Pusher electric trailer.

I just bought a used BOB trailer with a 16 inch rear wheel. I would like to turn it into a pusher electric trailer. What hub motor in 16 inch will give me around 500 watts of power with around a 25 MPH top speed? I think I want to use a geared hub motor, probably a Bafang? I know they have different windings and RPM but don't have enough experience to figure out what I need.
Thanks in advance!

Any feedback on this one?? I guess it would be nice to have regen braking on the trailer wheel. Looks like it might push me up to 35MPH. Hill climbing any good (6 to 7 percent long sustained grades)?
http://www.leafbike.com/products/diy-bike-conversion-kit/16-inch-electric-hub-motor-kit/newest-16-inch-48v-1000w-electric-bike-kit-front-hub-motor-wheel-977.html

LB doesn't get any points for honesty or integrity. that top speed would have to be with the wheel off the ground. 26-28mph would be more realistic on a bike. maybe a little less on a pusher trailer.


There might be better options by converting to a 20" wheel. That would also make the trailer roll better.

Drunkskunk said:

LB doesn't get any points for honesty or integrity. that top speed would have to be with the wheel off the ground. 26-28mph would be more realistic on a bike. maybe a little less on a pusher trailer.


There might be better options by converting to a 20" wheel. That would also make the trailer roll better.

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Thanks for the feedback. I researched them on ES and I think I want to steer clear of them.
Can't put a 20 inch wheel in the BOB trailer so my search continues!

BOB trailers tend to shimmy at speed even when they aren't pushing. Pushing will exaggerate this tendency greatly-- it's an unavoidable side effect of having the trailer pivot out behind the rear wheel. I say look for a motor that gives good efficiency at less than 20mph in a 16" wheel (like something designed for 25-30mph in a 26" wheel), with the potential option of adding voltage later for more speed if things are hunky-dory.

Chalo said:

BOB trailers tend to shimmy at speed even when they aren't pushing. Pushing will exaggerate this tendency greatly-- it's an unavoidable side effect of having the trailer pivot out behind the rear wheel. I say look for a motor that gives good efficiency at less than 20mph in a 16" wheel (like something designed for 25-30mph in a 26" wheel), with the potential option of adding voltage later for more speed if things are hunky-dory.

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Years ago I had a BOB trailer and never had a shimmy problem with it.
I modded it to take a motor with a chain drive and a 5 speed IGH. Used SLA battery at the time. It worked well except the crappy motor had a internal controller that would keep cutting out on me so I abandoned the project.

I bought a BOB IBEX for just that idea. Before attempting any mods, I gave it a trial run – hauling a load of groceries from my local… and I was not impressed. Never used it again; it remains stored in the back room.

Decided to built my own trailer using a “jumper” frame. It had some issues that caused me to delay my 2nd California cross-country attempt – though I got it sorted well enough, and was the wiser for it.

Even though the BOB claims it can haul up to 100 lbs. of material – don’t you believe it! The framework IMO is made of pot-steel which is heavy and weak. The frame connection concept is light- to medium-duty. I think it could handle 45 lbs. all day on a good hard trail, but going more than that is pushing the limits of the design. And then there’s the shock absorber which is not that much better than a spring.

From experience with my effort to create a pusher, it should never provide more force than the bike. In other words, have an electrified bike that is doing the majority of the work, plus there’s a trailer. And btw – it’s providing some small-in-proportion amount of work. The ebrake should be rigged to have it brake hard.

For my money, I ended up moving the motor to the rear wheel of my FWD – effectively creating a 2WD ebike, and that solved 98% of my issues with towing.

Lots of threads on this if you search around.
~KF
PS - I'd never consider having a BOB travel faster than 25 mph. However I had my DIY-trailer up to 44 mph downhill on the west side of CA-HWY 88 Carson Pass hauling 150 lbs. of gear

Kingfish,

Thanks for your feedback. I have read numerous reviews on the BOB trailer and most are pretty positive. I also had one and had pretty good luck with it, hauling lots of stuff on off road MTB treks.
I also looked at the trailer you made. looks nice.
I think my needs are different than yours. I mostly need a pusher trailer to get my regular hartdtail 29er mountain bike to the trailheads versus driving out there. I won't haul much gear so most of the weight in the trailer will be the battery, hub motor, controller and perhaps 10 pounds or less of gear.
As I mentioned before I did modify my old BOB to take a motor driving a 5 speed rear hub with SLA batteries, so I know that it will work as a pusher. I will ride mostly pavement with it, except for my 1/2 mile dirt road up to our house.
My main question is trying to find a 16 inch hub motor that will push it up to 20 to 25 MPH. The leafbike kit looked like it was exactly what I needed but it looks like some ES members have had bad experiences with them. I want to have motor that has at least 48 volts and 500 watts. I will pair it with a 15 amp hour lithium battery.

