Sanity check for my build?

[spisska]

Hi all. I really appreciate this group, and after a couple weeks of research, I'm getting close to taking the plunge.

I want to run a build by you in the hope that someone can tell me I'm about to make a horrible, horrible mistake.

I live in Chicago -- there are few hills, but plenty of weather. With that understanding, here are the goals of the project:

• * >=20m round-trip, motor only, 12-15m into a headwind.
  
  * 17-20 mph cruising speed, 25mph boost (assuming no wind).
  
  * Cargo capacity -- (I weigh about 180) front, rear racks, panniers, possible trailer mount. Decent range under load at ~10-15 mph.
  
  * Capable of moderate weather -- no downpours or blizzards, but I do not want to be afraid of light rain.
  
  * Stealthy -- battery pack and controller in removable triangle pack.
  
  * Nice looking, but not flash.
  
  * Total budget, ~$2,000 US.

So here's the build:

Bike: Beach-cruiser style, 7sp, steel frame, 26" wheels. I do plan to use the pedals, hence the 7sp.

Front fork: Springer fork with add-on disc-brake mount.

Drivetrain: This kit from em3ev

• * 12 FET, 40A controller
  * 12T or 10T winding (?)
  * Rear mount
  * 26" DM24 Disc (is this too wide for disc brake, freewheel, frame?)

Battery: Em3ev's 50V, 18.5 AH Samsung Li Ion triangle pack.

Replacement front wheel with disc: Not sure yet, but figuring something like this.

Add in the rest of the brake system, and that's about $1,800, not counting shipping.

Also, a sweet saddle, 'cause everyone needs a little bit of pimp.

So. How close do you reckon this will get to accomplishing the goals at the top?

I'm assuming that adding a bunch of weight and cargo, and running at 15+ mph is going to render the stock brakes dangerous, and that disc-brakes are going to be a lot safer. Is that a correct assumption?

Connectors: the goal is to be able to lock the bike, unplug two connectors (one to the motor, the other to the handlebars), stash them in a tiny triangle bag, and take the triangle pack with the controller and battery with me. So what are the connectors like, and does anyone sell a big-old plug that they can mount on?

Is there anything I can do to weather-proof the system, particularly the triangle bag? Not to ask a silly question, but what happens when I'm on a steel frame and something causes a high-discharge battery to short right underneath me? I'm not going to like the answer to that question, am I? Do I need to be worried about it?

Lighting system: I'm eventually going to want two front and two rear lights. Is it recommended to use a DC-DC converter and run off the main battery, or rig up a secondary battery system? It makes a lot of sense to me to use a much lighter battery to drive the lights, but I may be overthinking things.

So with all that info, am I onto something here, and will all the kids be jealous of my kick-ass ride? Or am I setting myself up for months of misery, electrical shocks, and an exploding bicycle?

Thanks for your input, and I'm happy to answer any questions.

 

[Drunkskunk]

Looks good in general.

The 10T is the better choice. you might also prefer the 500 watt ditect drive. it's bigger but much quieter, and with only 1 moving part, its more robust.

You don't need disk brakes at the speeds you are going to run. But if you want them, get them. the DX32 rim will work well with some fatty tires on that style bike, and give a comfortable ride.

That fork is a problem. brakes on the schwinn style bow armed springer are for cosmetics only. above 10mph, the whole front end tries to jack up when you hit the brakes. It makes modulation almost impossable and can cause a skid and crash. What you need is a monarch style springer. They have disk kits for those as well, and they work.

That custom wheel is going to look Derp with the rest of the bike. Radial lacing is a bad idea with disk brakes, and having that many spokes is going to lik strange compared to the rear wheel's 36. people will quickly spot the strangeness of the rear wheel with mismatched rims. Try having one built up with another DX32 36 spoke rim on a hub of your choice. It will cost a bit more but look better. Also, the tire profile will match the rear for balanced handling at speed.

That battery should be overkill, which is good. Generaly we recomend batterys sized at 36 watts per mile at 20mph, that gives you a reserve to handle headwinds, hills, and overweight conditions that come up without killing your battery. Your choice on battery exceeds that by a lot, so you shouldn't have any trouble.

Run a DC/DC converter for the lights. You have the extra capacity for it.

