My first project : eBike to work

Hello,

I'm new in the world of Electric Bike so I'm going to present you my project and read your comments / advise

Distance Home -> Work -> Home (20 km per day) and able to run for (4500 Km per year)
The country is flat so there is no up or down hill
I'm expecting to drive at minimum 50 km/h

So, it means that I really need something that will work over the year and everyday.
Batteries that will meet my requirement on a daily basis
And a good motor which will work by all kind of weather

Question:

1 - I'm planning to get a Cromotor (stop me now or never)
2 - And what do you think about 6 lipos 6s 5Ah, 66,6V 10Ah http://www.hobbyking.com/hobbyking/store/__9192__ZIPPY_Flightmax_5000mAh_6S1P_20C_DE_Warehouse_.html
3 - And ultimate question, should I switch to 20' BMX wheels or keep using 26' ?

There is a pic of my Monster 8)


Cheers,
Ben

Nice bike! Keep your 26" wheels. Drop down to 24" if you must but 20" in the DH Comp frame will be terrible. Cromotor sounds like a good choice if you are happy to have only a singlespeed gear at the back for pedalling.

According to ebikes.ca, with 26" wheels on flat ground with 120kg total weight you will need:
850 watts to maintain 45 km/h
1150 watts to maintain 50 km/h
1500 watts to maintain 55 km/h

Of course, accelerating requires much more power, but for only short periods. But, it's worth thinking about what speed you really want to maintain because it will have a big affect on the amount of batteries you'll need to carry.

Lets assume you want to stick with a 50 km/h speed and only recharge at home. Your 20 km commute will take 24 minutes at 50 km/h. 24 minutes at 1150 watts is 460 Watt-hours (Wh). Let's add 20% margin for accelerating or small hills (552 Wh). Now, discharging lipo below 20% capacity will shorten battery life so add that margin to find the rated battery power you'll want to carry (662 Wh). The batteries you selected have a nominal capacity of 666 Wh, so I think you've chosen well for your situation.

However, it's always nice to have a larger than necessary battery for the unexpected extra trip or if you miss the chance to do a full charge one day. Other options included keeping an extra charger at work, or having three spare 6s packs in a backpack to use as an emergency 18s1p pack. For example, carrying 3 of these would only weigh 1.8kg and give you another 266 Wh of power, or 14 minutes extra riding at 50 km/h.

Yeah! Another DH Comp!! My DH Comp was my first ebike as well

Couple of things I want to warn you about that you need to plan for.

1) Swing arm offset. Check out this thread: http://endless-sphere.com/forums/viewtopic.php?f=3&t=37026

I havn't done it yet... but apparently if you cut the spokes 3-5mm shorter then they are supposed to be on the brake side, the tire will center alot better.

2) 135mm rear swing arm won't fit the Cromotor without some stretching by hand and foot. I have to sit on the floor and pull the swing arm a good 5-10mm bigger.

3) What controller you plan on going with? I'm running at quite a higher voltage... but I'm constantly blowing up my 18-FET lyen because I'm getting power hungry.

I'm about to try the GreenTime 5kw 36fet controller. I'll let you know how it works out. http://www.aliexpress.com/snapshot/108736227.html

4) What kind of dropouts? Kiwi's dropouts have so far held up quite well with my abuse!

5) The addiction. Your poor wallet will suffer!

Ah man..what a frame..full bounce and with a big triangle..ideal

voicecoils said:

Nice bike! Keep your 26" wheels. Drop down to 24" if you must but 20" in the DH Comp frame will be terrible.

Click to expand...

What do you mean terrible ? Because of the power ?

voicecoils said:

According to ebikes.ca, with 26" wheels on flat ground with 120kg total weight you will need:

Click to expand...

Actually I'm 95Kg so I'm pretty sure that I'll pass 120kg on the bike with all the equipment

Thanks

FoolSpeed said:

voicecoils said:

Nice bike! Keep your 26" wheels. Drop down to 24" if you must but 20" in the DH Comp frame will be terrible.

Click to expand...

What do you mean terrible ? Because of the power ?

Click to expand...

I think because the bottom bracket will be very close to the ground. There was a guy on the ES Facebook page who did the 20inch rims... they looked pretty awesome!

binlagin said:

Yeah! Another DH Comp!! My DH Comp was my first ebike as well

Couple of things I want to warn you about that you need to plan for.

1) Swing arm offset. Check out this thread: http://endless-sphere.com/forums/viewtopic.php?f=3&t=37026

I havn't done it yet... but apparently if you cut the spokes 3-5mm shorter then they are supposed to be on the brake side, the tire will center alot better.

2) 135mm rear swing arm won't fit the Cromotor without some stretching by hand and foot. I have to sit on the floor and pull the swing arm a good 5-10mm bigger.

3) What controller you plan on going with? I'm running at quite a higher voltage... but I'm constantly blowing up my 18-FET lyen because I'm getting power hungry.

I'm about to try the GreenTime 5kw 36fet controller. I'll let you know how it works out. http://www.aliexpress.com/snapshot/108736227.html

4) What kind of dropouts? Kiwi's dropouts have so far held up quite well with my abuse!

5) The addiction. Your poor wallet will suffer!

Click to expand...

1) As I'm planning to put 20"wheel I think that I don't have to care much (should I ?) + I saw the post on the facebook page it's Paul's bike and I know him because we were talking a lot and he gave me pretty much good information about my project.

2) Ok, then I'll have to be strong tu put the wheel on my bike

3) 12 fets ( http://www.endless-sphere.com/forums/viewtopic.php?f=31&t=17683 )

4) I'll see if I can do it myself where did you find yours ?

5) ... I know

Umm 20 inch rear is small...but it it full bounce, so...can you alter the geometry a bit to regain some extra ground clearance?...swing the back end down a bit further.longer shock?maybe a differnt length linkage in there somewhere...or

If you are making clamping style torque plates/dropout adapters...drop the wheel lower that way. Large, thick triangular plate, one each side, with a bolt fitting in to each dropout, and bolting up tight. make it so the wheel sits that three or 4 inches lower than the original wheel below the original fitting position

if you're going to run this bike with that much power, I highly suggest some moto rims and tires. The handling is so much better! Talk to John at http://holmeshobbies.com/ He's awesome!

Salut,

sinon tu peux aller sur des jantes 17-18 pouces de motos. Le diamètre total fera autour de 22-24 pouces et ça sera increvable

Otherwise you can go with 17-18inch MC rims. OD will be 22 to 24inch.

It's up to you but with a 20inch BMX rim, the Cromotor will pull really hard and for a first ebike... Dangerous