Utility Cycling - Convert an Adam's Trailabike for utility
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08-11-08, 03:36 PM
Does anyone know anything about modifying an Adam's Trailabike for hauling loads? It came with two bike mounts, so I have one on my bike and one on my wife's and it takes 60 seconds to switch it over. My 6 year old is riding his own bike now, and although we still go out on this for long rides (relatively speaking to a 6 year old), in another year or so it won't be used at all. I was wondering if I could modify it to haul groceries or better yet, one of my kayaks! The latter is probably not applicable due to boat length, but I know my wife would use it for grocery-getting, and I might as well.
I more than got my use out of it, as I picked it up when my oldest was 3 and used it heavily for both boys. I don't care to get a whopping $25-50 for it on eBay, if I can get a different use out of it.
08-11-08, 06:37 PM
I was looking at using one of those but was kinda concerned about the stability from what I've read about single-wheeled trailers. But, since you obviously have experience pulling the kids around, I'd think modifying it to handle an extended rack or something should be fine.
08-11-08, 10:55 PM
I remember reading about someone who removed the seat and installed a standard bike rack on/through the bottom bracket. He had two bike racks, one where the kid would have been seated and one over the 20" wheel... which meant room for four panniers.
On all of the single wheeled cargo trailers I have seen, the "steering" pivot is behind the rear wheel. Nearly all of the reviews I have read mention some (greater or lesser) problems with fishtailing at high speed with loads.
All the trail-a-bikes have the "steering" pivot ahead of the rear axle. I have searched, and have found no mention of fishtailing problems with these. Given how protective (overly so IMHO) many parents seem to be of their children, I would think this would be mentioned if it happens.
I have done stability analysis comparing bumper pull to fifth-wheel automotive trailers. The critical factor that makes the fifth-wheel so much more stable is that the steering pivot point is at or ahead of the rear axle. The distance between the rear wheel contact patch and the hitch provides a lever that allows the trailer to steer the tug. If it is behind, then high speed stability is compromised.
When you compare the load ratings of the SW cargo trailers, to a trail-a-bike, it seems that this hitch location has a significant advantage.
08-13-08, 09:17 PM
You are right, Kevbo, fishtailing is not an issue with the Trail-a-bike.
The main issue is that there is a small unavoidable amount of play in the hitch, which is essentially a bolted-on universal joint. Even if there is almost no play at the beginning, play will develop as the bolts and holes in the universal joint will wear out (been there, done that). Addams has upgraded their hitch 3-4 times over the years (and at least one of these upgrades was due to a preventative recall)
So Trail-a-Bike lateral stability is an issue, but mostly a comfort / enjoyment issue rather than a true safety issue (i.e. it is a pain in the rear end if you ride a whole day and have to counter steer all the time, but you won't fall). I haven't tested it, but I suspect the problem will be much less severe with a load than with a child: after all, the load doesn't wiggle right and left during a ride.
Finally, even if fishtailing isn't a problem, the bike + trail-a-bike combo is bound to be more flexible than a single bike. So high speed shimmy, which is a potential problem with any bike, is even more likely with a bike + cargo trail-a-bike combination.
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