I think that if you aren't going to run it slow and loaded, then you would want to get the "fastest" wind of motor that you can, in the type and power-handling ability you're after, and then get a controller and battery to give it the voltage necessary to get the speed you're after with the load it'd be under on the slopes you will need it to climb at that speed.

To figure out what voltage you'd need, you'd want to find out what that motor's loaded max speed is at any particular voltage, then divide the speed by the volts. Then you have it's speed-per-volt, and you can then use that to figure out what volts you need to get the speed you're really after.


Oh, and if the motor doesn't come in a 16" you could have it relaced into one...but keep in mind that if it specifies a speed in a different size wheel, you'll need to do the ratio math to find out what the slower speed would be in the 16" wheel you want it in.

For a 16" wheel you really need the fastest wind you can get. Some of us are testing the Xiondga 2 speed motor, mostly in 20" wheels, but 16 allows more voltage for takeoff. The verdict is not in yet but it seems like a good bet. Golden makes a 16" wheel DD motor. I don't know anything about it. You will need at least 48 volts and maybe more to get even to 20 MPH. But the torque would be dynomite on trails.
otherDoc

amberwolf said:

I think that if you aren't going to run it slow and loaded,

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Note that the trailer can only push as hard as the weight it's carrying. In a lightweight, unloaded trailer, a powered wheel would simply skid when power was applied. In this case, a 15 lb hub motor and equal or heavier battery would constitute a moderate load and would allow the transfer of a moderate amount of torque.

Chalo said:

amberwolf said:

I think that if you aren't going to run it slow and loaded,

Click to expand...

Note that the trailer can only push as hard as the weight it's carrying. In a lightweight, unloaded trailer, a powered wheel would simply skid when power was applied. In this case, a 15 lb hub motor and equal or heavier battery would constitute a moderate load and would allow the transfer of a moderate amount of torque.

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Trailer 15 lbs
Hub motor and tire 15 pounds
Battery 15 pounds
Gear 10 pounds

Estimated weight 50 or so pounds

I am a fit and experienced cyclist so there will be pedal assist and I know how to control starts and speed. Just because it may be capable of 30 plus mph doesn't mean I have to use that speed. But on my old BOB it felt safe at speed on downhills where the trailer was pushing against the bike particularly while braking. Plus I have some experience with a similar pusher.
I have 3 bafang mid drive bikes which I really like but I need a pusher to eliminate the car trip to trailheads when I take my mountain bike out for a "real" ride.

Well my 1000 watt leafbike DD hub motor in a casted 16 inch size arrived. Of course with my luck the motor crapped out in a few minutes due to a broken ground wire in the main wiring near the hub axel. Got it fixed and installed on my BOB trailer. with a 15 amp hour lithium battery.
This thing hauls butt! Faster than my Bafang 750 watt mid drive. Easily 25 plus on long up hills and tops out at around 33 mph.
Main issue is unloaded it doesn't have great traction. Put on a nobbier rear tire and added around 15 pound of weight to it. This helped a lot and less tire spinning. This setup is only for the pavement since it doesn't have the traction to conquer dirt roads.
Bottom line is that I am pretty happy with it and it will do the job of pushing me and my mountain bike to trailheads within a 15 mile radius. Faster than I expected and more stable too. The looks that I get from people as I accelerate and whiz by is priceless!
I will post pics later on and a video too.

Knobs reduce traction on pavement, a lot. So there's another way to add some traction to your rig; put a street tire back on. The 16 inch Maxxis Hookworm is one of the very best in that size. I think you can get a Schwalbe Big Apple in 16 inch, too.

Keep the tire pressure nice and low; there will never be very much weight on it anyway. But do take care and do test rides, because any change in mass or system flex could bring a tendency to shimmy.

the tire I put on increased traction vs. the smoother one that I took off. yes of course you need to watch load weight and distribution but that is true of any trailer.

Leaf bikes specs seem to be accurate. Close to the max speed they claimed and the 1000 watt model has more power than my 750 watt bafang.

glad I didn't take everyone's advice! Ha ha! :wink: