fail: a full tilting 3-wheeled cargo bike

after building some "standard" cargo bikes i decided to get my hands dirty again, this time with something very special. i wanted to build an ideal cargo bike combining the stability of a three-wheeler (e.g. http://www.instructables.com/id/how-to-build-a-cargo-bike/ ) with the possibility to take curves like being on two wheels (e.g. http://www.instructables.com/id/build-a-2-wheel-cargo-bike/ ).
long story short: in the end i managed to build a bike that has the above features, but has simply become too heavy to load anything on it. plus steering is something you really have to learn with this monster:

surely it would be possible to improve this construction massively, but i think this would exceed my possibilities in regards of time and money.
BUT if some builders out there want to try their luck, here is what i learned so far and how i built this machine.

Step 1: Research

the first step was to do extensive research. since i am not an engineer it took me quite some time to understand the concepts behind it. an incredible source of technical inspiration was the tilting group over at yahoo: http://autos.groups.yahoo.com/group/tilting/ although primarily concerned with tilting concepts in regards to engine driven constructions the group is surely the best place to find information about constructing a tilter.

also very inspiring are tilting tricycle constructions built before:
- the jetrike: http://www.jetrike.com
- onya cycles' front-end loader. unfortunately the website (http://onyacycles.com) seems to be dead, but here are a some impressions: http://tinyurl.com/as2cc5m
- youtube has quite some videos about tilting trikes: http://tinyurl.com/ajkp98w

Comments

[FrozenIce]

Ever considered making Batman's Batpod using this design? i honestly think you are on to something with this steering design. It rides far more elegantly than a normal bike. Keep up the good work. 5*

[carkat]

thank you!

[mcsxr2]

Nice job ! You are very close to making it work. There are some great suggestions here to try. These links are very helpful. Gregs' early work with three wheelers is very well documented. The recumbent site is loaded with info. But when it comes to learning bike geometry Jetrike is the man,as well as Fleettrikes.
I'm building a front wheel drive tadpole with a 36" front wheel!! and two 20" rear wheels using Jetrikes lean system. A lot of trial and error as well.
Don't give up. ( I've been working on mine for years)



http://www.fleettrikes.com

.http://www.recumbents.com

Greg Kolodziejzyk

[carkat]

hi,
thanks a lot! lets see what will happen. currently i'm too busy (3 jobs and a family) to work on it again, but i guess there will be less busy times again. at these times i often catch up with older projects that stick in my head :-)

[IAC United]

The project might be better with a mechanical steering device, like an actual car steering. It appears your not only steering the bike conventionally but the freight as well. Maybe an upright steering wheel, connected to a vertical shaft and a chain drive to connect it to the wheels. Just a thought. I like the idea.

[carkat]

yeah, might be. though that makes it also more complicated to build (i guess). but you are right - i am steering the freight, too. i was thinking about the wether tilting the freight or not for a long time, but actuall i never thought of steering it or not! have to think that through...

[mcsxr2]

Sorry, mines a delta layout not a tadpole.

[espdp2]

Wow! Still a good project. The main difference I see between your and the front end loader is the electric power. I'll bet if you tweak the steering a bit and add an electric kit (I know, more money), it will transform into something much more satisfactory. I recommend 800-1,000 watts of power. :-)

[carkat]

right, but having a motor in it transforms the whole thing totally. i tried an electric cargo bike once and recognised that it behaves very different from a usual human powered one. i guess i would have to redesign the whole trike to keep up with the forces of the motor.

[Woodenbikes]

Its great to see the experiments and hear your findings! I don't know much about trike steering but it may be fairly easy to modify the head angle ( relaxing it to a shallower angle) to give a little more trail or caster. Or alternatively steepen the head angle to eliminate the trail. I wonder if that would ease or burden the steering.

[carkat]

yeah, this is surely something that should be figured out in this construction. and i think it really might improve steering, but i guess there are other flaws, too.

[carter5521]

I know you posted that as a failure, but that could be awesome as "no-snow" dog sled. I Bikejor with my dogs and have been looking for plans or ideas for a bike-sled for the dogs. Something you can steer and has brakes, but can haul stuff much like dog sled. You have a fantastic idea here! Great job! :)

[carkat]

great idea! maybe i should move to greenland and do a collaborative project with somebody there :-) would surely be fun!

[jolshefsky]

I wonder if your experience with the steering being a pain could be because you keep the steering wheels parallel. Although it's not necessary on a trike, I find it helps to use an Ackermann-styled mechanism: if the wheel on the inside of a turn turns tighter than the outside wheel, the steering feels more natural. I think that's because that steering geometry keeps the three wheels tracking the same turning circle whereas parallel wheels have the front wheels tracking a tangential line to the turning circle while the rear wheel tracks the circle itself leading to scrubbing or friction. I'm guessing that changing the steering direction while in motion is difficult and increases as speed increases. Ackermann geometry doesn't have that issue. I think you can also tune it to slightly favor tracking straight but I'm not sure how to do it.

[carkat]

hi,
in fact it is an Ackermann geometry, it's just not visible in the photos. the problem with steering, i think, arises because of the length of the vehicle and the fact that the force you apply by turning the handlebars has to travel quite a long way to get to the wheels. also it's totally crucial to build with -for a tinkerer like me- extreme accuracy. if it's not that precise, force gets lost and the loss adds up with every inaccuracy.
thanks!

[dZed]

Awesome build. I applaud you for posting about your "failure" -- lots to learn from those types of experience.

[carkat]

thanks a lot!