folding bike conversion?

RVD

RVD

1 kW
Joined
Apr 26, 2011
Messages
418
Location
Seoul, Korea
has anyone done a conversion on a folding bike? i did some searches and found a little bit of info but not really as much as i was hoping for.

i'm thinking of taking a dahon speed d7 (http://www.dahon.com/bikes/2011/speed-d7) to use as a base. this uses 20" wheels so i will likely get a 20" ebikekit geared rear hub motor and hook it up to a lyen 9 fet controller and run it on lipo (12s2p (44v) or 10s2p (37v)).

my goals are:

1) keep it somewhat lightweight since this is a folding bike after all. i believe i can just wheel the bike from place to place when i'm not riding but i would like to be able to lift it up short distances if needed (stairs, etc.).

2) decent range while maintaining usable weight. 15 miles would be great. 10 miles would be acceptable.

3) minimize cost since this isn't a primary bike but a secondary bike. i will probably just use a wattmeter instead of a CA, etc.

4) i chose the speed 7 instead of the boardwalk s1 because the boardwalk uses coaster brakes. i don't know much about coaster brakes but i believe the brakes are in the hub so replacing the rear wheel with a hub motor will force me to install V brakes? the speed also seems like a lighter bike.
 
I think Miles' is a Brompton folder, and there are a few others including a Dahon somewhere, but I don't have any links. :(

I wouldn't want coaster brakes even if they didn't have to be replaced; they aren't too hot for higher speeds or masses, plus many coaster-brake bikes *only* have rear brakes.
 
Dahon Speed D7 makes a great folding electric bike. Sounds like you've already picked out a motor and everything, I think it's going to work well.

One thing I would recommend is that you use good lock washers AND a torque arm and make sure that wheel is sitting all the way in the dropouts. Might even want to get a file to make sure it's seated in there well.
 
I'll get a set of norlock washers from shinyballs (emmanuel) and a set of torque arms from doctorsbass so that part should be well taken care of.
 
Easy answer.. yes a folder has been done before.

Ampedbikes bikes 500 watt kit with 20inch wheel and 36v 10 ah allcell battery.

Total cost around $900
 
Jason27 said:
Ampedbikes bikes 500 watt kit with 20inch wheel and 36v 10 ah allcell battery.
Click to expand...
Since when does allcell equate to minimising cost?
 
What else did you have in mind to minimize cost? Lead? Not everybody is willing to take the precautions advisable for lipo use. At least the allcell battery is fairly light and small compared to a ping pack.
 
dogman said:
What else did you have in mind to minimize cost? Lead? Not everybody is willing to take the precautions advisable for lipo use. At least the allcell battery is fairly light and small compared to a ping pack.
Click to expand...
I shouldn't really post late at night between flash programming cycles while debugging my motor controller software... too often it ends with incomplete posts :lol:.
Definitely not lead :lol:
Admitted allcell are light but all factors need to be considered. they seem to be one of the most expensive out there.
For a 500w motor suggested even LiFePo4 would be fine if the weight penalty over the all cell is acceptable which it might be.
The bulider will have to decide if the weight difference is more important than the cost difference and since they are the only one who can make the decision its good to list the differences.

Of course there is the option of RC LiPo but of course the risks and possible failures due to mistakes mean it is not always suitable for everyone although it is definitely light and relatively cheap provided mistakes are not made.

A lithium manganese pack is of course another option. safer than RC Lipo and fairly light.
As there is always tradeoffs the information should be provided rather than just stating a cell type with no reason
 
My wife's bike is a Dahon Speed 7, fitted with a Kepler eboost (RC motor friction drive) and 5S 10Ah of Lipo.

It's a great bike, really well designed and lightweight.

The rear dropouts are a little narrower than usual (around 130mm), just check that's not an issue with your selected kit. Front dropouts are only 75mm!

Good luck with it. :D
 
NYCE sell a lot folding models e bikes including Dahon.

http://www.nycewheels.com/electric-folding-bike.html

You'll get some good ideas for a DIY based folding ebike based on looking at what they've done.
 
A folding e-bike would be awesome. Dahon's definitely the good stuff. That project will be way expensive though. I was considering doing it to a Citizen Tokyo, but that project's on hold for now.
 
i'm using lipo because:

1) it's light
2) i already have a pretty decent lipo stash
3) i like the modular nature of lipo. i can configure a 10s1p block for short trips, 10s2p for medium distance, etc...i have enough lipo to build a 10s5p pack if i really wanted to (37v 30ah)...maybe even more.
4) i can share my lipo stash among my different bikes. 18s3p for higher power, 20 mile rides on my full size bike, 14s4p for medium power, 10s for my folder, etc.
5) i'm well versed with the risks and dangers of lipo. of course this doesn't mean that i'm immune to accidents, doing stupid things, etc. but i'm not a total noob when it comes to lipo.
6) i have lots of harnesses, etc.

this will be a fun project. bike is ordered. i'll order the motor today from ebikekits via their cyber monday discount.
 
research tells me that the rear dropouts on the dahon is 130mm. the ebikekit 20" wheel with 7 speed freewheel is 135mm. anyone think it should be safe to spread the dahon to 135mm? i also ordered a 1 speed freewheel because i figure that should fit for sure (may need spacers).
 
