First Build Thread: Cannondale Prophet Commuter

[GMUseless]

So here’s a thread documenting my first build. Hopefully (and that’s a kind a request) others will chime in and answer any of the various questions that arise.

When starting down the eBike path, reading member’s build threads provided a huge amount of insight and helped me get a grasp on the various fundamentals and aspects of DIY construction of my first eRide. Hopefully this will help others in that same situation.

To summarize:

Riding Goal: 37 mile round trip commute
Bike: 2007 Cannondale Prophet, Full Suspension mono pivot, single post Lefty fork.
Motor: Rear hub, geared motor, eZee kit from Justin at http://www.eBikes.ca
Controller: eZee Kit 20 amp
Battery: DIY 12S LiPo pack built from Turnigy 6S, 3000mah packs from Hobby King.


The starting point:




I’ll elaborate on these decisions in subsequent posts, as well as document the build, and hopefully get help with any issues that come up.

 

[GMUseless]

A little background:

I’ve ridden mountain bikes for 20 years, work professionally as an automation and controls engineer, and have been building analog synthesizers for some time. So eBikes are like a Holy Grail of hobbies for me… bikes, electronics, controls, and a bit of DIY punk attitude.

After renting a Craponix pedal assist bike one weekend in Chicago, I figured there must be somebody building real eBikes with a useful amount of power. I first became aware of eBikes and Bionsux hubs in a one page write-up in Outside magazine. And since Outside is generally pretty reliable, I thought I’d check them out.

And what an underwhelming let down…not to mention the substantial weight and price tag. They were more like “pedal encouraging” than “pedal assist.” They’re even rated in percentage of what you put into it. What? “Hey man if you like pedal 10 turns, I’ll kick in like two. Now buy me for a buck and five large.”

I later discovered this lack of fun was partially due to an attempt for legal compliance. But coming from someone who once won a blue ribbon in a southeastern regional moonshine competition, I found such legal considerations more suggestive than imperative.

After some googling, I quickly found eBikes.ca and ES, and soon resolved to build one. My goal: commute by bike to work. But this is an 18 mile one way run along the Mobile Bay Causeway, then over a 7,000 ft long bridge spanning the Mobile river, through downtown proper, then on to a small office outside of an industrial coal terminal. [ read that as dumpville ]

I knew this was out of the question for your typical bike commute. So it remained a back shelf dream for many years. But, it became obvious it was well within the reach of a properly built eBike.

As I first started reading through the ES threads a few months ago, I was working out in the gas fields in western Colorado. I was making a 3 hour round trip drive to the well heads every day. So when loading up the iPhone with podcasts…I found Troy Rank’s eBike Nerdcast. Sweet sweet eBike nerd goodness. It was almost eBike Porn!

I ate that shit up! I listened to every episode multiple times. That served as a good primer, and instilled some faux celebrity status I could assign to some of the ES regulars.

So I got introduced to some of the ES core via these interviews…which was kind of weird. I’ve got to admit I had to recalibrate a bit after listening to Luke’s interview…and thinking from his voice he must look a bit like a McLovin type...but then watching this total badass doing 130mph on an ICE rocket and being lit up with a flame thrower…that was a dude that I expected to talk like that mean prison guy from Scared Straight: “What you think you got LiPo all figured out! You don’t know sh*t! Give me you godd*mn shoes!”

At any rate, after digging into ES, I was continually amazed. Following good threadicate of searching the forum prior to posting noob questsions; every question I had, I could find the answer inside the threads. It forced me into Lurker mode since for every question I had, ES had every answer.

So while I’ll doubt I’ll contribute anything new here…hopefully it’ll be in package someone might find usefull.

 

[GMUseless]

Why Justin and eBikes.ca are the best. Period:



Even before Justin became our ES saviour, I had found eBikes.ca and asked some questions regarding my commute intentions and the best bet for a first build. Justin took the time to write some lengthy responses…explain the advantages and disadvantages of what he could offer to my particular situation.

I needed a substantial 40 mile range along a coast line with potentially high head winds…often in both directions as the winds change later in the day.

