Commuter Build - Advice Needed!

[sparkcrx]

Greetings from Melbourne, Australia!

I have been looking at building a long range commuter e-bike for some months now.
For the most part, I want this bike to replace my car for my 30km/19mile (60km/37.5mile round trip) daily commute.

I am looking for opinions on a suitable configuration for the job.

High on the priority list is: Reliability, efficiency, ease of use, weight

I have been looking to fit-out my 700C Giant CRX-1 with a FWD eZee and 36v 15ah/20ah Ping, but of course after many more hours of reading here, I’m not sure this is the way to go.

For example, the cell-man motor options look good, the 350W MAC or perhaps even the 500W DD. Would a DD be more efficient in terms of wh/mile?
I really like the simplicity of DD motors, but the weight is pretty well doubled and I am concerned about the drag of DD. Is he drag when off the throttle a real issue or not?

I can in-frame mount a 36V, 20AH Ping, which is as big as I would want to go, given that I would have to pull the battery off for charging at the office everyday.

I am looking for recommendations, even “clean-sheet” recommendations to suit the job! FS Mountain bike? BMX? LOL, any configuration you think would fit the bill.

My commute is all sealed-road or bicycle path. I need to be able to ride in all weather.

I also have an old 26” Cro-Mo Shogun Trailbreaker 1 (no suspension) which I could use as a test bed of sorts, if I decided to go the 26” wheel route.

Open to any ideas to achieve this goal!

Many thanks

 

[MadRhino]

Any hills? That makes a big difference.

If you charge at work, Lifepo4 is a good choice. If you have the budget, you can have better than Ping.

I prefer a DD hub, for reliability and regen braking, especially if you have to ride hills everyday.

 

[sparkcrx]

Hey Rhino, thanks for the reply.

Going into work it’s mostly down hill and flat… Some slight inclines, but nothing super serious.

Coming home, it’s mostly flat with probably 2 miles or so of inclines towards the end of the ride. Nothing super steep and there are breaks of flat in between the inclines.

I have been wanting to avoid DD because of the weight and drag when not powered, but is it true that it may be a better option in terms of reliability? How about in wet weather?

If DD ticks these boxes, then I may have to live with the weight and drag penalty in favour of reliable motoring.

Obviously the battery and motor size is going to be key in all of this. Especially if I decide to build a heavy machine that is reliant on electric power.
Perhaps if I was running a 200W mini motor and a small battery(3kg + 4kg’s), I could afford to run out of juice and still pedal reasonably well….
But with 6 or 7kg’s of motor on board, along with 7 – 10kg’s of Ping battery, I’m not sure that pedalling alone would be all that comfortable!!

Would you be looking at A123 batteries?


Cheers

 

[neptronix]

DD and geared both have the same wet weather problems. Water's just gonna get into the axle and maybe even the cover plate..
For water proofing, i like the idea of a hubmotor driving the rear wheel via a chain. Seems elegant, but it requires some welding, cutting of metal, etc etc. Not so easy...

For your use, a small geared motor would work, especially If you are okay with under 20mph.

My first build was with a 3kg 250w motor and 5ah of lipo batteries. If i didn't have hills to contend with, i'da prolly stuck to that design. The bike was way easy to pick up.!

Ah.. but then you get greedy and want more power, so a DD or large geared like the MAC or BMC is good.

 

[adrian_sm]

Hey sparkcrx,

How much do you plan on pedaling? I found that as soon as a had a motor on the bike I use it all the time, and you really don't notice or care about the weight of the bike.... until the battery runs out, or you forget to charge. Then you really feel the weight.

So if you plan to ride the throttle the whole time, just get a robust set-up with enough battery so you don't have to worry about range for your normal commute. Geared hubs are slightly less efficient on the flat, but better on the hills, and roll better. Both will be fine for you, assuming you don't over volt it too much.

I have a direct drive hub bike that weighs about 30kg, and cruises at 50kph. Which is awesome.