RVD said:
research tells me that the rear dropouts on the dahon is 130mm. the ebikekit 20" wheel with 7 speed freewheel is 135mm. anyone think it should be safe to spread the dahon to 135mm? i also ordered a 1 speed freewheel because i figure that should fit for sure (may need spacers).
Click to expand...

That's less that 1/4", or 1/8" per side. You should be fine, as long as you're careful.
 
1/4" of an inch is quite a bit! My only experience with something like this was fitting a Sturmey Archer CS-RK3 internal gear hub (purchased from here on the forum) into the back of a KMX Tornado tadpole recumbent trike and it was a snug fit. I was worried it wouldn't go in and I pulled it less than 1/4" total. If I had to stretch it that far, I'd be a bit worried.

Are there other kits that have a 130mm dropout spacing that would work? Best to go with something more suited for your bike I'd think. Maybe someone who's done this before can chime in. I can't imagine this is the first time a hub motor has been mounted on a Dahon.
 
Miles said:
amberwolf said:
I think Miles' is a Brompton folder,
Click to expand...
amber, I do have a Brompton folder but my only electric bike is based on the Moulton TSR (non-folding).
Click to expand...
Ooops. Sorry about that. :oops: I often think I could forget my own name at work if I didn't wear a name badge. :lol:
 
All of the rear wheel hub motors I have seen are 135mm. I have put hub motors on two Dahon bikes.

The Mu (I used a Mu SL) was possible but rather difficult to get the wheel in. I didn't permanently re-set the frame because with an aluminum frame I understand that is less safe. I just sprung it out a little bit. It was a very tight fit and the lip of the axle bit into the aluminum, deforming it a bit but also holding securely. I put 3000 miles on the bike at 48V/20A without a torque arm, although I wouldn't necessarily recommend that approach to others.

On the Speed D7, first of all it's a steel frame so it could be acceptable to re-set the dropouts. But also it seemed to me that it was probably actually a 133-135mm dropout already, because a 135mm hub motor was quite easy to install. But a torque arm and good lock-washers etc is a requirement to hold the wheel securely with the smaller harder steel dropouts.
 
I've got a Dahon Speed 21 with 3x7 on the rear wheel (Sachs). The front fork is narrow (79mm?) and there are very few motors which will fit it. The Crystalyte 209, from itselectric.ca is one that will.
I like the balance with the small hub motor on the front and a small pack on the rear. It's a good fast motor suitable for a 20" wheel, but the torque is fairly low. A nice bike for around town or cruising in slightly hilly terrain. And you can still fold it well.
 
Thanks stingray, real-world experience is invaluable.

Now we know it can be done! :D
 
Great info stingray. My bike arrived yesterday and my motor arrives tomorrow. I hope to work on this project next week.

I was going to use doctorbass torque arms but it looks like there isnt enough space. I will just use normal torque arms.
 
I'm found a cheap no name folding bike with 24" wheels that I'm using with a Currie USPD motor. I don't know if the USPD works with smaller wheels. The original spokes on the folder were pretty thin, and I must have broken half of them on the drive side. I replaced the wheel with some generic wheel from Craigslist, and I haven't broken a spoke since then.

Some day, I'll rewire the Kollmorgen motor I bought and install it ...
 
Shit I am too late - sorry, I would have recommended perhaps a slightly different route than Dahon... only due to their non-standard components in many bikes the offer and rather high prices for the end product.

Regards,
mwkeefer
 
mwkeefer said:
Shit I am too late - sorry, I would have recommended perhaps a slightly different route than Dahon... only due to their non-standard components in many bikes the offer and rather high prices for the end product.

Regards,
mwkeefer
Click to expand...

What other brands would you recommend?
 
You must log in or register to reply here.

Similar threads

U
Folding mid drive conversion options?
2 3 4 5 6
Replies
129
Views
4,768
kcikY
K
jonsully
!!SOLD!! 4kW (72V, 25.6Ah) Surly Ice Cream Truck Fat Tire Bike (HPC)
Replies
2
Views
333
jonsully
jonsully
M
2013 Trek Cyclecross drop bar conversion assist for hills Scotland
Replies
7
Views
151
neptronix
neptronix
Chilekesh
Folding Triple Motor All-Purpose E-Bike
Replies
5
Views
1,231
Chilekesh
Chilekesh
B
    • Like
Motor recommendations for 16% climbs?
Replies
18
Views
767
Ebike Bob
Ebike Bob
Back
Top