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Utility Cycling Want to haul groceries, beer, maybe even your kids? You don't have to live car free to put your bike to use as a workhorse. Here's the place to share and learn about the bicycle as a utility vehicle.

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Old 08-10-08, 11:57 AM   #1
BruceHallman
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My take on a home made cargo bike...

See photos...

http://www.flickr.com/photos/hallman...7606523339896/

Cost me two x $25 garage sale junk bicycles and $20 for two new chains bought on ebay.

The epoxy, fiberglass and plywood I had sitting around (because I build wooden boats too) but that is worth perhaps $25. So, for $95 I have a functional homemade xtracycle-clone, or what-cha-call-it bicycle.

Built in spare time sporadically over several months of time, maybe 20 manhours.

I suspect that some will question the strength of the epoxy, and fiberglass roving, used for the joint connections. My opinion, based on a lot of experience using these materials, (and based on the road testing so far with this specific experiment) is that they are plenty strong enough. Epoxy has spectacular adhesion, and the glass fiber has a very high tensile strength.

Also, the plywood is 1/8" thick, which when bent, takes on a surprising rigidity, and light weight qualities.
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Old 08-23-08, 09:46 PM   #2
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I wonder if polyurethane window adhesive could be used in place of epoxy to fill in the bottom bracket. I recall that some auto enthusiasts use it to fill in motor mounts to make them stiffer.

Did you sand down to bare metal before applying the fiberglass? Did you consider brazing the joints?
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Old 08-24-08, 02:26 AM   #3
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That looks a great solution. Well done.
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Old 08-24-08, 11:04 AM   #4
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Well done adaption of the xtra cycle idea. However, it is structurally
weak due to lack of welding at connection points. That said, as a
proto-type it's really good.
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Old 08-24-08, 02:00 PM   #5
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Well done adaption of the xtra cycle idea. However, it is structurally
weak due to lack of welding at connection points. That said, as a
proto-type it's really good.
Fiberglass can be pretty strong, not to mention that he's spreading the bonding load over >12 in^2 per joint instead of maybe 0.1 in^2 for a brazed or welded joint.

I probably would have tried to source some CF, but that's just me.
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Old 08-24-08, 08:09 PM   #6
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Your boat-building experience really shows in the elegant shape of the panniers/cargo pods. I like them but I do wonder how much they will hold... unless the interior space is auxiliary and the main cargo is meant to sit on the flat lids?
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Old 08-25-08, 09:13 AM   #7
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"My take on a home made cargo bike..." update

Answering of several questions above: Of course, there are infinite ways to do things, and my way was simply my choice. I do have quite a bit of experience with epoxy and fiberglass, obtained while building fiberglass boats. I didn't choose to grind down to bare metal, but the paint appears to have good adhesion, and after some field testing the joint seems plenty strong.

I am of the opinion that the difference between fiberglass and carbon fiber is not differences in total strength, as fiberglass is extremely strong, but rather that carbon fiber is lighter weight. For a freight bicycle saving an ounce or two of weight did not justify the high cost of carbon fiber. (Also, the fiberglass I had in my junk drawer, effectively was free.) It depends a bit on how you measure it, but ounce for ounce, fiberglass is actually stronger in tensile strength than steel.

Some testing could be done on the strength differences between brazed joints and epoxy/glass joints, but I suspect that they both would be found to be strong enough. Also, I am of the opinion that the fit up tolerance of brazed joints is tighter and requires more patience and accuracy to achieve the necessary tight fit. Epoxy/glass has the advantage of being more 'gap filling' therefore easier and forgiving for one-off cut and fit, retrofit projects like mine.

Certainly, other options could work for filling the bottom bracket connection point of the after frame with the forward frame, but I used epoxy because it is cheap, stiff and was easily available for me.

