Dahon Helios SL electric conversion advice

[Sean McGrath]

Hi all

My first post - pleasure to meet you all! I've just acquired a Dahon Helios SL which I'm very excited about; however I was really on the market for a light electric foldable and so I've taken a punt in the hopes that I can covert this super light bike into a super light electric bike. I know a bit about bikes (little compared to most on this forum) but know next to nothing about conversions. I was wondering if any of you could think, off the top of your heads, of a front wheel kit that might be compatible with the Helios SL? I haven't taken delivery of the bike yet but I'm assuming it will have a <80mm distance between the front forks and so know that I need to be careful about what I choose.

Budget is not really an issue - weight and quality is. I won't be doing more than 6 miles per journey, all flat terrain and I weigh about 12.5st. I'm fairly technical so feel I can read my way through this but if people think the contrary, I'd be willing to pay someone with the expertise to make sure it all goes to plan.

Any advice is appreciated. Looking forward to getting stuck in! Again, pleasure to be a member of the forum.

Cheers

Specs of bike:

SPEEDS: 8
GEAR INCHES 31" - 91"
DISTANCE: SEAT POST TO HANDLEBAR 670 mm (26.4")
DISTANCE: SADDLE TO PEDAL Min. 710 mm (28"); Max. 950 mm (37.6")
FOLDED SIZE 28 x 56 x 81 cm (11" x 22" x 33")
WEIGHT 7.6 kg. (16.7 lbs) base model w/o options and pedals
FOLDING TIME 15 seconds
SUGGESTED RIDER HEIGHT 142 cm - 193 cm (4'8" - 6'4")
MAX RIDER WEIGHT 105 kg. (230 lbs.)

FRAME Y Series, 7005 double-butted aluminum alloy, custom-drawn Sonus tubing, forged Lattice hinge, patented Re-Bar™, EmBed, ViseGrip technology, replaceable derailleur hanger
FORK Dahon SlipStream™, Puro™ U6 aluminum alloy, integrated, Fusion technology

STEERING COLUMN Radius ProLite, patented Fusion™ design, forged aluminum, patented InSide™ lock
HANDLEBAR Dahon CarbonLite riser, custom
HEADSET Dahon Fusion XP, Zero stack, machined aluminum cups, ACB cartridge bearings, sealed
GRIPS ProLite foam
SADDLE SDG BelAir FX, I-Flex design
SEAT POST SDG I-Beam Pro, SuperOversize, 2014 aluminum, forged clamp

BRAKES Kinetix UltraLite, forged aluminum V-brakes, micro bolts, front Flex stainless noodle, stainless anchor bolt
BRAKE LEVER Avid FR5
CABLES AND HOUSING LiveWire™ K, Kevlar SIS housing, slick cable, LubeTube oil port

FRONT WHEEL Rolf® Prima Accel™ - 390 grams
REAR WHEEL Rolf® Prima Accel™ - 640 grams
TIRES Dahon Special Edition Schwalbe Stelvio, Mango/Black, 28-406, 120 psi, foldable Kevlar bead, DualCompound Silica casing, RaceGuard anti-puncture protection

SHIFTERS SRAM X.7, 8 spd.
DERAILLEUR SRAM X.7, Dahon custom edition
CASSETTE SRAM, 11-32, 8 spd.
BOTTOM BRACKET American Classic UltraLight
CRANKSET Truvativ Elita, ISIS, forged 6061-T6 aluminum, 6061-AL chainring, alloy chainguard w/ CNC finish
CHAIN KMC Z82
PEDALS MKS Promenade, QR

CLIP SYSTEM Magnetix™ system
TOUCH UP PAINT Yes
ACCESSORY Reflective pants clip

 

[Deleted member 4366]

There are front motors that might fit, but they're not very powerful. You can't stretch the forks far because they're alloy, so no standard 100mm motor will fit. You didn't say how fast you want to go. A 36v 328 rpm Q100 rear motor will take you to about 18 mph. If you use 12S lipos as a battery you'll be able to scoot along at about 22 mph. You can just squeeze in a Q100C, which will allow you to keep your gears.

On my Dahon, I have a Q100C. I started with a frog battery, and then changed to a bottle battery. The first photo shows it with the frog battery case with two Turnigy 8000mah 6S lipos in, which gave really good performance:

 

[Sean McGrath]

Wow, it looks awesome - thanks. To be honest, I think I'll be okay going along at the legal 15mph, but if I can squeeze a bit more out of it, I don't mind living dangerously.

I'm keen to keep it front wheel so I don't have to screw about with gears. I see a few kits for a Q100 front wheel but no Q100C. Would something like this work http://www.bmsbattery.com/ebike-kits/576-250w350w-q-85100sx-motor-e-bike-kit.html or am I looking at getting a barebones motor and doing it myself (scary!).

 

[Deleted member 4366]

The Q100 front wheel won't fit. The Q100c is the Q100 with a cassette spline, so rear only.