I needed good water proofing as Mobile is one the rainiest cities in the U.S with almost 70 inches per year..mostly during the summer. And I’m not talking about some pansy ass northwestern drizzle. We call that humidity here. I’m talking some 5 inch per hour big fat Forest Gump type of rain.

I also wanted the ability to pedal some. Mostly because like all noobs I’m still under the impression that an eBike will still afford me some exercise…and hopefully help me defend against my slow progression towards living up to the cliché: American Fat Ass.

Justin suggested a geared hub would fit better with the lightweight Cannondale I intended to fit it to. I told him I thought I wanted a 9c. He explained the advantages and disadvantages of both. And highlighted the quality differences. I took his recommendation.

And here’s the killer thing. After playing with simulator at eBikes.ca, and after reading John in CR’s take on motor windings…I asked for the lower winding motor to be laced into a 26” wheel. No problem. Justin replies their wheel tech can do it for an extra $70. A custom built wheel for $70. Awesome.

So this week the shipment from Justin arrives. I’ll document that later. But today, I get a Paypal email documenting a $70 refund from Grin Technologies. Later Adam (from Grin/eBikes) sends an email explaining they found wheels they’d ordered factory laced with the low winding motor in the 26” wheel…so they didn’t need to do the extra labor in house. So they refunded my money.

Are you kidding me? Who else would do that? Talk about ethics. Any box shuffler profiteer (as LFP calls ‘em) would have pocketed that as the price of doing business. “That’s for all my cardboard paper cuts you web shoppin’ suckers!” I would have never known. And issuing a Paypal refund takes a little effort.

Good God folks. That dude is 100%. As good as they come. In a nutshell, the only way I’ll buy an eBike something from anyone else is if Justin doesn’t sell it. I wish he sold LiPo…and Meanwells…and 4mm bullets….and RC chargers….and……

Justin Fanboys:= Justin Fanboys +1;

 

[Pure]

That's a long distance to travel. You didn't mention (or I missed it) how many Ah your pack is going to be. But I can tell you are going to need a good sized pack for that kind of mileage.

 

[AussieJester]

Best of luck with your first e-bike, welcome to ES

KiM

EDiT: Just noticed haha the bike has a single sided front shock! second one posted on ES today albeit
the first was 'home made' Does that use a 'standard' 20mm axled hub? how is the axle/hub actually
held to the fork, i have never seen such a fork before :-| I wish to build a 4 cross replica and need to
mount hubs from one side only, so am interested in the options outside the frightfully expensive wheelchair hubs that the original 4 cross downhill 4 wheelers use

 

[dogman dan]

Always something different on the Cannondales, but the leftys are really wierd.

Couldn't agree more about Grin.

Re the mileage of the commute, can't you charge at work somehow? 18-20 miles, including a nice reserve for the windy days should be no sweat for 48v 20 ah, or any other combination that has similar WH. I don't recall what the voltage of the ezee is at the moment. Assuming you are traveling 25 mph, 1200 wh should do it, plus a reserve. Going slower increases range even more, but I doubt you want to take too much more than an hour to do the ride.

Even if you were to carry 30 pounds of pingbattery or equivilant, It won't be that bad if you can carry at least some of it up front on the frame. But a smaller battery is all you need if you can charge at work.

I do 15 miles one way, and it's no problem for a 48v 15 ah, or 36v 20 ah battery. Even on the days I climb the 1000 ft vertical to home into wind. 18 miles would still be easily in range for my battery, but I would have to slow down just a little bit on the worst headwind uphill days.

Re reading, I see you plan on lipo. Maybe that's why you don't want to charge at work. Seriously, for a longer distance daily commute, it's pretty hard to beat the ping. Perhaps you could even combine the two? If you carried a 48v 15 ah ping and recharged it, you'd only need about 6-9 ah of the 12s lipo as a reserve tank. Though handling won't be ideal, you can carry a 15 pound ping on a rear rack with a rear motor. The tiny lipo pack could then just carry on the handle bars or the frame. On the nice days, you'd make it on just the 48v 15 ah ping, though it would get close to 100% discharged.