And yes, the idea with the hard panniers is to hold the dense heavy things down at a low center of gravity, and the flat top surfaces are intended to provide a location to strap on and carry large awkward lower density items. I am toying with the idea of a custom shaped and sewn collapsible nylon duffel bag which has properly located nylon snap clips for attachment to the top deck of the hard panniers.
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Old 08-26-08, 04:38 PM   #8
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The panniers look great! Very slick-looking.

I would be a little worried about the fiberglass joints, too... the initial strength is probably fine, but it seems like there might be an issue over time, with those joints being load-bearing, and flexing repeatedly (especially if the miters aren't very precise, as you were saying). I imagine you could see hairline cracks forming long before they failed, though, if that really is an issue.

I'd love to hear how it's working for you over time. Good luck!
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Old 09-01-08, 09:17 AM   #9
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Thanks for the complement. I will keep track of the flexing issue, but I am quite optimistic considering that epoxy impregnated fiberglass is used with great success in boating applications, and boats are certainly subject to heavy repeated flexing. (Not to mention that I used double layering of extra thick glass roving, totaling 1/4" thick, which I'm guessing has 10x safety factor over-strength.)
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Old 09-01-08, 08:40 PM   #10
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Are those "Stitch and Glue" panniers?
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Old 09-02-08, 02:26 PM   #11
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What kind of epoxy did you use?
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Old 09-05-08, 09:47 AM   #12
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poor rockhopper...

looks nice though. I just love my rockhopper too much to make it a longchopper
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Old 09-08-08, 10:11 AM   #13
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poor rockhopper...

looks nice though. I just love my rockhopper too much to make it a longchopper
I think of it as a reincarnated rockhopper.

Yes, the panels are made using stitch and glue techniques from boat building. (Also, the dimensions of the expanded panel shapes are developed using boatbuilding software.) The theory is that the bended 1/8" plywood is both light weight and also very rigid. This makes the weight of the metal Xtracycle pannier frame tubes unnecessary.

I use the cheapest epoxy I can find, bought on ebay from the vendor "polymerproducts". I buy 10 gallons at a time (much cheaper bought in bulk) because it is handy around the shop and I use a lot in boat building.
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Old 09-18-08, 01:23 PM   #14
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Very cool. I've been thinking about doing something like this but wasn't sure how it would turn out without actually trying it. I now know what my winter project will be.


I wonder if a couple of nylon control arm bushings might work through the bottom bracket connection?
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Old 09-19-08, 08:38 AM   #15
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Hi Bruce,
You bike is very creative. I too, have had experience with fiberglass. And although some people are skeptical about the strength of fiberglass, the yield strength of fiberglass is about 45,000 pounds per square inch.
My Daughter designed this Fiberglass Ladies Utility Bike (the FLUB):


The cargo box is at the front of this bike. It is just the right size to hold a twelve pack of 12 oz can beverages.

Having looked at your photographs, I want to say that I wrapped all the joints of this bike with fiberglass, and the main frame rail/tube has a couple layers of spirally (helically) wound 4" wide glass tape. Maybe you should wrap the joint in more 'glass. The roving is strong, I know, but if it should "Delaminate" while you are riding , you could end up with road-rash.

Does it float?
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Old 09-19-08, 08:41 AM   #16
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Another picture, after more Bondo and some pink paint:

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Old 09-19-08, 10:16 AM   #17
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Another picture, after more Bondo and some pink paint:

Hot bike.....

a) I think they are missing you on the alt bike forum

b) I want to see how you get this on the SS/Fixie, Triathalon, and Tour de France forums....and the road forum would be also very interesting

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Old 09-19-08, 11:48 AM   #18
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Hot bike.....

a) I think they are missing you on the alt bike forum

b) I want to see how you get this on the SS/Fixie, Triathalon, and Tour de France forums....and the road forum would be also very interesting

a) I think the Fiberglass Ladies Utility Bicycle belongs in the Utility Cycling forum. The cargo box can hold lots of weight. I was actually reading the Utility Cycling forum today because I was thinking about starting a new thread. One of my previous threads was posted in the "Manufacturer Retailer and Consumer Feedback" forum, but the moderators moved it to "Alt Bike".

