Bob Yak trailer - can it be motorized


Local time
6:06 AM
Jul 5, 2008
Collierville, TN
Hey all,

What would you think about motorizing this trailer? Could it be done? Has anyone seen anything else close to this?


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I've seen one very similar trailer with a 5 HP Honda engine mounted just in front of the wheel, above a custom gearbox - chain drive to the right side of the wheel. Guy who built it elected to control the throttle with a solenoid servo controlled by a variable potentiometer thumb throttle, and an electric activated disc brake. I looked it over pretty carefully at the time, and talked with the owner/builder - he said the worst part was balancing the load. That was in Telluride, CO, in August of last year. He told me he was on an extended road trip, touring every national park, national scenic site, and memorable site he could get to in Colorado between June 8th and August 30th. Said he'd already put almost 2,600 miles on it that summer.

Bike was a Workman industrial with big pannier packs front and rear, and he and his shop students at the high school he taught at had spent the previous school year building it.
I think this trailer would be incredible. I would love to hook up a 4 or 5 hp engine to it with a small battery for electric start. Even an alternator would be cool to run lights. But, alas, I have no earthly idea how to do any of this. I would love it if somebody would make and market this type of product. There are lots of redneck engineered items out there, but something more professional looking like this trailer with the features above would be hot!
looks like it could be setup pretty easily with any horizontal shaft engine. you just need aclutch, with a sprocket and a bike bolt on sprocket. (engine kit seller or i think somone on the site manufactures custom bolt on sprockets.)

personally i would do a long throttle cable. what happens when your batteries die or the signal is dropped? espically with a disc brake, if the signal is dropped, and the fail safe is to brake, what happens if somone ie;you, doesnt know you are stopping?
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Moto Bob

A number of these were built about 6 years ago. The plug was pulled when BOB got anxious about their liability due to lack of real world engineering. They will revisit the concept within the next few years according to a friend that works for them.

But you can order a 16" 36v wheel from Thunderstruck with a controller, throttle and LiPo battery setup tomorrow and make one for about $1200. Plus the cost of the trailer.....not very cost effective. There was also a bikeshop in Vancouver, B.C. that was doing similar conversions but they have dropped off the face of the earth I think, at least I can't find them. I ran in to a guy a few years ago on Broadway that had one and he really liked it.

This is my current favorite system (pun intended)


I just got a like brand new BOB off the local Craig's list for a really good price that I am going to convert here this winter after I get my other project out of the way. The concept of having a unit that can attach and detach at will to any bike and carry cargo to boot is very desirable to me.

SS, I would have really liked to see that version in Telluride, did you happen to get any contact info? Or a picture?
I ran into him at the place I stopped in for lunch, and my camera was locked in the car. At that time I wasn't navigating very well, as I had an open wound on the ball of my left foot that had gotten infected, and I was still 3 days from home. So, I didn't get any pics, didn't think to get any contact details. Wish I had. I do like what you've done there, with your trailer.

You know, that trailer design is simplicity itself. If I had a welder I could build one in a weekend pretty readily, with a 20" donor bike for the rear triangle. I just don't like an articulated vehicle with power on one side of a flexible joint, and steering on the other. I've thought about a "power trailer" (small 1 - 1.5 KW gas powered generator, a couple deep cell batteries), and electric drive on the bike itself. If they weren't so expensive, I'd like a tadpole recumbent trike with 350 watt wheelmotors as the front wheels, and a wide gear range pedal power system to the rear wheel. Tow the power trailer, have a useful pedal trike when you feel like pedalling.