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Sunday
Apr132008

Cyclists Gone Wild


Taking the lane is one thing, but taking the whole lane for no reason other than you can if there is enough of you in the group, as I see it is just plain wrong.

After complaints from motorists, police in Winter Park, Florida were out with video cameras. What they filmed made to the news on an Orlando station.

At the start of the piece, I saw cyclists three or four abreast; at least one rider completely over the double yellow line. About twenty cars backed up behind the riders.

Then I saw the entire pack blow through a stop sign, and make a right, at a very high rate of speed even though there was other traffic passing.

It looked to me that this was an unofficial race, rather than a group-training ride. Here is the link, view for yourself and be your own judge.

Actually, in a large group like this it is often safer to ride two abreast. They can do so taking up half the lane, which gives motorists a chance to see around the group to determine if it is safe to pass.

Riding single file a group is twice as long, and takes twice as long to pass.

Stronger riders can stay at the front if they wish and change off by having one line constantly moving forward, and the other dropping back. Wind direction usually decides which line moves forward. (Picture left.)

Going through stop signs and lights, the whole group stops, and then moves off as a group, as if they were one vehicle.

Friday
Apr112008

Classic Dutch Bicycle Pictures

I found these wonderful classic Dutch bicycle photos from collector Andre Koopman.

It is a mixture of photographs of this collector's bicycles, plus prints made from the old original glass plate negatives, some dating back to the late 1800s. These came from the Fongers factory, a Dutch bicycle manufacturer.

One of my favorite set of pictures is of a Gazelle bicycle; (Top picture.) it comes with a pretty amazing story that goes like this:

In 1939, a man buys a new bicycle. Soon after WWII breaks out, and with the impending invasion of Holland, man hides new bike in attic. Soon after man becomes sick and dies. Bike remains in attic for the next 64 years.

The unused bicycle was discovered in 2003 and bought by this collector.

Even the original Gazelle tires were still good. The handlebars have a celluloid covering; yes, celluloid the stuff they used to make movie film, and was a forerunner of plastic.

The bike has dynamo lighting; the wiring has rubber insulation with a woven cotton outer casing.

The bike also has a leather dress guard, and a single front brake that consists of a rubber block that pushes down on the front tire.

Pictured below is another bike that caught my interest, and is also from WWII. It is a British made, BSA folding bike that British Paratroopers carried on their back when they parachuted into Holland during the war.

There must have been a large number of these left around the Dutch countryside after the initial drop.

Another even older military bicycle is this 1898 Fongers. (Below.) Looking surprisingly like an Alex Moulton.

I am thinking that the picture got “flipped” and was printed backwards. I have never seen a bike with the chainwheel on the left side. There is no point in this as it would require a left-hand thread on the rear sprocket.

You can view the rest of the pictures here.

My thanks to Bakfiets en Meer, Netherlands who found the pictures first.

Wednesday
Apr092008

A short cycling safety video



I came across this California League Cycling Instructor's bicycle safety video via Philadelphia Bicycle News.

I had to smile at this quote:

“It's duly noted that these are very skilled, faster cyclists interacting with relatively polite Southern California motorists traveling at moderate speeds.”

I’m not sure about Southern California motorists being more polite than in any other state; they have been known to shoot at each other on the freeway on occasions. It’s been a few years since I lived in So.Cal, maybe the threat of gunfire has improved their manners.

Anyway, I digress. I think this short video is excellent and packs a lot of useful information in a few minutes. There was not much here that I didn’t already know, however, just the visual image of cyclists having some control over other road users around them made me feel good.

I realize the video has been edited to serve its purpose, but nowhere do I see the flow of traffic being hindered. The cyclists come across as polite but assertive, and viewers should note that had they just blown through red lights and stop signs, all credibility would have quickly disappeared.

There is a big difference between assertiveness and arrogance. Assertiveness is taking the lane after signaling and making your intentions clear. Arrogance is cutting in front of people, running lights and stop signs, and not only breaking the rules of the road, but breaking the rules of decent human behavior.

Monday
Apr072008

Why are large frames more prone to shimmy?

Over on the Serotta Forum the subject of shimmy was being discussed; this subject is probably discussed on bike forums more that any other. One member posted the following:

“Am I nuts, or do all shimmy prone bikes have one thing in common? Large size frames. I ride a 52cm - 53cm frame. I've never experienced shimmy in any of the many bikes I've owned. It seems like every shimmy story has a tall person in the starring role.”

No, you are not nuts, large frames are more prone to shimmy. First of all, shimmy is a natural occurrence on two wheeled vehicles, bicycles and motorcycles have the same problem.

At a certain speed a spinning wheel will start to nutate, That is, not only is the wheel spinning about its axis, (The wheel spindle.) the axis itself is constantly moving. To demonstrate this to yourself, hold a wheel by the spindle in your outstretched hands, and move your hands in the motion of pedaling a miniature bicycle.

Even a child’s spinning top will hold steady with its axis vertical if it is spinning at speed. One would think it would spin slower and slower until it gently falls over. However, as it slows to a certain critical speed it will start to wobble then fall. In other words, it starts to nutate at a certain speed.

