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Saturday, September 5, 2009

Phoenix Sinkhole Roads, Bent Rim, 26" Test Results

Here we call our place "Phoenix, City Of Gophers", because there are so many holes and "under construction" signs.

Heck, the "End Road Work" signs all say "Thank You" on them. I've even seen "Please" spray painted over the "Thank You" part.

But the worst is not the actual road work, it's the places that *need* it. There are numerous road edges, usually where traffic is pretty heavy and the only safe place to ride because of the traffic is the side of the road, where the asphalt is pushed up several inches in mounds and ripples from the intense heat plus the vehicle weight/etc.

Most intersections are so bad where they curve around, for right turns, that every so often they have to scrape off the excess because it sticks up as high as the curb! Sometimes it looks gradual as you approach it, until you're on top of it and WHAM.

Sinkholes are another huge problem, because they don't build roadbeds first, they just pour asphalt in layers till it's flat. When they repair it they don't even worry about the flat part, and usually it has undulations in it that'll make you sick if you ride over it at the right speed. Sometimes those are as much as an inch between trough and crest, too--I dunno what they use to "flatten" them but they aren't doing it right. It takes months to years for it to eventually settle down to flat from the summer heat, at the edges of the road, or on less-travelled back streets.

The sinkholes are super dangerous, because they look like any other small pothole until you're on top of it. Then it may be too late, if there's traffic. The whole sand and gravel underneath the asphalt just falls away over time, sometimes into broken sewer drains under the road, sometimes just the sand compacts with water over time leaving an unsupported asphalt sheet in places. Usually it breaks at the edges of the road, right where it joins the sidewalk or gutter.

I hit one today because of an impatient and stupid pickup truck driver with a trailer, who couldn't be bothered to either wait the minute until we reached the intersection and he could turn right, thus no longer caring about me being slow in front of him, or he could have passed me using one of the other two unoccupied lanes, even if only partly moving over into one, but instead he just honked and honked and laid on his horn, when I was already at the legal limit of 20MPH for my ebike (in the 40MPH street), at "as close to the right edge as practicable" based on the huge ridges and holes along that part of the road.

I waited until it widened out into a right-turn-into-a-parking-lot lane and scooted over a bit into that so he could pass, since he obviously was too stupid to use the other two empty lanes to the left of him to do it like a normal person, or just pass me super-close anyway like most people do in the daytime, and he gunned his engine, squealing and smoking his tires pulling against the load in his trailer, passing me but not very quickly. Must've been a pretty heavy trailer.

I started to pull back into the lane again before he was fully past me, simply because I was out of lane to stay in without climbing onto the sidewalk, and first I hit one of the ridges, then I managed to avoid the sinkhole with the front wheel but clipped the edge of it with the rear wheel, which slipped into it and WHAMMO against the farthest edge as I passed it.

The impact almost made my lower jaw into a bandanna, my spine into a pretzel, and actually knocked the chain off both my pedal drive on the left side and my regular bike drivetrain on the right, so I just coasted to a stop after I went thru the green traffic light, being unable to use pedals *or* motor to continue.

Walked the bike up into a parking lot and saw that not only did it jump the chains, but it also gave me a slightly flat spot on the aluminum rim I JUST installed on the bike LAST NIGHT to test using a 26" wheel instead of a 24", with freehub instead of freewheel, and my road bike tire (much better than the MTB knobby styles I'd had to use till now).


It's not flat enough to even really notice while riding, but I can see it. I can't really tell for sure unless it is rotating, though. But now the wheel is bent enough out of true side-to-side that it badly rubs the tire against the chainstays on each side during rotation. The axle *might* also be bent; it's a hollow-core with quick-release, which I don't like but can't change; it's larger diameter than any solid axle I have.

So now I get to take the whole bike backend apart again to change the wheel out (yeah, it's a crappy design but I don't have a choice with the parts I currently have available without some major changes to them). I'll take the freehub out and relace it into a different rim, and save straightening this one out for another time.

I'm recharging both the bike's batteries and mine right now, and when that's done, I'll go take it apart and see what I can do, with a steel rim this time, most likely.

Now, as for the results of the actual 26" wheel tests, it's a success.

First, I think with the smaller wheel it'd've been worse with the impact on that pothole, though being a steel rim it might not have damaged it (or maybe not as badly).

Second, the ride on the smooth-centered road tire was MUCH better.

An unexpected good thing is that the bike "feels" better in handling with the taller rear tire, even though it's only 1" different in ride height in the back. The slope of the bike is different, and even that feels better, oddly enough.

Third, that extra height makes a huge difference in the turning ability; I can lean much farther and turn sharper without hitting the cargo pods on the road.

Fourth, that freehub is way quieter than the freewheel--cruising unpowered when up to speed is almost silent (before the impact, at least-afterward it sounded like a nest of angry bees on a windmill blade...bzzzBBZZZZzzzzbbbzzzBBBBZZZBbbbbbzzz, from the tread rubbing on the chainstays).

