Can anyone suggest hub conversion kit options for a Dahon Helios P8 with 74mm front axle and 130mm rear?

[guerney]

I'm thinking of tranferring the BBS01B from my Dahon Helios P8, to a faster bike I've just bought. It's a Dahon Espresso, which originally looked something like this:

...but the bike I've bought is definitely a project, haven't picked it up yet: some parts are rusty, buggered chain, rusty Shimano Tourney, but the 7005 aluminium frame looked in structurally in good condition, but with many scratches ranging from tiny to small in size. A grabbed bargain on ebay at £72.

If the BBS01B is transferred to the Dahon Espresso, I'd have the opportunity to explore the strange and arcane world of KT kits, and am wondering if there's a motor compatible with the Dahon Helios P8, front or rear (74mm front axle and 130mm rear), but rear preferred. If this isn't possible, the Helios could simply be reverted to an "Acoustic"/manual bike, or I could convert the Espresso with another BBS01B, or hub, and use the same 36V battery for both.

 

[guerney]

I've heard tale of a Japanese made narrow version of the Aikema AKM-13.0 Dillinger use in their conversion kits, which can be seen on this listing installed on a Dahon Vitesse, which also has a 74mm font fork. I can't find this version of this motor availabe to buy on it's own:

Dahon Speed 7 folding bike electric | eBay

Find many great new & used options and get the best deals for Dahon Speed 7 folding bike electric at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[guerney]

I can't find the 60mm version above, the narrowest I've found is 75mm, which is an entire millimeter too wide And I can't find this available to buy either:

AKM85SX

Our 85SX Series e-bike front hub motor is one of the best electric bike motors on the market.The features are lightweight,only 1.6 kg, Max torque 30N.m , efficiency 80%.

www.aikema.com.cn

 

[Nealh]

Brand Akm 74mm 36v 250w High Speed Brushless Gear Ebike Hub Motor 250w Akm Front - Electric Vehicle Components - AliExpress

1.6kg AKM-74SX 36V250W EBike Front Driving Hub Motor Fork Size 74mm for Brompton Bike [AKM-74SX 36V250W Front Motor] - $152.00 : Zen Cart!, The Art of E-commerce (topbikekit.com)

1.6kg TBK-74AD 36V250W Front Driving Hub Motor Fork Size 74mm For Brompton Bike [TBK-74AD 36V250W Front Motor] - $122.55 : Zen Cart!, The Art of E-commerce (topbikekit.com)

Electric Motor Brompton | Akm Electric Bike Motor | Front Hub Motor 28 Inch - Motor 74mm - Aliexpress

Electric Bike Motor 74mm | 74mm Bicycle Motor | 16inch Hub Motor | 74mm Hub Front - 74mm - Aliexpress


For a rear hub one is going to have to spread the drop outs 5mm .

 

[guerney]

Brand Akm 74mm 36v 250w High Speed Brushless Gear Ebike Hub Motor 250w Akm Front - Electric Vehicle Components - AliExpress

For a rear hub one is going to have to spread the drop outs 5mm .

Wow that's brilliant! Thanks a lot! Well found, I couldn't find anything suitable on AliExpress at all. And it just so happens both my rims are 28 spoked! My preference is for a rear hub - spreading aluminium dropouts shouldn't be too difficult, filing should also be quite easy.

The ebay seller may be having second thoughts. I think she was expecting a higher selling price and may be selling the Dahon Expresso elsewhere. Oh well, if she backs out she'll have to pay ebay's listing fees even after refunding me, plus she'll get a black mark for not following through. There were 6 bidders for that bike, and the bid I beat was for £70 - I simply entered £102 as my max bid 2 seconds before the end. £102 because bidders tend to enter multiples of 5 or 10, and I added £2, in case someone else thought of that and entered +£1.