I have also been building a very light weight set-up on a road bike with a custom friction drive that is ridiculously light for a ebike, and rides like normal when not using the power. But has a few quirks in operation, like the RC whine noise, and not being able to power from stand still. But apart from that is a get light weight assist. My current setup only adds about 4kg to the bike, can put out ~2000w, with a 400wh battery. It cruises at ~40kph, and I have been averaging about 15wh/km using full throttle assist 90% of the time, this could be much lower if I took it easy. This is a new design, so if you are looking for ultimate reliability I would stick with a proven hub motor.

Anyway, if you want to take one of my bikes for a spin, to get a feel for an ebike drop me a PM as I am in Melbourne (Eastern suburbs) too.

As for water. I have been riding my hubmotor ebike to work every day rain hail or shine for the last 18months in Melbourne, no problem.

Cheers,
Adrian

 

[MadRhino]

Look where I ride mine:

The DD hub never had any problem with water, but the connectors did. It needs good waterproofing on all electrical connectors, every week. This bike is not fun to pedal alone, it weights 85 pounds. But, it flies at 50mph and accelerates faster than any car.

I was not targetting that performance last summer when I started, but it's highly addictive and many of us are after more and better, always making plans to imprrove. A DD hub has the advantage to be upgradable, you just have to feed it more juice, more power; and it's gonna go faster, stronger.

 

[neptronix]

snowy and rainy are two different things entirely..

Dunno where the original poster lives, but many manufacturers say that things are waterproof or whatever... but it never turns out that they are Oregon-proof. Try 5 months of rain..

This is why i park my bike in the winter and spend more time talking about riding than riding

 

[sparkcrx]

Hey Guys,

Thanks for the responses.
Adrian, I’ll PM you tonight.

I can understand why you have both a friction drive and a traditional DD bike.

In my experience (for me anyway), just about all motorised machines need to be made faster and more powerful!
Then, one day, you realise you are living with a range of deficiencies that come with all that power and speed.
So you basically get over it - and decide to become a minimalist.
Then, after a while, “minimalist” is just too gutless, so you decide to build a machine that is somewhere in the middle, only to find it doesn’t exist.

So you end up with two machines…… At least that is my experience with cars and motorcycles!

Climate wise in Melbourne, the absolute lowest we would see in the thick of winter is 1 or 2deg C.
We certainly don’t have constant months of rain – like you do up there in Oregon neptronix! That would tough to deal with.

So it seems like I need to make a decision as to the approach I take: (and I’m keen to make one and get riding)

1. Unconventional / light weight: I’m always up for challenge! - This might include friction drive and Li-po to keep the weight down.
The bike remains reasonably light weight, but in my eyes may not be a reliable everyday bike until the kinks are ironed out.

2. 200W – 350W FWD geared hub motor + in frame 36V battery. Road bike. What is the lightest-duty Ah battery I could use to make the 30km’s plus say 15km in reserve?

3. 350W – 500W RWD geared or DD hub motor + 36V or 48V battery. Is there a “sweet spot” in terms of motor and battery combination in a heavier setup like this that
gives a reasonable top speed and range? That is, be realistic about top speed so that a 20kg battery is not required.

I know there is no definitive answer to these, the variables are too numerous + at a certain point I will simply need to jump in and try it for myself.

MadRhino, that bike looks awesome… Must be a blast to ride. To answer your question, I’m a pretty keen peddler, but I’m out of shape compared to back in the day….

Thanks again for the responses guys, if you get time, maybe you can suggest what in your opinion is a good battery/motor/bike combo for this type of commute!

I’m open to any idea except a recumbent… although…. :wink:

 

[neptronix]

The downside of friction drive is that it eats tires and grip material. Oh yeah, and it sounds like a blender cross-faded with a storm of angry bees on fast forward.. lol. It is quite light though, lightest setup you can get really.

