Dave Moulton

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What we say, as opposed to what we want to say

I got an email from someone the other day; it said, “Can I build a carbon fiber frame?”

I wanted to reply, “Sure, go ahead, knock yourself out.”

But I didn’t; instead I directed him to this website.

It reminded me of an incident some thirty years ago in England. A man walked into my bicycle framebuilding business, accompanied by an extremely beautiful woman; he asked, “Can I get a frame for my wife?”

I wanted to say, “That sounds like a very fair exchange, I could probably throw in a pair of wheels also.”

But I didn’t; instead I took his order and built a frame for his lovely wife.


The Cooper River Bridge: Continued

Labor Day, Monday, September 4th. Had to ride over the Cooper River Bridge again. Not just because it is there, but because some of the best cycling routes in the area are on the other side of the bridge.

The ride was not without incident; between North Charleston and the bridge it started to rain. I encountered some railroad tracks running at 45 degrees to the road. I swung out wide then turned to cross the tracks at a right angle; at the last second I realized I was heading for a large pothole along side the track.

I swerved to avoid it which put me at an angle to the tracks again. The wet steel tracks slicker than a couple of snakes in a bucket of snot, and down I went. Luckily my hip and my elbow broke my fall and the bike was undamaged. I always find you never bleed too long and wounds heal quickly, but scars on paint are for ever.

By the time I got to the bridge it had stopped raining and it was fairly quiet. I guess the threatening weather had kept most cyclists and runners indoors. I took the gradual climb easily this time and didn’t feel over geared like the week before.

Once over the bridge I took Coleman Blvd. to Rifle Range Road and over to the IOP Connector. For those who don’t know this area IOP stands for ‘Isle of Palms.’ To me IOP Connector always sounds like something that belongs on a computer; as in “My printer’s not working, I have to get to Radio Shack and buy a new IOP Connector.”

The connector road is nice; wide with a shoulder to ride on. The passing traffic created a back-draft that gave me a boost and I found myself flying along at a good pace, and then another little steep but short climb over a bridge crossing over to the Island. Once on the Isle of Palms I turned right to head back towards home, and the skies opened up again.

There was no shelter and I got pretty wet, but eventually I pulled under a canopy outside a motel; I waited for the rain to abate which it eventually did. I rode about a hundred yards further and the road was bone dry and the sun was shining. I crossed over to Sullivan’s Island and people fishing from the bridge were oblivious to the rain a couple of hundred yards back down the road.

Another 5 or 6 miles and I was back to the Cooper River Bridge again. By now I had quite a few miles in my legs and this time I suffered on the climb. I wanted to quit so bad but I was so near the top I just couldn’t; so just gritted my teeth and struggled on. Of course once at the top I was glad I didn’t quit.

The ride the rest of the way should have been uneventful except I took a wrong turn somewhere in North Charleston and went about six miles out of my way. Unfamiliar territory told me I was on the wrong road but streets were deserted and there was no one to ask.

I passed a little biker bar and a guy on a Harley was about to leave; I stopped and asked him the way to Rivers Avenue. He told me to turn around, ride back to a light and make a right. I rode back at least three miles, turned at the light and then knew exactly where I was; I was in the old Naval Shipyard area. From there it was back over the Ashley River and an easy shot home.


I Rode the Biggest Hill in Charleston

The area around Charleston, South Carolina is known as The Lowcountry and with good reason. It is flat; like the proverbial billiard table. So the only hills are man made; in other words bridges.

The biggest bridge and therefore the biggest hill in Charleston is the new Cooper River Bridge that opened in 2005; a beautiful suspension bridge that the planners had the wisdom to add a pedestrian and bike path. The bridge replaced two older bridges one built in 1929 and the other in 1966 both very narrow with no shoulder so impassible on a bicycle.

Before the new bridge opened it was not possible to ride a bike from Charleston to Mount Pleasant on the other side. So if you wanted to ride this area and the adjoining beach communities of Sullivan’s Island and The Isle of Palms you would first have to transport your bike over by car.

Having been back on my bike for a month I felt I had to go ride the bridge, as I had driven over it many times in a car. Charleston is a peninsula with the Cooper River on one side and the Ashley River on the other. The two rivers meet to form a bay and natural harbor, which is why Charleston was built there in the first place.

As I live in West Ashley which is actually south of that river for whatever reason I had two rivers to cross. The first bridge I chose to cross the Ashley River was the Cosgrove Road bridge which is a main connector to the Int.26 freeway to Columbia and extremely busy during the week. However early Sunday morning the traffic was light enough to not be a problem.

Cosgrove took me into North Charleston and then right onto Rivers Avenue, which I assume was the main road into Charleston before the freeway was built. A typical neglected and rundown old highway that you see all over the East Coast; wide enough but made up of concrete slabs with gaps in between just the width to drop a bike wheel in.

Traffic was still light and Rivers Avenue became King Street which is one of the main streets in downtown Charleston. The towers of the Cooper River Bridge were now in sight and soon the road veered left and over to Bay Street. I spotted a crowd of road cyclists congregated on the opposite side of the road.

