Bike Trailer

Discussion in 'Travelling, Commuting & Safety' started by atomichurley, Nov 23, 2009.

  1. atomichurley

    atomichurley Member

    I was thinking of making a trailer for my bike so my friend can sit on it for when we need to go somewhere, i was thinking of including a seat. Do you think my engine would be powerful enough?. i have a 66cc Zbox 2 stroke engine.
    Thank you

  2. Fabian

    Fabian Well-Known Member

    This is my setup.

    I did a test run with a total weight of 60 kilos (trailer 20 & cargo 40) hanging off the back of the bike.
    I'm using a SickBikeParts shift kit allowing the use of the bikes 9 speed cassette.

    With the old engine that had a modified carburettor intake pipe, i managed to get up a reasonable hill in first gear and travel at around 30 km/h on flat ground with the standard 69cc Chinese engine.


    Attached Files:

  3. atomichurley

    atomichurley Member

    nice trailer, wow you can change gears on your bike i would love to make a bike like that for my next build
  4. stevolandis

    stevolandis New Member

  5. motor_head

    motor_head Member

    looks cool with the tires up inside the box
  6. Fabian

    Fabian Well-Known Member

    Hi Stevo

    The trailer is built out of scrap materials: right angle aluminium from the scrap yard and plywood from packing crates.

    A recumbent bicycle manufacturer was having a closeout special on it's Burley dog trailers at a price i couldn't refuse.
    The trailer frame and hitch mechanism formed the base of my box trailer.

    I will say that the trailer could be built using lighter materials to reduce it's top heavy effects.
    Having said that, the extra weight is handy when wind conditions are strong and blustery.

    The storage volume is amazing and no other product on the market offers anything even close.
    Two full size wheelbarrows can be emptied into the trailer and there is still room for a backpack and spare wheels.
    Naturally the bikes brakes become an issue in trying to stop 60 kilos when pushing from behind.
    I would not recommend anything other than a good set of disk brakes with a 200mm front rotor.

    If money is not an issue my preferred choice would have to be a BoB Ibex ( http://pedal**** )with it's excellent rear suspension.
    A uni-wheel trailer is much more stable in it's towing dynamics when used for a bicycle application.

    So far i've traveled 3000 kilometers, most of it with trailer attached.
    I've had a few nervous moments in strong wind when towing on empty but so long as you understand the driving dynamics you can modify your riding and also trip route to compensate for conditions.

    Another interesting twist on the BoB Ibex design.

    Last edited: Jan 23, 2010
  7. Stink Bike

    Stink Bike Member

    I bought a trailer on Ebay last week for $99.00.I expect it to be delivered in a day or 2.
  8. This is not generally true, especially with anything over 50 pounds. The biggest contributor to trailer stability is hitch location. Ideally, you want the trailer hitch to attach as closely as possible to the rear tire's contact patch. Here's a bit more info about bicycle trailer dynamics:
  9. BikeMan

    BikeMan Member

  10. Seat-post mounts are bad

    With large loads and high speeds, seat-post trailers will severely affect your handling. The higher up the mount, the more leverage the trailer weight has to push the bike from side to side.

    The most stable trailer is something like the Bongo

    or if you want a single-wheel trailer (for riding single-track and off-roading), the extrawheel is tough to beat. And because the weight is almost entirely borne by the trailer's wheel, these work just fine with full suspension mountain bikes.
  11. BikeMan

    BikeMan Member

    A bit confusing on the prior post about seat post connected trailers being unstable.I have seen several seat post trailers do just fine under load,no instability.Since some seat post trailers have different hitch and arms from others,maybe its all in how its made?? Or after going over a certain weight or height causes some to get tippy?? Not sure,just saying is all.I would definitely not rule out seat post trailers but simply do ones homework first.
  12. Bikeman:

    It doesn't have much to do with the hitch mechanism itself, but rather where that hitch connects in relation to the rear-tire contact patch. Picture it this way: You have a seatpost-mounted trailer with 100 pounds on it. You're entering a corner with the bike leaned over a bit (a bike won't turn any other way) and you are braking. The deceleration causes the weight of the trailer to push against your seatpost partially forward and partially to the side due to the angle between bike and trailer. Because your pivot point is the tire contact patch, the effect is that the trailer is trying to push your bike upright, counteracting the turn you're trying to make. This effect is very noticeable. The higher mount gives the trailer more leverage to push the bike around, lowering the mount reduces this. As a demo, sit on your bike and heave a friend push sideways against your seatpost and then against your rear axle. It should be clear that it takes much less force to change the roll angle of the bike when pushing from the post than it does from the axle.