Once/if I have the new old Expresso with rusty spots in my possession, I can start enquiring about controllers for the Helios and rear AKM you've linked. I'd like a KT controller which is capable of up to 25A, then I can look into swapping out the LG MH1 battery's BMS for a 25A if necessary, if the hub motor's torque isn't sufficient, to use on both bikes (but not at the same time). I don't think there are any other choices for 74mm or 130mm axles.

 

[guerney]

The black version is marked 16 inch, and the silver is marked for 700c... Presumably I'd have to get the black for higher RPM? I won't be able to accept a substantially slower Helios.

The Helios is rock solid stable at 52kph and faster (downhill, coming up to a small rise pictured):

 

[Nealh]

Yes if a listing doesn't show the RPM then one will have to go by the wheel size for a RPM listing. I would say 17a max for the lightweight hubs, even the akm100 is 20a max as many users on ES years ago including Cwah mashed the planetary gears with too much power.
If you want more power then opt for the AKM 128 for 25a.

I have used 20a at 48v on the Q128c and suspect 25a will be good as well.

 

[RogerA]

Are you sure it's a130mm rear spacing? I've converted a Dahon Matrix which looks like the same frame and that was 135mm with an 8 speed cassette. I'm using an AKM100CST hub with a 15A KT controller and it'll cope comfortably with 15% gradients on road. I've removed the front triple and have a single 42T ring with guard. I've set the speed cutoff at 20kph because I only want hill assist but I can comfortably pedal at 25mph on a slight downhill.

 

[guerney]

Are you sure it's a130mm rear spacing?

I'm pretty sure the rear axle of the Dahon Helios is 130mm (intended conversion candidate for the AKM), but will measure properly before ordering. I'll be able to measure the Dahon Espresso's axles when it arrives in about two hours, after the ebay seller's husband Percy drives it 127 miles to drop it off to my house, I've been told he's on his way. I might decide to keep the Helios with BBS01b as is, and convert the Espresso with a hub drive.

Are you sure it's a130mm rear spacing? I've converted a Dahon Matrix which looks like the same frame and that was 135mm with an 8 speed cassette. I'm using an AKM100CST hub with a 15A KT controller and it'll cope comfortably with 15% gradients on road. I've removed the front triple and have a single 42T ring with guard. I've set the speed cutoff at 20kph because I only want hill assist but I can comfortably pedal at 25mph on a slight downhill.

That's great! At last another Dahon! That your similarly equipt similarly shaped and sized bike copes with 15% gradients at 15A, is what I needed to know. The Matrix is the other Dahon I was keeping my beady ebay eye open for. I've got 42T and 48T chainrings for the BBS01b that I'll probably be transferring over from the Helios, which at present uses a 52T for speed, which also manages any hill I've encountered (20" wheels). The motor is even game when attempting 45 degree inclines, but the Helio's balance isn't, because the heavy 19.2ah battery is on the rear rack - the battery will have to be mounted to the rear rack of the Espresso too, because I need that bike to also retain it's folding capability.

When the Espresso arrives by Percy Express, I'll inspect the hinge mechanism for cracks in the welding, it looked ok in the photos. The seller claims it hadn't been used much, and they've had it from new. There's a security sticker attached to the frame, hope they've de-registered it.

 

[guerney]

Percy tells me that this bike belonged to his cycling enthusiast dad, who passed away a few years ago, and it had been stored in a shed at his mum's, until she passed away two years ago, because she was born with her heart on the wrong side and died too young aged 55 as a consequence of that and the hole in her heart - the explanation of her unusual medical condition and history was detailed, long and mind boggling. Her house was two miles away from mine, but then the bike was moved to Percy's house 180 miles away, then to another house 127 miles away when he moved, and he's delivered it just now to my house, 2 miles away from it's original location. He's left to see his brother who lives in his mum's old house, where the bike was in the first place.

