Build check- Mercier Mini Velo

[worldpax]

I've been going back and forth a lot on what I want to build. Some of this is a product of the Ebike learning curve and some due to the fact that I'm waiting for that quarterly bonus check from work to get here. Anyway, I think I finally have my vision sorted out and would like to hear what everyone thinks. Planned use is a relatively flat commute of 10 miles which might grow to up to 20 miles in the next year.

The plan:

I plan to start with one of these. This one has been converted to single speed, but they actually come as a seven-speed with the shifters mounted to the headtube. Steel frame and fork and 135mm in the back. Converting to a flat bar should be no problem.

For the motor I plan to go with Grin. I want to order the Clyte 3540 in a 20" wheel. I don't think that will be a big deal. I'm going to get the 40 amp controller and use 18S2P 8000mah lipo which should equate to about 12.8a/h usable. Plan is to mount the lipo in the frame, but I will probably start out with them in a box bolted to the seat stays above the rear wheel and the controller mounted inside the rear triangle. I plan on charging at home and work and will take the proper precautions so I don't burn anything down. I'm not going to charge to the full 4.2V and don't plan on discharging past the cliff.

What I like about this plan, if the simulations are correct, is that top speed should be in the 35mph range and the acceleration should be pretty perky. On the 10 mile commute range should be ok at WOT if I charge at work or if I throttle back to under 30mph, should be able to do the full route there and back. If my commute gets longer, I can dial the power back with the CA and will have to charge at work.

Comfort is not a huge concern for me and I know I'm giving some up on this build. I know I could probably do it cheaper, but I have gone the cheap route on so many other things before and this time I don't mind spending a bit more. I do see an issue that even with a 54 on the front, I will run out of gear around 27-30mph. I think I can live with that.

Did I miss anything?

 

[Jonathan in Hiram]

As tall as the bike is and with that short wheelbase it's gonna be a wheelie monster if you get it on hard, of course you can turn down the amps in the CA to keep the front wheel down but I'd consider putting the batteries in front of the steer tube in a bag something like this, would also give you some room for cargo.

Also with that short wheelbase, 20" wheels and at 30 plus mph the ride will be brutal on anything less than pristine pavement, consider something like Schwalbe Big Apple balloon tires and/or a Thudbuster to take the edge off the harshness. I have the Big Apples on a bike with a 20" rear and a rigid frame and they helped smooth the ride considerably as well as being remarkably easy rolling.

 

[worldpax]

Nice Moulton Jonathan!

Thanks for the input. Good suggestion on the Thudbuster, and pretty much what I was thinking along with a suspension stem if the ride ends up being too harsh. Wheelie machine is actually kind of what I'm hoping for I mean just because I'm commuting doesn't mean I can't have fun doing it. Ideally I will get the batteries in the front triangle or on a front rack.

 

[wesnewell]

I've got over 3 years and 11K miles on my motor. Total cost minus the new seat, handlebars, windshield was <$700. All these motors come from the same country. My advice would be to get a cheap 26" bike with steel dropouts, install one of the many sub $300 48V 1000W kits on it, and then put 20ah of 12s rc lipo on it. All this can be done for about $800 or less, including a 12s charger. Here's the kit I bought over 3 years ago for $280.
http://www.ebay.com/itm/48V1000W-26-Rear-Wheel-Electric-Bicycle-Motor-Kit-E-Bike-Cycling-Hub-Conversion-/231132763662
And here's more info on it.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=49638
This would be the kit I'd buy today, simply because it supports disc brakes if you want them. Looks like a redesign for that.
http://www.ebay.com/itm/26-Electric-Bike-Bicycle-Motor-Conversion-Kit-eBike-Rear-Wheel-48V-1000W-/370934929537
And these dealers are in the US.

 

[Drunkskunk]

That looks like it's going to be an interesting build. I would move away from putting the batteries behing the seat. that much weight that far up and back will make a short wheelbase tail heavy bike like that unpleasent to ride. Getting the weight low in the center will greatly improve the way that bike rides.

you might also consider fitting the largest, fattest tires you can on that frame.

 

[worldpax]

Have a friend in Japan looking into one of these for me

 

[worldpax]

The plan is coming together. I have the bike and last night I finally took a leap of faith and ordered the kit.

Here is the bike, I converted it to a flat bar.

And it's getting this kit:
Upgrade EM3ev vers. Mac , 500/1000W Pick'n'Mix Kit
- Motor Speed 410rpm loaded @36V 6T Upgrade
- Front/Rear Motor Rear
- Controller Type 12 Fet 40A (36-52V, IRFB3077)
- Wheel Type 20" Alex DM24 CNC
50V 18.5Ah Samsung Triangle Pack (17.5Ah & 25Ah Option)
Aluminium Case Charger 58.8V 5A,14S Li Ion/NCM (with Switch)
7sp DNP 11T Freewheel
Grin Tech Rev4 Rear Torque Arm
EB3 Program Cable

I'm hoping for a zippy commuter. Something quick and agile for dicing it up on the streets, with a top speed in the 30mph range. So far with just the bike I'm half way there. It fits like a full size flat-bar hybrid, but rolls like a BMX race bike. I know it's an unusual choice, but I really didn't want a big heavy MTB and there are very few choices for street/urban style bikes with 26" wheels. I could have built one from scratch, but I'm saving that for my next project (something Wesnewell would like with an ebay kit and lipo).

It's funny, I think of this build as the ebike equivalent of a Honda Civic Si. My next one would equate to a Camaro Z28 and maybe someday I'll be able to afford a BMW M3.

Now the wait begins for the kit to arrive. Come on Cellman!