How my home-built bicycle trailer lowers my MPG
 

(Originally written Nov. 06)

Just posted a new page at metrompg about...

How the cargo trailer I made for my beater 10-speed bike is hurting my MPG:

http://www.metrompg.com/posts/photos...r-tranny-s.jpg

(130+ lbs: moving two Metro/Firefly transmissions by bicycle.)

Of course, total fuel used is the most important consideration, but since I typically get better mileage in sub/urban driving than I do on the highway, every time I use the bicycle for a local trip, my proportion of highway mileage for a given tank increases, so my overall mileage drops. http://www.gassavers.org/images/smilies/frown.gif

Other than for avoiding crappy weather, the main reason I use the car for local trips used to be to transport something too heavy/awkward for the beater 10-speed to handle.

But with the cargo trailer, I don't need the car for that any more.

So the MPG suffers. (I was going to calculate a figure, but, nah...)

On the plus side, kids seem to love seeing me hauling stuff behind the bike. It's kind of fun hearing them shout "cool! Where did you get THAT?" when I go by.

http://www.metrompg.com/posts/bike-trailer.htm

People always ask how it's connected to the bike...

Same thing as my brother's kiddie trailer - a stout spring, the ends held in steel tube. If you click into the article on metrompg.com, there's a zoom in pic that shows the hinge close up.

There are also some ball-joint type hinges you can make out of (apparently) common inexpensive hardware store parts. See this site for examples:

Community Bike Cart Design - A simple, homemade, low-cost bike cart for car independence and community

EDIT: the cost of my trailer was an afternoon & about $23. Plus I got exactly the size & shape I wanted.

A safety note about construction...

If you're going to weld/braze zinc-coated EMT conduit for the frame, best to do it outside with a breeze (or fan) http://www.gassavers.org/images/smilies/smile.gif

The fumes of the heated zinc can cause "metal fever".

The thing has turned out to be remarkably useful. I never used to be worried about my beater bike getting stolen, but now that it has half the trailer hinge permanently attached to the rear axle, I sometimes worry about losing it.

Just to clarify, yes, my MPG is actually worse now.

Because of the trailer, I use less fuel overall, true (and that's the important fact).

But by omitting some local driving (where I can achieve my highest MPG figures), my driving is further biased towards highway use. As a result of the higher proportion of (lower MPG) highway driving, my calculated MPG for a given tank is lower than it would have otherwise been had I just driven the car locally instead of using the bike/trailer.

http://www.tomswenson.com/images/bob.jpg

These are neat too.

2 downsides I can see, based on my limited experience:

- heavy loads will directly affect the bike's balance, since there's no torsional "give" at the hinge in the "roll" axis;

- related to that - if you lay the bike down, you could spill the trailer contents, since it has to lay down with the bike. So you'd either need a kick stand, or something to lean the bike against when you park

Small points, but there you go.

Cool! Check that bike cart design website. I think some of the designs use a larger wheel, but they offset the platform so it's not at axle height.

Bikes at Work sells just their trailer hitch, but it's $50, and if you can weld you can probably make the same thing for about $12

Anyway they also have a cool bike-trailer calculator that shows you how much you can supposedly carry (in lbs.) on a bike trailer.

And there's even a pic of someone hauling 1000 lbs of cargo on three trailers with one bicycle. I think they used to have a video of the 1000lb haul, but I can't find it anymore.

http://bikesatwork.com/hauling-cargo...e-trailers.jpg

Awesome pic.

I'd think if you were doing 1000 lb hauls, you'd want to be pulling with a trike! Either that, or be a pro at trackstanding.

forget trackstands, I think the key would be NEVER coming to a stop. :D

Darin, if you tell me you had no part in this, I won't believe you!

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