Granted this bike looks kind of like a motorcycle, but that's on account of the styling of the fiberglass box. I think what I've done is put ten pounds of sugar in a five pound bag... It's too much at once.
I'm seriously thinking my next cargo bike should have a plain (rectilinear) box , with no attempt to style it like a MC.

b) The FLUB is a true ten speed. I never considered making it a fixed gear.
Triathalon Forum? I guess I could start a thread there and ask if I can use an amphibious bike in the water leg of the triathalon. I think the answer would be "No" and it would be a joke.
Tour de France forum? Fairings are not allowed in the Tour de France, they are considered "cheating".

Just try to picture a similar bike with a plain box on the front, with no aero styling. Maybe it should have a platform instead of a box? I've been thinking of making a "stake bed" version, and building a canopy top out of 2"x2"s and Viscreen, that I can put on for foul weather riding. Then I would have to post it in the Velomobile forum (Do we even have a Velomobile forum?... No, there is no Velomobile forum at bikeforums.net).

Again, the FLUB (Fiberglass Ladies Utility Bicycle) was styled/designed by my Daughter Mellisa, who had toured 38 of the contiguous 48 States with her Uncle in his Kenworth diesel truck. It was her idea to create a semblance of the KW's styling. If you don't like it, don't complain to me.

Next time , I will either make a plain 90 degree box, or a flat platform, or perhaps a dump body (like a wheelbarrow, or a dump truck) so I can dump gravel quickly and clandestinely to improve bike trails and bike lanes. Either way, the next bike will have mounting holes for 2"x2" stakes.

c) I've also posted the FLUB in the Recumbent forum.
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Old 09-19-08, 01:40 PM   #19
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Oh. My. God.

The FLUB is entirely flabbergasting! The Bigfoot of the bicycle world, if there ever was one. I'm calling a photoshop jobbie on this one It's part jetski, part bike, part ridiculous, and part awesome. It I were to see that in person, well, I thought I've seen it all. Ever see that episode of Friends where Phoebe was possesed by the old woman?

I suppose, all I can really say is I really *dig* your daughter's style
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Old 09-22-08, 09:03 AM   #20
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>Does it float?

Actually, it could float. (I did drill a couple drainage holes in the low points to let out liquids, rain/dew/beer).

The idea of the bent 1/8" plywood panels was to exploit the light weight to strength 'shell strength' qualities of bent panels. Notice that the metal tubing frames found on the Xtracycle are eliminated and replaced by the hard thin shells which serves double duty as the carrying container and as the cargo structural element.

I agree that fiberglass has similar strength to steel. The weak link, in my opinion, is not that the fiberglass would break, but rather the weak link would be the epoxy/paint/steel adhesion. The joints I have used are spread over several square inches of surface area, and to my evaluation and field testing, they measure up as plenty strong.
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Old 09-22-08, 09:56 AM   #21
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>Does it float?

Actually, it could float. (I did drill a couple drainage holes in the low points to let out liquids, rain/dew/beer).

The idea of the bent 1/8" plywood panels was to exploit the light weight to strength 'shell strength' qualities of bent panels. Notice that the metal tubing frames found on the Xtracycle are eliminated and replaced by the hard thin shells which serves double duty as the carrying container and as the cargo structural element.

I agree that fiberglass has similar strength to steel. The weak link, in my opinion, is not that the fiberglass would break, but rather the weak link would be the epoxy/paint/steel adhesion. The joints I have used are spread over several square inches of surface area, and to my evaluation and field testing, they measure up as plenty strong.
Okay,
If it works, that's good. When I built my Daughter's cargo bike, I may have overdid it. I wrapped strips of fiberglass tape so it would take more than the adhesive strength of the resin. "Lashing" I believe the boat-builders called it.
I would rather have the bike overweight, than see it fail. (Especially the first one).

PS- I'm sorry your thread got hijacked... Mellisa's bike always gets people going. I want to start a new thread about Utility Bikes.
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