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Thursday, April 17, 2008

Trailer nearly makes full trip till winds tip over

Yesterday, I went to pick up a couple of small bikes from a member of the Freecycle list, and decided to use the trailer on the roadbike (Columbia), since the test bike is really not in good enough shape to go that far (in this case, at least 11 miles each way), and certainly not as comfy a ride (it has NO shocks at all).

The pic above shows the combo as they were that night a short while after I got home; earlier that day I had just repainted the trailer itself from the various colors of the items it's made of to match the style of the roadbike for visibility. Not many bikes have trailers on them, so I wanted to be as sure as possible that drivers would know it was there. :-)

I "knew" I would be back long before dark, so I didn't put any lighting on it, just the rear reflectors, and a pair of spoke reflectors. Unfortunately, somewhere during the ride, the spoke reflectors seem to have vibrated off without me noticing, since they didn't really fit very well in those small wheels. I'll have to epoxy or silicone the next set in, and not trust the screwmounts. The righthand rear reflector is also missing; more about that in a minute. I didn't actually make it back until over an hour *after* dark, because the winds changed direction during the ride, when I was nearly at my destination. They started out as headwinds against me by maybe 15MPH steady, and 30MPH gusts (enough to tip the trailer up on one wheel when empty several times, though not enough to turn it over until I was almost there--but enough to blow me on the bike into the road and nearly into various vehicles a few times during my southbound trip). When they changed direction at first they died down a lot, then began gusting very very strongly, and that's when the trailer tipped over (taking me and the bike down with it, though I got off without falling). Fortunately, this was in a completely deserted industrial area, with no traffic.

It would not have tipped except that it seems to have a resonance problem: When it starts to bounce, one side bounces first, probably because the wheels' axles are not perfectly aligned with each other and thus one hits a bump just a bit before the other. With the tires fully inflated to 50PSI (where I usually keep my bike's tires at, or higher), then once I reach a certain speed on a road with semi-regular bumps in it (common along the sides where bike paths are, usually from cracks in the road that have been tarred over or repaved but with "ripples" in the surface that can be easily felt at speeds over 7-10MPH), the tires begin bouncing alternately, first left then right, and each bounce gets a bit higher, until it would tip too far if I didn't stop or slow down. I had this problem all the way there, but only randomly, and I didn't figure out why until it actually tipped. In this case, I felt it tipping, but then just as I would have stopped, a gust of wind simply picked up the already-lifting side and tossed it (and me and the bike) over.

That was a problem I didn't have on the test bike, because on the test bike the mount for the trailer is a tube almost the same diameter as the clamp, while on the roadbike I didn't really have time to work one out or move the other one over, so I just clamped it to the much thinner cargo basket rear-handle. That left a lot of play, which solved one test bike problem but introduced this tipping/bouncing problem. The solved problem was that I could not corner well at all, and had to make very very wide turns (as wide as a car or even moreso), because the test bike could not tilt at all during turns due to the trailer holding it level by the mounting bar/clamp. That turning problem was potentially dangerous, because I could never have made some of the turns to get out of the way of unobservant drivers with the large turn radius it forced on me. I have another potential solution for it, but have to see what I've got that will fit the BOM for it.

The solution to the bouncing was to let a lot of air out of the tires, bringing them down to maybe 20PSI instead of my preferred 50PSI. I tried it at various levels before getting that low, but didn't really stop it until they were pretty squishy, that way, and lots of drag because of it. But no worries about bouncing, at least, so I could ride at normal speeds (as much as the wind would let me).

I had, up to this point, been able to stay in 2nd gear on the pedals, and 3rd to 5th gear on the rearwheel. I had to stay in 1st to 3rd on the rear wheel after that, losing quite a bit of speed because I couldn't pull the trailer as easily due to the extra friction from low tires, plus the wind (which at least wasnt' a direct headwind at the time but was still obnoxiously strong and gusting, pulling me and the trailer all over the place). Once the trailer was loaded, and I was against the even stronger winds on my way back, I was down to 1st gear on the pedals, and started out at 3rd or 4th on the rearwheel, but was down to 1st on that as well less than 1/3 of the way home, and wishing I had even lower gears. :( I *really* need to get this motor thing going.

Now, the real problem was that when it tipped, somehow the righthand upper side bracket (orange and white in these pics) must have hit the ground just right because it snapped the weld at the front end of it, away from the front vertical bars on the trailer. The rear weld on it is very solid, and didn't budge, but the front one wasnt' a full-around weld, only 4 points, and it snapped them all in one go. I probably didn't weld them right in the first place; I'm still not practiced enough. Fortunately I didn't need that bracket to hold my cargo in this trip, as I had already planned for the front bar and the rear bottom bar to be the main supports for the bikes (taking their rear wheels off and sticking the triangles into the gap in the bottom bar/mesh area, then hanging the handlebars off the front bar and tying it all down). So it could have been a lot worse, as a warning to me that my trailer needs some more reinforcement "just in case" and my welding leaves a lot to be desired before I use it on an actual bike. :-) The tipping over is also where the righthand rear reflector disappeared, I think, since it had been mounted on the bar with the broken weld (though nowhere near the weld, it probably *was* close to the actual impact point of the bar on the ground, up at the corner, like the left reflector that did stay on).

I tried to take pics of the broken weld, but couldn't get a usable pic at night, and forgot to do so today while it was still light enough. I've not felt well even yesterday (the day before I was sick as a dog most of the day and all night), but had to go get those bikes before I lost the chance to do so; today I both still didn't feel well plus was hurting and exhausted from fighting the wind all the way there *and* back, especially back, where the winds were more directly against my direction of travel for all the last part of my trip, plus traffic was awful even on back streets for some reason, with vehicles roaring past me very close (within inches, instead of the legally-required 3 feet). That made for a very stressful time, because I could not control the bike very well with the wind directly in my face, especially since the gusts would be so strong they would push the bike to one side or the other, and I had to fight to keep it straight and upright while I was at almost zero speed. The loaded trailer actually helped a little, because it's mass kept me from being shoved backwards during strong gusts, even though they often stopped me completely from my very slow progress home. Without the trailer, I would have been pushed backwards, potentially even just tipped over as I tried to stop that (it's happened before in really gusty high winds).

One more thing I need to add to the trailer is a front balance point or stand of some sort, so that when I'm parked I can lower it to keep the trailer (especially when loaded) from pulling the bike off it's kickstand on uneven surfaces. Got some ideas on that, including modifying the kickstand mountpoints that are still on the bikeframe parts of the trailer on each side.

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