2. 200W – 350W FWD geared hub motor + in frame 36V battery. Road bike. What is the lightest-duty Ah battery I could use to make the 30km’s plus say 15km in reserve?

10-15ah should do that at that low power level, most definitely.
Lipo is good as it keeps the weight down.

 

[MadRhino]

Charging Lipo at work is not practical for most, a simple plug and go setup is better for charging away from home. Lifepo4 is good for that, you can let them charge without supervision. Lipo is the best power density, 10Kg of them makes a big power reserve, but they need some babysitting. I can charge my Lipo at work, but it's not the case for everyone.

A 9C 2807, or the new Chrystalyte HS 35, are lightweight DD hubs that would suit a long commute that is mostly flat. They will give fair speed and range with 36 or 48v battery, 20Ah should be enough for the range that you need. Ping is cheap and would be enough for your need, better Lifepo4 is available if you have the budget.

The same bike can be made for performance or reliable commute, one just need to use different battery setups. Feeding a DD hub at 36v 20A is a reasonable ride that is safe and reliable, at 72v 40A it comes alive, at 100v 100A its a beast that requires mods. Most of us will build many bikes, you can have one to commute, while you develop another one.

 

[adrian_sm]

The downside of friction drive is that it eats tires and grip material.

Actually that is a bit of a myth. I haven't noticed any additional tyre wear on mine. Except when it isn't set-up right. Time will tell, but it definitely isn't ripping up the tyre or anything.

Oh yeah, and it sounds like a blender cross-faded with a storm of angry bees on fast forward.. lol. It is quite light though, lightest setup you can get really.

:lol: The sound is not stealth, if you want stealth go for a hub. I don't find it very loud, most people don't notice it when I ride by. But definitely not like my hub motor, where you hardly hear it at all.

2. 200W – 350W FWD geared hub motor + in frame 36V battery. Road bike. What is the lightest-duty Ah battery I could use to make the 30km’s plus say 15km in reserve?

I would start off with what sort of speed you want to cruise at, that will tell you what sort of wh/km you will be getting. Then pick a motor/voltage combo that gives you the speed you want. Then pick the Ah to give you about 50% more range than your typical commute to account for detours, and battery degredation over time

Personally I would recommend a cruise speed of about 40kph. This is a good compromise between speed and efficiency. I was averaging about 12wh/km at these speeds with my crystalyte 408 at "48v" or 16s LiFePo4. So I had a range of about 40km with a 48v10Ah pack. Once I bumped my voltage up to~ 70v, my cruise speed went up to 50kph, but my effciency was about 22wh/km. So my range dropped even with the extra capacity. I have a switch which can limit the speed and power to give me similar performance to my 48v setup, and then I get get back all the range at a slower speed again.

If you are looking at a modest <1000w setup most of the hub motors people are using here DD or geared will be fine for relatively flat commuting, no point in over analysing it. The bigger decision is really the battery.

BTW. I charge my LiPo's unattended every day using one of the RC LiPo chargers.

- Adrian

 

[dogman dan]

A lot will depend on the speed you want to go. To do that trip in one hour each way, you'll need some speed to make up for stops and starts along the way. That leads to the question of can you go that fast and not draw the cops on yourself in Australia.

DD will be fine, you won't be doing much of the ride with no throttle, but you will also want to pedal all the way. Get some big front crank gears and you can keep up with the motor fine, and reduce your watts some.

Gearmotor will also be fine, but for lower speeds, like 25-30 kph using 36v. To do that ride in an hour, you'll need to hit about 40kph when cruising. For that speed a dd motor and 48v 15 ah battery would work best. The range, if ridden that speed will be a tad tight. So if you know you have a big headwind, you'll need to slow down that day to make it all the way.

Go with 26". This is not going to be a problem, since a 20 mile range at speed is going to be heavy anyway from the battery alone. Later on, you have the option to upgrade to a full suspension bike perhaps. In any case, 40 miles a day you will want to at least use some cushy tires.