    The other problem with post-mounted trailers is that when you stand in the saddle (say to climb a hill or accelerate from a stop) the bike rolls left to right. This side-to-side motion is much greater at the seatpost than it is at the axle. As you pedal, that side-to-side motion moves the seatpost hitch around and changes the steering angle of the trailer with each pedal stroke. This is less efficient than a trailer that tracks straight and by isolating the trailer from the roll axis of the bike (something an axle-mount does) the trailers effect on the rider is reduced.

    Now, none of this means that a seatpost hitch won't work. There seems to be a lot of hair-splitting on forums that gets amplified to the point where it seems that one solution is totally defunct and the other pristine. So yes, i agree that a post-mount trailer will indeed work. However, if you're looking to get a trailer that has the least effect on bike handling or if you intend to ride aggressively with heavy loads, an axle-mount trailer will be noticeably safer and better than a post-mount trailer. Google Bikes-at-work for more info on this topic and to see some cool photos of some serious bike loads (house moving, etc.)
  13. loquin

    loquin Active Member

    I agree with you re the inertia when braking, being applied high up.

    However, side-to-side loading caused by cornering (centrifugal forces) aren't bad, as the weight on the low trailers is very low to the ground, and the 'lever' moment arm is at the center of mass for the load/trailer. So, the effective lateral force is reduced significantly.

    The advantage of the seat-post mount is that the tongue weight is split between BOTH wheels (as with a goose-neck trailer on a pickup,) which improves handling.

    However, on a low, rear axle mount, all the the tongue weight. and all the load intertia when braking in a turn, is on the rear wheel alone, which introduces it's own issues.
  14. tom80

    tom80 New Member

    I would just use bmx pegs.
  15. stevolandis

    stevolandis New Member

    Hitch idea...

    My idea for a hitch is to bolt a small metal plate to the axle, with an eye bolt bolted to it that a side hitch would latch onto. It's a low center of gravity and has 360* of movement. If the weight on the cart is balanced, the hitch won't have much stress- check this out-

    Also, see the attached file for a google sketchup model jpg of the hitch.

    Attached Files:

  16. lennyharp

    lennyharp Member

    trailers good

    I have thousands of miles towing a trailer with a bicycle and never tipped it over. Wife would have killed me if I lost our kids I made the trailers with a seat post mount. Here was a flatbed of cromoly tubing that weighed only 22 lbs. and carried 200 lbs. Photo dates to early 1990's

    Attached Files:

  17. mabman

    mabman Member

    I have to go with Wiley on this one for sure. I have ridden with both and the axle mount is way more stable in all situations. I not only have towed them but used each with motors mounted as pusher units. Once again the axle mount is superior.

    This is very apparent while turning corners over 45 degrees at slower speeds and using the throttle. Because the trailer is not following the bike exactly it wants to push the rear end to the outside. When it is a seatpost mount it will even high side you excaberated by the oscillating effect that they have also. It is still touchy with the axle mounts but at least it doesn't do the high side oscillating thing which is sketchy believe me.

    Single wheel trailers can be jackknifed to park them but they do take up a bit more room that way.
  18. chainmaker

    chainmaker Member

  19. Fabian

    Fabian Well-Known Member

    Hi Chainmaker

    Thankyou so very much for posting that link to the Kamp-Rite Midget Bushtrekka Bicycle Camping Trailer.

    It's exactly what i want - a pivoting tandem wheel set is a revolution in trailer stability.

  20. Fabian

    Fabian Well-Known Member

    Here are the pics.

    Attached Files: