how to build a cargo bike

Step 12 S**t...

cutting the front frame, making it smaller and building a new pivot (taken from another old bike) were the next things to do.

Comments

[sillywilly]

I'm not carkat but I have a good suggestion for you. See attached file I have redone to show bigger angle brace between seat post and downtube. I suggest a headtube angle of zero! This will keep the distance between downtube and box the same throughout steering range. You will see in attached drawing that there are two red dots. The one to the left should be location of a fixed castor wheel to aid steering and support box loads at 2nd point. The right red spot is my suggested axle mounting point, centered in box. You will notice that head tube is about 8 inches ahead of center for castor affect. This should ease steering inputs, track true, and might even allow "hands off" riding?

[carkat]

hey, thank you for your thoughtful comment. it seems you know what you're talking about. are you some kind of engineer?

[sillywilly]

Naw, just a lifetime of loving to tinker, build, experiment, etc. I like tadpole trikes (among other things) and would be peddling one now except for a bad knee. My light trike preference is a recumbent-seat with full suspension, motor assist, and a super light full body cover for year-round usage. I belong to a Yahoo group called "CabinScooters" where we confer, toss about ideas, and help each other in the building of covered 2 or 3-wheelers of all sizes from powered velomobiles to super screamer sport performance trikes. they are rated from type 1-to- 5 with 1 being the lightest/slowest and 5 the heaviest/fastest but none over 1500lbs. The reason is because this category can be registered in most states as a motorcycle with a whole lot less restrictions as to builds than 4-wheel cars. http://autos.groups.yahoo.com/group/CabinScooters/

[Quoniam]

This pivot go to support a lot of stress. Look to the reinforcements http://photos.ugal.com/3834/14972/2413/142572/vectocustomphoto.600.jpg Its possible the pivot have some angle to make the bike return itself from the turn.

[carkat]

yep, good idea... maybe i should add some reinforcements, too. after riding the bike for some time now i must say that it's not too easy to ride at higher speeds - the front part becomes quite hard to keep on track. maybe the angle of the pivot helps in such situations.

[Quoniam]

Its possible is better to put the pivot displaced to the front, with the wheel axis behind. This make the front part function like a free-wheel (like the one in the front of a wheelchair).

[carkat]

right, sounds reasonable. though in this case it would need a reconstruction of the frame... moving the wheels backwards here wouldn't make much sense, so the only thing possible would be moving the pivot more to the front. this would need a longer bar below the box. i guess in case of a reconstruction both should be done.

[mostly water]

I am not sure what the angle is of the pivot post (that would be good to add). Judging from the pics though, could you not just flip the cart around and move the handle bars & brakes to change the the relation of the wheel axis & pivots?

[carkat]

would make sense, yes. though since the pivot then is in the middle and the wheel axis behind i think there would be a lot of stress on the pivot if there is some weight in the front part of the box. so there i am again thinking about a reconstruction of the frame as mentioned above...

[sillywilly]

SW again,
What about eliminating the head stock pivot all-together and replacing it with a lazy susan ball bearing plate? You could then drop the bottom of the box down another 5 to 6 inches thereby lowering center of gravity for loads that much more? You could use one larger tube going underneath the box or two tubes parallel to each other, welded to the outward edges of lazy susan plate. They would have to come together before mating to the crank area so pedals & feet don't hit.

[carkat]

hey,
thanks a lot for all your thoughts! hope i can build one or the other idea when i have time again to do some improvements or a new bike :-)

[scomstock1]

Hi carkat. I am going to build a long john and then a cargo such as the one you show. It seems straight forward but, do you have any idea where the head stock angle finally worked best? You did a great job on this.

[carkat]

hi,
thank you! since i didn't test any other head stock angle the only thing i can say is that a straight angle works well. you just have to get used to lean into curves when riding but that's all. the angles mentined in the instructable are there because i thought that christiania is building this kind of bike for quite some time now and they probably know what they're doing. . .
also have a look at the last comment from sillywilly with the reworked pic of the trike, he's making a good point there.
good luck!