A slow build Plan

[tentman]

Hello Folks (from southern New Zealand)

I'm planning a build for a bike to largely replace my 4wd (and enable me to go further and walk less). I like to be in our mountains, exploring and sometimes hunting.

The first quality of my bike will be to climb, its not unusual to have to climb 400M (1500') at gradients of 1:12 (8%) steady with pinches of double or a bit more that sort of grade.

The second thing is water, its wet down here, if its gone 5 minutes since a river was crossed the next one is now. Typically 300mm (1.0') deep. With that comes mud, there's frequently 100M of track with 150mm deep mud - the hop off and walk beside sort of mud cause if you don't you're eating it.

I'm a "slow" sort of person - always preferred horses to motorbikes, and as a non expert bike rider on the wrong side of 55 I want to be able to go slow with control 30 Kph (18 Mph) will be plenty fast enough I think. I need to be able to carry it over the bigger rivers.

There is an 8Km dedicated cycle path to town (I did ride a bike to work there for more than 20 years) and I would certainly anticipate riding it frequently on errands to reduce my carbon footprint.

I want to assemble this thing from components as much as possible myself, I have a pretty decent shop and tools.

The vital statistics:

My weight 85 Kgs (190 lbs) with up to another 25 kgs (40 lbs) of equipment/game
Desired Range 35 km (20 miles)
Machine weight 35 Kgs (80 lbs) Max
Cruise speed off road ?? Maybe 10 Kph (6 mph) - probably less
Cruise speed on pavement 30 Kph (18 Mph)
Flat out speed 35 Kph (22 Mph)

Currently I'm thinking of a Qulbix 76 "Bicycle" with a Lightening Rod's mid drive with 26" front (and maybe a 24" rear??) if I could make my weight limit with enough battery to achieve my desired range.

Thoughts and suggestions??

Thanks
Foster

 

[Grantmac]

Do you want to be able to peddle along or will it be on the motor most of the time?

 

[SlowCo]

With those requirements it seems a Qulbix is way overkill.
Why not just mount a mid drive motor kit like a BBSHD to a decent MTB?

 

[markz]

Go with a direct drive MXUS 3000W or 5000W in a 4T winding you can buy it directly from MXUS, I did years ago.
Lace it into a 19" motorcycle rim which is equal to a 24" bicycle rim, gives you more torque then 26" bicycle rim. It is a nice trade off because you dont want too small a wheel, you still want to be able to soak up the bumps, rocks, roots. I used to love riding in creeks, sweat power :wink: now I am ebiking and I havent installed a chain on my ebike in a year!

Buy a sealed Kelly Controller model NM 24-72V they go by Phase Amps so 270A is $199usd, which is good because thats like 125A battery.

Battery will be expensive.
EM3EV in China is your best option.
Grin Tech www.ebikes.ca is in Vancouver Canada


Go to www.ebikes.ca
Tools
Trip Simulator BETA
Scroll down to Chart Options and Input Type, Choose Google Maps
Zoom out, go to NZ, zoom in and see if your route is there. If not choose something similar, roadway, pathway.
Right click to start your route
Right click again to end your route
Left click to move the blue route line to you route
Click X to close the window, and it will do the math.
Choose the Parameters

Play with different wheel sizes, input power is your pedal power 50W is weak lazy pedaling like what I do :lol:
Your controller input parameters will matter, so go to custom. Phase amps and battery amps. Battery amps is half of phase amps.

 

[E-HP]

Can you elaborate on your 6mph off-road cruising speed and whether part of your requirement is to climb the 8%-16%+ grades at that speed? Also, how will you be carrying/hauling your gear/game?

(Based on the ebike motor simulator, a lot of gearless hub motors will overheat in 2 or 3 minutes if climbing 8% at 6 mph, even with Statorade and hub sinks).

https://www.ebikes.ca/tools/simulator.html

Sent from my iPhone using Tapatalk

 

[tentman]

Hey - thanks for the input guys!

I will pedal, I'm pretty fit and can climb the hills myself quicker than most people on foot, the idea of the bike is to cover ground that would otherwise be done in a 4wd, and to get further in the time available.

A BBSHD is right in the mix, however I really like to support "small shop guys" (I'm one of those myself) hence having Mike's mid-drives in centre focus.

I don't really know if I'll be able to ride at 6 Mph up grades - that was just a guess, I know my horse and I with gear can climb them at a good 4Mph if she's fit. I'll treat my bike (as I do all my machinery) like a horse, give it a rest if it starts to labour at all.

I was hoping to hear a bit more about the water resistance of various motors/controllers. It's dammed near impossible to keep all water out of any machine used here, the best thing is to know what to do to minimise the effect on both immediate performance and for the long term.

Its an incredibly robust environment here, our NZ mountains/rivers are very hard on men and machines, and while I tend to "baby" my gear, reliability (and/or redundancy) is a good thing to have.

Cheers

 

[amberwolf]

Instead of trying to keep water out of motors/electronics, etc, your best bet is to coat all the corrodable surfaces inside with non-corroding paints/etc., and then ensure there are places for all water that gets in to drain out easily.

What usually happens to "waterproofed" stuff is that water still gets in, but it doesn't escape, so it corrodes even worse than if it had been left alone.

 

[amberwolf]

Regarding the speeds...just to be sure you understand--the slower you use the motors, the less power you can use them for, before they overheat.

So if you were able to use the motor at just enough power to climb a hill at 15MPh, but then run into a hill that you cna only still use that same power but can only climb at 4MPH, the motor is very likely to melt down quickly from the waste heat (since much of the power going into it at that point is becoming heat instead of work to rotate it).

Using a drive thru the gears so you can change gear ratios is much easier on the motors than a fixed-ratio in-wheel motor, for situations like that.

 

[dogman dan]

What you will need is not on the shelf imo, but might be made from something off the shelf.

Because of the wading, a motor with integrated controller down on the pedals might not be ideal. You might look into an electric version of the typical gas bike made from a scavenged motor. This goes on a bike with no rear suspension.

Start with perhaps a 500w motor from a scooter, then mount on top of the rear rack, close as possible to the seat. Belt drive it to a gigantic pulley attached to the left side of the wheel, by adapting the disk break mount on the hub.

Gear it insanely low, huge pulley on the wheel, so the motor is happy with 5 mph, but more or less unable to go a lot faster. Aim for maybe 10 mph top speed.

Now you have a 5 mph rock crawler, but with the motor above water. Battery carried high too, like on the handlebars to balance out the rear motor weight.

 

[fechter]

A BBSHD with a 30t chain ring would meet all of your requirements except maybe the water crossings.

On my fat bike below, the motor sits about 12" above the ground. While the controller part is potted and things are pretty well sealed, it was not made to go underwater. With some modifications, it might survive short submersions. I use this thing to climb some pretty steep grades and it can easily go 20 miles. The BBSHD is very efficient at slow climbing speeds.