Lipo is smaller and lighter than ping lifepo4, but twice as much lipo is not smaller and lighter.

 

[GMUseless]

Thanks for the insight Dogman.

So more info on the battery: I do plan on charging at work. So the real world number is just under 19 miles one way. I was planning on running 12S of 3000mah packs at 7P…so around 21aH. I ordered 16 packs from Hobby King...allowing for 2 spares / bad packs. The eZee hub runs at 48v, so that was the target pack voltage.

I originally intended on getting a battery with LiFePo4 packs. In fact, I started off thinking I’d get a Ping. The Plug-n-Play features of the Ping are ideal for commuters. But there were a few things that bothered me with the Ping. I didn’t like not being able to service the pack without chopping it up. And I didn’t like the stories I‘d heard about the BMS failures and charger problems (even though granted most of those were previous gens.) And, I didn’t like the low C rating. So, I figured I’d be better off with a self-built pack.

So, I started pricing LiFePo4 packs to build one. But when comparing theses LiFePo4 to LiPo I soon realized these Lifer things were expensive fat pigs. I built a spreadsheet comparing the packs with a 48V, 20ah target.

[EDIT: updated spreadsheet.]





So the LiPo’s are not only lighter per watt hour, but also cheaper per watt hour. So I did some more research, calmed my fears over LiPo safety, and made the decision.
I went with the Turnigy 3000mah 6S packs…because I could arrange them to get my target voltage of 48v. Even though the 5s 5000mah packs were a better value, I couldn’t get my taget voltage out of them.

 

[GMUseless]

Thanks Kim.

The fork is a Cannondale Lefty. It indeed looks a bit weird. The intent is mainly performance with weight savings. You get 5.5” of travel with half the weight of normal fork. BUT, you do sacrifice some stability.

The Lefty does flex a bit. Not much more that standard forks but it’s still there. While riding, I can weight it and torque it to the side…like trying to drag the wheel sideways…and I’ll hear the front disc rub the pads. Granted you can do that even with a double crown fork…but it takes much less force with the Lefty.

I’ve never had any problems with it…but it’s intent is for cross-country. Freeride is a stretch. True downhill a no go. I’ve taken it off some 6 foot drops, which it will handle…but you’ve got to land it with a good solid attitude and good balance.

I road some real downhill trails at Keystone in Colorado last week…on a real downhill bike. Drops with off camber landings..sloppy entrances / exits on high speed berms. I’d never attempt to do that with a Lefty.

As far as the Hub, it’s not standard…they’re made specifically for the Lefty shock. Mine is a Mavic…but I think Shimano made some as well. Also, there are some third party hubs that are made for the Lefty:

http://www.woodmancomponents.com

This shows the break away:


The owner’s manual for my model can be found here:

http://cdn.cannondale.com/Manuals/2007_lefty_max_owners_manual_supplement_en.pdf

If you want some real photos, I can post some for you.

 

[Pure]

21Ah will be plenty of battery for your needs. That's a pretty good spreadsheet..any chance you could add these to it? http://www.evassemble.com/index.php?main_page=product_info&cPath=2&products_id=18 Hell go nuts with the cells listed on their site.

 

[jimw1960]

Does your work have a safe place for charging lipo, or maybe they don't mind the occasional lipo fire.

 

[dogman dan]

20 ah of 12 s should be quite sufficient. 17 ah might even be enough, if you are willing to slow down some on the days with really bad headwind. Most days, I bet you end up using about 14 ah. 19 mile is not so far untill you start wanting 19 miles at 40 mph. At 25 mph or so, peice of cake. Being able to charge at work is cruicial. 40 mile range, while possible, is just a pain to carry compared to 20 mile range.

Re ping, you don't need the c rate with that particular kit. Once you buy enough range, you have plenty of c rate. You won't be that likely to have a problem. But if you do, yes indeed, chopping up the pack is a pain compared to a pack repair for lipo. With lipo, just toss a few bad packs and slot in new ones. So easy.

