New E-Bike Builder in need of Advice

[Magnus579]

This will be my first motorized bicycle build. I am interested in a daily commuter bike to take me to and from work (6 miles). Most of the ride is flat with one hill (about 1000ft at 8-10% grade if I had to guess).

I would like some guidance on my bike choice. I need something fairly cheap to enter the hobby so I'm looking at a Schwinn Network 7 Hybrid (all steel frame with front suspension forks). I am going with the 7 speed thinking that the ebikekit direct drive rear hub setup with the 7 speed freewheel will still work with the stock de-railers. Is that a correct assumption?

I'm also concerned about the fit of the rear hub kit. This is a 700c hybrid that uses thinner tires than a MTB but larger tires than a road bike. I believe they are 700c x 38 but will need to confirm that. I can't find dimensions on the ebikekit (with the 7 speed freewheel) or dimensions on the bike itself (going to call around and try and get those). Does anyone know what I should be concerned with in fitting the rear hub motor on this bike?

I am going to go with a ping LiFePO4 Battery Pack and was leaning towards the 36V 15AH V2.5 LiFePO4 Battery Pack (mainly due to price). One item of note is that it states "up to 600 Watt, 450 Watt suggested" where the where the ebikekit states "1 x Hand-Built Wheel w/ 500w(nominal)-750w(peak at 36v) Brushless Hub Motor." With the ping batteries you can't get up to the 700w range without going to 20AH...will that be a problem if I go with the 15AH? Also, will the 15AH have enough juice to make it the 6 miles (one-way) of my trip to work?

I'm thinking I can pull this off at around the 1k mark for my first bike.
Thanks a head of time for your help.

 

[LI-ghtcycle]

Welcome!

A few items needed to answer your question exactly, however, given the short distance of your commute, I would say "yes", your proposed plan should work well.

However, this is a qualified "yes" with out knowing the total bike & rider weight, how fast you want to go, and how long you want a battery to last. Generally, I think most people here are of the opinion that 36V while not bad, 48V is MUCH better, meaning, over the years you use said battery, it will show some "wear" meaning over the years your battery will have less capacity, so I would say get more battery that you think you need so that you will have a good experience, longevity, since a battery that isn't pushed hard lasts longer and gives better performance.

Also, it really depends on the motor you choose. If you were using a 26" wheel, it would be really easy, I'd definitely recommend a 9 X 7 DD hub motor (there are different windings of the motor you speak of that is commonly referred to as a "9C" motor) unless the 700 x 38c wheel is going to increase your top speed enough to make the hill climb a chore. I doubt it would, and the nice thing with that winding is that you can adjust your speed with higher voltage for top end, while still retaining good hill climbing torque. (at least in a 26" wheel)

If you still go with 36V, I think most would recommend the 20AH ping for longevity, but IIRC the 48V 15AH is the same price, and for the average rider, this would mean a good healthy top speed (25+ on the flat and 12 MPH on a 10% with no pedaling for long hills at least with a 26" wheel)

Hope this helps! There is also a calculator on Ebikes.ca that will help you decide what motor might be best, I'm sure the folks there or Ebikekit can suggest a good combination for you.

 

[jondoh]

Just to clarify, you're talking a horizontal distance of 1000 ft (a little less than a quarter mile) and NOT a vertical climb of 1000 ft with a 8% ~ 10% grade-- which is still pretty significant.

I'm thinking that if you're climbing daily like that, a smaller wheel would be better as the torque is better. My giant revive conversion has a phoenix racer on the back wheel and that bike climbs very very well as it has 20" wheels. Smaller wheels have higher torque just due to the mechanical leverage which should mean less amps and less stress on your battery. Ping is a good battery but it may get strained (even with a 15 amp hour) if it's pushing a big wheel big bike heavy rider up a 10% grade every day.

If your heart is set on a 700c wheeled bike (I've electrified an Origin 8 cutler 7 and it's soooo smooth-- so i understand the appeal of big wheels), get a cycle analyst or a watt meter of some kind. I've had decent luck with the turnigy watt meter from hobby king and if you can wire it so that it's in front of you (this meter needs to be wired inline between the battery and controller) it tells you everything you need to know to protect your batteries going up a hill. What you might find out is that you will have to pedal a fair bit to keep your Ping batteries happy when going up this grade. For example, i've learned that a 12 mosfet controller rated at 500 watts driving a geared hub motor also rated at 500 watts can draw 30 amps. I would hesitate to draw this current from a ping for longer than 5 or 10 seconds at a time for fear of shortening the life of the battery. A continuous draw closer to 20 amps is better for ping.

My only deal with a rear hub motor is that you don't always have space for all 7 gears. 6 gears is better and 5 should work on just about any bike. It's mostly a matter of how much space you have in the rear. Not all bikes are the same. Sometimes there is space for the gears but somehow the bike isn't able to use all of them after the conversion. This can happen sometimes.