Percy had no idea which bike security company the marker is registered with, but has death certificates to attempt deregistration. After Googling the phone number on the label, it's:

Retainagroup

www.retainagroup.com

I've asked the seller to deregister the bike, so I can register it. Whether they will I have no idea. Oh well, my receipt should get me out of the slammer after I've been clapped in irons and hauled away, as the Police attempt to contact Percy's late father to inform him that they've located his bike. They'll have to host a seance at the Police station, by the sounds of things

The frame is structurally sound, scuffed with tiny scratches (which Percy assures me are nearly all from being moved from place to place, which might be trie given their location), plus some larger scratches, but the hinge welds look fine. The handlebars are too narrow, having been replaced by Percy's father to reduce folded width - those will have to go. I'll get around to sorting this bike out eventually, there's loads to do. Quite lightweight for it's size: 15kg allegedly, 4.3kg heavier than the Helios was before conversion, upgrades and accessories. By the time I finish with it, it'll weigh much more. I'm thinking very fat tyres...

 

[guerney]

Brand Akm 74mm 36v 250w High Speed Brushless Gear Ebike Hub Motor 250w Akm Front - Electric Vehicle Components - AliExpress

1.6kg AKM-74SX 36V250W EBike Front Driving Hub Motor Fork Size 74mm for Brompton Bike [AKM-74SX 36V250W Front Motor] - $152.00 : Zen Cart!, The Art of E-commerce (topbikekit.com)

1.6kg TBK-74AD 36V250W Front Driving Hub Motor Fork Size 74mm For Brompton Bike [TBK-74AD 36V250W Front Motor] - $122.55 : Zen Cart!, The Art of E-commerce (topbikekit.com)

Electric Motor Brompton | Akm Electric Bike Motor | Front Hub Motor 28 Inch - Motor 74mm - Aliexpress

Electric Bike Motor 74mm | 74mm Bicycle Motor | 16inch Hub Motor | 74mm Hub Front - 74mm - Aliexpress


For a rear hub one is going to have to spread the drop outs 5mm .

I see you've added more motors to your post. Thanks a lot!

 

[guerney]

If you want more power then opt for the AKM 128 for 25a.

I shouldn't need too much power judging by @RogerA 's post, besides the Helios' wheels are are only 20". Which is great: not more than 15A, as much soldering required. Heavy trailer hauling duties will be the Espresso's + BBS01B. The Helios with AKM will then be for final few miles between train stations and destinations/commuting - I think a lightweight front hub should be bearable for that. If I miss the last train, I can pedelec up to 43 miles home.

 

[RogerA]

Sorry Guerney, I misread your original post. I was thinking you were looking for a hub motor for the Espresso. My Matrix is the same frame as that, not the Helios, so you may well be right about the 130mm spacing.

 

[guerney]

My Matrix is the same frame as that

I'd be interested in seeing photos of your hub converted Dahon Matrix. If yours is the same shape as the Espresso, it's not the older Matrix frame design, which needed an Allen key to fold/unfold the bike. It wasn't obvious that the older Matrix frames folded, they looked like normal road bikes. Newer frames were designed by Joe Murray, who also designed bikes for some other manufacturers - I'm unsure if the Espresso was one of them, the very similarly shaped newer Cadenza certainly was.

https://www.cyclemotion.co.uk/dahon/dahonnews14.htm

https://en.wikipedia.org/wiki/Joe_Murray_(cyclist)

I'm using an AKM100CST hub with a 15A KT controller and it'll cope comfortably with 15% gradients on road.