I just keep recomending ping for commuter bikes less than 30 amps because it does work real well, and charging is hassle free. In my 4th summer of ping commuting, I don't see the downsides. I only see it worked great for me. I love lipo, don't get me wrong. I just use the lipo on faster ebikes that don't commute.

Re the target voltage, 12s is a great voltage, and possibly the perfect commuter voltage. But it's not 48v. It's about halfway between 36v and 48v. 15s is awkward, since many 48v controllers come with 63v caps, and it charges to about 63v. Some just go for it, but IMO cutting it that fine is great on your fun bike, but a commuter should have a bit of wiggle room eh? Ping 48v charges to 60v, and once you rid the surface charge is 56v, so that's a bit more breathing space than 15s lipo for sure. 14s lipo, is ideal 48v. But that's more awkward to charge unless you are bulk charging, and just set your power supply to 58-59v. Not so awkward if you use multiple RC chargers either.

12s though, remains simple to wire and rewire to charge if you do that. So I can see why you chose it. Speed wise, it's just about right too for commuting. It tends to hit the sweet spot between reasonably fast and reasonably efficient.

 

[GMUseless]

Thanks Dogman. Yeah, I realize the 12s is really below 48 volt...I just didn't want to go over the spec limits of the eZee motor. And I couldn't find a 7s sub pack that would work for me.
One of the other reasons for choosing LiPo over the Ping, was I wanted the option of re-purposing the pack into another build. I think you're right, 1C is probably fine for my commute with a 20ah pack. (But I still think there's a fundamental problem with using C rating as a battery load metric...since it relies on average discharge over time...rather than peak discharge points. Certainly a one hour ride at a steady 20 amps has a different effect on the battery than say a 58 minute ride at 18 amps followed by 2 minutes at 75 amps. Both still add up to 20 ah over an hour, i.e.1C. but the later has to be harder on the chemistry.)

One of my goals was to be able to build a LiPo pack that didn't require constant rewiring. I got the Hyperion 14S charger...so I don't plan on rewiring to charge the battery pack. I'll charge it at 12s. My bench supply at work is 24v, 800 watt...so I'll use that. At home, I've got some smaller 10a 24v supplies. I'll either parallel those, or just buy a larger supply. I've got some massive dirty DIY supplies I built for a CNC machine that are really just a transformer, full wave recitifier, and single smoothing capacitor...but I haven't yet been able to determine the implications of using that type of pulsing DC on LiPo. Any suggestions on that?

As far as the LiPo fires...I still think those are rather unlikely. Obey Luke's Golden Rules for LiPo. Never over charge, never overdisharge. I'll use the CellLogs, the Cycle Analyst, and the Hyperion to help with that. Regardless, I've got a reasonably safe place for charging right next to my desk...with fume vent just in case.

 

[GMUseless]

That's a pretty good spreadsheet..any chance you could add these to it? http://www.evassemble.com/index.php?main_page=product_info&cPath=2&products_id=18

Thanks. I updated it with your request. It wouldn't let me post the .xlsx file. The Headways came out to $.47/watt-hour and .022 lb / watt-hour.

 

[dogman dan]

I dig it why you chose lipo. Sounds like the charge it at work thing is no problem for you, since you seem to have good power supplies to run a charger there. Other kinds of work, you'd have to leave em charging unattended causing a small risk. That's the usual issue, you are charging lipo while in another place too far away to keep an eye on it. With lifepo4, you might have a charger blow and stink up the place, but actual pack fires while charging a never abused ping are super rare.

With the Ezee controller, 12s sounds perfect. That kit is ideal for the wet you will be riding in. But it's controller is never goin gto pull enough amps to bother a 20 ah ping. It won't even hit the 40 amps a 20 amp ping can easily supply for a short time. But that's not anything to argue about. A ping that lasts you 3-5 years or more is not what you want later, when you do make a bike to do fun things off road, and need 100 amps capability.