The motors that fit are the Q85 (maybe), I think Outrider and Keyde do a 80mm motor, and possibly Crystalyte do a 74mm one
http://outrider.en.alibaba.com/
http://www.keyde.com/?do=product&lang=en&event=view&ids=07
http://shop.crystalyte-europe.com/product.php?productid=16513&cat=250&page=1

 

[Sean McGrath]

Thanks mate. Based on the links you have sent, the only one I can see that includes a full kit with the 80mm dropout is http://shop.crystalyte-europe.com/product.php?productid=16235&cat=320&page=1
Are any of these motors better than others? Should I juts man up, get the motor and figure out how to fit it to my existing wheel? How hard is it? I'm assuming it's not straightforward! Thanks again for the advice.

 

[Deleted member 4366]

nothing is difficult if you know how. You can get all those motors as a kit.

The Crystalyte is a direct drive. It's not everybody's cup of tea because it doesn't free-wheel quite as well.

I can't understand why you want to make life difficult for yourself by fitting a front motor. Is there a reason?

 

[Sean McGrath]

1. Most of what I've read suggests that if you want to maintain foldability, it makes life easier.

2. I liked the idea of chucking a wheel on rather than messing with the gears.

3. I don't want to lose the gears.

I am more than happy to be told that rear wheel is the way to go if it is the way to go.

 

[Deleted member 4366]

There's no problem with foldability with a rear motor that I've ever heard of.

You don't have to lose the gears with a Q100C. The only messing you moght have to do is reset the end-stops, which takes about two minutes.

The one thing you will have to sort is getting the rim central. Front wheels are normally OK because they're symmetrical, but on rear wheels, the flanges are off-set and the Chinese always build the rim central to the flanges. Already the Q100C is wider than the drop-outs, so is a bit of a squeeze to get it in. 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.

None of those front motors have very much power

 

[Sean McGrath]

Okay, sounds good in theory. Thanks. How heavy are these Q100Cs? Will I have any problems stretching aluminium alloy forks? Also, any vendors you recommend for them (that sell with controllers etc.)

Really appreciate all your input d8veh.

 

[Deleted member 4366]

If you mean your front forks, I doubt that they'll go to 100mm without heat. If you search really hard, there are some replacement 1 1/8"steel forks that you could stretch. IIRC there's another piece you need to convert to them. Do a search for 1 1/18 steel Dahon forks and see what comes up on the various folding bike forums, or search for Dahon 100mm hub.

You can get the Q100C from BMSBattery.com, greenbikekit.com and Elifebike.com. They all have a different designation for it. I prefer BMSB because they have a better choice of controllers and batteries, but maybe one of the others has exactly the battery you want, so have a good look at them all.

Q100C is about 2.2kg IIRC.

 

[Sean McGrath]

Im just looking on BMSBattery now (like the controllers too) and I don't see a Q100C kit with 328rpm. Only 201. I've emailed them but...whattsup with that? :|

 

[Deleted member 4366]

They have the bare motors. at 238 rpm, so I don't see why they can't build a wheel with it.
http://www.bmsbattery.com/rear-driving/618-250w350w-q-85100sx-motor-e-bike-kit.html

 

[Sean McGrath]

Yeah. Will see what they say. Just looking at other sites. Name changes are throwing me off. Is this the badboy I'm after? http://www.greenbikekit.com/gbk-100r-36v-rear-driving-kit-bottle-lithium-battery.html

 

[Deleted member 4366]

No. This one:
http://www.greenbikekit.com/100cst-cassette-freewheel-e-bike-kit-36v-250w.html

 

[Sean McGrath]

Got it. One other question (for now). You mentioned in your first post, 12S batteries. What do you mean by 12S.

Thanks for helping me find my way.

 

[Deleted member 4366]

Lithium-ion batteries are made of cells, which are 3.6v each, so 10 cells in series (10S) makes a 36v battery. You can buy lithium polymer batteries (lipos) in 1S, 2S, 3S, 4S, 5S and 6S packs; so you can put two 6S packs together to male a 44v pack, which gives 20% more torque and speed than a 36v pack. A 36v controller can still work with a 44v pack, so it's an easy way to get a power boost. The other advantage of lipos is that they can give a lot of current for their size, which makes a very light 5ah pack feasible, though you can't go as far, obviously.

 

[Sean McGrath]

Makes sense. I'm just having a think about the tyres and it seems that the Helios SL makes most of its weight savings from the ultra-light Rolf wheels. When every gram counts, it seems a shame to replace one with a clunky heavy thing. I can't find any specs on the wheels offered but I'm assuming they are heavier than 640 grams. Does anyone offer/know of a service, where I could send the wheel (and motor) to have it fitted?

Thanks

 

[Deleted member 4366]

I doubt that that spoke pattern is strong enough for the torque of a hub-motor. If a spoke goes, you'll be stranded too.

 

[Sean McGrath]

fair enough Any suppliers that give precedence to weight or are they all roughly the same? Is there anything that you'd do different if you were trying to build the lightest e-bike possible?

 

[Deleted member 4366]

Power and weight tend to go together. If you want less weight, you can get a lower powered motor. The Keyde is the lightest. After that, it's down to your DIY skills. There's also the Kepler Commuter Booster:

http://www.commuterbooster.com/home