mexicanhanu wrote:Hey man awesome build. I love this build. I have been wanting to build a mid drive ebike for quite a while and have two questions
1. How much did this build cost you? Specifically how much did the cnc cost you? Also where did you get the 80-110 alien motor? I don't see them on their website anymore.
2. Is there a specific reason why the motor is geared lower twice? (gear -> hub(?) -> rear sprocket) does it need that much torque?
3. Going off question 1. is the 3 point bolt on for the motor mount strong enough to withstand the motor's torque?
4. Any advice for people wanting to start mid drive bikes? My current goal is to make something similar (around 7kw, lithium ion batterypack(probably 12s), directdrive with crank freewheel to have regen braking). However I am concerned with a budget (hoping less than $2000(1800 euro I believe)).
1. It's hard to tell how much the build costed me. Before this one, I built two 'prototypes' which also costed a lot of money, but building these gave me a lot of knowledge and experience. If I have to make a rough guess, all parts I made and all things I tried and didn't work costed me more than €3500,-. However, in the beginning I burnt two ESC's costing about €500-600 in total because I was not experienced enough. Doing a lot of research (and by that I really mean A LOT) and having an engineering background will reduce the costs. (At this point, I am almost done with my study Mechanical Engineering. When I first started building E-bike's I didn't even start the study and I didn't know much about engineering) Sorry, the motor is actually called a 80-100, but the length is 110mm. You can find it here: http://alienpowersystem.com/shop/brushl ... 0kv-7000w/
2. The double gearing is indeed needed because of the total reduction. The motor has 130kv, at 37 volts nominal this is about 4800 RPM. This RPM has to be reduced by a lot at the wheel.
3. What do you mean by the 3 point bolt exactly?
4. Yes, do a lot of research. Read through forums a lot. This will help you in designing your bike and keep the costs down because you will make less mistakes. You will have to put a lot of effort in it before you have a reliable bike. I think €1800 would be possible if you buy a cheap second hand bicycle. Remember that RC ESC's don't like regenerative current, you either have to use a freewheel or use another controller. (I think a Kelly controller or something like that, there's lot of info on the forum)
Ecyclist wrote:Very cool build. I also like Alien motors and hope to use one once I get it.
Can you tell me why you didn't use the Alien controller?
I did try the Alien controllers but I always had problems with them. Mostly problems concerning programming.
Wheazel wrote:Nice project, but with such fabrication possibilities and skills, I ask myself why keep the frame as is?
You are putting a lot of effort into this, and it seems logical to me to go over the complete solution,
and not be limited to complicated work-arounds and compromises originating from how the frame is shaped.
I did think about that. But Ecyclist is right, welding is a special kind of engineering. I also don't have much experience with welding and don't have a cheap source to do it. Another reason is that I don't want to modify the frame at all, it should be use able as a normal bike in the future.
The plan is to build another bike after this one, I am still considering building my own frame for that one but not sure on that.
(Canadian here) LOVE the "Dutch" (the Netherlands)! ... and re "ebikes", in 2012 yer Fietsberaad reported ONE MILLION "EPACs" on your roads (aka vastly superior bicycle infrastructure)...
BUT, not much hills to speak of? (I gather that winds off the Atlantic can be a "bitch" as headwinds.)
So. Given that any "Olympic-class" human can pedal "fast" consuming ... per Wiki:
On firm, flat ground, a 70 kg (150 lb) person requires about 60 watts to walk at 5 km/h (3.1 mph). That same person on a bicycle, on the same ground, with the same power output, can travel at 15 km/h (9.3 mph) using an ordinary bicycle, so in these conditions the energy expenditure of cycling is one-third of walking.
WATTS UP with "11,000 Watts"?
Just curious... Tks
(PS. Reasons for liking the Dutch include boats and trade ("business") but also windmills and dykes.
Not much hills, you're right! I travel by bicycle everyday (not an electric one) and the headwinds are a bitch!.
I think JOHN in CR described it perfectly. It's such a blast and gives a huge smile on my face when I ride it, every single time. It is awesome to have so much power in such a lightweight package. Did you ever driven a high powered car? You could compare it with that. The only differences are:
- A high powered car makes a beautiful sound, my bike doesn't unfortunately
- A car is heavy as shit, this bike is ultra lightweight which makes the fun factor very big
- A car is expensive to drive, this bike costs almost nothing in energy costs or maintenance
Somebody also asked me to write about the reduction of the bike. The primary reduction consists of two carbon steel #25 sprockets, the small sprocket is 14T, the big one 54T. Making a first gearing ratio of 1:3,85. The big sprocket is mounted on a 1/2" case hardened shaft and supported by two ball bearings. On the other side of the shaft is an adapter mounted for the White Industries freewheel which is 16T. From here to the back I used a very strong Connex 1G8 chain to handle all the forces going through this reduction stage. The last sprocket is also mounted on an adapter (both adapters from Recumpence/Matt) which is 39T. The total reduction ratio is 1:9.4 which gives me a approximate top speed of about 65 km/h - 40 mph.
Oh, I am very busy with my graduation/school and I still haven't worked on the plastic gearing/motor cover and wiring case. I hope I can do this this weekend. I ordered a camera mount to make a few video's as the weather is getting better and better