If you live around Silicon Valley, I can help you get started.

 

[John in CR]

Welcome to ES, and all good questions, so you're thinking things through properly. Yes, the gear spacing can be different, so you want to match the gear stacks to avoid installation headaches. Also, a steel frame can easily be stretched to fit the motor width.

We should get things defined a little tighter to be sure you're happy with the result.

Hub motor geared or direct drive? If direct drive, find out what motor wind they are putting in the 700c.
Lots of stops and starts or few?
Charge at work?
Total load?
How much assist will you add with the pedals?
Speed you desire?
Do you see yourself wanting more performance after proving how well this ebike thing really works, or are you a past cyclist who knows you'll be perfectly content with normal bike speeds even in the future?

Then there's the hill, which is everything, especially it's 1000ft high. Elevation change? Actual grade? Is there an easy way around, and if so how much longer is it? Is it up and down, so you have to cross the hill each way? Even if it is only 80ft high and less than 1/4 mile long, there's a huge difference between wanting to ride up it with little to no pedal assist or being willing to stand on the pedals, because the bike can slow tremendously and put the motor in a much less efficient range of operation that will also draw a lot more current from the battery.

 

[dogman dan]

You will find that if you build it to the stuff you spec in the first post it will work fine. You should have no serious issues fitting the hub to the bike, other than perhaps bending the frame a few mm, and readjusting the brake pads. Once you get into disk brakes and 9 speed clusters, then it gets a bit trickier,.

36v 15 ah will do just fine with the stock controllers that come in the 9 continent kits. If you should upgrade to a 35 amp controller to get up the hill better, then get a 36v 20 ah battery.

Range should be at least 15 miles including the hill, at full throttle. So no problems there, you can charge just at home, and still have several miles range for the scenic route.

48v will climb the hill better. I recomend it if you have 1000 feet of vertical to climb daily. I do that kind of climb daily on a 26" wheel. 36v works just fine, but 48 v gets me up the 1000 feet of vertical at a faster speed. Both can do it no pedaling if I'm tired that night.

The wheel size will make getting up hills at 36v more difficult for the motor, so you will ascend without pedaling a bit slower. Nothing that brisk pedaling for a small part of the ride won't cure.

Your proposed route would be perfect for any of the gearmotors too. Riding just 12 miles a day won't put any wear on em.

 

[Ykick]

I haven't touched my de-railers (shifters) in over a year. Using the motor I always leave it in highest gear. Gearing can be a life saver if/when you run out of battery or experience motor/controller failure but I just never use the bike gearing anymore. It's often a PITA to fit a throttle where shifters live on the handlebars.

Oh, don't forget good mirrors! I'm fond of Mirrcycle - 'pair of 'em may look un-cool but it's best to keep tabs on all the distracted drivers hurtling around in much heavier machinery.

These kind ES folks have brought up most relevant hardware considerations so what remains is probably more of a mental aspect. Are you experienced riding bikes/motorcycles in traffic? Will you be riding at night? Carrying cargo? Cold, warm, wet, hot? What's your road shoulder or bike lane/path situation like? Local laws regarding eBikes?

These are important considerations before building a totally capable eBike but finding out that it's somewhat more harrowing to actually ride on your intended route.

IMO don't put all your eggs in one basket - most of us build more than one bike anyway. There's always something about one design that might appeal to you for certain situations and/or application? And having a spare is always a good thing - flat tires, etc.

Cool thing is that 1qty battery can power other bikes in your stable and you can always find free/cheap local candidates for conversion. Basically, a 2nd eBike doesn't have to cost much more than 2nd motor kit but gives you the ability to taste-test differences in frames, wheels, brakes, gearing, seating and possibly suspension variations. Find the style that best suits your needs...

 

[Drunkskunk]

Welcome to the Sphere.

What you proposed will work fine.
Ping battery's ratings are for the motor's constant load. The 9C is a 500 watt motor, so any of those will work. But to climb that hill, you will probably be more happy with 48 volts. a 48v 10Ah would work, a 15Ah would be better as it means less strain on the battery. 36V is fine but its going to struggle more on that hill.

a 7 speed will fit, sort of. Ebikekit.com says no, but only because it won't fit in a stock configuration. It ends up being something like 4mm too wide. But it's easy enough to spread the frame 4mm by hand as you install the motor. And by using the tabbed washer that comes with the motor, installed inside the drop out, instead of onthe outside, you get the correct spacing. I've done that for 2 bikes now. 700c X 38 fit fine on the rims from Ebikekit.com. Its a style rim closer to a 29" or a 700 MTB, a little heavier than a Hybrid, much heavier than a roadbike 700c

 

[FMB42]

Welcome Magnus579.

The previous suggestions and tips should be a "big help" for your first build.

