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.
Bike Trailer
- Thread starter atomichurley
- Start date
wileydavis@gmail.com
Member
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.)
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.)
loquin
Well-Known 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.
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.
tom80
New Member
I would just use bmx pegs.
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- http://photos1.blogger.com/photoInclude/blogger/3676/3321/1600/TrailerB1.jpg
Also, see the attached file for a google sketchup model jpg of the hitch.
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- http://photos1.blogger.com/photoInclude/blogger/3676/3321/1600/TrailerB1.jpg
Also, see the attached file for a google sketchup model jpg of the hitch.
Attachments
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
Code:
Attachments
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.
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.
chainmaker
Member
Here is a pretty cool and pricey model beet you could take a long trip with this http://www.target.com/Kamp-Rite-Bus...=Kamp-Rite Bushtrekka Bicycle Camping Trailer
Cheers
Cheers
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.
Fabian
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.
Fabian