 

[Ykick]

You'll get bit by the bug and for this length and frequency of commute I see a 2nd eBike in your future. It's good to have a spare for when throttles break, tires go flat, spokes break, etc. One battery can serve many platforms and with Lipo it's easy enough to split up and share the joy of eBike recreation with friends and family.

Plus, a 2nd eBike allows you more license to experiment and apply lessons learned from the 1st attempt. 'looks like you got a great mind and situation for Lipo, enjoy the ride!

 

[gtadmin]

...
Justin Fanboys:= Justin Fanboys +1;

Nope: ++Justin Fanboys;

 

[BikeFanatic]

Great spreadsheet. I think it could help a lot of noobs decide which type of battery to buy. Maybe you could post a new thread in battery section and call it lipo and lifepo4 - compare price and weight. ?

Justmy 2 cents, Lipo does not come with a charger, Ping does, so the price is actually closer once you add the charger.
Good luck with your build!

 

[GMUseless]

...
Justin Fanboys:= Justin Fanboys +1;

Nope: ++Justin Fanboys;

Justin.Fanboys++; //I'm more of a C# guy...

 

[gtadmin]

...
Justin.Fanboys++; //I'm more of a C# guy...

In that case, it's justinFanboys++; //camelCase of course

 

[Pure]

That's a pretty good spreadsheet..any chance you could add these to it? http://www.evassemble.com/index.php?main_page=product_info&cPath=2&products_id=18

Thanks. I updated it with your request. It wouldn't let me post the .xlsx file. The Headways came out to $.47/watt-hour and .022 lb / watt-hour.

Those are def some interesting numbers. I've done the math and knew those cells from EV assemble are very economical choice, it's just nice to see it in actual comparison with other options like that. Wile I wouldn't trust buying whole packs or or BMS's from EVA I would have no issues in ordering cells from them. That is at least until we hear back from Neptronix on if they have upped their game on the quality control dept after he gets done reviewing their pack they sent him.

 

[gtadmin]

My opinion on a first build commuter, where it just has to work day in, day out, is to use a hubbie. Ultra reliable! And have a RC motored bike for fun, where it doesn't matter if you break something. My 2¢ FWIW

 

[GMUseless]

That was my train of thought as well. The commuter build has a pretty low 'wow' factor. I was tempted to build something with a direct drive hub motor...with the possibility to run high voltages through it...but I quickly figured out that is "2cnd bike" territory where efficiency has to be low on the priority list.

Plus, I didn't think the Prophet was the right platform for a higher-speed build. At it's most aggresive geometery, the head angle is 67.5°, and the Lefty doesn't exactly scream stability. I'm allready on the lookout for a Kona Stinky frame circa 2000-2004 for that second build.

 

[GMUseless]

eZee Kit from Grin Tech:


I recently received my shipment from Justin. Everything was well packed, without the apparent common issue of the hub / axle poking through a cheap box.




So here’s what I got:

eZee hub (20-inch motor laced into a 26" wheel), with Schwalbe Marathon tire, and Weinmann X-Plorer wheel laced up with 13g Sapim spokes:



eZee 20 amp mostly-waterproof controller:
View attachment 7

Large Screen direct plug-in Cycle Analyst with Speed sensor:


eBrake:


Rear annoying red light:


Throttle, with matching grip:
View attachment 3

7 gear cassette and freewheel:


Shimano 160mm rotor:


And this thing…not sure what it is for…any ideas?:

 

[ambroseliao]

And this thing…not sure what it is for…any ideas?:

It looks to me to be a cable keeper. You bundle up the extra cables during your setting up of your bike and then pull off the red sticky tape to stick it to your bike. Just a guess...

Ambrose

 

[GMUseless]

And this thing…not sure what it is for…any ideas?:

It looks to me to be a cable keeper. You bundle up the extra cables during your setting up of your bike and then pull off the red sticky tape to stick it to your bike. Just a guess...

Ambrose

Off course...That explains the cable holes on either end. Kind of small though. I'm used to wiring up panels where we'll loop 10 meters of cable slack around the panduit like a weaving loom. I'll only be able to shove a few inches of wire in this little thing. I guess I'll have to measure twice...