As far as the gears go, I'd go with a 6 spd for sure.

Ebikekit suggested that I use a 6 spd as a replacement for the stock OEM 7 spd and this proved to be very good advice for my first build (it was an "easy" fit). I have since purchased both a 5 and 6 spd freewheel to "have around" for the next 2 builds that I have planned (i.e. a full suspension "cross road" hybrid and a Schwinn based "board track" style bike). I figure that I'll have little or no problem fitting most dropouts by using either the 7, 6, or 5 spd freewheels that I have on hand.

As for the "700" wheels, consider a "torque wind" DD hub as previously mentioned. Otherwise, consider Dogman's advice of using a geared hub motor due to their light weight, free wheeling ability, and good overall torque (especially "off the line"). I myself, would probably go with a geared hub motor in your case...


You may also want to "take a look" at the "ebike.ca" motor calculator:

http://www.ebikes.ca/simulator/

 

[Evoforce]

It seems as though you have been reading up on doing your prospective build. Good job! I vote for the larger amp hour and voltage battery. Once you start enjoying your e-bike, you will be going as many miles as your battery and buttocks will allow. So for me, I also vote for a lawn tractor seat and pulled back ape hangers. I also prefer the big crystalyte motors. The Magic Shine 1400 lumin lights(night riding) and a cycle analyst for your battery. Good luck and happy holidays!

 

[Magnus579]

Thanks for all the responses. After this thread I've decided to go ahead and go for the 48V 15AH V2.5 LiFePO4 Battery Pack. It's about $100 more than I was originally planning to spend (and breaks my 1k limit) but I think it will serve me better in the long run.

I talked to one of the guys at ebikekits and he said my hill should be easy (potentially no pedaling at all based on my weight etc) with the Direct Drive kit and the 48V battery. He also mentioned the top speed would be in the 26mph range with my setup (which is more than I will probably be doing but hey, at least I have the option). I do plan on picking up a computer when ebikekit gets more of the direct connect computers in (they are currently out and said it would be a few weeks)...kind of stuck on them right now because I have a 20% discount (basically makes the computer free based on the amount of my order).

One thing of note, he did echo that I could go for the geared motor as well but that running the geared motor at 48V would void my warranty. I know the geared motor is about 6 lbs lighter and doesn't have the added drag but I'm not concerned with getting the lightest setup (the bike I have planned has a steel frame etc). If I want to workout, I'll drag out the road bike :wink:.

Lastly, the ebikekits call also revealed that the 7 speed should be doable (using the washers and bending the frame out an additional few mms - much like many in this thread have mentioned).

As to some of the questions:

The hill is 1/4 mile long (not 1000ft vertical climb). It is only one way - on my way to work. The return (to get to the top of the hill) is MUCH more gradual and spread over 2 miles. I weigh in at 175lbs but will need to haul a few items (laptop, spare change of cloths etc).

I'll be operating in central texas so my worst time of year will be summer. It only freezes about 3-5 times a year here and even then it doesn't get that cold (high 20s at the worst). Summers can hit 105-108 degrees and we see multiple weeks of triple digits. I'll be traveling in the morning (before it heats up) so the worst ride will be the one going home (where it will be over 100 on some nights). I do need the flexibility to travel at night in case of later work nights so I'll need lights etc.

Are there any recommendations on traveling in wet conditions? I don't mind lugging around rain gear but I'm more interested in the ideal tires etc. I avoid cycling in rainy conditions due to the possible spills from slick roads. We do get a fair amount of rain here so I would like to be able to travel in wet conditions.

My route is city traveling so there will be a few stops and starts (the drive takes me 15 minutes in a car to go the 5.9 miles).

What are recommendations regarding charging the LiFePO4 battery pack? My total commute will be 12 miles (6 miles each way). I can charge at work but I'd rather just charge once a day (overnight in the garage). Does anyone see any issue with a single daily charge given my commute on the Ping 48V 15AH V2.5 LiFePO4 Battery Pack?

Thanks again for everyone's advice.

 

[dogman dan]

Once a day charging will be fine. You'll have at least 20-25 mile range in the battery. Charging daily, you can expect as much as 2-3000 cycles. Your depth of discharge should be around 50-60%

And you'll get up that hill fine with 48v, and a few brisk pedal strokes. 100f weather won't faze the motor. I ride further and climb further all summer in 105f and can't get a 9c motor to melt despite my best efforts to do it deliberately when testing motors for folks.

You will find the 27 mph a bit fast for pedaling along with typical gearing, like 48-14 on an MTB or hybrid. But you can get 11t rear freewheels that pedal a bit faster. Or just back off the throttle and ride a comfy 20 mph. Short ride, slow down and enjoy it.

I can't comment on rain riding, I live near El Paso. Rain? I remember some once. The drought is back on here for sure.