Get a Cycle Analyst. http://em3ev.com/store/index.php?route=product/product&path=41&product_id=103 You will never understand how you survived without one after using it. But especialy if you plan to run a MAC motor with that 40A controller. the controller has the ability to melt the motor, and you need the Cycle Analyst to limit the controller to around 30 amps. No worries if you get the direct drive motor, they can handle the higher power, and even more if you learn to modify them.

 

[spisska]

Thanks for advice.

The 10T is the better choice. you might also prefer the 500 watt ditect drive. it's bigger but much quieter, and with only 1 moving part, its more robust.

I'm still tilting between the DD and the geared hubs. From a purely engineering perspective, I prefer the DD -- simpler is almost always better. From a stealth perspective, I prefer the smaller size of the geared hub.

That fork is a problem. brakes on the schwinn style bow armed springer are for cosmetics only. above 10mph, the whole front end tries to jack up when you hit the brakes. It makes modulation almost impossable and can cause a skid and crash.

This is extremely helpful, and exactly the sort of info I was looking for. Thank you.

That custom wheel is going to look Derp with the rest of the bike.

Yeah, I know. This is much more the ticket, but it's left-side disc only, and this vendor only has a right-side front mounting bracket for the caliper. But you're right. This is not the wheel I'm looking for.

I'm thinking of a worst-case scenario where I'm loaded down and pulling a trailer, so about 100+ pounds extra, going 15 mph, have wet rims, and need to make a sudden stop. I just don't know that I trust beach brakes in that situation.

Get a Cycle Analyst.

.

Yes, this is already in the budget. Should have mentioned it above.

Thanks again for the reply. You've been very helpful.

 

[dogman dan]

10t for sure, unless you are fine with about a 20 mph max speed even when unloaded. The 12t will pull the trailer nicer, but really, are you going to load up like that every day? I doubt it. The 10 t will be fine for 50 pounds on panniers, plus the battery in the bag.

Because you live in a place more cold than hot, because the hills won't be extreme, I'd say the 10t should work fine for you running on 48v.

You don't need a 40 amps controller whalloping your battery. 30 is plenty. even 20 would be quite sufficient. But if you get a CA, you can limit the amps. I don't see the point, don't get the 40 amps.

The bike. The brakes are fine. Even towing, you will be fine. If it's wet, plan ahead, and kiss the brakes when approaching a stop sign. If it's wet, don't haul ass and get surprised. Even wet, rim brakes still work. In ice or slush though, that can be different.

No springer fork. Find out if the headset is 1 1/8. If so, find a good tunable shock fork with 100mm of travel or less. Back off the preload to make it ride more like half compressed when you are loaded down. 50mm will be enough for funky road surfaces, but not jack up the frame and make it ride too funny. That fork will of course, have a disk brake mount. Front disk and you are good to go with braking.

The battery bag from EM3ev is very weather resistant. It's really a nice bag. At most, if you must ride in a real downpour, tape a trash bag across the frame top to shed water off the zipper.

Leave the controller on the bike. You will have a pannier rack anyway, so mount the controller on the top of that right under the seat. All the plugs, wrap them up in some kind of boot. Low tech a baggie, high tech a small box with grommets. The controller itself can be sealed up, and a small sheet metal shield easily fabricated to shed heavy rain off it, yet allow free air flow. YOU DON'T SMOTHER THE CONTROLLER IN THE BAG.

You can unplug the motor if you wish, but taking a section of wire leading from the battery box to the controller will make it impossible to run the bike when you wish to leave the battery for a short stop.

 

[dogman dan]

And now to throw a real monkey wrench in your plan.

You want weatherproof? See this.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=53528

Faster than you want, and his slower trike kit is a bit different. But it sure passed the weather test.

 

[spisska]

Thanks for the info, this is very helpful.

The springer fork is out, and I'm thinking a monarch-type fork instead.

Based on what I'm hearing here, I think I'll still go with a disc in front, but maybe leave the rim brakes in the back. If nothing else, that'll save me about $100.

Is there any specific disadvantage to a 40A controller held back a bit vs a 30A controller pushed hard? I was thinking the cost both in money and weight is not that much for the stronger controller, and there might be some particularly cold days where the extra current and capacity come in very handy.

As far as mounting the controller permanently to the frame, this was definitely my original idea. In fact, I was thinking the 'gas-tank' gap on this frame would make an ideal mount point that also leaves room to hide the electronics. Of course it's very hard to visualize with only pictures and a tape-measure. On (or under) the rear rack is also an obvious mount point.

Thanks again for the help.