The smaller rear cassette rings did actually end up making the bike ride about the same speed using the larger wheel. Since I'd also replaced the derailer and adjusted it so that it would always correctly engage the outer smallest ring (unlike on the other shifter/wheel), I managed to get to 20.2 MPH even against the very strong headwind (storm was blowing in) at the time. I might've been able to push that farther, but as that's the legal limit on the road, and I was only riding on the street this time (no testing in other places I might be able to try those speeds out, today). I didn't try pedalling hard with it, just a little bit. I might've been adding half a mile per hour with my own input. ;-)

The one problem is that using the smaller chainrings and the bigger wheel takes more motor current to do the same thing. A lot more. Where I'd been running average of 6 to 10 Amps for any particular gear and speed with the 24" and it's cassette, it took 11 to 16 amps to do the same thing on the 26" and it's cassette.

That's really annoying, because I like all the good things the 26" wheel gives me.

Obviously, I could lace the freehub into a 24" steel rim instead of a 26", since I have to move it anyway, and that'd give me the smaller chainrings for faster speed if I wanted it, plus the quietness of the freehub, and it's reduced friction.

But I still can't use the smoother road tires on it, and I think that is one thing I definitely like the feel of.

I also don't get the slightly increased rear ride height, and the good handling changes it brings.

A disadvantage of using the freehub at all is it's hollow axle and quickrelease spar, partly because it is not possible to fully release the lever and get the wheel out to fix anything without taking the whole rightside cargo pod off, and the lower mounting rail (at least, not without weakening that rail too much). Since the axle itself may be bent, it might be a moot point, unless I can replace it with a solid axle somehow (it's at least 1mm larger diameter than any other axle I have, so probably not).

So...I'm probably going to first test out a regular 26" steel rim (that is 1/4" wider than the bent aluminum one) with a thread-on freewheel type hub that I've already got laced up from previous stuff I did on my upright bike, using the cassette I'd already had on the 24" wheel. It's going to make the bike slower than it was, but that's going to remove the aluminum rim problem, and also the quick-release spar/lever problem, while still leaving me the handling improvements and road tires and whatnot.

Then I'm just left with it being a noisier freewheel, and taking more motor current to do the same job because of the larger wheel diameter.

The motor current does affect the range, but I got something like 11 miles in today on one charge, most of it at high motor currents and bike speeds (plus several miles with the messed up wheel rubbing on the frame!) and the pack was only down to 36.5V under load. It's at 40.2V floating when I start out after letting it sit for a few hours after a charge, about 39.5V under load. Totally dead would probably be about 30V, but I don't want to run it down that far, so I'd probably call it a day at 33V, maybe.

I guess I could up it to 48V, adding another battery, and gear the motor down more at the gearbox output shaft's sprocket, which is currently 24T (to a 52T receiver), changing to a 21T or less. I'm just not sure the motor will deal with double it's original voltage all that well, though it seems fine on 36V (as long as I watch the heat buildup).


  1. I think you will be happier with the steel rim. Most of my contraptions are pretty heavy and aluminum spoke type rims just don't seem to take to that too well from my experience. I dished a few of them. I'm currently using the aluminum 20" 5 spoke mag type wheels on my delta trike though because that type is strong enough to handle all the extra weight.

  2. So far, I am happier with the steel rim. I would have used a steel one to start with if I had not already had this one setup and working on my other bike, with the cassette on it I wished to test. :(

    I do wish I had lighter steel rims, though--the ones I have are cheap stuff off cheap bikes, as are the aluminum ones, I think (though the one I bent actually was "Made in the USA", at least).

    The mag wheels could still have bent under the circumstances I bent mine in, if it struck the edge of the hole between spokes. I'm just glad I didn't have plastic rims on there. ;-)

  3. Don't underestimate those plastic rims. I have two on the front of my tadpole trike that I wouldn't trade ANY brand of spoke type rims for. They were actually 20" cart wheels I got from Great Northern tool company but have held up better than 3 sets of regular rims on the trike. They have been in use now for over two years. These things ignore road drain grate slot pinches and bumps and just keep on rolling.

  4. I guess they must be a different plastic than the ones I've seen on various bikes at the thrift store, mostly kids' bikes. Those tend to already be cracked, or have that rough-looking surface that indicates surface degradation of unknown depth (usually from long exposure to sun).

    I'd love to see some like yours, around here, but so far the used ones aren't much, if any, good.

    One thing I really do like about spoked rims is that if something bends it I have a half a chance of bending it back to a rideable condtion on the road with little more than a hand-sized rock and a pair of small pliers (which I always have with me) or a spoke wrench (which I don't have).

    With any solid-spoke wheel, metal or plastic, it'd probably be impossible for me to fix if I did somehow break it. Then again, if I had some as tough as yours, I probably wouldn't have to worry about that. ;)

    Spoked wheels also allow me ability to dish them as desired for different applications, reusing the same wheels in different projects--I couldn't do that the same with solid wheels like that.


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