dave yates tag-a-long
- Thread starter johnonthetyne
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johnonthetyne
Dirt Disciple
the lenght from centre of bb to top of seatube is 14", the seat post has some adjustment and the bars move back or forth.ive just mocked it up against bike to give you an idea,as you can see as i said the paintwork is a bit chipped.
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me and our Tommy have great fun on something similar, but ours has a 20" wheel. You wont regret it Dr. S. Cars give you a wide berth, lots of hoots and waves and everyone wants a go when we're in the park. But I cant get the little #### to pedal up hills when I'm stuffed.
johnonthetyne
Dirt Disciple
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This design of tag-along has a basic geometric error that causes the trailing bike to lean as its axis moves left and right of the leading machine. The error is caused by the use of the trailing bike's angled headstock, as a pivot axis.
This can throw both the leading and trailing riders off ballance. At large angles (70-90 degrees) the trailing bike will fall over.
One fix is to have a lead bike that has a rear wheel small enough to allow the trailling bikes headstock axis to be vertical, or more accurately, forming a right angle with the ground.
Also, the linkage can be modified by adding an extra pivot between the leading bike's rack and the trailing bikes' steering-tube adapter. The rotation of the steering tube in the headstock also needs to be disabled.This fix makes the system work very well, especially off-road. The trailing bike follows in the rear wheel tracks of the lead bike even when the angle between the two bikes is 90 degrees or more.
System, complete with geometric fix shown below.
The only downside is that front wheel of the lead bike is more likley to lift on steep hills. Children realy enjoy the roller-coaster style ride though they do expect you to do most of the work.
This can throw both the leading and trailing riders off ballance. At large angles (70-90 degrees) the trailing bike will fall over.
One fix is to have a lead bike that has a rear wheel small enough to allow the trailling bikes headstock axis to be vertical, or more accurately, forming a right angle with the ground.
Also, the linkage can be modified by adding an extra pivot between the leading bike's rack and the trailing bikes' steering-tube adapter. The rotation of the steering tube in the headstock also needs to be disabled.This fix makes the system work very well, especially off-road. The trailing bike follows in the rear wheel tracks of the lead bike even when the angle between the two bikes is 90 degrees or more.
System, complete with geometric fix shown below.
The only downside is that front wheel of the lead bike is more likley to lift on steep hills. Children realy enjoy the roller-coaster style ride though they do expect you to do most of the work.
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when we set ours up, it was quite unstable when junior tried to get out of the saddle. I guess the headtube was angled as you suggest. Someone pointed out that it would handle a lot better if the trailers headtube was forward of my backwheel axle. Mine has an adjustable rack, so I did this and it handles good. By chance the headtube is vertical, but the "short" rack on my bike now means no room for panniers. Out trailer also has a curved downtube to allow it to fit round my back wheel, if you get me.
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The setup in my photo, with the pivot behind the rear wheel, is designed so that the trailing bike follows in the rear wheel track of the leading bike.
This is great for off-roading on narrow and winding forrest tracks but is not the best design for isolating the lead bike from the antics of a wobbly child.
Your experience with the high and forward pivot point makes sence. In theory the best pivot position for stability is high up and on a vertical axis that aligns with the lead bike's rear axle. (This is a 'first class' lever arrangement where the mechanical advantage of the trailer bike over the lead bike is small).
Lower pivot point bikes, like mine, only work if the lead bike's rider is much heavier than, and has enough inertia to subdue the wobbles of the trailing rider.
This is great for off-roading on narrow and winding forrest tracks but is not the best design for isolating the lead bike from the antics of a wobbly child.
Your experience with the high and forward pivot point makes sence. In theory the best pivot position for stability is high up and on a vertical axis that aligns with the lead bike's rear axle. (This is a 'first class' lever arrangement where the mechanical advantage of the trailer bike over the lead bike is small).
Lower pivot point bikes, like mine, only work if the lead bike's rider is much heavier than, and has enough inertia to subdue the wobbles of the trailing rider.