“Is this the entrance to the bike path?” I asked. I was told it was. The path divided into two lanes with a yellow line down the center; I naturally rode on the right. After being yelled at by a few runners I discovered the right lane is for runners and walkers and the left lane is for bikes. Interestingly enough it changes on the way back and the right lane is for bikes.

A long steady climb of maybe two miles to the top I soon realized with my old skool six speed 13 to 18 rear cluster I was over geared especially when other roadies blew right by me pedaling much lower gears. But as this is the biggest hill in Charleston I decided to deal with it, get out of the saddle and muscle it to the top. I thought to myself, riders in California and Colorado where they have mountain passes rising thousands of feet would scoff at this climb, and if I couldn’t climb it on 42 x 18 (63 inches) I have no business being on a road bike.

I reached the top and coasted down the other side, got to the bottom, stopped and checked the time; I was one hour out from home. I turned right around and headed back. The climb on the Mount Pleasant side is shorter and steeper and about half way I realized I had not given myself enough time to recover and I was not going to make it all the way to the top.

Luckily I had my camera with me and I could stop on the pretext that I wanted to take a few photos. I was snapping the view up the incline when this guy in the orange shirt came running down.

He offered to take my picture which I thought was very nice of him; or maybe he was looking for an excuse to stop also.

After putting the camera away and taking a good long drink of water; I got back on the bike and stomped it all the way to the top. I stopped and took a few more pictures at the summit. I rode home the same route and arrived home still feeling good having been out for about two and a quarter hours.

The next time I ride the bridge I plan to continue on to The Isle of Palms and ride along the coastline which will be a very pleasant ride. But I want to get a few more miles in my legs so I can get over the bridge keeping up with the other local roadies.


Back on the Bike: The First Month

I have been back on my bike for a little over a month now after at least a 15 year break from cycling. I am amazed at how quickly I got back into it; I guess a body remembers. Not that I have been a couch potato since I last turned a pedal; up until three years ago I was running up to six miles a day and my resting heart rate was 36.

I had to quit running when my hip started hurting, but I continued walking. Now when you have a resting heart rate that is just barely ticking over, walking only brings it up to the pace that most others would experience getting up from the couch and walking to the refrigerator for a beer.

The other problem with walking (or running) in Charleston, South Carolina, is that it gets brutally hot here in the summer months. It is mostly in the upper 80s or 90s with very high humidity. You can just stand still and sweat let alone do anything strenuous like running or walking.

Riding a bike I find if I get out early before it gets too hot, once I get above 10 mph I’m creating a cooling breeze, and the faster I go the more airflow. Modern cycling helmets as well as looking cool actually have a cooling effect. Made from high density polyurethane; basically the same stuff that drink coolers are made from, so what better to wear on your head on a hot day. The built in slots channel air and add to the cooling effect.

Modern cycling clothing too is wonderful; made of a material designed to wick sweat away from the body so you feel cooler. Of course you are still sweating but as long as you keep hydrated by drinking plenty of water you are fine, and it’s easy to carry water on a bike. On my walking route I had to take in series of stops at hardware stores and city parks that had drinking fountains.

My first few days back on the bike my neck hurt. I imagine the human head weighs around ten pounds. (I’ve never actually weighed one.) So naturally leaning over in a racing position means you are holding your head up and it is going to make your neck muscles sore if you are not used to it.

So why is my bike set up in a racing position? It’s the way I have always ridden and my pride won’t allow me to adopt any other way. Of course I could have raised the handlebars level with the seat and used a shorter handlebar stem, but what kind of a dork would I look wearing all the latest racing gear and sitting on the bike looking like a monkey humping a football? I may not be fast yet, but damn it I’m going to at least look fast.

Anyway the sore neck muscles went away after the first week, and so did the puffing and panting on the slightest incline. My bike handling skills quickly returned and already it feels like I had never stopped riding.

I’m riding five days a week and up to thirty miles a day. I’m only averaging 15 mph; not fast but I feel it is respectable for the first month. I can’t ride at a leisurely pace; the slightest incline or a headwind and I feel I have to ride as hard as I can. I feel that burning sensation in my upper thighs and I remember what it was like when I was at the peak of fitness. On my rest days I still feel the ride in my legs from the day before and it feels good.

I can’t imagine taking Advil for sore muscles from cycling, like the TV commercial suggests; to me that dull ache in my leg muscles is the greatest feeling in the world. But then only an ex bike racer or athlete would think that way; I guess a body does remember.

The picture at the top is me on the new Cooper River Bridge, which happens to be the biggest hill in Charleston, SC. But that’s another story that I’ll write about next time.


Shimmy Re-Visited

Speed wobbles or shimmy occur on bicycles and motorcycles because the front wheel is free to turn about its steering axis and at the same time the whole bike can move from side to side along a horizontal axis with the pivot point being the front and rear wheels being in contact with the road. Think of the motion of climbing a hill out of the saddle and you are swaying the bike from side to side.

