving on this ASAP so rather than order a dishing gauge and wait - do you think my bike shop will dish the wheel for me? Woop! very exciting..

You can make the rim central by spacing it on the left side which will make the hub even wider. I think that's just about feasible, or you can dish the wheel, or a combination of both.

 

Can you explain what you mean by spacing it?

I advise you to get this sine wave 48v controller with battery integrated with your Q100C:

https://bmsbattery.com/battery/680-bottle-ebike-battery.html

 

I have the same thing but on my Q100H and it is really quiet and convenient. It a really lovely kit.

 

 

Alternatively, if I was you, I would consider getting the BBS01 or BBS02, which is a bit heavier but that doesn't have so much difference with the Q100H because controller is integrated.

Then add a 52 ring chainring:

http://em3ev.com/store/index.php?route=product/product&path=46&product_id=193

 

And you'll be able to have speed from low to over 25mph speed.

 

 

With your super lightweight helios, you'll soon be frustrated to max out at 15mph when you should easily be able to do that on your human power only

Thanks cwah. I can't fork out $400 on a battery at the moment. Open to alternatives. I agree, 15mph will be frustrating so think I'm going to try 44v setup.

Okay, a worrying development. My mate came round - knows a LOT about bikes. He said that the dishing on the wheel was set up for a single speed configuration. That because the spokes were not crossed (I think he said laced) there would not be enough spoke to dish the wheel far enough over. Said it was dished as if it wasn't going to have a cassette on it. Does this sound plausible? Im guessing sending stuff back to China is a no go? Image of wheel... http://postimg.org/image/keezv4nc3/

don''t worry about spokes not long / short enough for the amount of dishing you'll need to make the wheel central. We are talking about 2-3mm here.

Just fit the wheel first, use washers to bring the wheel as near to central as you can. Then post another picture of the wheel in the bike for us to see how much more dishing you'll need.

Thanks. I can't use washers without stretching the framehttp://img42.com/iMOlK+

Just loosen every spoke by half a turn on the non drive side and tighten every spoke by half a turn on the drive side - rinse/repeat until the dishing is correct. I doubt you'll run out of spoke threads - it's not that far out.

I've started the process and it's certainly working but they seem to be varying levels of tightness, which begs the question, why am I doing highly controlled half turns. Would another method not be to tighten the driver side until is...tight and loosen the other side until it is loose and then work backwards? Reinventing the wheel :|

don't worry about controlled half turns. It's just an easy way to get the wheel moving in the right direction.

Bring the wheel to the centre line, then bring all the spokes to the same tension. If you do this for the first time, make sure your spokes are tight but not too tight, you can ride a few days then tighten them up a bit more.