“Rotation” means an object spinning around a fixed axis; “nutation” means the axis is also moving as the object spins. The front wheel is not only fluttering back and forth in the vertical plane, but in the horizontal plane also. Therefore, the head tube of the bicycle or motorcycle is shaking violently from side to side.

The rear wheel does not shimmy because it is fixed withing the frame. Just as on three or four wheeled vehicles the wheels are not prone to shimmy because the axels are held in one plane. Although on older cars, for example, when wheel bearings and steering joints start to wear allowing the wheel’s axis to move, they too will shimmy or wobble at a certain speed.

On a bicycle, most of the rider’s weight is towards the rear. The rider’s weight on the saddle and the rear wheel in contact with the road provide two anchor points holding the rear of the bike steady, while the front end can start to shake violently.

Because the seat tube slopes rearwards, as the frame gets taller the rider’s weight is more directly over the rear wheel. On a large frame this makes for a near vertical pivot line between the rider’s weight on the saddle, and the rear wheel’s point of contact. (See picture below.)

It is about this pivot line that the bike will start to shake, and if the rider then grips the handlebars tighter, his body will also start to shake along with the bike and a crash will probably ensue.

When nutation and the resulting shaking starts, it will only get worse unless speed or weight distribution changes; especially if the rider becomes part of the shaking mass.

On a motorcycle shimmy, (Or tank slapper, as they are called.) they are often so violent the rider is thrown from the machine. In this motorcycle tank slapper video, you will notice the front wheel is not just fluttering side to side about the steering axis, but the wheel is also moving side to side about a horizontal axis, throwing the whole bike and rider side to side.

On a smaller bicycle frame, the rider’s weight is more forward and the pivot line is less than vertical. (See picture below.) This means that even if the rider is riding “no hands” there is still a certain amount of weight on the front wheel.

This is a clue to avoiding shimmy if you are tall and ride a large frame. When descending at speed, move your weight forward and keep your back low so that air pressure on your chest is not forcing more weight to the rear.

Transfer weight from the saddle to the pedals, thus breaking one of the solid anchor points. Often a knee pressed against the top tube will dampen a shimmy. A loose headset may not cause a shimmy, but tightening a headset very slightly may have a dampening effect. Don’t over tighten a headset, or this in itself will make the steering erratic.

This is the third time I have written on this subject, and I don’t want to keep repeating myself. However, it is a subject that will always be around and so will continue to be discussed, and continue to surprise those who experience it for the first time.

In my first article “High Speed Shimmy” I called it a design flaw. This may have been a little strong, but frames I built did not shimmy as a rule, even the larger sizes; so, design and construction do play a role. The only time I was told a Fuso shimmied was when rear pannier bags were fitted, and the frame was not designed for this purpose.

I built my frames with slightly more trail than most other bikes; maybe this factor was enough to prevent shimmy. It doesn’t take much to alter a bike’s handling characteristics. Sometimes different wheels or a slightly heavier tire is all that is needed to stop a bike from shimmying.

I went into the subject in depth in my second piece called “Shimmy Re-visited.” I am now of the opinion that this is not so much a flaw, but a natural phenomenon inherent in any two wheel vehicle. Simply because the front wheel’s axis is free to move in any direction.

All the years I built bicycles, I never gave this subject much thought; I didn’t have to because I never had this problem. I do not have an engineering or science degree, and those who do will no doubt correct me if I am wrong.

I have not written about harmonic vibrations and the reasons why wheels start to wobble, what is needed is not more theories as to why this happens, but ideas to minimize the problem.

Bicycle designers and manufacturers should be concerned, and be looking for a cure. In the mean time, all an individual can do is get to know the limitations of their bike, and ride within those limitations.

Friday
Apr042008

An old friend comes home


In 1982, soon after I started building my own custom frames, I built a 58cm. frame that was somewhat of a showpiece. It was dark blue with lots of chrome.

I am pretty sure this was the frame I posed with in the Masi shop, and was used in one of my early ads. (Left.)

The frame was eventually sold to Bud’s Bike Store, in Claremont, California, and built up as a display model. This bike brought in many other orders, including this one built in 1983.

Then around 1984 this display model was sold, and bought by Lorin Youde. In his own words he told me, “I rode the heck out of it, then for some unknown reason, sold it in 1994.” He added, “Even my wife told me not to sell it, and it was not long after I realized I had made a big mistake.”

Lorin tried to fill the void with other bikes I had also built; he bought this John Howard two years ago.

Then he bought this Recherché in near new condition; it was the one I featured in this post.

Last year Lorin decided to track down the bike he sold. The person he sold it to had resold it, and the bike was in now Spokane, Washington. The new owner had just had knee surgery and so was willing to sell.

A price was negotiated, and the bike returned to it’s original owner at the end of last year. Lorin just sent me pictures. In an email he told me, “I replaced the 8 speed Dura Ace components with period correct Super Record and while not quite in pristine a condition as Chuck Schmidts' it still looks pretty good and is a pleasure to ride.”






Actually, I think the original paint looks pretty darn good for a bike that has “Had the heck ridden out of it.” There are more pictures here.