So if the bike is swaying from side to side and the front wheel is turning from left to right at the same time the front wheel is in Nutation. Rotation is an object spinning around a fixed axis; Nutation means the axis (or axel in the case of a wheel) is also moving as the object is spinning. Think of an orbiting planet; the Earth spins but its axis also moves as it orbits the Sun

To demonstrate to motion of a front wheel in a shimmy hold a bicycle wheel by the axel in your outstretched hands (not spinning) and move your hands in the motion of pedaling a miniature bike. If the wheel was spinning while you were doing this the wheel would be in nutation. If you spin the wheel you will notice that the axel is difficult to move because the gyroscopic action of the spinning wheel is preventing nutation.

Now get someone to tap the side of the wheel as it is spinning; it will nutate (wobble) briefly but quickly return to spinning straight as the gyroscopic action dampens the nutation. So nutation is a constant and natural occurrence as a bicycle is being ridden caused by the movement of the rider pedaling the bike, side winds, bumps in the road, etc.

We do not normally notice this because the nutation is constantly dampened out, by gyroscopic action; the bike’s trail which provides a caster action keeping the front wheel straight, and the damping effect of the rider’s hands on the handlebars. However at a critical bike speed, the front wheel nutation frequency matches the bike + rider natural frequency amplifying or sustaining the nutation. And you have shimmy.

During a high speed shimmy the front wheel is not just fluttering back and forth about its steering axis but is also moving side to side in the horizontal plane shaking the head tube violently from side to side; the rider’s weight on the saddle provides an anchor point, the rear wheel on the road provides another making a pivot point for the front end of the bike to move from. Adding a pannier or saddle bag behind this pivot point will increase the likelihood of shimmy and cause the bike to shimmy at lower speeds because it gives an added sling-shot effect, especially if the load is loose and free to move.

It is a well know fact that tall riders on large frames are more likely to experience shimmy. I believe this is because the seat tube slopes backward and as the frame gets taller and the rider’s weight is more directly over the center of the rear wheel. This provides a near vertical pivot line between the riders mass on the saddle and the rear wheel on the road for the bike to shake and weave. With a smaller frame the rider’s weight is more forward with a less than vertical pivot line, making it less prone to shimmy.

Pressing your knee against the top tube will often stop a shimmy; in doing so you have dampened the shaking top tube through the muscles and tissues in you leg without actually connecting the leg to the top tube. This is also a clue that the rider needs to be holding the handlebars lightly so that you are damping the nutation rather than being connected to it by grasping the handlebars tightly.

In extreme cases if the rider is gripping the handlebars tightly the body starts to shake along with the head tube and handlebars. It becomes difficult to loosen your grip on the bars with your body shaking violently and because the shaking mass now includes your body it is much larger, higher and more fluid making the situation much worse and a crash may ensue.

This is more likely to happen with motorcycles and it has often been observed that a rider will be thrown from the bike, the bike will then stop shaking (because there is no longer a rider in harmony with the machine’s vibrations) and the bike with continue on for a while on its own before it hits something or looses momentum and falls.

An article on Wikipedia stated that frame flex has nothing to do with shimmy, but I am not so sure. Frame flex may not be the cause of shimmy but I believe it can sustain it. If the seat is not moving because the rider’s mass provides an anchor. And the rear wheel is not moving sideways at its point of contact with the road; but at the same time the head tube is shaking side to side, something has to be flexing and twisting, either the frame or the rear wheel.

Frames I built do not shimmy as a rule; so what did I do different? My bikes had a little more trail so possibly the damping effect of the extra trail helped. But I believe another factor is that all my California built frames had Columbus SP (heavier gauge) chainstays, making the rear triangle much stiffer and less likely to flex.

There could possibly be flex in the rear wheel if you consider that the upper spokes are under tension and the lower spokes are not; making the wheel likely to flex at the bottom. Also a dished wheel has unequal tension on the drive and non-drive sides. So if you have a bike that is prone to shimmy maybe think about switching to a stronger more tightly built wheels.

Most high speed shimmies occur while coasting down hill so here are a few things you can do to avoid this phenomenon. Lifting your weight from the saddle without actually standing up will transfer your weight to the pedals which are a much lower and more forward point of contact. Keep one pedal down and most of your weight on that pedal; you can switch pedals as you corner keeping the lower pedal on the outside. This will make the point of contact between you and the bike very low, but also off center of the frame.

Keep your knee lightly against the top tube as I have already mentioned, and hold the bars lightly. Many riders report that a shimmy it gets worse when applying the brakes. Well of course when you squeeze the brakes you automatically grip the handlebars tighter. So practice applying the brakes while loosely holding the bars.

Try switching your hands to the brake hoods and applying the brakes over the top with your fingers. It may take some nerve to do this if your bike is already shaking, but letting go of the bars for a split second may bring you out of the shimmy. Remember it is the connection between you and the bike that is causing the shimmy and the more connected you are the worse it will get.