Finding rims wide enough with 36 holes could be tricky in 20":

AKM-100CST Cassette 36V250W EBike Rear Driving Hub Motor 32/36 holes [AKM100CST EBike 36V250W motor] - $97.65 : Zen Cart!, The Art of E-commerce

Zen Cart! AKM-100CST Cassette 36V250W EBike Rear Driving Hub Motor 32/36 holes [AKM100CST EBike 36V250W motor] - ★★★★★ AKM-100CST Cassette 36V250W EBike Rear Driving Hub Motor Specification: 1. Voltage: 36V. 2. Brake type: V-brake, rim brake and disc brake are compatible 3. Connector: 9Pins...

www.topbikekit.com

....because finding rims or wheels which can accommodate 1.75" safely (for a more comfortable riding experience - suspension isn't possible to add to the front) was a challenge; in the end I had to buy 28H Tern wheels, which are safe according to Schwalbe for tyres up to 2.125" wide, but for me 1.75" have worked out well. Too narrow original Dahon Kinetix 36H 20" rims are easy to find, I have two the Helios was bought with.

All of the older 20" & 16" Dahon folders have narrow rims, particularly originals with 36H. Maybe Japanese roads are optically flat or something. There are compatible 20" 406 rims on AliExpress purporting to be wider, but they tend to be badly made. Luckily I'm not in a hurry to convert the Helios, again. In the short to medium term, it'll probably be reverted to non-electrified. Had the Helios been hub motor converted, reversion could have been difficult if any filing of dropouts had been done, but simply removing the BBS01b kit will be easy.

 

[guerney]

I've converted a Dahon Matrix

Currently I think it's just you, me and @AntonyC with Dahons. I'm unsure whether @AntonyC 's Vitesse is currently currented/converted.

 

[guerney]

According to my digital luggage scale, this Espresso with tyres and rear rack etc. weighs 14.9kgs. The extra 4.2kg over the Helios' pre-conversion weight will make no difference to the BBS01b. At some point, I'll have to swap out the almost unworn "Continental TravelCONTACT SafetySystem" tyres for fatter, also puncture resistant, more grippy somethings.

https://www.conti-tyres.co.uk/commuting-touring/contact-travel

Discovered this morning that the Espresso's seatpost contains an integrated bike pump, which works and is quite effective. Inner tubes are fine. I already have the right chain, it's the spare KMC X8 for the Helios.

 

[guerney]

@Nealh - with one of those chainring adapters you mentioned some time ago, I may have the option of retaining this bike's triple chainwheel for BBS01B use, the largest of which is 48T, but I could go with something like a 58T>11T or 60T>11T for the occasional rare fast blast.

For Bafang Mid Drive Motor Chainring Adapter 104BCD 130BCD Spider Black G6U8 | eBay

[Applicable motors]Perfectly compatible with for Bafang electric bicycle mid drive motor. [Scope of application]104BCD: suitable for 32T-55t 4-hole positive and negative chainrings; 130BCD: suitable for 38-60T 5-hole positive and negative chainrings.

www.ebay.co.uk

75T could be excessive:

https://www.amazon.co.uk/Driveline-AL7075-Bicycle-Chainring-ST1496/dp/B07D6JHN5J

 

[RogerA]

Guerney,
Apologies for the state of my bike. It's badly in need of a good clean.
I think this frame was the older one, and the lockjaw one that required an Allen key was later. https://www.world-wheels.co.uk/bikes_07.htm Mine is the matrix large shown on the link.
Without the bar bag and battery my bike is about 19kg.

 

[guerney]

@RogerA - Is your controller in the handlebar bag? My Espresso is also a large, but there is the option of reducing weight by replacing the frame with a brand new/old stock medium or small, which CH White & Son (the son) told me this morning they have many of in their warehouse, as well as many Matrix, Cadenza, Jack and other frames. As usual, they haven't a clue about what their huge warehouse actually contains. There's always a set of their Dahon special builds featured on their website, using rare and quite hard to source original Dahon parts, which they won't sell in isolation (I've tried). I might stick with the structurally sound but cosmetically unattractive to bike thieves Espresso frame that I have. Moving all the parts over between frames could end up being a 'mare.

 

[RogerA]

@guerney The controller is squeezed in the small compartment at the front of the battery case.

The AKM100 hub isn't visible between the brake caliper and Cassette, so it's only the battery and a small handlebar display that shows its a conversion.